NRC updates earthquake risk analysis schedule

The US Nuclear Regulatory Commission (NRC) program to analyse earthquake risk at US nuclear plants will be completed sooner than planned after the regulator found that in-depth studies are needed at fewer plants than originally thought.

All of the USA's operating nuclear plants were required to re-evaluate their seismic hazard information as part of the ongoing learning process following the 2011 Fukushima Daiichi accident in Japan. The NRC completed initial reviews of submittals for the 60 reactor sites in central and eastern USA in May 2014 and for the three reactor sites in the more geologically complex western region earlier this year, drawing up a list of 33 power reactor sites which were required to carry out further in-depth risk analysis.

However, the NRC has now completed its full review of the updated hazard information, as well as considering earlier probabilistic risk assessments related to seismic hazards, and concluded that thirteen sites with low to moderate re-evaluated risks are no longer expected to perform an in-depth analsysis. It has drawn up a revised submittal schedule for the completion of the studies at the 20 sites remaining on the list. The first studies are now expected to be completed up to three months earlier than originally scheduled. The revised schedule sees the completion of all submissions by the end of 2019, up to a year ahead of earlier deadlines for some plants.

"Our substantial reviews have shown that fewer reactors than we first thought actually need the in-depth analysis," said Bill Dean, director of the NRC's Office of Nuclear Reactor Regulation. "This outcome means both the NRC and industry can better focus their seismic expertise to work on the plants most in need of additional analysis," he added.

The regulator also reviewed plants' evaluations of any interim measures necessary pending the completion of an in-depth analysis, and "continues to conclude" that US reactors are safe to continue operating while the analyses are carried out.

The first submittal deadline under the revised schedule is for Vogtle, by the end of March 2017. Indian Point unit 2, Watts Bar, Beaver Valley, Diablo Canyon, Callaway and Pilgrim have also been given deadlines during 2017, while North Anna, Peach Bottom, DC Cook, Indian Point 3, Summer and Oconnee have 2018 deadlines. Columbia, Robinson, Dresden, Catawba, Palisades, Browns Ferry, McGuire and Sequoyah must complete their studies by deadlines in 2019.

Researched and written
by World Nuclear News