B83 Modern Strategic Bomb
In 1983, the US nuclear arsenal acquired the B83 strategic nuclear gravity bomb. The B-52H, B-1B, and B-2 bombers all can carry it. The B83 has delivery and fuzing options that include free-fall air or ground burst, retarded air burst, and retarded ground burst or delayed ground burst (or "laydown"). These capabilities make this bomb a full fuzing option (FUFO) weapon.
In 1999 the Defense Nuclear Facilities Safety Board (Board) recently reviewed the Weapon Safety Specification (WSS) for the B83. 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.
The B83 is one of the most modern nuclear weapons in the stockpile. It is considered inherently safe by DOE as compared with older nuclear weapons. The weapon has an insensitive high explosive (IHE) main charge and fire-resistant pit features. However, the detonators consist of a more sensitive conventional high explosive. Yet the WSS asserts that it is acceptable to use IHE handling procedures and controls.
According to the WSS, there are no known safety issues associated with the B83. The Stockpile Surveillance Program has identified no safety findings. However, the WSS states that the emphasis on development testing and design details, materials testing and certification, and production quality control (reliability) is insufficient to ensure high quality and reliability of the nuclear assembly components during the projected stockpile lifetime of several decades. This lack of data to determine performance might imply the same lack of basis to determine safety. No information was provided in the following three sections of the report, which are marked "TBD (to be determined).: Appendix B, "Review of Pantex Assembly Operations"; Appendix C, "Review of Pantex Disassembly Operations"; ! Appendix D, "Pantex B83 Archiving Methodology" At a minimum these sections would be expected to include tooling, processes, and lessons learned, which are not currently discussed in the WSS. The WSS cited a number of safety-related recommendations for which there is no disposition. The following are examples of these recommendations: There is a need to better characterize lightning arrest connector performance in thermal and crush environments. There is a need to better characterize the mechanical strength of the MXB-71 phenolic firing set case material to determine its performance at elevated temperatures. Use of a relief valve or rupture disc design to avoid disassembly of the nuclear system and bomb electrical system in fires should be investigated. As new B83 drawings are issued or revised, Pentagon S (/S/) callouts for nuclear safety-critical items should be included. The incomplete sections of the WSS and the inclusion of open-ended recommendations showed inadequate follow through on DOE's Implementation Plan for Recommendation 93-6, Maintaining Access to Nuclear Weapons Expertise in the Defense Nuclear Facilities Complex. Revision 1 of the implementation plan, dated January 30, 1996, clearly states that the WSS will be the single source document for all safety-related information and identifies the requirements for capturing safety-relevant information in the WSS.
In 2001 the B83 Systems Engineering group at Sandia completed development of Alt 355 for the B83 Modern Strategic Bomb. Alt 355 is a near-term field retrofit kit that incorporates design modifications to the present B83-0/1 Gas Transfer System (GTS) hardware. It is the first Alt to complete the stringent Phase 6.X process. Also, a series of field tests were conducted, in conjunction with Alt 355, using two B83 Transportation Environmental Sampling Units (TESU). Both TESU test units were equipped with a data acquisition system and used to collect vibration and shock data during a variety of transportation scenarios. The data were used to compare Stockpile-to-Target Sequence specified levels for these environments. The Stockpile-To-Target-Sequence specified environments were shown to govern and remain unchanged.
A new high-G shock test method using the Sandia rocket sled track was invented, developed, and qualified in 2002 by Sandia for assessing weapons component subassemblies for survivability in penetration environments. The test capability enables Sandia to respond quickly and less expensively to future weapon requirements. Both W87 and B83 subsystems have been tested against the simulated hard target penetration shock delivered by this novel test method. A second method to test full systems impacting concrete targets under controlled impact conditions is under development.
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