DTIC – “Geologic Site Characterization of the North Korean Nuclear Test Site at Punggye-Ri: A Reconnaissance Mapping Redux”

United States Defence Technical Information Centre.

http://www.dtic.mil/docs/citations/ADA625872

Accession Number : ADA625872

Title : Geologic Site Characterization of the North Korean Nuclear Test Site at Punggye-Ri: A Reconnaissance Mapping Redux

Descriptive Note : Final rept.

Corporate Author : LOS ALAMOS NATIONAL LAB NM

Personal Author(s) : Coblentz, David ; Pabian, Frank

Full Text : http://www.dtic.mil/dtic/tr/fulltext/u2/a625872.pdf

Report Date : 30 Nov 2013

Pagination or Media Count : 68

Abstract : High-resolution information about the geologic setting for denied-access sites is critical for the monitoring and detection of clandestine nuclear test (e.g., the evaluation of seismic wave propagation, the prediction of gas releases, and evaluation of tunnel layouts). An important case-in-point is the lack of precise, large-scale geologic maps for North Korea’s underground nuclear test site near Punggye-ri. As a proof-of-principle, we have developed and applied a geologic assessment methodology at the NKTS which employed a novel geomorphometric analysis technique to produce a high-resolution (5-meter) geologic map of the site. This map helps refine the USGS reconnaissance geology map (which was based on the analysis of ASTER spectral imagery data and extrapolations from nearby 1930’s Japanese ground survey reporting) at the Punggye-ri site. Our assessment provided the means to evaluate a number of geologic factors related to the testing at the Punggye-ri site, including the proximity of carbonate rocks to the test locations, the relationship between fracture rock and containment, and possible motivation for continued tunneling at the South Portal location.

Descriptors : *GEOLOGY , *MAPPING , *NORTH KOREA , *NUCLEAR EXPLOSION TESTING , *RECONNAISSANCE , DETECTION , GEOMORPHOLOGY , HIGH RESOLUTION , IMAGES , MAPS , METHODOLOGY , MONITORING , POSITION(LOCATION) , PREDICTIONS , SEISMIC WAVES , SITES , SPECTRA , TEST FACILITIES , TUNNELING , TUNNELS , WAVE PROPAGATION

HAVE YOU GOT THIS RICHARD BROINOWSKI: ITS NOT A FURPHY DING BAT

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Nuclear Leaks At Nth Korean Test Site – real or “a Furphy” according to Broinowski ? Real, says Langley

I have been following the story of radiological dangers posed by the increasing stressed geology of the North Korean nuclear test site for some months. Over the last week the story was again raised by the Australian newspaper. This motivated me to find the closest Chinese authority. The story was, as far as I can gather, published this week in The South China Morning Post on Wednesday 25 April 2018. The article, written by Stephen Chen, is entitled “North Korea’s nuclear test site has collapsed … and that may be why Kim Jong-un suspended tests“. The first paragraph explains further: “The mountain’s collapse after a fifth blast last fall has led to the creation of a massive ‘chimney’ that could leak radioactive fallout into the air, researchers have found….” before I go any further, there are two questions to ask: 1. How credible is Stephen Chen’s reporting and 2. Who are the researchers involved? eg are they retired diplomats only or are they qualified to comment in a scientific manner? If so have their findings been peered reviewed?
(what journalists say is irrelevant to me except when the articles lead me to find the peer reviewed papers published by scientists. Newspapers seem not to put relevant links to source documents up which is a crying shame.)

1. Stephen Chen: his bio on the SCMP site states: “Stephen covers breakthoughs in science and their impact on society, environment, military, geopolitics, business – pretty much all aspects of life. His stories often travel across the globe. Stephen is an alumnus of Shantou University, the Hong Kong University of Science and Technology, and the Semester at Sea programme which he attended with a full scholarship from the Seawise Foundation. In his spare time, Stephen reads and writes novels. He lives in Beijing with a beautiful wife and two lovely kids.”

fair enough, signs look hopeful that the article is not reporting a scientific “furphy”, as Broinowski described the generic story on the Australian ABC TV this morning. But let’s dig a nanometer deeper. Who are the researchers Chen is referencing? Does he name them and are they famous? (fame = mass readership and lots of grant money):

“A research team led by Wen Lianxing, a geologist with the University of Science and Technology of China in Hefei, concluded that the collapse occurred following the detonation last autumn of North Korea’s most powerful thermal nuclear warhead in a tunnel about 700 metres (2,296 feet) below the mountain’s peak.

The test turned the mountain into fragile fragments, the researchers found….” end quote from the SCMP/Chen.

Further, Chen reports: “A research team led by Wen Lianxing, a geologist with the University of Science and Technology of China in Hefei, concluded that the collapse occurred following the detonation last autumn of North Korea’s most powerful thermal nuclear warhead in a tunnel about 700 metres (2,296 feet) below the mountain’s peak.

The test turned the mountain into fragile fragments, the researchers found. ” source: ibid.

Describing these findings and the dangers posed by the scientific observations as reported by Chen does not smack of “Furphy” or fantasy Richard B. (No I don’t mind who your sister is, you should know better).

Wen Lianxing et al have been tracking North Korean nuclear tests, as far as I can find (hamstrung as I am, because I cannot speak or read Chinese), from at least 2006, and certainly since 2009, when the team became the first in the world to precisely locate the location of a North Korean nuclear test. : “High-precision Location of North Korea’s 2009 Nuclear Test”
Article in Seismological Research Letters 81(1):26-29 · January 2010 authors: Lianxing Wen, University of Science and Technology of China (Hefei, China); Hui Long, Stony Brook University (Stony Brook, United States).

Have a read of it Mr Broinowski. You might find it sensible and not a furphy.

Ok, on with the real matters at hand. Underground nuke tests invariably leak radionuclides into the biosphere. The US underground nuclear test regime has created a legacy of cost and risk, to put it mildly, which continues to this day. Name a US underground shot, and go to DOE Opennet and enter the shot’s code name. Up pops reams of documents detailing the test, the immediate result, and the long term consequences in terms of risk and costs.

There is no reason to suspect that the risks and costs of North Korea’s underground will be any more “furphy” ridden that the US underground tests were. And continue to be.

So without any further ado, even if I have to drag Richard B kicking and screaming into 1954, is some more non furphy from Chen and the SCMP:

“It is necessary to continue monitoring possible leaks of radioactive materials caused by the collapse incident,” Wen’s team said in the statement.

The findings will be published on the website of the peer-reviewed journal, Geophysical Research Letters, likely next month.

North Korea saw the mountain as an ideal location for underground nuclear experiments because of its elevation – it stood more than 2,100 metres (6,888 feet) above sea level – and its terrain of thick, gentle slopes that seemed capable of resisting structural damage…..

“The mountain’s surface had shown no visible damage after four underground nuclear tests before 2017.

But the 100-kilotonne bomb that went off on September 3 vaporised surrounding rocks with unprecedented heat and opened a space that was up to 200 metres (656 feet) in diameter, according to a statement posted on the Wen team’s website on Monday. ….

“As shock waves tore through and loosened more rocks, a large section of the mountain’s ridge, less than half a kilometre (0.3 mile) from the peak, slipped down into the empty pocket created by the blast, leaving a scar visible in satellite images.

Wen concluded that the mountain had collapsed after analysing data collected from nearly 2,000 seismic stations. ….

“Three small earthquakes that hit nearby regions in the wake of the collapse added credence to his conclusion, suggesting the test site had lost its geological stability.

Another research team led by Liu Junqing at the Jilin Earthquake Agency with the China Earthquake Administration in Changchun reached similar conclusions to the Wen team. ….

“The “rock collapse … was for the first time documented in North Korea’s test site,” Liu’s team wrote in a paper published last month in Geophysical Research Letters.

The breakdown not only took off part of the mountain’s summit but also created a “chimney” that could allow fallout to rise from the blast centre into the air, they said. …

“Zhao Lianfeng, a researcher with the Institute of Earth Science at the Chinese Academy of Sciences in Beijing, said the two studies supported a consensus among scientists that “the site was wrecked” beyond repair.

“Their findings are in agreement to our observations,” he said.

“Different teams using different data have come up with similar conclusions,” Zhao said. “The only difference was in some technical details. This is the best guess that can be made by the world outside.” ….

“Speculation grew that North Korea’s site was in trouble when Lee Doh-sik, the top North Korean geologist, visited Zhao’s institute about two weeks after the test and met privately with senior Chinese government geologists.

“Although the purpose of Lee’s visit was not disclosed, two days later Pyongyang announced it would no longer conduct land-based nuclear tests.”

” Hu Xingdou, a Beijing-based scholar who follows North Korea’s nuclear programme, said it was highly likely that Pyongyang had received a stark warning from Beijing.

““The test was not only destabilising the site but increasing the risk of eruption of the Changbai Mountain,” a large, active volcano at China-Korean border, said Hu, who asked that his university affiliation not be disclosed for this article because of the topic’s sensitivity.

“The mountain’s collapse has likely dealt a huge blow to North Korea’s nuclear programme, Hu said.

Hit by crippling international economic sanctions over its nuclear ambitions, the country might lack sufficient resources to soon resume testing at a new site, he said.

“But there are other sites suitable for testing,” Hu said. “They must be closely monitored.”

Guo Qiuju, a Peking University professor who has belonged to a panel that has advised the Chinese government on emergency responses to radioactive hazards, said that if fallout escaped through cracks, it could be carried by wind over the Chinese border.

“So far we have not detected an abnormal increase of radioactivity levels,” Guo said. “But we will continue to monitor the surrounding region with a large [amount] of highly sensitive equipment and analyse the data in state-of-the-art laboratories.”

“Zhao Guodong, a government nuclear waste confinement specialist at the University of South China, said that the North Korean government should allow scientists from China and other countries to enter the test site and evaluate the damage.

“We can put a thick layer of soil on top of the collapsed site, fill the cracks with special cement, or remove the pollutants with chemical solution,” he said.

“There are many methods to deal with the problem. All they need [to do] is ask.” end quote . source: ibid.

For the sake of ignorant ex diplomats everywhere, let me list all the qualified scientists Chen gives as sources for his article:

1. Wen Lianxing
2. Liu Junqing
3. Zhao Lianfeng
4. Hu Xingdou
5. Guo Qiuju
6. Zhao Guodong

The above qualified people consider that North Korean nuclear tests have, and do, pose a continuing radiological risk to North Korea and to China. This is due to the geologic damage the test series have caused. As any rational person with knowledge of the US underground test era knows, such risks are extremely well documented in the case of the US tests and appalling documented in the case of North Korea.

Dissenters from my point view and the content of Chen’s reported based upon his 6 expert sources are: 1. Richard Broinowski, retired diplomat. Not a scientist.

blows rasberry at RD. so sue me.

P.S. and another thing Richard B. You won’t close the South Korean nuclear plants down by going on TV and denying the North Korean radiological mess, which is probably an undisclosed actual disaster for the people there. Underground nuke test sites have many ways of leaking radionuclides. Over the years a test site’s hydrology is main vector, but anything can happen at the time, and, in the US experience has happened. The chances of uncontained radionuclides let loose into the biosphere is very high in North Korea and no ideology can successfully hide that fact. Your comments on the ABC TV this morning were damaging to the movement and frankly, in my opinion, bloody ignorant. Would you accept the facts of the matter if the scientists Chen cites were all born in London and were named “Watt”?

This post has been posted on Mr Stephen Chen’s facebook page. with thanks to him and his sources.

Vulnerability of the Nuclear Power Plant in War Conditions

“The Krško Nuclear Power Plant (Slovene: Jedrska elektrarna Krško, JEK, or Nuklearna elektrarna Krško, NEK, Croatian: Nuklearna elektrana Krško) is located in Vrbina in the Municipality of Krško, Slovenia. The plant was connected to the power grid on October 2, 1981 and went into commercial operation on January 15, 1983. It was built as a joint venture by Slovenia and Croatia which were at the time both part of Yugoslavia.

The plant is a 2-loop Westinghouse pressurized water reactor, with a rated thermal capacity of 1,994 thermal megawatts (MWt) and 696 megawatts-electric (MWe). It runs on enriched uranium (up to 5 weight-percent 235U), fuel mass 48.7 t, with 121 fuel elements, demineralized water as the moderator, and 36 bundles of 20 control rods each made of silver, indium and cadmium alloys to regulate power. Its sister power plant is Angra I in Brazil.[1] ” Wikipedia.

Source Link :http://www.iaea.org/inis/collection/NCLCollectionStore/_Public/38/056/38056717.pdf

Vulnerability of the Nuclear Power Plant in War
Conditions

A. Stritar, B. Mavko
‘Jožef Stefan” Institute
Ljubljana, Jamova 39
Slovenia

Presented at First Meeting of the Nuclear Society of Slovenia, Bovec 11.-12.6.1992

ABSTRACT – In the summer 1991 the Nuclear Power Plant Krško in
Slovenia found itself in the area of military operations. This was probably
the first commercial nuclear power plant, to which it was threatened with
the air jet attack. A number of never before asked questions had to be
answered by the operating staff and supporting organizations. In this paper
some assets of the nuclear power plant safety in war condition are
described: the selection of the best plant operating state before the attack
and the determination of plant system vulnerability. It was concluded, thdt
the best operating mode, into which the plant should he brought before the
attack, is the cold shutdown mode. The problem of Nuclear Power Plant
safety in war conditions should be addressed in more detail in the future.

INTRODUCTION
The Nuclear Power Plant Safety in war conditions is practically a completely new
area, which is seldom addressed in the literature. Although the physical protection of the plant in such a condition is the task of military, police and civil defense forces, it is the responsibility of nuclear professionals to investigate possible scenarios and their consequences from the nuclear safety point of view. Everybody involved with the Nuclear Power Plant operation in Slovenia, found himself in a situation, that was hardly encountered before. Our Nuclear Power Plant was probably the first commercial PWR in the world, that found itself in the middle of the war area. The Iraqi research reactors in a Gulf war 1991 were maybe in the similar situation. Very little guidance about the appropriate preventive measures for such a situation could be found in the literature. Number of preventive steps were performed on the site by the plant personnel, while this paper describes some of related activities of the Reactor Engineering Division of “Jožef Stefan” Institute at that time.

ANALYSIS OF THE EXPOSURE OF PLANT VITAL SYSTEMS
No Nuclear Power Plant anywhere in the world is designed against an air attack by military bombs or missiles! Provisions are only taken against the terrorist attack from the ground by the light weapons. Some nuclear power plants are designed to withstand the crash of an aircraft, but without any explosive materials. It was clear at the beginning of the crisis in Slovenia, that there is no way to completely prevent damage to the equipment in the case of an attack. All our efforts were therefore directed into the minimization of the possible public radiological consequences during such an event.
The critical safety functions in such conditions were checked:
a) Subcriticality,
b) Core cooling,
c) Heat sink,
d) Integrity,
e) Containment,
0 Inventory.
Subcriticality is not a problem, if the plant is shut down and the primary water
properly borated. All other functions are endangered: Containment is directly
exposed to missile attacks and may be considered as the most endangered one. Next is heat sink, since the water intake structures and pump stations at the river are also completely exposed. Integrity of the primary system is endangered in the case of heavier bombing. Inventory may be endangered as a consequence of the loss of integrity, while the core cooling is primarily vulnerable through the loss of off-site power. Fortunately, if the plant is shut down, it is much easier to maintain or replace ail degraded critical safety functions.
In order to get an estimate about the vulnerability of different plant system to the missile attack, die exposure of each system was evaluated and the “rose of
vulnerability” similar to the example in Figure 1 was constructed. The vulnerability of each system after the attack from different sides may be seen from it. This kind of diagram is helpful in preparation of preventive measures and determination of most vulnerable systems.

The rose was constructed with the help of 3D computer plant layout model. The
assumption was, that the system is completely destroyed, if it is located on the side, from which the attack is coming from, that it is damaged, if it is in
the shade of one building and that it is not damaged, if it is located on the opposite side of die site.

Our main concern was further devoted to maintenance of the core cooling in the core and to integrity of the spent fuel pit.

CORE COOLING
Immediately after the shutdown of the reactor, it had to be decided, in what
operational state the plant should be brought to. The following
proposals were considered:

1. Removal of the fuel from the core,
2. Refuelling mode,
3. Normal cold shutdown.
The analysis had to be performed fast, therefore there was no time for any extensive
analytical work using sophisticated computer codes. It was mainly based on
engineering judgment and expert opinion. Following are main results of the analysis:
1. Removal of the fuel from the core would certainly assure, that there would
be no big danger for the exposure of the population in the case of the major
damage of the containment building. But the only possibility for the
immediate removal is into the spent fuel pit on site. Spent fuel pit is, like in
most similar NPPs, located outside the containment building and is even
more exposed, than the structures inside it. In addition, the sole process of
fuel removal is increasing risk and is also requiring considerable time. The
reactor vessel and the core are located so deep in the containment and
shielded by various structures (containment building, steel containment,
concrete structures, steam generators, pressurizer etc.), that very strong or
concentrated repetitive missile deployment would be needed to achieve it’s
destruction. The idea about fuel removal was therefore rejected.

2. Refuelling mode was considered as the only normal operational mode, in
which the primary system may be opened. The reactor vessel is covered with
the few meters high layer of water, which would certainly represent some
protection against falling structures or missiles. On the other hand there is a
high probability, that missile impacts would cause displacements of some
structures in the containment and deformation of the seal ring around the
reactor vessel. The refuelling water would leak into the reactor cavity and be
lost as a protection of the core. If the reactor vessel head happens to be
removed from the top of the core in such a case, there would be an
immediate release of the radioactivity into the containment. This option was
also rejected.
3. Cold shutdown mode was found to be the most appropriate option. The
primary system is at the atmospheric pressure, therefore there is no problem,
even if part of the system gets damaged. The core cooling is provided by the
residual heat removal system, the heat is transported via the essential service
water system into the river. The core is protected by all the structures above
the reactor vessel and by the reactor vessel itself. There are also no
complicated manoeuvres necessary to bring the plant into that state.
After selecting the cold shutdown mode as a most suitable operational state of the plant, further studies of the vulnerability were done. Besides the possibility of the direct damage to structures, that would cause release of the radioactivity, were are two important subjects, that have to be considered:
a. AC and DC power supply,
b. ultimate heat sink.
In the coW shutdown mode the residual heat from the core is removed by the
Residual Heat Removal system via Essential Service Watei> system to the river. RHR pumps are electrically driven. To prevent heat-up of the core the long term power supply and ultimate heat sink have to be assured. But, since the residual power of the core is relatively low, it is possible for the plant to withstand even a certain period without it. In order to get an approximate answer about the time, during which the plant may loose the power and heat sink without a damage, the following scenario was analyzed by a simple hand calculation.

LOSS OF AC POWER AND HEAT SINK IN COLD SHUTDOWN
It was assumed, that prior to the loss of heat removal capabilities (AC power and/or beat sink), the power plant was in cold shutdown for several days, producing about 5 MW of constant heat, which is about 2.6% of full power (in reality the power level is decreasing with time). The heat had been removed via RHR system. There was only about 25% of water in the pressurizer, the rest was filled with the Nitrogen. Both Steam Generators were filled with water. At the beginning of the transient the heat removal from the primary system via RHR is completely lost.

The heat, generated in the core, would cause the primary system to heat up. Since we have assumed, that the Power Operated Relief Valve at the top of the Pressurizer is closed, the primary pressure would rise. The natural circulation would establish in both primary loops, transferring heat from the core to the secondary side of Steam Generators. Secondary side would also heat up, but with some delay. PORVs at the secondary side were assumed to be opened, therefore the highest temperature, that the secondary water could reach, is the boiling temperature at atmospheric pressure, i.e. around 373 K. It may be expected, that because of the increased pressure the subcooling in the primary system would not be lost. Therefore the natural circulation would be sustained and the heat from the core could be transferred to the secondary side.
The equation (1) has been used for calculation of the time needed for the whole
primary and secondary system to reach boiling temperature at atmospheric pressure,
373 K (100 °C). see original text for calculaiton
t, Time to heat up primary and secondary water to 373 K,
mpr Mass of liquid in primary system,
mSG Mass of liquid in secondary side of the Steam Generator,
hs
Liquid saturation specific enthalpy at atmospheric pressure,
hpr Initial specific enthalpy of primary liquid,
Qt
Core power.

By inserting data for the NPP Krško into the equation (1) gives approximately 4
hours before the entire water in the primary and the secondary side reaches boiling temperature.
The equation (2) could be used to estimate the time rlb before the whole water on the secondary side of both steam generators is boiled dry.

see original text for calculation

where h, is saturated steam specific enthalpy. Specific plant data gave about 27
hours.
If we also consider boiling water in the primary system (in which case the PORV on the pressurizer should be opened), we get some 47 hours available, before the whole primary system completely dries out.
In order to remove the residual heat by steaming secondary water while maintaining the water level in Steam Generators, the following amount of water has to be added
from the river:
4b K-K
(3)
where hr is the river water specific enthalpy. For the conservatively assumed core residual power of 5 MW the water flow rate q amounts to less than 2 kg/s.

There is one further concern connected with the heat removal by natural circulation
from the core to the secondary side of the steam generator. If the primary water
starts to boil, the natural circulation flow in primary loops may be interrupted
because of the formation of steam in upper parts of steam generator U tubes. If the
PORV on the pressurizer is left closed, the pressurization of the primary system may
be expected. That would prevent primary coolant from boiling. The following
calculation checks the amount of the primary pressure increase.
With the next equation we can calculate the level change in the pressurizer after the
heat-up of the whole primary system from 323 to 373 K (50 to 100 °C).
see original text for calculation
where
Apr pressurizer cross section,
p50 primary coolant specific density at 323 K,
pm primary coolant specific density at 373 K.

For the amount of primary coolant in our NPP and the cross section of it’s
pressurizer, we got an estimate of the level increase to be 1.3 m.
In the cold shutdown there is a nitrogen in the upper part of the pressurizer. If weassume it to be an ideal gas, we can get an estimate of the pressure increase after above calculated level change in the pressurizer. The compressibility of the primary coolant is of course neglected.

see original text for calculation

wherePso> T$o» V50 pressure, temperature and nitrogen volume at 323 K (50 °C),
Pia» T](X» VJOO pressure, temperature and nitrogen volume at 373 K.
The piessure in the plant would rise from atmospheric pressure to 1.57 bar. That
would prevent primary coolant from boiling, provided the heat is transferred to thesecondary water at 373 K.
Results are summarized in the table 1. These results give the operator ample time for mitigating actions. More then a whole day is available to provide required amount of water for heat removal. This amount is raljier small (less than 2 kg/s) and can be easily supplied even by a mobile pump ie. fire engine. This supply of the water even doesn’t have to be constant and continuous. The level in the secondary side of steam generators may be recovered in batches every several hours if necessary.
The described scenario has assumed a closed primary system. But even if it is
opened or damaged, one can expect, that reflux boiling in steam generator U tubes would provide enough heat transfer for successful cooling of the core. This phenomenon, however, couldn’t be easily calculated by hand. More thorough system analysis code calculations would be
needed.

All the calculations in equations (1) to (4) have been done under the assumption, that there is no heat loss from the primary and secondary system into the containment and environment. But since this is not true and heat
losses at that power level are expected to be relatively high, even
longer time before the complete dry-out and even less water for the successful heat removal would be needed. In that respect our assumption is conservative.

CONCLUSIONS
Quick analysis during the crisis has shown, that consequences of a military attack to the plant by jet fighters could be serious, but with the proper preventive measures and preparedness the environmental consequences could be minimized. The plant in the cold shutdown condition can sustain loss of all off-site power and cooling for a period long enough for establishing a variety of possible emergency solutions.
There should be more attention addressed to this subject by national and international bodies responsible for nuclear safety all over the world. In addition to purely political measures by international community, that would minimize the probability of an military attack to the nuclear power plants, detailed studies covering all different aspects of nuclear safety in war conditions should be initiated and included in emergency plans for each nuclear power plant. The help in a form of expert advice should be available and provided to any reactor operator, whose power plant would be found in an area of military activity.
It appears, that in the future the efforts of the international research community should nevertheless be devoted to gaining better understanding of true vulnerabilities and to enhancing measures for protecting nuclear power plants in the event of military attack.

Grid Failure + ECCS Failure Part 3 – reactor 3.

The following post consists of highly selected quotes from the TEPCO document chronologies given by the text “Measures Taken at Fukushima Daiichi Nuclear Power Station and Fukushima Daini Nuclear Power Station (December 2011 Edition)”. The quotes are taken from the 166 page appendices of the document and focus upon the timing of events and the consequences of grid and ECCS failures at Fukushima Diiachi. The document is authored by TEPCO, Japan and the appendix only is available at :
http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/111222e18.pdf

Chronology of Main Events at Fukushima Daiichi Nuclear Power Station
Unit 3 from Impact of Earthquake through Tuesday, March 15

Friday March 11 2011
16:03 The RCIC was started up manually.
15:38 All AC power supplies were lost.
11:13 The DDFP started up automatically.
11:36 The DDFP stopped.
11:36 The RCIC stopped automatically.
12:06 The DDFP activated and started an alternative S/C spray.
12:35 The High Pressure Coolant Injection System (hereafter the “HPCI”)
started up automatically (reactor water level low).
Sunday, March 13, 2011
2:42 The HPCI was stopped in order to shift to the DDFP as an alternative
means of water injection into the reactor.
2:45 An operator tried opening one Safety Release Valve (hereafter “SRV”) but the valve did not open. Subsequently, the operator tried opening all the valvesone by one but none of them opened.
3:05 It was reported to the Main Control Room that the formation of an alternative line of water injection into the reactor had been completed.
3:51 The reactor water level meters were restored.
4:52 It was confirmed that although an operator had opened the large valve of the vent valve (AO valve) of the suppression chamber (hereafter the “S/C”), it
closed because the filling pressure of the air cylinder was 0.
5:08 Alternative spraying the S/C with the DDFP started (discontinued at 7:43).
5:10 The Power Station failed to inject water into the reactor through the RCIC.
The Emergency Countermeasures Headquarters accordingly decided on the
occurrence of a specified event (loss of the reactor cooling function) subject
to the Provisions of Article 15 Clause 1 of the Disaster Prevention Act and
reported this to the competent government departments and agencies at 5:58.
5:15 The Site Superintendent instructed operators to complete the formation
of a vent line except for the rupture disk.

5:23 Operators started replacing air cylinders to perform an “open” operation of
the large valve of the vent valve (AO valve) of the S/C.
5:50 Press release on vent operation.
6:19 The Emergency Countermeasures Headquarters decided on the reach of the
top of active fuel (hereafter “TAF”) at 4:15 and reported the event to the
competent government departments and agencies.
7:35 The Emergency Countermeasures Headquarters reported the result of its
dosage assessment in the event that the vent was operated to the competent
government departments and agencies.
7:39 Operators started spraying the primary containment vessel. The Emergency
Countermeasures Headquarters reported the operation to the competent
government departments and agencies at 7:56.
8:35 Operators opened the vent valve (MO valve) of the primary containment
vessel (“hereafter the “PCV”).
8:41 By opening the large valve of the vent valve (AO valve) of the S/C, the
formation of a vent line, except for the rupture disk, was completed, and
reported to the competent government departments and agencies at 8:46.

8:56 In the area around monitoring post No. 4, a radiation dose exceeding 500μSv/h (882μSv/h) was measured. The Emergency Countermeasures Headquarters accordingly decided on the occurrence of a specified event (abnormal rise in radiation dose on the site boundary) subject to the provisions of Article 15 Clause 1 of the Nuclear Disaster Prevention Act and reported the event to the competent government departments and agencies at
9:01.
9:08 (Approx.) Operators manipulated the safety release valve to rapidly reduce the reactor pressure. The Emergency Countermeasures Headquarters informed the
competent government departments and agencies at 9:20 of its plan to start
water injection into the reactor through the Fire Protection System line.
9:25 A fire engine started freshwater (containing boric acid) injection into the
reactor through the Fire Protection System line.
9:36 It was confirmed that the venting operation had triggered a decrease in
the drywell (hereafter the “D/W”) pressure at around 9:20. The
Emergency Countermeasures Headquarters also reported to the
competent government departments and agencies that it had started
water injection into the reactor through the Fire Protection System line.
10:30 The Site Superintendent instructed operators to work with seawater
injection in mind.
11:17 It was confirmed that the large valve of the vent valve (AO valve) of the S/C had been in a “closed” state (due to a decrease in the pressure of the
operational air cylinders).
12:20 Injection of freshwater completed.
13:12 The fire engine started seawater injection into the reactor through the
Fire Protection System line.
14:15 In the area around monitoring post No. 4, a radiation dose exceeding
500μSv/h (905μSv/h) was measured. The Emergency Countermeasures
Headquarters accordingly decided on the occurrence of a specified event
(Abnormal rise in radiation dose in the site boundary) subject to the
provisions of Article 15 Clause 1 of the Nuclear Disaster Prevention Act and
reported the event to the competent government departments and agencies at
14:23.
14:31 The measurement results of radiation doses were reported, which indicated
300mSv/h or more at the double door on the north side of the Reactor
Building and 100mSv/h on the south side.
14:45 (Approx.) The radiation dose in the area surrounding the double door of the Reactor Building was on the increase. Like the Reactor Building of Unit 1, there wasa possibility of hydrogen having accumulated in the Reactor Building of Unit 3. Since the risk of explosion was high, workers started to evacuate their work sites (work resumed at around 17:00).

Monday, March 14, 2011

5:20 An operator started the “open” operation of the small valve (AO valve) of the vent valve of the S/C.
6:10 An operator confirmed the “open’ state of the small valve of the vent valve
(AO valve) of the S/C.
6:30 (Approx.) The D/W pressure increased and there was a possibility of explosion, hence workers started evacuation (work resumed at around 7:35).
9:05 Seawater supply started from the Shallow Draft Quay to the reversing valve
pit.
9:12 In the area around monitoring post No. 3, a radiation dose exceeding
500μSv/h (518.7μSv/h) was measured. The Emergency Countermeasures
Headquarters accordingly decided on the occurrence of a specified event
(Abnormal rise in radiation dose on the site boundary) subject to the
provisions of Article 15 Clause 1 of the Nuclear Disaster Prevention Act and
reported the event to the competent government departments and agencies at
9:34.
11:01 An explosion occurred at the Reactor Building.

16:30 (Approx.) The fire engine and hose sustained damage in the explosion, which led to the discontinuance of seawater injection. The fire engine and hose were thus replaced and a new line of water injection into the reactor from the
Shallow Draft Quay was formed. Seawater injection was resumed.
21:35 In the area around the main gate, a radiation dose exceeding 500μSv/h
(760μSv/h) was measured. The Emergency Countermeasures Headquarters
accordingly decided on the occurrence of a specified event (Abnormal rise in
radiation dose on the site boundary) subject to the provisions of Article 15
Clause 1 of the Nuclear Disaster Prevention Act and reported the event to the
competent government departments and agencies at 22:35.

Tuesday, March 15, 2011

6:00 to 6:10 (Approx.) A large impulsive sound broke out. The ceiling on the Unit 4 side of the Main Control Room shook.
6:50 In the area around the main gate, a radiation dose exceeding 500μSv/h
(583.7μSv/h) was measured. The Emergency Countermeasures Headquarters
accordingly decided on the occurrence of a specified event (Abnormal rise in
radiation dose on the site boundary) subject to the provisions of Article 15
Clause 1 of the Nuclear Disaster Prevention Act and reported the event to the
competent government departments and agencies at 7:00.
7:00 The Emergency Countermeasures Headquarters informed the competent
government departments and agencies of a temporary evacuation of personnel
to Fukushima Daini, except for the personnel needed for monitoring and other
operations.
7:55 It was confirmed that steam was rising on the upper side of the Reactor
Building, which was reported to the competent government departments and agencies.

8:11 In the area around the main gate, a radiation dose exceeding 500μSv/h
(807μSv/h) was measured. The Emergency Countermeasures Headquarters
accordingly decided on the occurrence of a specified event (Abnormal
emission of radioactive materials on fire or explosion, etc.) subject to the
provisions of Article 15 Clause 1 of the Nuclear Disaster Prevention Act and
reported the event to the competent government departments and agencies at
8:36.
11:00 The Prime Minister issued an order confining local residents indoors staying in areas within a 20 to 30-km radius of the Fukushima Daiichi power station.
16:00 In the area around the main gate, a radiation dose exceeding 500μSv/h
(531.6μSv/h) was measured. The Emergency Countermeasures Headquarters
accordingly decided on the occurrence of a specified event (Abnormal rise in
radiation dose on the site boundary) subject to the provisions of Article 15
Clause 1 of the Nuclear Disaster Prevention Act and reported the event to the
competent government departments and agencies at 16:22.
23:05 In the area around the main gate, a radiation dose exceeding 500μSv/h
(4548μSv/h) was measured. The Emergency Countermeasures Headquartersaccordingly decided on the occurrence of a specified event (Abnormal rise in radiation dose on the site boundary) subject to the provisions of Article 15 Clause 1 of the Nuclear Disaster Prevention Act and reported the event to the competent government departments and agencies at 23:20.
End of file

Fukushima Daiichi Nuclear Power Station Unit 3
State of Alternate Coolant Injection

○ Activities after “16:03 of March 11 when manually starting up the Reactor Core Isolation Cooling System (hereafter the “RCIC”)” (Reactor 3)

Although all the AC power supplies were lost, the DC power supply remained intact and available. Pursuant to the operation procedure description, the Emergency Countermeasures Headquarters worked to reserve the reactor water level by using the Reactor Core Isolation Cooling System (hereafter the “RCIC“) and the High Pressure Coolant Injection System (hereafter the “HPCI“), both of which use DC power for operation control.

[Reserving the reactor water level by the RCIC]
・ To stabilize the reservation of the reactor water level by the RCIC, operators took measures to prevent automatic shutdown due to high reactor water level and to save the battery power needed for operation control.
 To prevent automatic shutdown due to the high reactor water level, the Main Control Room operated the RCIC control panel to form the following two lines that supply water to a water injection line in the reactor and a test line used for regular functional tests (from the condensate storage tank (hereafter the “CST”), water source, to a line returning to the CST), while monitoring the
reactor water level. The Main Control Room defined the range of water level arrangements used to reserve the water level.

Two operators were assigned to monitor the reactor water level, while a further two operators were assigned to operate the RCIC and exchanged information with each other. In addition, for the next means of water injection, operators prepared for smooth HPCI startup after stopping the RCIC by, for example, tagging switches, etc. on the HPCI control panel.

It was crucial to preserve battery power. Thus, the operators set flow rates by adjusting the opening of valves on the test line and with the FIC so that the reactor water level would change slowly, meaning a reduced number
of valves in operation and the flow instrument controller (hereafter the “FIC”) operation.
Operators also repeated the method involving an operator changing the flow rate setting when the reactor water level approaches the upper or lower
end of the water level adjustment range (rated flow: 25.2L/s) within the range 100% to approx. 75%).

 To save even more battery power, operators disconnected the loads of monitoring instruments, control panels and computers from others except those facilities crucial for monitoring and operation control. Monitoring instruments are doubled into systems A and B, only one of which was used at any one time to
reduce the battery power consumption. In addition, emergency lights and clocks
in the Main Control Room were disconnected while fluorescent lights of other
rooms were pulled off.

[Starting up the diesel-driven fire pump (hereafter the “DDFP”) and alternative spraying of the S/C (“S/C”)]
・ After the earthquake, the status indicator of the DDFP, used for alternative water injection, indicated a halt state in the Main Control Room. At 3:27 on March 12, an operator tried manipulating operation switches in the Main Control Room. However, the DDFP did not start up.
・ Since the RCIC was injecting water into the reactor, steam from the motive turbine was exhausted into the S/C, hence from March 12, the drywell (hereafter the “D/W”) pressure was on the rise. Accordingly, the Emergency Countermeasures
Headquarters studied alternative spraying of the S/C using the DDFP, to limit the rises in S/C and D/W pressures. To this end, operators confirmed operation
procedures and locations of valves based on the AM operation procedure
description.
・ Operators were subdivided into two teams to form an alternative line of spraying the S/C through the residual heat removal system (“RHR”) from the Fire Protection System (“FP”) line. The two teams headed for the Reactor Building and the Turbine Building. Since the solenoid valves for the line had no power source, the Main Control Room was unable to operate those valves. Putting on a full-face mask, operators using flashlights amid complete darkness manually opened five valves, including the RHR valve on the morning of March 12.

○ Activities “after 11:36 of March 12 when stopping the RCIC”
[Stopping and re-starting the RCIC]

While operators were steadily maintaining the reactor water level, the RCIC status indicator in the Main Control Room indicated a halt state. Consequently, the indication values, including those of flow rates and discharge pressure meters, also indicated zero, hence operators confirmed that the RCIC had stopped. However, no “stop” alarming functioned due to the loss of power.
・ Although an operator tried starting up the RCIC on its control panel in the Main Control Room, the RCIC soon ceased to operate after starting up, hence two
operators headed for the RCIC room in the basement of the Reactor Building to
check the conditions. They wore a full-face mask and long boots used for outside
patrols. Using flashlights, they entered the RCIC room through the HPCI room and
found that the floor was covered in water ankle-deep. Water also dropped from the ceiling of the room on the steam stop valve, etc. of the RCIC.
・ The operators checked the site and confirmed that there was no defect of the of the steam stop valve mechanical structure units. When an operator in the Main Control Room tried starting up the RCIC, the steam stop valve closed soon after startup, and the RCIC stopped.

[Maintaining the reactor water level and reducing reactor pressure with the HPCI]

Operators were urged to check the conditions of the halted RCIC and for startup
operation. At 12:35 on March 12, the HPCI automatically started up due to the low reactor water level and resumed water injection into the reactor. Since the motive turbine of the HPCI spent the steam from the reactor, the reactor pressure started to go down.
・ As was done for the RCIC, operators manipulated switches on the HPCI control panel to form two water supply lines, namely the reactor water injection line and the test line. Two operators were assigned to monitor the reactor water level, and a further two operators to operate the HPCI. Since the flow rate of the latter exceeded that of RCIC, the reactor water level rose rapidly, making it difficult for the operators to set the HPCI flow rate. Thus, after setting more variable water level adjustment, the operators maintained the reactor
water level to prevent automatic shutdown of the HPCI due to the high
reactor water level. In addition, operators set the minimum flow valve
to shut down to prevent a rise in the water level of the destination S/C.
・ To save battery power, as with RCIC measures, the operators set flow rates
by adjusting the opening of the valves on the test line and with the FIC so that the reactor water level changes slowly. The operators repeated the method whereby they changed the flow rate settings when the reactor water level approached the upper or lower ends of the water level adjustment range (flow rate: 268L/s) within a range of 100 to approx. 75%.

At 20:36 on March 12, the power of the reactor water level meter was lost, which resulted in the reactor water level not being monitored by operators. The flow rate setting of the HPCI was thus raised slightly to monitor the operational state with the reactor pressure and HPCI discharge pressure, etc.

○ Activities “after 2:42 on March 13 when the HPCI halted”
[State of the HPCI halt]

The rotation speed of the HPCI turbine was lower than the operational range specified in the operation procedure description, while the discharge pressure of the HPCI was so low that it could have stopped anytime. Consequently, operators were unable to monitor the reactor water level, which hence remained unknown.
・ Operators monitored the reactor pressure, the HPCI discharge pressure, etc. while considering whether “water was being injected into the reactor,” “whether the reactor water level is being maintained,” and “when to shift to the DDFP,” etc.
・ Under the circumstances, from 2:00 on March 13, the reactor pressure that had
remained stable at approx. 1MPa began to decline. The power generation team and
the Main Control Room were afraid of possible damage to facilities due to the
decline in the reactor pressure, since it would trigger a further decline in the rotation speed of the HPCI turbine, exposing the facilities to greater vibration and possibly causing damage.* In addition, since the reactor pressure and HPCI discharge pressure were nearly equal, The Power Station estimated that the HPCI was unable to inject water into the reactor. Under these circumstances, the Power Station decided to inject water into the reactor through the DDFP, as an alternative means, and stop the HPCI, hurriedly.

* In the event that damage occurs around the HPCI turbine, steam from the reactor will be emitted in the HPCI room as motive steam.
・ Operators headed for the Reactor Building prior to stopping the HPCI, in order to check the DDFP operational state and manually open the RHR injection valve prior to shifting to alternative water injection into the reactor from the alternative spray of the S/C.
・ At 2:42 on March 13, an operator informed the power generation team of the HPCI of the halt, pressed the HPCI button on the HPCI control panel in the Main Control Room, closed the steam inlet valve of the HPCI turbine with the switch, and halted the HPCI.

(Paul Langley: as a brief aside: the turbine spoken of above is the emergency core cooling system turbine which is stream by the pressure difference between the pressure vessel and the torus. A steam line from the pressure vessel is connected to the turbine and a steam line connects the outlet of the turbine to the torus. Thus, when activated in an emergency, the turbine drives a pump which impels water flow through to the HCPI and the RCCI. The heat is removed from the circuits by condensers located on the roofs of the reactors. The torus itself, having a large surface area radiates some heat in a crude heat exchange with its surroundings. The bearings of the turbine burn out and pressure difference between the pressure vessel and the torus diminishes as the turbine works. The American expectation was and is that any station blackout could not possibly last more than 8 hours anywhere on planet earth under any circumstance. Why they believed and believe that profound lie is based not in reality but upon nuclear ideology – “reactors are safe and such an event is irrational to consider”. I hope this is clear to everyone. The chronology of reactor 3 is the most profound description of the reactor’s emergency core cooling systems failing one after the other as time went on without grid reconnection. With the explosion and damage to the roof, the main thing to report in terms of reactor function would be the loss of the ECCS heat removal condensers. I expect severe abuse from nuclear “experts” who, since 1969, have unable to come up with any solution to these well known, decades old, safety concerns regarding station blackout.

In emergency, “the ultimate heatsink” is NOT the primary cooling loop, it is the ECCS multiple cooling loops. Supposed nuclear experts such as Gundersen have done no service to the world in their phony explanations to the world. imo so sue me Arnie.)

From 5:08 on March 13, operators tried starting up the RCIC on the RCIC control panel in the Main Control Room after setting a low flow rate with the FIC so that the bite-in state of the mechanical structure would have no impact during the RCIC startup. However, the mechanical structure of the steam stop valve was dislocated, resulting in the closure of the valve and stoppage of the RCIC.
・ Since the RCIC startup failed, the Emergency Countermeasures Headquarters
decided at 5:10 on March 13 that the event came under the category of a specified event (Loss of reactor cooling function) as defined in the provisions of Article 15 Clause 1 of the Nuclear Disaster Prevention Act, and reported the event to the competent government departments and agencies at 5:58.

[Preparing an alternative water injection line in the reactor with a fire engine]
・ While restoring the SLC and other permanent reactor water injection facilities, the Emergency Countermeasures Headquarters concurrently arranged fire engines.
・ At around 5:30 on March 13, fire engines owned by Kashiwazaki Kariya Nuclear
Power Station, which stood by in Fukushima Daini, left Fukushima Daini and
arrived at Fukushima Daiichi at around 6:30. When operators checked the fire
engines on the side of Units 5 and 6 at around 6:00, they were identified as available for operation and thus collected for water injection into the reactor of Unit 3.
・ As was done for Unit 1, the formation of a seawater injection line from the reversing valve pit of Unit 3 as a water source was completed. Subsequently, however, the line was changed to a freshwater injection line from the anti-fire water tank as a water source.

Water injection into the reactor with the DDFP or fire engines required a reduction of the reactor pressure with SRV. The Emergency Countermeasures Headquarters estimated that ten 12V batteries (DC power 125V) would be necessary to start up the SRV. However, such batteries had been used for the restoration, etc. of the instruments of Units 1 and 2.
・ At around 7:00 on March 13, the Emergency Countermeasures Headquarters asked
TEPCO employees in the Seismic Isolated Building to offer batteries of their private cars. After a sufficient number of willing employees had gathered, they removed the batteries from their cars. These batteries were then gathered together in front of the Seismic Isolated Building, whereupon five members of the recovery team transported them with their private car to the Main Control Room of Unit 3.

・ At around 9:08 on March 13, the SRV was opened. Reduction of the reactor pressure started rapidly. Along with reduction of the reactor pressure, operators started water injection with the DDFP and from 9:25, with fire
engines. The Emergency Countermeasures Headquarters requested additional freshwater supply from others. The fire brigade drew up water from the
simulant fuel pool in the Technical Training Center in the Power Station site and other sources, which was then supplied to the anti-fire water tank to continue water injection.
・ At around 9:40 on March 13, the operation to connect ten batteries serially was completed and they were connected to the SRV control panel. Operators opened the SRV with the operation switch and maintained the reduction in pressure

[Studying measures to prevent explosions]

After the explosion at the Reactor Building of Unit 1, the Nuclear Restoration Teamof the Head Office Disaster Control HQ believed from an early stage that hydrogen had caused the explosion and accordingly started to study how to release accumulating gas in the Reactor Building.
・ At around 9:40 on March 13, the Site Superintendent explained the key to
preventing similar explosions, although the cause of the explosion may not have
been hydrogen. Together with the Head Office Disaster Control HQ, the Emergency
Countermeasures Headquarters started to study preventive measures.

【Evacuating before explosion and study on methods to prevent explosions】
・ At around 14:45 on March 13, the radiation dose behind the double doors of the
Reactor Building indicated approx. 300mSv/h. The Emergency Countermeasures
Headquarters anticipated another explosion of accumulated hydrogen in the Reactor Building like that of Unit 1 and, therefore, decided to temporarily evacuate workers in the Main Control Room and field.
・ After the evacuation, at around 17:00 on March 13, the Emergency Countermeasures Headquarters cancelled the evacuation of the workers engaged in checking venting lines for soundness and reworked the seawater injection line. Workers resumed operations.

On the afternoon on March 13, the Chief Cabinet Secretary held a press conference on the situation of Unit 3 at the Prime Minister’s Office and announced a possible explosion of hydrogen.
・ Subsequently, as means of releasing the hydrogen in the Reactor Building, a number of methods were proposed including “release of the blowout panel,” “piercing the ceiling of the Reactor Building,” and “using a water jet to make a hole in the Reactor Building wall.” Methods other than the “water jet” carried a high risk of explosion due to the sparks created when making a hole. The high radiation dose on the work site also prevented the adoption of other methods.
・ The Emergency Countermeasures Headquarters focused on studying the “water jet”
method and made arrangement for facilities.

・ The fire brigade, which had been monitoring the water level of the reversing valvepit of Unit 3 and the pressure and flow rate of the fire engine that was injecting water, guided water wagons for water supply to the reversing valve pit of Unit 3.
While the fire brigade was guiding several water wagons, an explosion occurred,
whereupon the surroundings immediately turned white due to smoke, etc. After a
while, debris began to drop from the sky, clattering. To protect themselves, the fire brigade members escaped behind nearby pipes. Although the shelter was inadequate, miraculously, all workers were unscathed.
・ When the surrounding smoke eased off, two injured employees were walking near
the service building of Unit 3. The fire brigade, after calling for workers at the work sites to gather together, started walking to evacuate through the road between Units 2 and 3 where debris was scattered.
・ When the fire brigade members and other workers passed the gate between Units 2 and 3, a truck of the Self Defense Forces of Japan arrived. All the members then got on the loading space of the truck and returned to the Seismic Isolated Building.


Appearance of Unit 3 immediately after the explosion
(Photo taken on March 21, 2011) Source: TEPCO

・ At 11:01 on March 14, an explosion occurred at Unit 3, smoking. Later,
pictures of the building werebroadcasted on TV.
・ The Site Superintendent instructed subordinates to evacuate and check
for safety. The Site Superintendent also ordered the security team to
measure and report radiation doses. Since a tsunami warning had been
issued, Site Superintendent ordered the earliest evacuation.
・ Workers other than operators at the Main Control Room suspended their work and
evacuated to the Seismic Isolated Building.
・ At 11:15 on March 15, the parameters of Unit 3 were reported. The reactor pressures of systems A and B were respectively 0.195 and 0.203MPa. The D/W pressure was 380kPa[abs]. The S/C pressure was 390kPa[abs]. Since parameters remained available and based on the measurement values of the reactor pressure and the Primary Containment Vessel pressure, the Site Superintendent decided that these facilities remained sound.
・ At around 11:30 on March 14, the results of checking personnel for safety were
immediately reported to the Emergency Countermeasures Headquarters. According
to initial reports, some 40 persons were missing and there were several injuries. The Emergency Countermeasures Headquarters requested ambulances via the Head Office Disaster Control HQ (the total injured included four TEPCO employees, three workers of contractor companies, and four soldiers of the Self Defense Forces of Japan).
・ At around 11:40 on March 14, the Emergency Countermeasures Headquarters
confirmed the safety of operators at the Main Control Room. It was reported that a total of seven persons, consisting of six soldiers of the Self Defense Forces of Japan and one worker of a contractor company, were missing. Later, the Self Defense Forces of Japan retreated.

At 13:05 on March 14, when all the operators and workers still remained shocked at a second explosion following that of Unit 1, the Site Superintendent issues the following instruction to take measures for control Unit 2: “The reactor water level of Unit 2 is confirmed as declining. If this state continues, the reactor will reach the TAF (top of active fuel) at around 16:00. We will form a reactor water injection line and restore the reversing valve pit of Unit 3, the water source, by 14:30. Be careful to avoid other explosions. The explosion at Unit 3 might have disrupted facilities.
Do not easily assume that facilities are available for operation.”

・ At 14:50 on March 14, it was reported to the Emergency Countermeasures
Headquarters that the blowout panels on the sea side of Unit 2 were open. (A
subsequent survey identified that the explosion at Unit 1 had caused the opening.)

From 13:05 on March 14, immediately after the instruction of Site Superintendent, the fire brigade headed for the work sites to check the situation. They were exposed to high radiation doses when passing through roads with scattered debris. ・ At around 16:30 of the 14th, The fire engine was started up to resume the seawater injection line. End of file

Activities since the “vent line configuration was completed except for the ruptured discs by opening the suppression chamber vent valve (AO valve) large valve at 8:41 on March 13.”
[Maintenance of the vent line]

From around 2:00 on March 14, the D/W pressure continued to increase* and the rising trend could not be stopped even by increasing the amount of water to be injected to the reactor. Accordingly, we decided to open the S/C vent valve (AO valve) small valve and started the operation of opening the S/C vent valve (AO valve) small valve at 5:20.
Then we finished the opening operation at 6:10.
* 255 kPa [abs](1:30) → 265 kPa [abs](2:00)
・ At 11:01 on March 14, an explosion occurred in the Unit 3 Reactor Building.

(Works on March 15)
・ At 16:00 on March 15, it was confirmed that the S/C vent valve (AO valve) large valve was closed due to the failure of the small generator that had been used for excitation of solenoid valves of the large and small valves. Then we conducted the opening operation at 16:05 by replacing the small generator and exciting the S/C vent valve (AO valve) large solenoid valve.
・ The valve was difficult to keep open due to the difficulty in keeping the drive air pressure and the excitation of the solenoid valve in the air supply line for the S/C vent valve (AO valve) large and small valves, and hence the opening operation was conducted several times.
(S/C vent valve (AO valve) large valve)
 At 21:00 on March 17, the valve was confirmed to be closed; around 21:30 on March 17, opening operation was conducted
 At 5:30 on March 18, the valve was confirmed to be closed; around 5:30 on March 18, opening operation was conducted
 At 11:30 on March 19, the valve was confirmed to be closed; around 11:25 on March 20, opening operation was conducted
 Around 18:30 on April 8, the valve was confirmed to be closed. (S/C vent valve (AO valve) small valve)
 At 1:55 on March 16, opening operation was conducted
 Around 18:30 on April 8, the valve was confirmed to be closed.

Grid Failure + ECCS Failure Part 2 – reactor 2.

The following post consists of highly selected quotes from the TEPCO document chronologies given by the text “Measures Taken at Fukushima Daiichi Nuclear Power Station and Fukushima Daini Nuclear Power Station (December 2011 Edition)”. The quotes are taken from the 166 page appendices of the document and focus upon the timing of events and the consequences of grid and ECCS failures at Fukushima Diiachi. The document is authored by TEPCO, Japan and the appendix only is available at :
http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/111222e18.pdf
(Yes, Wally, I am cherry picking. Read the whole document and come to a different conclusion if you have an inculcated clock for a brain instead of independent cognition.)

Chronology of Main Events at Fukushima Daiichi Nuclear Power Station
Unit 2 from Impact of Earthquake through Tuesday, March 15

Friday, March 11, 2011
14:46 The Tohoku-Pacific Ocean Earthquake occurred. Automatic proclamation
of Level 3 State of Emergency.
14:47 Automatic reactor SCRAM. The main turbine shut down automatically. The
emergency diesel generator started up automatically.
14:50 The Reactor Core Isolation Cooling system (hereafter the “RCIC”) was
started up manually.
14:51 The RCIC shut down automatically (reactor water level high).
15:01 The reactor in a subcritical status confirmed.
15:02 The RCIC started up automatically.
15:27 A first tsunami wave arrived.
15:28 The RCIC shut down automatically (reactor water level high).
15:35 A second tsunami wave arrived.
15:39 The RCIC started up automatically.
15:41 All of the AC power supplies were lost.
16:36 The Emergency Countermeasures Headquarters was able to check
neither the reactor water levels nor the water injection conditions. Thus,
the Emergency Countermeasures Headquarters decided and reported to
the competent government departments and agencies on the occurrence
of a specified event (Inability of Water Injection by the Emergency Core
Cooling System)
subject to the provisions of Article 15 Clause 1 of the
Nuclear Disaster Prevention Act at 16:45.
21:02 Since the headquarters was able to check neither the reactor water level
nor the water injection in the reactor through the RCIC, the Emergency
Countermeasures Headquarters reported to the competent government
departments and agencies that the reactor water level might reach the
top of active fuel (hereafter the “TAF”).
21:13 The Emergency Countermeasures Headquarters assessed the TAF reach time
as 21:40 and reported to the competent government departments and
agencies.
21:50 The reactor water level was confirmed as being at TAF+3400mm. The
Emergency Countermeasures Headquarters assessed that it would take
time before reaching the TAF and reported the assessment to the
competent government departments and agencies at 22:10.
2:55 It was confirmed that the RCIC was in service.
4:55 It was confirmed that radiation dose in the Power Station site rose (Near the main
gate: 0.069μSv/h (4:00) → 0.59μSv/h (4:23)). The rise was reported to the
competent government departments and agencies.
5:00 Shifting the water source for RCIC completed.
15:36 An explosion occurred at the reactor building of Unit 1.
16:27 Surrounding of monitoring post No. 4 measured a radiation dose beyond
500μSv/h (1,015μSv/h). The Emergency Countermeasures Headquarters
accordingly decided on the occurrence of a specified event (Abnormal rise in
the radiation dose on the site boundary) subject to the provisions of Article 15
Clause 1 of the Nuclear Disaster Prevention Act and reported the event to the
competent government departments and agencies.
8:10 The vent valve (MO valve) of the Primary Containment Vessel (hereafter the
“PCV”) was opened.
8:30 An HVPS car was started up to re-supply electricity to Unit 2 P/C. Due
overcurrent relays activated , however, no electricity was transmitted.
8:56 Surrounding of monitoring post No. 4 measured a radiation dose beyond
500μSv/h (882 μSv/h). The Emergency Countermeasures Headquarters
accordingly decided on the occurrence of a specified event (Abnormal rise in
radiation dose on the site boundary ) subject to the provisions of Article 15
Clause 1 of the Nuclear Disaster Prevention Act and reported the event to the
competent government departments and agencies at 9:01.
10:15 The Site Superintendent ordered operators to operate Venting.
11:00 The formation of a Venting line, except for the rupture disk, was
completed.
12:05 The Site Superintendent ordered operators to promote preparation for
using seawater.
13:10 A formation was completed where a battery was connected to the Safety
Release Valve (hereafter the “SRV”) control panel so as to control opening
operation on the operation switch.
14:15 Surrounding of monitoring post No. 4 measured a radiation dose beyond
500μSv/h (905μSv/h). The Emergency Countermeasures Headquarters
accordingly decided on the occurrence of a specified event (Abnormal rise in
radiation dose on the site boundary) subject to the provisions of Article 15
Clause 1 of the Nuclear Disaster Prevention Act and reported the event to the
competent government departments and agencies at 14:23.
15:18 The Emergency Countermeasures Headquarters again reported to the
competent government departments and agencies the result of its dosage
assessment in the event that Venting was operated.
11:01 An explosion occurred at the Reactor Building of Unit 3.
12:50 It was confirmed that the circuit for the solenoid valves that excite the largevalve of the vent valve (AO valve) of the suppression chamber (hereafter the”S/C”) had been dislocated into a “closed” state.
13:25 Since the reactor water level declined, there was a possibility that the RCIC
function had been lost. The Emergency Countermeasures Headquarters
accordingly decided on the occurrence of a specified event subject to the
provisions of Article 15 Clause 1 of the Nuclear Disaster Prevention Act
(Loss of reactor cooling function) and reported the event to the competent
government departments and agencies at 13:38.
15:28 The Emergency Countermeasures Headquarters assessed the TAF reach time
as 16:30 and reported the assessment to the competent government
departments and agencies.
16:30 Fire engines were started up to inject seawater in the reactor.
16:34 The Emergency Countermeasures Headquarters started reduction of the
reactor pressure and reported its plan to start seawater injection from the Fire
Protection System line to the competent government departments and
agencies.
17:17 The reactor water level reached the TAF. At 17:25 of the day, the Emergency
Countermeasures Headquarters reported the event to the competent
government departments and agencies.
18:00 (Approx.) Reduction of the reactor pressure started (reactor pressure : 5.4MPa → 19:03
0.63MPa).
18:22 The reactor water level reached TAF-3,700mm. The Emergency
Countermeasures Headquarters estimated that the entire fuel had been
exposed and accordingly reported the event to the competent government
departments and agencies at 19:32.
19:20 It was confirmed that the fire engine to use for seawater injection in the
reactor has been out of fuel and halted.
19:54 Fire engines started seawater injection in the reactor through the Fire
Protection System line (individual fire engines started up at 19:54 and
19:57, respectively).
21:00 (Approx.) The small valve of the vent valve (AO valve) of the S/C valve was opened.
The formation of a vent line, except for the rupture disk, was completed.
21:20 Two SRV valves were opened. It was confirmed that the reactor water level
was being restored. The Emergency Countermeasures Headquarters reported
the formation to the competent government departments and agencies at
21:34 (as of 21:30, the reactor water level was TAF-3,000mm).
21:35 Surrounding of the main gate measured a radiation dose beyond 500μSv/h
(760μSv/h). The Emergency Countermeasures Headquarters accordingly
decided on the occurrence of a specified event (Abnormal rise in radiation
dose on the site boundary ) subject to the provisions of Article 15 Clause 1 of
the Nuclear Disaster Prevention Act and reported the event to the competent
government departments and agencies at 22:35.
22:50 Since the drywell (hereafter the “D/W”) pressure exceeded the maximum
allowable working pressure of 427kPa[gage], the Emergency
Countermeasures Headquarters decided on the occurrence of a specified
event (Abnormal rise in the pressure of the Primary Containment Vessel) subject
to the provisions of Article 15 Clause 1 of the Nuclear Disaster Prevention
Act and reported the event to the competent government departments and
agencies at 23:39.
23:35 (Approx.) Since the pressure on the S/C side was lower than rupture disk working pressure and the pressure on the D/W was on the rise, the Emergency
Countermeasures Headquarters decided to operate venting by opening the
small valve of the vent valve.
Tuesday, March 15, 2011
0:01 It was confirmed that the small valve of the vent valve (AO valve) of the
D/W was closed several minutes after the small valve had been opened.
3:00 Since the D/W pressure exceeded the maximum allowable working pressure
in design, the Emergency Countermeasures Headquarters tried reducing the
pressure and injecting water in the reactor. However, the pressure was not
successfully reduced. The Emergency Countermeasures Headquarters
reported the situations to the competent government departments and
agencies at 4:17.
6:00 to 6:10 (Approx.) A large impulsive sound thundered. The indication value of the
S/C pressure turned 0 MPa[abs].
6:50 Sounding of the main gate measured a radiation dose beyond 500μSv/h
(583.7μSv/h). The Emergency Countermeasures Headquarters accordingly
decided on the occurrence of a specified event (Abnormal rise in the radiation
dose on the site boundary) subject to the provisions of Article 15 Clause 1 of
the Nuclear Disaster Prevention Act and reported the event to the competent
government departments and agencies at 7:00.
7:00 The Emergency Countermeasures Headquarters informed the competent
government departments and agencies of a temporary evacuation of
personnel to Fukushima Daini except for the personnel needed for
monitoring and other operations.

8:11 Sounding of the main gate measured a radiation dose beyond 500μSv/h
(807μSv/h). The Emergency Countermeasures Headquarters accordingly
decided on the occurrence of a specified event (Abnormal emission of
radioactive materials on fire or explosion, etc.) subject to the provisions of
Article 15 Clause 1 of the Nuclear Disaster Prevention Act and reported the
event to the competent government departments and agencies at 8:36.
8:25 It was confirmed that smoke (something like steam) was rising from around
the 5th floor of the reactor building. The Emergency Countermeasures
Headquarters reported the event to the competent government departments
and agencies at 9:18.
11:00 The Prime Minister issued an order of in-house evacuation to the local residents
staying in the areas ranging from a 20km up to a 30km radius of Fukushima
Daiichi Nuclear Power Station.
16:00 Sounding of the main gate measured a radiation dose beyond 500μSv/h
(531.6μSv/h). The Emergency Countermeasures Headquarters accordingly
decided on the occurrence of a specified event (Abnormal rise in the radiation
dose on the site boundary) subject to the provisions of Article 15 Clause 1 of
the Nuclear `Disaster Prevention Act and reported the event to the competent
government departments and agencies at 16:22.
23:05 Sounding of the main gate measured a radiation dose beyond 500μSv/h
(4584μSv/h). The Emergency Countermeasures Headquarters accordingly
decided on the occurrence of a specified event (Abnormal rise in the radiation
dose on the site boundary) subject to the provisions of Article 15 Clause 1 of
the Nuclear Disaster Prevention Act and reported the event to the competent
government departments and agencies at 23:20.

Fukushima Daiichi Nuclear Power Station Unit 2
State of Alternate Coolant Injection

Activities after “16:36 on March 11 when “Inability to Inject Water of the Emergency Core Cooling System” was determined and reported on
[Study and preparation for alternative means of water injection]

Considering the radiation dose in Unit 1, the Emergency Countermeasures Headquarters decided to form an alternative line of water injection into the reactor via the residual heat removal system (RHR) before the radiation dose rose. After completing the formation of an alternative line of water injection for Unit 1, from around 21:00 on March 11, operators started forming such
line for Unit 2. However, the operators were unable to work in the
Main Control Room due to the lack of power. The operators thereforewore full-face masks, took flashlights to light their way in complete darkness to
the Reactor Building, and manually opened four solenoid valves, including the
RHR valve. During March 11, they completed the formation of an alternative line
of water injection.
・ In particular, the RHR injection valve fixed on a pipe of approx. 60 cm diameter, pipe had a manual handle, also approx. 60 cm in diameter, which was very heavy to rotate. In addition, since the stroke of the stem was a large and long valve, operators had to climb up a ladder into the small spot for operation. A total of ten operators in rotation rotated the handle and it took approx. one hour to open the valve. (Normally, it takes approx. 24 seconds to fully open the valve electrically by operating switches at the Main Control Room.)

The status indicator of the diesel-driven fire pump (hereafter the “DDFP”) in the Main Control room had gone out. Since the basement of the Turbine Building
where the DDFP was installed was submerged in approx. 60 cm of water,
operators were unable to enter the FP pump room. However, operators confirmed
that the DDFP was in service because they saw smoke from the DDFP exhaust
duct outside the building. Even subsequently, the operators continued to check the exhaust duct for smoke. At 1:20 on March 12, however, operators saw no further smoke from the exhaust duct and confirmed that the DDFP had halted.

[Checking the state of the Reactor Core Isolation Cooling System (RCIC)]

At around 1:00 on March 12, operators headed for the work site to check the state of the RCIC operation, wearing self-contained breathing apparatus and with flashlights. Dedicated boots, used for entering controlled areas, had been washed away and submerged, hence operators wore long rubber boots,
normally used for outside patrols. The water in front of the RCIC room in the basement of the Reactor Building was deep, meaning their long boots were almost submerged in the water. When an operator opened the door of the RCIC
room, water flowed from the room, hence the operator soon closed the door. Although operators were unable to enter the RCIC room, they heard metallic clank screaming. Since operators were unable to check the rotary unit, they
were also unable to determine the operating state. Because no PHS was available
for communication, they returned to the Main Control Room and reported the
・ At around 2:10 on March 12, operators headed back to the RCIC room to check
the operation state. Although the water level in front of the door exceeded before, operators opened the door to check the operation state of the
RCIC. Although water slowly flowed from the room, the operators
entered the room and identified the pointer of the pump inlet pressure meter
shaking in the pressure instrumentation rack at the entrance to the RCIC and again heard the operation sound. Subsequently, the operators confirmed that the RCIC instrumentation rack on the 1st floor of the Reactor Building indicated an RCIC discharge pressure of 6.0MPa and that the reactor pressure in the instrumentation rack of the Reactor Pressure Vessel system on the 2nd floor of the Reactor Building indicated 5.6MPa. Since the RCIC discharge pressure exceeded the reactor pressure, the RCIC was seemingly in service (functioning). The operators returned to the Main Control room and reported the situation at 2:55 to the Emergency Countermeasures Headquarters.

[Checking the state of the high pressure coolant
injection system (HPCI)]

Since all of the DC power supplies needed for operation control were lost and the status indicators of the Main Control room had gone
out, the HPCI was no longer workable.
・ From 16:39 on March 11, the restoration team started checking the on-site conditions of power supply facilities after the earthquake
and tsunami. Since the service building where DC power supplies are installed was submerged approx. 1.5-meter deep on the basement floor
, the restoration team gave up checking.

○ Activities after “2:55 on March 12 when confirming the RCIC in service”
[Shifting water source of the RCIC]
・ Operators decided to shift the water source to the S/C from the CST, considering the fact that the water level of the condensate storage tank (hereafter “CST”), the water source of the RCIC, was declining, the water level of the suppression pressure (hereafter the “S/C”) was likely to rise: and that the CST would be the water source for alternative water injection facilities. From 4:20 on March 12, four operators, putting on C equipment
and full-face masks, headed for the RCIC room.

Amid the echoing operating sound of the RCIC, operators using flashlights manipulated three solenoid valves to shift the water source formation line from the CST to the S/C. All the valves, with long stem strokes and manual handles, were very heavy to rotate. In addition, since the operating site was located so high and without scaffolding, operators had to climb up a ladder from and extend their arms to rotate the handle.
・ One operator was assigned to the entrance of the RCIC room to monitor the
pressure indicated by the pump inlet pressure meter in the instrumentation rack
near the entrance, while two operators in rotation engaged in handling the valves. The remaining operator carefully played the role of lighting and coordinating worker, with the operator monitoring the pressure to prevent the RCIC from halting. The operation was completed at 5:00 on March 12. (Normally, such a shift would take no more than five minutes by manipulating the electrical operation switch in the Main Control Room.)

[Confirming the RCIC operation state]
Under circumstances where the DDFP and the HPCI, which are facilities to inject water into the reactor requiring no power supply, were unavailable for operation, operators continued periodical checking of the operating state of the RCIC, the only water injection facility left.

At around 10:40 on March 13, an operator confirmed that the discharge pressure
indicated pressure ranging from 6.0 to 6.4MPa in the RCIC instrumentation rack
installed on the 1st floor of the Reactor Building, while the reactor pressure
indicated 6.1MPa in the Reactor Pressure Vessel instrumentation rack installed on the 2nd floor of the Reactor Building. Thus, the operator confirmed that the
RCIC discharge pressure exceeded the reactor pressure.
 At around 13:50 on March 13, an operator confirmed that the discharge pressure
in the RCIC instrumentation rack installed on the 1st floor of the Reactor
Building showed 6.3MPa, indicating the continuous operation of the RCIC.

Preparing for a reduction in reactor pressure by seawater injection and with the safety release valve (hereafter the “SRV”)]

For Unit 3, ten 12V batteries as a DC power supply (125V) were needed to drive the SRV that would reduce the reactor pressure by injecting water. At around 7:00 on March 13, the Emergency Countermeasures Headquarters asked its employees staying the Seismic Isolated Building to offer the batteries of their private cars.
Such batteries would also be required for Unit 2 later. Thus, at the same time, the Emergency Countermeasures Headquarters asked its employees to offer batteries. The required number of persons who were ready to offer batteries gathered together.
Each removed the battery from his/her vehicle and took it to the front of the Seismic Isolated Building.
・ Five members of the restoration team transported batteries in their private cars to the Main Control Room of Unit 3, and then returned to the Anti-Earthquake Building to transport batteries to Unit 2. When they reached the entrance of Units 1 and 2, they received temporary evacuation instructions, because the Primary Containment Vessel of Unit 3 was going to have venting operation. Thus, the members of the restoration team moved toward the main gate of the Power Station and stood by there. They confirmed that smoke was flowing from the main stack of Units 3 and 4.

At 13:10 on March 13, the operators connected batteries to the SRV control panel in the Main Control Room so as to open the SRV valve on the operation switch of the SRV control panel, as they had done for Unit 3, to maintain the reduction in the reactor pressure.

Operators connected ten 12 batteries serially to supply the DC power needed to start up the SRV. Wire-cutting and coat stripping needed fine finger work. Wires and terminals were directly connected and fastened with insulation vinyl tape, which could have resulted in accidental electric shock and/or short circuit. Using flashlights alone, the full-face mask provided a narrow view. The insulation vinyl tape sometimes twisted around the rubber gloves. At times, the wire accidentally came into contact with the battery,
sparking and fusing part of the terminal.
 The utmost caution was needed for workers wearing two pairs of rubber gloves in picking and grasping small screws for terminals while tightening them with a screwdriver.

Activities after “11:01 of March 14 when an explosion occurred at the reactor building of Unit 3” (added : as relevant to responses to the emergency at Reactor 2)
[Resuming the formation of a seawater injection line]

After the explosion, workers were suspended from operation at their work sites.
However, following the instruction by the Site Superintendent, the fire brigade
headed for the work sites at 13:05 on March 14. Exposed to a high radiation dosecaused by scattered debris, the fire brigade checked the target sites. The water injection line, the formation of which had already been completed, had sustained damage to the fire engines and hoses, which were no longer usable.
・ Since the fire engine that had been supplying seawater to the reversing valve pit of Unit 3 from the Shallow Draft Quay was undamaged in the explosion, the fire brigade decided to use it to inject seawater into the reactors of Units 2 and 3 from the Shallow Draft Quay as the water source. Thus, the fire brigade promoted efforts to establish an alternative line of water injection by, for example, replacing damaged hoses.
At 13:18 on March 14, the reactor water level was found to be declining. At 13:25, the Site Superintendent decided that the RCIC had lost its function, and anticipated reaching the TAF (top of active fuel (in the core) around 16:30, judging from the facing conditions. The fire brigade continued preparation for seawater injection into the reactors. At around 14:43, the fire brigade succeeded in connecting the fire engine to the water supply outlet of the FP.
・ From past 15:00 to 16:00 on March 14, aftershocks occurring in a Fukushima offing as the seismic center led to the suspension of work and temporary evacuation.

At around 16:30 on March 14, the fire brigade started up a fire engine and made
arrangements to restart water injection after reducing the reactor pressure.

[Reducing the reactor pressure]

Prior to starting water injection with a fire engine, operators needed to open the SRV to reduce the reactor pressure. The previous day, the SRV was set to a state to perform opening operation. However, the S/C had high temperature and pressure (149.3℃ and 486kPa[abs] pressure as of 12:30 on March 14). Thus, there was the possibility that even if the SRV had been opened, steam in the S/C might not have condensed and the pressure could not have been reduced. Thus, the Emergency Countermeasures Headquarters decided to prepare to vent the Primary Containment Vessel (hereafter “Vent/Venting/”) prior to opening the SRV to reduce the reacto pressure and perform seawater injection.
・ At around 16:20 on March 14, it was forecast that it would take time before the vent valve could be opened. Around 16:28, the Site Superintendent prioritized reducing the reactor pressure by using the SRV and instructed operators to promote venting preparation concurrently.

At 16:34 on March 14, the SRV puffing sound, along with rises in the reactor
pressure, reached the calm Main Control Room. Operators tried opening the SRV on the operation switch but the SRV did not open.

All ten batteries were once disconnected from the wiring and then all re-connected serially.・ At around 18:00 on March 14, the serial batteries were connected directly to solenoid valves that opened a discrete SRV for excitation. During the 5th SRV opening operation, the reactor pressure began to decease.

At around 16:30 on March 14, a fire engine was started up and members of the fire brigade started operation to reduce the reactor pressure from 16:34. Although pressure reduction started at around 18:00, the S/C had a high temperature and pressure that were unlikely to have condensation.
Reactor pressure: 6.998MPa (16:34) → 6.075MPa (18:03) → 0.63MPa (19:03)
・ At 19:03 on March 14, the reactor pressure declined to 0.63MPa.
・ During this time, members of the fire brigade had to check the operating conditions of the fire engine, etc. in rotation amid high radiation doses at the work site. At 19:20 on March 14, a member found that the fuel of the fire engine used to inject the water had run out and it was no longer functional. After refueling the fire engine, the fire engine started seawater injection into the reactor through the Fire Protection System line. (At 19:54 and 19:57 on March 14, fire engines were started up respectively.)

At around 21:00 on March 14, the reactor pressure rose. One more SRV was added to open, but did not open. When another SRV was used for the opening operation, the SRV opened at 21:20. While the reactor pressure was decreasing, the indicator showing the downscaled reactor water level meter showed an increase.
Subsequently, the Emergency Countermeasures Headquarters continued reading the
reactor water level, reactor pressure and D/W pressure every few minutes. While
focusing on plant behavior, the headquarters continued water injection into the
reactor.

Fukushima Daiichi Nuclear Power Station Unit 2
Circumstances of Venting of Containment Vessel

At 23:40 on March 14, the reactor pressure was 1.170MPa[gage], whereas the D/W
pressure was 740kPa[abs]. The S/C pressure was 300kPa[abs]. The reactor pressure was declining, the D/W pressure remained constant. At 23:46, the D/W pressure indicated 750kPa[abs].
・ The Emergency Countermeasures Headquarters and the Main Control Room that was
operating the D/W small vent valve (AO valve) had only two hot lines to communicate.

(Works on March 15)
・ At 0:01 on March 15, the Emergency Countermeasures Headquarters excited the
solenoid valves to open the D/W small vent valve (AO valve). However, it wasconfirmed several minutes later that the small valve was closed.

At 0:05 on March 15, the reactor pressure was 0.653MPa[gage]; the D/W pressure was 740kPa[abs]; and the D/W pressure remained constant. At 0:10, the reactor pressure was 0.833MPa[gage]; the D/W pressure was 740kPa[abs]; and the S/C pressure was 300kPa[abs] or so and remained unchanged. The reactor pressure began to rise. The recovery team received an order to prioritize connecting batteries to excite the SRVsolenoid valves required to open the SRV. The recovery team continued the operations.

At 0:22 on March 15, the reactor pressure was 1.170MPa[gage]. The D/W pressure was 735kPa[abs]. Since the reactor pressure was rising, the operators tried opening another SRV. However, at 0:45, the reactor pressure rose to 1.823MPa[gage], hence the SRV did not open and the operators tried to open other SRVs.
・ At 1:10 on March 15 when the operators tried opening an SRV, the reactor pressure began to decline. The D/W pressure, however, remained constant at around 730kPa[abs].
The S/C pressure remained at around 300kPa[abs] and stable. Subsequently, the reactor pressure remained at around 0.63MPa[gage] and stable. At 2:22, the reactor pressure was rising and reached 0.675MPa[gage]. Thus, the operators began to open the next SRV. In addition, the D/W pressure rose slightly and at 2:45 reached 750kPa[abs].
・ The recovery team at the Main Control Room engaged in opening the SRV to reduce the rising reactor pressure and opening the vent valve to reduce the rising pressure of the D/W since the evening of March 14. Following the instructions of the Emergency Countermeasures Headquarters to cope with the plant conditions, members of the recovery team put on full-face masks and rubber gloves. With the help of flashlights, members connected wires, while keeping the SRV open to stabilize the reactor pressure and strove to form a venting line.

Activities “after 6:00 to 6:10 on March 15 when a large impulsive sound thundered, causing the S/C pressure to show a reading of 0 kPa[abs]

At around 6:00 to 6:10 on March 15, a large impulsive sound thundered.
・ An operator who engaged in monitoring the plant at the Main Control Room of Units 1 and 2 felt shocks that differed from the explosion at Unit 1. The operator who engaged in collecting data almost at the same time confirmed that the S/C pressure had an indication value of 0kPa[abs] and reported it to the Emergency Countermeasures Headquarters .
・ At around this time, the ceiling on the Unit 4 side of the Main Control Room of Units 3 and 4 shook with an impulsive sound.

Three operators heading for the Main Control Room of Units 3 and 4 for a work
shift at 6:00 on March 15 felt wind pressure on their backs when entering th service building of Units 3 and 4. After entering the Main Control Room and checking the situation, the power generation team informed them of the
temporary evacuation.
Six operators, consisting of three operators and a further three operators staying at the Main Control Room, started to evacuate into the Seismic Isolated Building. When they left the service building of Units 3 and 4, the surroundings were full of debris. The six operators got in the car that they had just came in and headed for the Seismic Isolated Building. When they looked up at the Reactor Building of Unit 4 on the way, they confirmed that the area around the 5th floor was damaged.
The road near the Reactor Building was full of scattered debris and the car could no longer advance. The six operators left the car, ran away from the Reactor Building of Unit 4, and then walked toward the Seismic Isolated Building. On their way there, they came across cars heading for the main gate to evacuate the Power Station. The six operators finally reached the Seismic Isolated Building and reported on the conditions of Unit 4 to the Emergency Countermeasures Headquarters.

At around 6:30 on March 15, the Emergency Countermeasures Headquarters decided to temporarily move personnel into Fukushima Daini Nuclear Power Station, except for the personnel monitoring the plant and needed for emergency recovery. Each of the team leaders of the Emergency Countermeasures Headquarters appointed the persons needed for the above mentioned operations. Approx. 650 workers started to move into Fukushima Daini. Immediately after the evacuation, some 70 workers were left in the Emergency Countermeasures Headquarters.

At around 11:25 on March 15, operators confirmed that the D/W pressure had
declined. (730kPa[abs](7:20) → 155kPa[abs](11:25)) (ie Reactor 2 Dry Well)

Grid Failure + ECCS Failure = Fukushima Diiachi Disaster.

The following post consists of selected quotes from the chronologies given by the text “Measures Taken at Fukushima Daiichi Nuclear Power Station and
Fukushima Daini Nuclear Power Station (December 2011 Edition)”. The quotes are taken from the 166 page appendices of the document and focus upon the timing of events and the consequences of grid and ECCS failures at Fukushima Diiachi. The document is authored by TEPCO, Japan and the appendix only is available at :
http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/111222e18.pdf

The series of quotes follow the Tepco chronology of events for each afflicted in numerical order. The focus of the quotes I have selected are. !. Grid connection failure, steps to restore grid power, time taken to restore gird power. 2. Emergency Core Cooling System performance for each of the three such ECCS possessed by each of the afflicted reactors and the consequences of these failures.

It has been the expectation of the general public of the world that, in event of any emergency, no matter what that emergency was or will be, that where cooling of reactors was under threat for any reason, then the Emergency Core Cooling Systems WOULD perform in a guarantee manner to prevent core over heat, melt down and release of radio active material into the biosphere. This expectation was implanted in the mind of the world’s general public by nuclear industry in 1975 during court hearings which, on the basis of the technical promises of guaranteed core cooling, lifted the suspension on the granting of licences for new nuclear power plants. The ECCS controversy had commenced with the publication of the Ergen Report on Emergency Core Cooling Systems in the late 1960s. This US AEC report, coupled with Ralph Lapp’s (AEC) public discussion of the technical details (See New York Times for Lapps essay “The Problem of Nuclear Plumbing”) led to much public discussion and inspired the film “China Syndrome”. The Japanese industry, using designs and cultures directly imported from and by the US AEC (long since disbanded for conflict of interest and failure to properly respond to public needs and expectations) continued from the 1970s until 2011 with the precise centrally commanded structure and ethos which had caused so much dysfunction within the industry in the USA, both in regard to failures of duty and failures to communicate in an open and honest manner with the American people. The Japanese people from 2011 rapidly experienced a Japanese analogue of the American Downwinder experience of the 1950s to 1970s.

It is from the early American experience and independent research that many Westerners learned in the 1970s that ECCS systems as designed in America would probably fail under real emergency situations. What happened at Fukushima Diiachi in March 2011 can in fact be read out loud from both technical texts and public books dating from early 1970s. The industry itself new of the dangers from the 1960s on.

Nothing known at the time though caused General Electric and TEPCO to take a conservative approach to ECCS design. Apparently the best they could do in a quake and tsunami prone land was lower the land at Fukushima by blasting, build the reactors over a high flow rate aquifer, and build the basements below sea level. It was foreseeable that a large tsunami would result in the flooding of basements. The design to place emergency generators and electrical switchgear on in the basements at Fukushima Diiachi amounts to a grave act of negligent design. The US concepts and blinded engineering which mandated and still mandates that a nuclear power plant design has to include ECCS which works for a mere 8 hours and that a NPP has to survive without mishap grid disconnection for 8 -14 hours are arrogant and totally blind to the realities of disaster scenarios both in the US, in Japan and elsewhere around the world.

Since the accident, there have been many hours of TV and media ink spent on explaining the alleged reasons for the disaster. The truth is far simpler from these alleged qualified expert accounts. Nuclear Industry Defence in Depth, of which multiple emergency core cooling systems are an integral part, must prevent core melt and the release of radioactive material into the biosphere. That, for decades, has been the industry promise. Those who have, since the 1970s in particular, questioned the concepts of safety promoted by the industry have been constantly mocked and isolated by that industry. In Japan, highly qualified scientists and academics have been denied full inclusion into the Japanese science, technology and academic cultures for decades. Arrogant design cannot be covered be covered up by arrogant and inadequate explanations. Not when the truth of unresolved questions regarding the adequacy critical safety systems of NPPs has been on the public record for nearly 50 years. The preceding post shows that the US Nuclear Regulatory Commission considered the adequacy of NPP safety systems to be an open question: “results indicate that estimated core melt frequencies from station blackout vary considerably for different plants and could be a significant risk contributor for some plants….action should be taken to resolve the safety concern stemming from station blackout. The issue is of concern for both PWRs and BWRs. “ NRC, 1988. (see previous post). Thus the chronology of events I selectively quote from TEPCO confirm not only the observations of Ralph Lapp, Nader and Abbott and many others, but also Ergen (AEC) and US NRC 1988. If today’s industry denies these facts, it has to account for why the world’s leading nuclear regulator was incorrect in its assessment of 1988 as quoted above. Calling me a radiophobe for pulling proofs from a TEPCO in a condensed and selective fashion has no effect upon me or the record the workers at the afflicted reactors created as they learned the truth the hard way. After decades of lies and negligence from their government and regulators.

TEPCO, December 2011.

Chronology of Main Events at Fukushima Daiichi Nuclear Power Station
Unit 1 from Impact of Earthquake through Saturday, March 12

Friday, March 11, 2011
14:46 The Tohoku-Pacific Ocean Earthquake strikes. Automatic reactor SCRAM.
Automatic proclamation of Level 3 State of Emergency.
14:47 Automatic shutdown of main turbine, emergency diesel generators start up
automatically.
14:52 The isolation condenser (IC) starts up automatically…….
15:27 Arrival of first tsunami wave.
15:35 Arrival of second tsunami wave.
15:37 Total loss of AC power.
15:42 A specified event (total loss of AC power) in accordance with stipulations
of Article 10, Clause 1 of the Act on Special Measures Concerning
Nuclear Emergency Preparedness (hereafter abbreviated “Nuclear
Emergency Act”) was determined to have occurred, government and
other authorities were notified.
15:42 First state of emergency declared.
Emergency Countermeasures Headquarters
(merged with Emergency Disaster Countermeasures Headquarters)….
16:10 The Power Distribution Department of the Head Office instructed all the
branch offices to reserve high and low voltage power source cars and check
relocation routes.
16:36 Reactor water levels could not be confirmed and state of water injection was unknown, thus the specified event (emergency core cooling system water injection impossible) in accordance with stipulations of Article 15, Clause 1 of the Nuclear Emergency Act was determined to have occurred, government and other authorities were notified at 16:45.
16:36 Second state of emergency declared..
16:39 Checks of power supply facilities (offsite power, in-site power) for soundness started.
16:45 Reactor water level was confirmed, thus a specified event (emergency core
cooling system water injection impossible) in accordance with the stipulation of
Article 15, Clause 1 of the Nuclear Emergency Act was determined to be
rescinded, government and other authorities were notified at 16:55.

16:50 High and low voltage power source cars reserved by all the TEPCO offices
left for Fukushima one after another.
16:55 The on-site check of a diesel fire pump started.
17:07 Confirmation of reactor water level again became impossible, thus a specified event (emergency core cooling system water injection impossible) in accordance with stipulations of Article 15, Clause 1 of the Nuclear Emergency Act and accordingly reported the event to the competent government departments and agencies at 17:12.
17:12 Site Superintendent ordered staff to study a method for water injection into the reactors through the Fire Protection System line, which had been
installed as part of the accident management measures, and through fire
engines.
20:50 After the alternative reactor water injection system line had been set up, the suspension state was lifted. The diesel fire pump automatically started failure recovery operation (a state enabling water injection after reduction in the reactor pressure).
20:50 The Fukushima Prefecture government issued an evacuation order to localresidents staying in areas within a 2km radius of Fukushima Daiichi Nuclear
Power Station.

21:19 The reactor water level was identified as top of active fuel (hereafter “TAF”) +200 mm.

21:23 The Prime Minister issued an evacuation order to local residents staying in areas within a 3km radius of Fukushima Daiichi Nuclear Power Station andan order confining local residents indoors staying in areas within a 3 to 10km
radius of the power station.

21:51 The radiation dose in the Reactor Building rose. An order to prohibit entry intothe Reactor Building was issued.
22:00 (Approx.) The arrival of an initially dispatched high voltage power source
(hereafter “HVPS”) car from Tohoku Electric Power was confirmed.
22:10 It was reported to the competent government departments and agencies that the reactor water level was around TAF+450 mm.
23:00 It was reported to the competent government departments and agencies at 23:40 that the survey results had indicated rises in the radiation dose in the turbine building (1.2 mSv/h in front of the double doors on the north side of the first floor of the turbine building and 0.5 mSv/h in front of the double doors on the south side of the first floor of the turbine building).
Saturday, March 12, 2011
0:06 There was a possibility of the drywell (hereafter the “D/W”) pressure exceeding 600kPa abs, which could require venting of the Primary
Containment Vessel (hereafter “Vent/Venting”). Thus, the Site
Superintendent ordered to prepare for Venting.
0:30 It was confirmed that the government’s measure to evacuate local residents
had been completed (evacuation of local residents staying in Futaba-machi
(town) and Okuma-machi (town) within a 3-km radius of Fukushima Daiichi
Nuclear Power Station, which was reconfirmed at 1:45).
0:49 Possibility of the D/W pressure exceeding 600kPa abs exists, so a specified event
(abnormal rise in containment vessel pressure) in accordance with stipulations of
Article 15, Clause 1 of the Nuclear Emergency Act was determined to have
occurred, government and other authorities were notified at 0:55.
1:20 (Approx.) The arrival of a TEPCO HVPS car was confirmed.
1:30 (Approx.) Proposal to vent Units 1 and 2 made to the Prime Minister, Minister of Economy, Trade and Industry, and Nuclear and Industrial Safety Agency and consent obtained.

1:48 It was confirmed that the diesel fire pump had been stopped….
4:00 (Approx.) Freshwater injection into the reactors started from the fire engine through the Fire Protection System. Injection of 1,300 liters completed.
4:01 The result of assessing radiation exposure in the event of operating Venting was reported to the competent government departments and agencies.
4:55 It was confirmed that radiation dose in the Power Station site had risen (Near the main gate: 0.069μSv/h (4:00) → 0.59μSv/h (4:23)). The rise was reported to the competent government departments and agencies.
5:14 The radiation dose in the Power Station site was rising, while the D/W pressure was on the decline. Emergency Countermeasures Headquarters decided that an “outside leak of radioactive materials” had occurred and accordingly reported the event to the competent government departments and agencies.
5:44 The Prime Minister issued an evacuation order to local residents staying in the areas within a 10-km radius of Fukushima Daiichi Nuclear Power Station.

5:46 A fire engine resumed freshwater injection into the reactors through the Fire Protection System.
5:52 The fire engine completed 1,000 liter freshwater injection into the reactor through the Fire Protection System line.
6:33 It was confirmed that a study was underway to evacuate residents of
Okuma-machi into Miyakoji areas.

6:50 The Minister of Economy, Trade and Industry ordered Venting operation(manual Vent) in accordance with law.
9:15 (Approx.) The vent valve (MO valve) of the Primary Containment Vessel (hereafter the “PCV”) opened manually.
9:30 (Approx.) Operators tried manipulating the small valve of the vent valve (AO valve) of the Suppression Chamber (hereafter the “S/C”). However, they had to give up the efforts because of high radiation dose.

9:53 Emergency Countermeasures Headquarters again reported to the competent
government departments and agencies the result of its dosage assessment in the
event that Vent was operated.
10:15 (Approx.) It was confirmed that 72 power source cars sent from TEPCO branch offices and 32 from Tohoku Electric Power had arrived at Fukushima Nuclear Power Stations (Fukushima Daiichi received 12 HVPS cars and seven low voltage power source cars, while Fukushima Daini received 42 HVPS cars and 11 low voltage power source cars).
10:17 The Man Control Room opened the small valve of the vent valve (AO valve) ofthe S/C (in anticipation of residual pressure in the compressed air system for
instrumentation)
10:40 Since the surrounding of the main gate and monitoring post No. 8 indicated a higher radiation dose, it was judged that the rise would be highly attributable to the Vent operation that had led to emission of radioactive materials.
11:15 Radiation dose is falling, thus indicating that venting was not likely sufficiently effective.
11:39 Emergency Countermeasures Headquarters reported to the competent
government departments and agencies that one of the employees who had entered the reactor building for Vent operation had an exposed dosage beyond 100mSv(106.30 mSv).
14:30 When the restoration team installed a temporary air compressor around
14:00 to operate the large valve of vent valve (AO valve) of the S/C, the team
identified a decline in the D/W, decided that the decline was attributed to “emission of radioactive materials,” and reported the event to the
government and other authorities at 15:18.

14:53 The fire engine completed approx. 80,000 liter freshwater injection into the reactor (in total of accumulation).
14:54 The Site Superintendent ordered operators to inject seawater in the reactor.
15:30 (Approx.) The restoration team formed a route where electricity from an HVPS car is supplied to the Unit 1 MCC through the Unit 2 P/C. The team started supplying electricity up to a point just before the standby liquid control system.
15:36 An explosion occurred at the reactor building.
16:27 Surrounding of monitoring post No. 4 measured a radiation dose beyond
500μSv/h (1,015μSv/h). Emergency Countermeasures Headquarters accordingly
decided on the occurrence of a specified event (Abnormal rise in radiation dose
on the site boundary) subject to the provisions of Article 15 Paragraph 1 of the
Nuclear Disaster Prevention Act and reported the event to the competent
government departments and agencies.

18:25 The Prime Minister issued an evacuation order to local residents staying in areas within a 20-km radius of Fukushima Daiichi Nuclear Power Station.
18:30 (Approx.) The results of checking the state of the fire engine, buildings, etc. confirmed that
these areas were in a mess. Damage was also identified to the power supply
facility for the standby liquid control system and to the seawater injection
hose that had been reserved. They were confirmed as unworkable.
19:04 The fire engine started seawater injection into the reactor through the Fire Protection System line.
20:45 Seawater was injected in the reactor after being mixed with boric acid.

Fukushima Daiichi Nuclear Power Station Unit 1
State of Alternate Coolant Injection Activities after “16:36 on March 11 when “Inability to Inject Water of the Emergency
Core Cooling System” was determined and reported on

[Checking the reactor water level]


・ Since all the status indicators of the Main Control Room had gone out and the DC power supply needed for operation control had been lost, the HPCI was also
unavailable.

Activities after “17:12 on March 11 when the Site Superintendent ordered that an alternative means of water injection be studied as part of accident management (hereafter “AM”) measures and a method for injecting water into the reactor using fire engines (installed on a lesson from the “Chuetsu-oki Earthquake”)”

At 18:35 on March 11, the operation room used the DDFP to form an alternative line of water injection into the reactor through the Core Spray System (hereafter the “CS”) from the FP line. Since no power supply was available, the Main Control Room had no control over the line. A total of five members, consisting of four operators and one member of the power generation team, wore full-face masks and headed for the Reactor Building. With the help of flashlights, the members reached the Reactor Building where they manually opened five motor valves, including the CS, and at around 20:30, completed the formation of an alternative line of water injection into the reactor.
・ The CS injection valve in particular has a manual handle, with a long stroke of the stem and approx. 60cm diameter, hence the members’ full-face masks after the manual operation were all in a sweat.

Operators estimated that the IC had malfunctioned. Considering that the piping
needed to supply water for the shell side had not been formed, an operator set the
return pipe isolation valve (MO-3A) to a “closed” state at 18:25 on March 11. In
addition, since no alternative line of water injection into the reactor had been
formed, establishing an alternative line formation of water injection by the DDFP
was prioritized.
・ Operators anticipated the restoration of the DC power supply of the HPCI, like thatof the IC, because both power supplies were installed in the same area. Despite expectations at start up, however, the status indicator did not light up.

Preparation to establish an alternative line of water injection into the reactor was
completed. At 20:40 on March 11, an operator tried cancelling the “stop” state of
the DDFP operation switch in the Main Control Room but it did not work.
・ Because there were limited means of telecommunication between the control room
and the other work site, an operator was assigned to a spot between them to
mediate communications. The operator cancelled the “stop” state of the operation
switch in the Main Control Room while the operator at the other worksite
continued pressing the trouble restoration button. At 20:50 on March 11, the
operator at the work site confirmed the startup of the DDFP. It was set to a stateallowing the injection of water after the reactor pressure had been reduced (a state where the discharge pressure of the DDFP exceeded the pressure in the reactor).

○ Activities after “15:36 of March 12 when an explosion occurred at Unit 1 of the Reactor Building” (Situations at the explosion]

The entire Main Control Room shook vertically with a thundering sound. The whole room was covered in dust. Operators were unable to do anything.
・ Together with workers of a contractor company, the fire brigade was operating the fire engine to inject water into the reactor near the reversing valve pit
of Unit 1. When members were outside the vehicle to refuel the
fire engine, a terrible shock occurred. The members squatted down on the spot.
When they looked up, debris was spreading all over the sky and then falling.
Workers of the contractor company were led to the condensate storage tank beside
the nearby Unit 1 Turbine Building to shelter from flying debris. Shortly after the explosion, a worker of the contractor company by the fire engine was identified as being unable to stand. Although a member of the fire brigade called him, the worker was unable to walk. Thus, two members stood on both sides of the worker and shouldered him to take away slowly away from the spot to escape. “It’s exploding!” they shouted and headed for the gate between Units 2 and 3. On their way to the Main “Anti-Earthquake Building”, they loaded the immobile worker into a nearby car and returned to the building.・ Other fire brigade members, together with soldiers of the Self-Defense Forces of Japan, were moving on a fire engine of the Self-Defense Forces to form a seawater
injection line. At the moment when the fire engine traversed a spot between the
Turbine Building for Units 2 and 3 respectively, the members saw the ground
surface as if deformed, followed by a thundering explosion sound. The blast
instantly shattered the windscreen of the fire engine. Debris flew in all directions, injuring one of the members. The fire brigade members got on the fire engine and returned to the Seismic Isolated Building.

[Post-explosion measures taken]

At 15:49 on March 12, it was reported to the Emergency Countermeasures
Headquarters that several persons had been injured. Under instructions for
evacuation from the work sites, the Emergency Countermeasures Headquarters
started to rescue injured persons and writing task for work sites around 15:54.
・ At 15:57 on March 12, the Main Control Room of Units 1 and 2 reported to the
Emergency Countermeasures Headquarters that the control room kept checking the
reactor water level. Thus, the headquarters estimated that the Reactor Pressure
Vessel had not been impacted in the explosion but remained in a sound state. After the explosion, the temporary lights in the Main Control Room were no
longer available due to the damage tothe compact generator that had been
restored the previous day.
It was reported
to the Emergency Countermeasures Headquarters that preparation of a power
supply for the standby liquid control system (hereafter the “SLC”) that had
received transmitted electricity from a power source car would need new
preparation. Under circumstances where the cause of the explosion remained
unknown, the Emergency Countermeasures Headquarters continued checking
employees and workers for safety, rescuing the injured, and writing tasks for work sites, etc. Under these circumstances, however, there was an urgent need to resume water injection into the reactor. At 16:15 on March 12, we decided to go to the work site to check whether the fire engine was available.
・ At 16:17 on March 12, it was confirmed that monitoring post No. 4 indicated
569μSv/h at 15:31, which was a specified event subject to Article 15 of the Nuclear Disaster Prevention Act and accordingly reported to the competent government departments and agencies. (At 16:53 on March 12, the report was corrected, stating that the radiation dose had been 1,015μSv/h at 15:29.)
At 17:20 on March 12, the ceiling of the Reactor Building of Unit 1 was lost in the explosion, whereupon the spent fuel pool on the 5th floor was exposed. Thus, the Emergency Countermeasures Headquarters decided to use a helicopter to check the condition of the spent fuel pool the following day when it became light.
The surrounding area of Unit 1 showed scattered debris with high radiation dose.
Under the supervision of the security team, the fire brigade cleared the scattered debris (iron plates, etc. around the Reactor Building of Unit 1) and promoted the re-laying hoses by gathering them from outside hydrants.
・ The fire brigade succeeded in connecting three fire engines in series to form a water injection line, using the reversing valve pit of Unit 3 as a water source. The fire brigade started seawater injection at 19:04 on March 12.

Activities after “16:36 of March 11 when deciding and reporting on the Inability of the Emergency Core Cooling System to Inject Water”

・ Operators at the Main Control Room took out the accident management (hereafter
“AM”) operation procedural description and put on the shift supervisor seat to check the content. In addition, together with the valve checklist, operators started to confirm the valves needed for venting and their locations.
・ While watching the AM operation procedural description, the power generation team started to study the venting operation in case no power supply was available.
・ The recovery team examined related drawings and made inquiries with contractor
companies to check whether the type and structure of the vent valve (air-operated valve (hereafter “AO valve”)) of the suppression chamber (hereafter the “S/C”) needed for venting operation would allow manual operation. Based on the drawing, the team confirmed the presence of a handle attached to the S/C small vent valve (AO valve) that is available for manually “opening” operation, which was reported to the Main Control Room.
[Radiation dose started increasing in the building]
・ At 21:51 on March 11, entrance to the Reactor Building was prohibited because the radiation dose in the building rose.
[Rise in drywell (hereafter the “D/W”) pressure confirmed]
・ At around 23:50 on March 11, when a member of the recovery team in the Main
Control Room connected a compact generator, installed for temporary restoration of lighting for the Main Control Room, to the D/W pressure meter in the Main Control Room, the value indicated 600kPa[abs] in confirmation. It was reported to the Emergency Countermeasures Headquarters.
Activities after “0:06 of March 12 when the Site Superintendent instructed for
preparation … because of the possibility of the D/W pressure having exceeded
600kPa[abs]”
[Starting to study specific venting procedure]
At around 1:30 on March 12 when the Emergency Countermeasures Headquarters
proposed the venting operation to the Prime Minister, the Minister of Economy, Trade and Industry, and the Nuclear and Industrial Safety Agency, the headquarters obtained their approval. The Head Office Disaster Control HQ notified the Emergency Countermeasures Headquarters that the Emergency Countermeasures Headquarters strongly wished to operate the motor-operated valve (hereafter the “MO valve”) by any means. The Minister of Economy, Trade and Industry and TEPCO are going to announce a venting operation at 3:00. Venting shall be operated after the announcement.”

At 2:30 on March 12, it was confirmed that the D/W pressure had reached
840kPa[abs] (maximum allowable working pressure 427kPa[gage]*).
* Maximum allowable working pressure 427 kPa[gage] is 528.3kPa[abs] when
converted into absolute pressure)(528.3kPa[abs] = 427kPa[gage] + 101.3kPa)

At around 3:45 on March 12, the Head Office Disaster Control HQ conducted a surrounding radiation dose assessment on the venting operation and shared the detailswith the Emergency Countermeasures Headquarters. When the double doors of the Reactor Building were opened to measure the radiation dose inside, operators saw white “fumes” inside and immediately closed the double doors, hence the radiation dose was not measured.

end selected brief quotes.

Continued Next post.