Los Alamos National Laboratory’s PF-4 Plutonium Processing Facility is structurally sound enough to withstand potential seismic events, the Defense Nuclear Facilities Safety Board found in a recent study of the building.
The Defense Nuclear Facilities Safety Board (DNFSB) has worked with the Department of Energy on the seismic safety of PF-4 and Los Alamos since laboratory personnel first identified elevated seismic hazards in 2009, board chair Joyce Connery wrote in an Aug. 15 letter to Secretary of Energy Jennifer Granholm.
A Los Alamos team recently completed a “probabilistic risk analysis” and concluded that the seismic safety risk at PF-4 is acceptable, for now, Connery wrote. A new, site-specific seismic hazard study is due in 2025 when the facility should be largely rehabbed and updated in preparation for producing at least 30 plutonium pits a year for use as the primary stages for nuclear weapons.
“The Board finds that the conclusions of the LANL project team were technically defensible and that the accompanying peer review process was robust. However, DOE would benefit from improving documentation of the effort,” Connery’s letter said.
To meet the 30-pit-per-year goal sometime before 2030, the lab is in the process of replacing many of its plutonium-handling gloveboxes, including boxes designed to withstand seismic activity. The Exchange Monitor saw an example of these sturdier gloveboxes, with thicker, seismic-attenuating legs, during a recent tour of the facility.
DNFSB considers the lab’s approach to assessing seismic risk for PF-4 a best practice that DOE should consider applying at other defense nuclear facilities, the board said. Lab personnel followed a risk-informed approach like the one that the Nuclear Regulatory Commission adopted for the commercial nuclear industry, Connery said in her letter.
The risk analysis provided information on the likelihood of PF-4 failing to perform its credited safety function, considering all potential earthquake scenarios at the LANL site.
“This was a commendable effort, representing a comprehensive application of such an approach for a defense nuclear facility,” Connery wrote.
The DNFSB in June 2021 issued a seismic hazards assessments technical report that identified concerns regarding other aspects of DOE’s approach to seismic safety. One concern was ensuring that DOE sites properly apply the unreviewed safety question process following updates to the probabilistic seismic hazard analysis.
In May DOE issued a document to all its sites clarifying that an increase in seismic hazard not covered by the approved safety analysis should follow the unreviewed safety question process as advised by DNFSB.
