235U and TRU Holdup Measurements on the 321-M Sawbenches

Dewberry, R

Savannah River Site (S.C.)

关键词: Sodium Iodides;    Neptunium;    Actinides;    Germanium;    22 General Studies Of Nuclear Reactors;   

DOI  :  10.2172/890222
RP-ID  :  WSRC-TR-2004-00147
RP-ID  :  DE-AC09-96SR18500
RP-ID  :  890222

美国|英语

来源: UNT Digital Library

【 摘 要 】

The Analytical Development Section of Savannah River Technology Center (SRTC) 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 & Accountability, and to meet criticality safety controls. This report covers holdup measurements on two sawbench components that were used for cutting U-Al fuel rods. The benches contained U-Al residue scattered on the bench tops and bagged up in plastic containers. It was very important to obtain an estimate of the HEU content of this residue in order to remove criticality concerns before vacuuming it into a much smaller volume. 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 Np-237 and Am-241 that were observed in these components. 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 components to disposition the saw benches 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 < 0.8 mg on each of the two bench tops and < 3 {micro}g in the bag of chips. The reported values for Am-241 are < 500 ng on the two bench tops and < 15 ng in the bag of chips. Our results demonstrate an upper limit of {sup 235}U content of 0.4 g on the two benchtops and of 0.1 mg in the bag of chips. These reported values completely eliminated the criticality concerns. 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 saw benches.