US Particulate and Xenon Measurements Made Following the Fukushima Reactor Accident

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US Particulate and Xenon. Measurements Made Following the. Fukushima Reactor Accident. 1 Pacific Northwest National Laboratory, Richland, Washington, …
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US Particulate and Xenon
Measurements Made Following the
Fukushima Reactor Accident

1 Pacific Northwest National Laboratory, Richland, Washington, USA
2 The University of Texas at Austin, Austin, Texas, USA
INGE 2011 Yogyakarta Workshop,
Justin McIntyre1, Steve Biegalski2, Ted Bowyer1, Matt Copper1, Paul
Eslinger1, Jim Hayes1, Derek Haas1, Harry Miley1, J.P. Rishel1, Vincent
Woods1

“Views expressed here do not necessarily reflect the
opinion of the United States Government, the United
States Department of Energy, or the Pacific Northwest
National Laboratory.”

Event
Network
Atmospheric Transport
Detections
Isotopic Ratios
Conclusions
Outline
Material in this presentation is covered in more depth in the following journal submissions.
S. Biegalski, et al., US Particulate and Xenon Measurements Made Following the Fukushima Reactor Accident, accepted
for publication in Jour. of EnvirRadioactivity, 2011
T. Bowyer, et al., Elevated Radioxenon Detected Remotely Following the Fukushima Nuclear Accident. Jour. of Envir.
Radioactivity 102 (7):681-687. doi:10.1016/j.jenvrad.2011.04.009
P. Eslinger, et al., Source Term Estimation of Radioxenon Released from the Fukushima Daiichi Nuclear Reactors Using
Measured Air Concentrations and Atmospheric Transport Modeling, to be submitted in Jour. of Envir. Radioactivity, 2011

Page 4 skipped – it contains a representation of the NOAA data which is oceanographic, not radiological and which people confuse, so I am not putting it here.

Page 5 – a sectional view of GE Mk1 in which the illustrator failed to show the bottom up control rods.

Fukushima Radioactive Release Timeline

(authors forget to include the word “substances” – should read Fukushima Radioactive Substances Release Timeline)

Evidence of radionuclide
released reached the
Japanese IMS station
within 2-3 days

First evidence of the plume
hitting the United States
came to PNNL’s
experimental equipment
about 1 day later (March
16)
(plus graph)

Page 7 map of US Radionuclide Stations.

First detection of radioxenon in US at Richland WA

Xenon-133 measurements
were x450,000 our detection
levels using a SAUNA-II
xenon measurement system
Noble gas does not “wash-
out,” and is the first emitted
from any possible fuel
damage
Levels persisted for weeks
and isotopes were ultimately
detected across the northern
hemisphere and around the
world
U.S. IMS Station Detections

U.S. stations detected both
particulate and noble gas
emitted from the event.
Initial 133Xe detections in
Richland, WA (non-IMS
station) were on March 16,
2011.
Several volatile radio-isotopes
were detected
Missing were several
isotopes that were highly
indicative of a nuclear
explosion
(plus particulate radionuclide graph) ( (page 9 of 27)

Page 10 I131 concentrations: Sacramento, CA, Melbourne, FL, Upi, Guam, Charlotteville, VA.

Page 11 Activity Concentration graphic

Page 12 I131 Activity Concentration graph

SCALE6/ORIGEN-ARP models were conducted to model
predicted isotopic ratios (same models used for inventory
calculations).
Comparisons were made between model and measurements.
Good comparison adds validity to models and to
measurements.
Shows that all stations are measuring the same event.
Isotopic Ratios

Isotopic Ratios

SCALE6/ORIGEN-ARP models were conducted to model
predicted isotopic ratios (same models used for inventory
calculations).
Comparisons were made between model and measurements.
Good comparison adds validity to models and to
measurements.
Shows that all stations are measuring the same event. (page 13)

I 133 /I 131 Activity Ratios Graph (Indicative of gases releases) (page 14)

Cesium 134/ Cesium 137 Isotopic ratio graph (page 15)

Cesium 136/ Cesium 137 Isotopic activity ratio graph (page 16)

Xenon 134/ Xenon 131m Isotopic activity ratio graph (page 17)

Aerosol Observations/ Lessons Learned
Aerosol Network Take Away Points
Network worked as planned
Event was equivalent to a 20kT above-ground nuclear explosion
Indicates network is capable across at least 5 orders of magnitude for
measured concentrations
Sampling sites were able to report fission products without being overwhelmed,
site closest to accident had trouble because of extremely high activity and power
outages.
Radionuclide concentration analysis clearly indicated that this was a reactor
accident/release.
Isotopes measured are consistent with a nuclear reactor
Lack of short-lived refractory isotopes indicative of a reactor
Nearby stations had significant increases in MDC’s caused by this event, however
ATM allowed predictive plume hits and impact to down wind stations.
Not all of the network was affected all of the time
Need additional analysis to determine how impacted nearby stations were and
would they still be able to detect a 1kT above ground test
Aerosol Observations/ Lessons Learned
Aerosol Network Take Away Points (2)
Potential improvements
Initial RASA measurements were possible before the filter was measured
Detector may need additional shielding from environmental influences
Intermittent power loss was significant at RN-38
Improved mechanisms for recovery from power loss
Takes ~3 days to get sample counted and reported
Need “first look” early response systems with real time measurements (e.g.,
NaI, CsI) for high activity events
Suggest the need for a “emergency situation” software script or state to
reduce per-sample activity (sample for 6, 12, or 24 hours)
Potential to incorporate future accident measurements into existing radiological
safety protocols (discussed at ISS-11)
Not unlike the seismic network tie in after the 2005 Tsunami
Clearly outside of the original scope of the network

onclusions
Radioxenon Network Take Away Points
Network worked as planned
Event was equivalent to a 1Mt below-ground nuclear explosion with
1% leakage
The xenon measurements made by IMS-like equipment were the
highest fidelity measurements made and far superior to what was
available post-Chernobyl
Radionuclide analysis clearly indicates that the plume was from a
nuclear reactor
2 of four radioxenon isotopes were easily detected from the
Fukushima event across the globe.
Xe-135 MDC was only slightly elevated by this event, providing key
indicator of nuclear explosion
Impacted stations are not blinded to underground nuclear
explosions.

as Observations/ Lessons Learned
Radioxenon Take away points (2)
SAUNA dead time observed in samples with elevated count rate and was
significant with very high count rates
Sauna dead time corrections needed
Initial high Xe levels saturated the RN-38 detector so no spectral analysis was
possible
Nuclear detector electronics needs to be updated to handle high count rate
The MDC of the detector was highly effected from high memory effect
Research and implementation on reduction of memory effect necessary (in
progress).
Inconsistencies with meta-stable ratios.
Need to re-analzyedata sets
Need better analysis methods (currently working on SDAT ).
Desire >2X improvement in conversion electron resolution
Xewas first observed at Richland WA which is not part of the IMS network
Need higher density of Xe systems

Conclusions
The IMS network demonstrated that it is capable of measuring
and reporting radionuclides from a single event across the
globe.
Measurements were significantly above the detection limits for
many systems.
Combination of atmospheric transport, radiation detection, and
reactor modeling were fused to provide a picture of the event.
Careful analysis mitigates source blinding
More data analysis is required to demonstrate and further
enhance second event detection.

Page 25 PNNL Aerosol Data

Page 26 I Cs 137 Activity Concentrations

Page 27 Unit 1, 2 and 3 Xenon Inventories

Combining atmospheric transport, ground measurements, and inventory
shows that between 85% and 103% of radioxenon inventory was released
from the three reactors.

End quote.

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