Unsuccessful Attempts to Remove a Midcase from an Assembly BWXT-Pantex; Investigation Summary Report NTS-ALO-AL-BWXP-Pantex-2005-0007

Washington DC: U. S. Department of Energy, Office of Price-Anderson Enforcement, 2006. Presumed First Edition, First printing. Spiral bound wraps. Good. [2], 10, [1] single-sided pages. Clear plastic covers. Rear cover and last sheet have a corner creased. Together with a two page (single-sided) transmittal letter dated May 10, 2006 from Stephen M. Sohinki, Director, Office of Price-Anderson Enforcement to Dan J. Swaim, General Manager, BWXT Pantex L.L.C. There were three unsuccessful attempts to remove a midcase from an assembly at the Pantex Plant between March 30, 2005 and April 26, 2005. This document addresses the investigation of the facts and circumstances surrounding these unsuccessful attempts. The investigation concluded that violations of DOE nuclear safety requirements (Quality Assurance Requirements) apparently occurred. The transmittal letter had the Investigation Summary Report enclosed and called for an enforcement conference to be held. BWXT-Pantex (BWXT) was the prime contractor responsible for nuclear weapons assembly and disassembly, evaluation of weapons, high explosive research and development, and interim plutonium pit storage at the Pantex Plant. On March 30, 2005 Production Technicians (PT) attempted to remove the midcase from the assembly of a weapon. Prior to this attempt approximately 60 midcase removals had occurred without incident. Believing separation had occurred, the PTs turned the jackscrew and began raising the midcase. The PTs noticed that the high explosive was still attached to the midcase and that damage to the weapon was evident. A maximum force of 3750 lbf had been applied which exceeded the procedural limit of 3400 lbf. A post event analysis of the clutch mechanism revealed that it had slipped. A positive Unreviewed Safety Question Determination (USQD) was declared as a result of the unanalyzed disassembly point.