Initial measurements of BN-350 spent fuel in dry storage casks using the dual slab verification detonator

Conference · Fri Jan 01 00:00:00 EST 2010

OSTI ID:1017486

Santi, Peter Angelo ^[1]; Browne, Michael C ^[1]; Freeman, Corey R ^[1]; Parker, Robert F ^[1]; Williams, Richard B ^[1]

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1. Los Alamos National Laboratory

The Dual Slab Verification Detector (DSVD) has been developed, built, and characterized by Los Alamos National Laboratory in cooperation with the International Atomic Energy Agency (IAEA) as part of the dry storage safeguards system for the spent fuel from the BN-350 fast reactor. The detector consists of two rows of 3He tubes embedded in a slab of polyethylene which has been designed to be placed on the outer surface of the dry storage cask. By performing DSVD measurements at several different locations around the outer surface of the DUC, a signature 'fingerprint' can be established for each DUC based on the neutron flux emanating from inside the dry storage cask. The neutron fingerprint for each individual DUC will be dependent upon the spatial distribution of nuclear material within the cask, thus making it sensitive to the removal of a certain amount of material from the cask. An initial set of DSVD measurements have been performed on the first set of dry storage casks that have been loaded with canisters of spent fuel and moved onto the dry storage pad to both establish an initial fingerprint for these casks as well as to quantify systematic uncertainties associated with these measurements. The results from these measurements will be presented and compared with the expected results that were determined based on MCNPX simulations of the dry storage facility. The ability to safeguard spent nuclear fuel is strongly dependent on the technical capabilities of establishing and maintaining continuity of knowledge (COK) of the spent fuel as it is released from the reactor core and either reprocessed or packaged and stored at a storage facility. While the maintenance of COK is often done using continuous containment and surveillance (C/S) on the spent fuel, it is important that the measurement capabilities exist to re-establish the COK in the event of a significant gap in the continuous CIS by performing measurements that independently confirm the presence and content of Plutonium (Pu) in the spent fuel. The types of non-destructive assay (NDA) measurements that can be performed on the spent fuel are strongly dependent on the type of spent fuel that is being safeguarded as well as the location in which the spent fuel is being stored. The BN-350 Spent Fuel Disposition Project was initiated to improve the safeguards and security of the spent nuclear fuel from the BN-350 fast-breeder reactor and was developed cooperatively to meet the requirements of the International Atomic Energy Agency (IAEA) as well as the terms of the 1993 CTR and MPC&A Implementing Agreements. The unique characteristics of fuel from the BN-350 fast-breeder reactor have allowed for the development of an integrated safeguards measurement program to inventory, monitor, and if necessary, re-verify Pu content of the spent fuel throughout the lifetime of the project. This approach includes the development of a safeguards measurement program to establish and maintain the COK on the spent fuel during the repackaging and eventual relocation of the spent-fuel assemblies to a long-term storage site. As part of the safeguards measurement program, the Pu content of every spent-fuel assembly from the BN-350 reactor was directly measured and characterized while the spent-fuel assemblies were being stored in the spent-fuel pond at the BN-350 facility using the Spent Fuel Coincidence Counter (SFCC). Upon completion of the initial inventory of the Pu content of the individual spent-fuel assemblies, the assemblies were repackaged into welded steel canisters that were filled with inert argon gas and held either four or six individual spent-fuel assemblies depending on the type of assembly that was being packaged. This repackaging of the spent-fuel assemblies was performed in order to improve the stability of the spent-fuel assemblies for long-term storage and increase the proliferation resistance of the spent fuel. To maintain the capability of verifying the presence of the spent-fuel assemblies inside the welded steel canisters, measurements were performed on the canisters using the Spent Fuel Attribute Monitor (SPAM), which was a neutron coincidence counter very similar in design to the SFCC, but with a larger operational volume to accommodate the canisters. The analysis of the neutron coincidence data from the measurements of the welded steel canisters using SP AM yielded a Canister Attribute (CA) that was shown to be proportional to the total amount of Pu mass that was present inside the canister and comparable to the CA values that were calculated based on the previous SFCC measurements. The next step in securing the spent fuel from the BN-350 reactor is the packaging of the steel canisters into Dual-Use Casks (DUCs) and the transportation of the DUCs to a remote dry storage site.

• Research Organization: Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC52-06NA25396
• OSTI ID: 1017486
• Report Number(s): LA-UR-10-03849; LA-UR-10-3849; TRN: US1103278
• Resource Relation: Conference: INMM 51st Annual Meeting ; July 11, 2010 ; Baltimore, MD
• Country of Publication: United States
• Language: English

Related Subjects

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL PROTECTION
ARGON
BN-350 REACTOR
CASKS
CONTAINERS
CONTAINMENT
DETONATORS
DRY STORAGE
FAST REACTORS
NEUTRON FLUX
NEUTRONS
NUCLEAR FUELS
PLUTONIUM
POLYETHYLENES
PROLIFERATION
REACTOR CORES
SAFEGUARDS
SECURITY
SPATIAL DISTRIBUTION
SPENT FUELS
STEELS
STORAGE
VERIFICATION