W54

The W56 Minuteman II warhead is being disassembled and will continue at least through FY 2005. The Moscow Treaty's flexibility regarding warhead disposition recognizes that the United States and Russia have fundamentally different stockpile maintenance practices. Key to the difference is that Russia continued to produce new warheads while the United States currently has no capacity to manufacture nuclear weapons.

In 1999 the Defense Nuclear Facilities Safety Board (Board) recently reviewed the Weapon Safety Specification (WSS) for the W56 dismantlement program. The WSS plays an important role in safe nuclear weapons operations at the Pantex Plant as defined by the DOE Albuquerque Field Office in Appendix 56XB, Development and Production Manual: to ensure that lessons learned from surveillance program data and relevant as-built information are properly incorporated in the Seamless Safety for the 21st Century (SS-21) process at the Pantex Plant, and to provide essential information for the safety basis documentation.

In essence, the function of the WSS is to identify hazards inherent in the weapon itself, and to provide a summary of the analyses concerning mechanical, electrical, thermal, and chemical insults to a nuclear weapon. This information is drawn from design drawings, baseline process flows, use control reports, criticality reports, intrinsic radiation reports, and past surveillance data that are pertinent to safety. The as-built information provided in the WSS should pertain to the characteristic design features, safety attributes, and hazards for a nuclear weapon or family of similar nuclear weapons. In addition, skills and knowledge drawn from individuals involved with initial production, surveillance operations, system modification operations, and disassembly operations are also key features of an adequate WSS. The document is intended as a tool to facilitate interactions with the Pantex contractor during the development of the authorization basis. The WSSs are also to be reviewed and updated (if needed) annually. The design agencies are the principal authors of the WSS.

In light of difficulties with stuck threads on the W56 warhead radiation case, the staff reviewed the W56 WSS for historical data that could provide insight on this problem. This review was augmented by observations of the staff and the Board's outside expert of interactions between the W56 Project Team and Y-12 staff with expertise in bimetallic joints. The surveillance history summary in the WSS provides a list of Unsatisfactory Reports and SFIs and states that none of these were safety-related. This summary fails to disclose a worker safety issue related to a fire hazard that is documented in the Y-12 hazard analysis and could be relevant to safety at the Pantex Plant.

Given that the W56 was in the stockpile for more than 25 years, one would expect a historical overview of the type and characteristics of the tooling used during the life of the program. Archival information of this nature would have been helpful in safety reviews of the modern tooling developed under the SS-21 process for W56 dismantlement. In addition, any SFI reports of operational difficulties related to the bimetallic joint would have provided additional insight, even if they had not been classified as safety-related when they were written. Finally, a more thorough effort to document the experiences of Pantex Production Technicians would have been helpful in identifying potential pitfalls.