Gamma-Ray Holdup Measurements of U-235, Np-237, and Am-241 Content in the C and D Out-gassing Ovens in the Deactivation and Decommissioning Activities in 321-M

RAYMOND, DEWBERRY

Savannah River Site (S.C.)

关键词: Multi-Channel Analyzers;    Ovens;    12 Management Of Radioactive Wastes, And Non-Radioactive Wastes From Nuclear Facilities;    Deactivation;    Personal Computers;   

DOI  :  10.2172/840796
RP-ID  :  WSRC-TR-2004-00002
RP-ID  :  AC09-96SR18500
RP-ID  :  840796

美国|英语

来源: UNT Digital Library

【 摘 要 】

The Analytical Development Section of Savannah River National Laboratory (SRNL) was requested by the Facilities Disposition Projects (FDP) to determine the holdup of enriched uranium in the 321-M facility as part of an overall deactivation project of the facility. The 321-M facility was used to fabricate enriched uranium fuel assemblies, lithium-aluminum target tubes, neptunium assemblies, and miscellaneous components for the production reactors. The results of the holdup assays are essential for determining compliance with the Waste Acceptance Criteria, Material Control and Accountability, and to meet criticality safety controls. This report covers holdup measurements in the C and D out-gassing ovens that were used to remove gas entrained in billet assembly material prior to the billets being extruded into rods by the extrusion press. A portable high purity germanium (HPGe) detection system and a portable sodium iodide (NaI) detection system were used to determine highly enriched uranium (HEU) holdup and to determine holdup of Np-237 and Am-241 that were observed in these components. The HPGe detector was run by an EG and G Dart (TM) system that contains the high voltage power supply and signal processing electronics. A personal computer with Gamma-Vision software was used to control the Dart (TM) MCA and provide space to store and manipulate multiple 4096-channel spectra. The NaI detector was run with a Canberra NaI plus MCA card that converts a personal computer to a full function multichannel analyzer and with Canberra Genie-2000 acquisition and analysis software. The measured Np-237 and Am-241 contents were especially important in these components because their presence is unusual and unexpected in 321-M. It was important to obtain a measured value of these two species to disposition the out-gassing ovens and to determine whether a separate waste stream was necessary for release of these contaminated components to the E-Area Solid Waste Vault. The reported values for Np-237 are (17 plus or minus 7) mg in oven C and less than 0.5 mg in oven D. The reported values for Am-241 are (1.3 plus or minus 0.2) in oven C and less than 400 ng in oven D. Our results indicate an upper limit of U-235 content of 0.2 g for oven C and (0.105 plus or minus 0.048) g in oven D. This report discusses the methodology, non-destructive assay (NDA) measurements, and results of the holdup measured for each of the three actinide species in these out-gassing ovens.