50 years after need identified, US NRC demands reactor venting changes to prevent reactor explosions


The Times Herald


LIMERICK — In an effort to prevent hydrogen explosions like the one that destroyed parts of Japan’s Fukushima nuclear plant two years ago, the government is requiring 31 U.S. nuclear plants with a similar reactor design to install an upgraded ventilation system in six years.

The order, issued June 6, applies to GE Mark I and Mark II Boiling Water Reactors. The two nuclear reactors at Exelon Nuclear’s Limerick Generating Station are of the Mark II design.

This new order supersedes one issued in March 2012 , which also required new venting systems.

The new order “contains more specifics on what Mark 1 and 2 Boiling Water Reactor (BWR) owners must do to meet our new requirements for reliable hardened vents,” Nuclear Regulatory Commission, spokesman Neil Sheehan wrote in an e-mail to The Mercury.

The requirements “include having vents capable of handling the pressures, temperatures, hydrogen concentrations and radiation levels that would be expected to result from a damaged reactor. The enhancements also ensure plant personnel can operate the vents safely if the reactor core is damaged,” he wrote.

“The accident at the Fukushima Dai-ichi power station reinforced the importance of reliable operation of containment plants for vents with Mark I and Mark II containments,” Eric J. Leeds, director of the office for nuclear regulation for the NRC, wrote in a June 6 order.

The explosions at Fukushima occurred during the earthquake and tsunami-fueled disaster that rocked northern Japan in March, 2011.

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