Sens. Tom Carper, D-Delaware, and Sheldon Whitehouse, D-Rhode Island, sent a letter on April 1 to Nuclear Regulatory Commission Chairman Kristine Svinicki requesting additional details and documents to shed light on the NRC’s decision to drop mandatory seismic and flood risk testing requirements in their January finalized rule responding to the 2011 Fukushima nuclear disaster.

Svinicki and all NRC commissioners testified April 2 at an EPW oversight hearing examining NRC’s work.

In the proposal, the NRC required the nuclear industry to take mandatory actions to address seismic or flooding concerns that may not have been known at the time the reactor’s license was issued. Two years after a final rule with these mandatory requirements was sent to the commission for approval, the NRC finalized a rule that looked remarkably different than the proposal. Under the chairman’s direction, the NRC decided to make mandatory safeguards against seismic and flooding hazards voluntary in the finalized rule. These changes do not seem to be made as a result of recommendations from career NRC staff or apparent opposition throughout the comment period from any stakeholder, including industry.

In the letter, Carper and Whitehouse express dismay at this decision, which disregards years of staff research and lessons learned from the Fukushima disaster, and demand documents that could elucidate the NRC’s decision-making process.

“We are concerned that changes from the proposal, issued in 2015, unnecessarily backtracks from critical safety requirements to protect our nuclear reactors against the flooding and seismic hazards that they face today and in the future,” wrote Carper and Whitehouse. “In the final rule, NRC decided to ignore staff recommendations and make preventive actions to address beyond-design flooding and seismic events voluntary. Most of industry has already addressed these issues, but not requiring mandatory action to continually address the two main issues that arose during Fukushima seems very concerning. These concerns are also reflected in the votes submitted by your colleagues, Commissioners Baran and Burns. What is most peculiar is that when our staff asked the NRC about any public comments calling for these changes, they were told there were none. From what our staff have found, there seem to be no calls from outside groups or from career staff asking for the weakening of this rule.”

The text of the letter is available at bit.ly/2Vg24pc.