Confinement Vessel Assay System: Calibration and Certification Report

Frame, Katherine C.¹  Bourne, Mark M.¹  Crooks, William J.¹  Evans, Louise¹  Gomez, Cipriano²  Mayo, Douglas R.¹  Miko, David K.¹  Salazar, William R.¹  Stange, Sy¹  Vigil, Georgiana M.¹ 

[1] Los Alamos National Laboratory;Retired CMR-OPS: OPERATIONS

关键词: CALIBRATION;    CONFINEMENT;    CONTAMINATION;    LANL;    PLUTONIUM;    SAFEGUARDS;    SPALLATION;    STEELS;    VERIFICATION;   

DOI  :  10.2172/1046537
RP-ID  :  LA-UR-12-23092
PID  :  OSTI ID: 1046537
Others  :  TRN: US1203822

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来源: SciTech Connect

【 摘 要 】

Los Alamos National Laboratory has a number of spherical confinement vessels (CVs) remaining from tests involving nuclear materials. These vessels have an inner diameter of 6 feet with 1 to 2 inch thick steel walls. The goal of the Confinement Vessel Disposition (CVD) project is to remove debris and reduce contamination inside the vessels. The Confinement Vessel Assay System (CVAS) was developed to measure the amount of SNM in CVs before and after cleanout. Prior to cleanout, the system will be used to perform a verification measurement of each vessel. After cleanout, the system will be used to perform safeguards-quality assays of {le} 100-g {sup 239}Pu equivalent in a vessel for safeguards termination. The system was calibrated in three different mass regions (low, medium, and high) to cover the entire plutonium mass range that will be assayed. The low mass calibration and medium mass calibration were verified for material positioned in the center of an empty vessel. The systematic uncertainty due to position bias was estimated using an MCNPX model to simulate the response of the system to material localized at various points along the inner surface of the vessel. The background component due to cosmic ray spallation was determined by performing measurements of an empty vessel and comparing to measurements in the same location with no vessel present. The CVAS has been tested and calibrated in preparation for verification and safeguards measurements of CVs before and after cleanout.