Staff Reports
NS&D Monitor
2/13/2015
The Defense Nuclear Facilities Safety Board is raising a number of seismic safety issues at two Y-12 production facilities—Beta-2E and Building 9215—that have become integral to the National Nuclear Security Administration’s revised strategy for scaling back the scope of the Uranium Processing Facility and getting out of the decrepit 9212 complex as soon as possible. In order to make the revised UPF strategy work, NNSA is proposing to extend the life of Beta-2E and Building 9215 and possibly add missions to their current activities, and the safety board is pointing out a number of potential pitfalls—especially the structural concerns in the event of a major earthquake. “Building 9204-2E (Beta-2E) and the 9215 Complex have known structural performance deficiencies and do not meet modern structural design requirements,” DNFSB Vice Chairman Jessie Roberson said in a Feb. 4 letter to NNSA Production Office Manager Steve Erhart. “These deficiencies result in an increased potential for structural collapse and release of radiological material following certain seismic events.”
According to a new DNFSB review of Beta-2E and 9215, the remaining operational life of the two buildings under the new UPF strategy is now approaching the life assumed for new designs. Therefore, the DNFSB is recommending NNSA consider an updated analysis of the buildings using more accurate modeling techniques. “The current evaluations of the 9215 Complex and Building 9204-2E do not consider the large extension of their operational lifespans and fail to explicitly acknowledge the impact of the lack of structural ductility on each building’s design margin, particularly for the 9215 Complex,” the DNFSB said in a report accompanying Roberson’s letter.
With New Strategy, Risk Profile for Buildings Has Changed
The DNFSB staff report evaluated the deficiencies as they exist and how the risks have been assessed. NNSA, she noted, had previously accepted the risks for near-term work at the two facilities because of the overall plan to consolidate virtually all of Y-12’s work inside the completed UPF. With the new strategy, however, the safety board emphasizes how the risk profile has changed and how previous evaluations need to be updated.
Roberson said the latest DNFSB review was designed to get the safety board up to speed on the potential concerns at 9215 and Beta-2E and to pass along the technical information to NNSA to use “for possible life extension and mission capability additions.” The staff report cites structural and technical issues in the two buildings that are old but not as old as the notorious 9212 complex and vulnerable to seismic events. Beta-2E was completed in November 1969 and Building 9215 was completed in November 1956. “The designs of the 9215 Complex and Building 9204-2E do not include the ductile design concepts that are used in modern structural design, and thus lack seismic margin to collapse compared to a contemporary structure,” the DNFSB said. “This weakness was acknowledged by B&W (the former contractor at Y-12) engineers, who used full elastic demands to qualify non-ductile structural components. Should seismic demands exceed the elastic capacities of certain structural members, undesirable failure modes may be triggered such as column or joint failures that can rapidly lead to progressive collapse.”
