The National Nuclear Security Administration (NNSA) believes it can safely continue building the Uranium Processing Facility, and operate it starting this decade, after taking a court-ordered look at federal earthquake data from 2014.

In a lawsuit filed by environmental groups, the U.S. District Court for Eastern Tennessee last year ordered the semiautonomous Department of Energy nuclear weapons agency to use the seismic data from the U.S. Geological Survey to prepare a supplemental analysis to a 2011 NNSA environmental impact statement for uranium hub being built at the Y-12 National Security Complex at Oak Ridge, Tenn.

In a draft of that supplemental analysis, published online and dated April 9, the NNSA said its review of the 2014 seismic data determined that “the potential impacts associated with an earthquake accident at [the Y-12 National Security Complex] would not be significantly different” than those the agency already considered in 2011, in the Final Site-Wide Environmental Impact Statement for the Y-12 National Security Complex.

In that earlier document, the NNSA said “minor to moderate damage could typically be expected from an earthquake” at Y-12.

The plaintiffs in the lawsuit — the Oak Ridge Environmental Peace Alliance, Nuclear Watch New Mexico, and the Natural Resources Defense Council — argued the agency should have prepared a supplemental environmental impact statement after formalizing in 2016 a decision to split the manufacturing hub for weapons second stages into three buildings from one. A supplemental environmental impact statement involves a mandatory public comment period and could conceivably take years to prepare, compared with months for a supplement analysis.

The groups said splitting the UPF meant the NNSA would continue to rely on certain Cold War-era buildings for decades longer than would have been necessary if it had built a large facility that could sponge up their missions.

The plaintiffs were also upset that the NNSA did not halt construction of the Uranium Processing Facility while it prepared the supplement analysis. The agency continued building the facility after Chief Judge Pamela Reeves handed down her order, and continues to do so, even amid the COVID-19 pandemic.

The plaintiffs argued that a construction pause was implicit in Reeves’ order in the trial court, but Reeves was silent on the matter. The NNSA hopes to finish construction by December 2025 at a cost of no more than $6.5 billion.

The plaintiffs have already lodged an appeal in the case. This week, they said the NNSA should hold a public hearing on the draft supplement analysis, and indefinitely postpone the public comment period on the document.

The draft supplement analysis “postulates significant increases in risks to the public since the last time DOE/NNSA held a public meeting, ten years ago, on its plans for modernization of the enriched uranium program at Y-12,” the Oak Ridge Environmental Peace Alliance stated. “In light of this, the NNSA and DOE have a responsibility to address the people of Oak Ridge and Knoxville.”