March 17, 2014

NNSA RESPONDS TO DNFSB SAFETY CONCERNS ON UPF

By ExchangeMonitor

The National Nuclear Security Administration is still analyzing whether portions of the Uranium Processing Facility can withstand an aircraft crash without a release of radiological material, according to a letter recently sent from acting NNSA Administrator Bruce Held to the Defense Nuclear Facilities Safety Board detailing the agency’s response to the Board’s UPF safety concerns. In August, the DNFSB outlined 13 specific concerns in a letter to Held, chief among them a fear that ancillary UPF structures might not be able to withstand an airplane crash. “As you mentioned in your letter, I am also encouraged by the progress that the UPF project has made to improve integration of safety into UPF’s design,” Held said. “I am confident that the UPF project will continue to improve execution of an effective safety basis program that will ensure safety controls are identified and incorporated into design.”

In his Nov. 22 letter, Held confirmed that the main portion of the building is being designed to withstand an airplane crash, but he confirmed that the design of a connector to the Highly Enriched Uranium Materials Facility and other ancillary structures did not meet Department of Energy guidelines. Held said material in the other ancillary structures—like a connector to the administrative portion of the building, a loading dock and truck bay, and enclosed dock and dock vestibule—would be limited to help meet the guidelines, but several options were still being considered for the HEUMF connector. Those include hardening the facility to fully withstand an aircraft impact or implementing controls to limit material in the connector, as well as a middle ground solution that would harden the walls but also limit material. “The structure exceeds the frequency threshold, but the quantities and types of materials present in any given time in the connector are still being determined,” an NNSA analysis attached to Held’s letter indicated.

Held also responded to DNFSB concerns involving fire in canned sub-assemblies; the release of toxic materials; glovebox fires in areas where disassembly and quality evaluation of warhead parts involve highly hazardous and thermally reactive materials; problems associated with a hydrogen explosion in the assembly environmental room, where lithium hydride and lithium deuteride compounds are handled; concurrent releases of multiple hazardous materials in some UPF fire scenarios; steam overpressure in casting furnaces; hydrogen explosion in the hydrogen reduction fluidized bed reactors that is used in enriched uranium purification; violent chemical reactions in the special oxide production processes; and dust explosions.

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