Authorized Limits for the Release of a 25 Ton Locomotive, Serial Number 21547, at the Area 25 Engine Maintenance, Assembly, and Disassembly Facility, Nevada Test Site, Nevada

Jeremy Gwin and Douglas Frenette

关键词: CONTAMINATION;    DECONTAMINATION;    LOCOMOTIVES;    NEVADA TEST SITE;    RADIOACTIVITY;    RELEASE LIMITS;    RADIATION PROTECTION;    CULTURAL OBJECTS locomotive;    radiological;    decontamination;   

DOI  :  10.2172/979387
RP-ID  :  DOE/NV/25946--943
PID  :  OSTI ID: 979387
Others  :  TRN: US1100033

学科分类：核能源与工程

美国|英语

来源: SciTech Connect

【 摘 要 】

This document contains process knowledge and radiological data and analysis to support approval for release of the 25-ton locomotive, Serial Number 21547, at the Area 25 Engine Maintenance, Assembly, and Disassembly (EMAD) Facility, located on the Nevada Test Site (NTS). The 25-ton locomotive is a small, one-of-a-kind locomotive used to move railcars in support of the Nuclear Engine for Rocket Vehicle Application project. This locomotive was identified as having significant historical value by the Nevada State Railroad Museum in Boulder City, Nevada, where it will be used as a display piece. A substantial effort to characterize the radiological conditions of the locomotive was undertaken by the NTS Management and Operations Contractor, National Security Technologies, LLC (NSTec). During this characterization process, seven small areas on the locomotive had contamination levels that exceeded the NTS release criteria (limits consistent with U.S. Department of Energy [DOE] Order DOE O 5400.5, ???Radiation Protection of the Public and the Environment???). The decision was made to perform radiological decontamination of these known accessible impacted areas to further the release process. On February 9, 2010, NSTec personnel completed decontamination of these seven areas to within the NTS release criteria. Although all accessible areas of the locomotive had been successfully decontaminated to within NTS release criteria, it was plausible that inaccessible areas of the locomotive (i.e., those areas on the locomotive where it was not possible to perform radiological surveys) could potentially have contamination above unrestricted release limits. To access the majority of these inaccessible areas, the locomotive would have to be disassembled. A complete disassembly for a full radiological survey could have permanently destroyed parts and would have ruined the historical value of the locomotive. Complete disassembly would also add an unreasonable financial burden for the contractor. A decision was reached between the NTS regulator and NSTec, opting for alternative authorized limits from DOE Headquarters. In doing so, NSTec personnel performed a dose model using the DOE-approved modeling code RESRAD-BUILD v3.5 to evaluate scenarios. The parameters used in the dose model were conservative. NSTec???s Radiological Engineering Calculation, REC-2010-001, ???Public Dose Estimate from the EMAD 25 Ton Locomotive,??? concluded that the four scenarios evaluated were below the 25-millirem per year limit, the ???likely??? dose scenarios met the ???few millirem in a year??? criteria, and that the EMAD 25-ton locomotive met the radiological requirements to be released with residual radioactivity to the public.