Review of the Safeguards Measurements Program on Fast-Breeder Reactor Spent Fuel from the BN-350 Reactor

Beginning in 1998, a series of safeguard measurements have been performed on the spent nuclear fuel from the BN-350 fast-breeder reactor in the Republic of Kazakhstan in support of the Trilateral (KZ-IAEA-US) BN350 Spent-Fuel Disposition Project for the packaging and eventual transportation of the spent fuel to a permanent dry storage site. These safeguards measurements consisted of an initial quantitative verification of the declarations of the plutonium content of the individual fast-breeder spent-fuel assemblies prior to the packaging of the assemblies into sealed containers. The initial set of measurements used the Spent Fuel Coincidence Counter (SFCC) to quantitatively measure the plutonium content while the spent-fuel assemblies were located underwater in the facility storage pond. This was the first direct quantitative NDA measurement of the Pu content of spent fuel performed under the auspices of the IAEA. The RMS% difference between the measurements of plutonium content of individual fuel assemblies and the corresponding facilities declarations was between 8% and 13% depending on the measurement procedure that was used. Upon completion of the initial packaging campaign, a second set of measurements were performed using the Spent Fuel Attribute Monitor (SPAM) to determine a canister attribute value which is related to the amount of plutonium that is present within the canister. The initial measurements using SPAM were compared to calculated canister attribute values that were based upon the SFCC measurements of the individual spent-fuel assemblies. This effort enabled the IAEA to maintain a continuity of knowledge (COK) on the spent-fuel assemblies after packaging was complete. In this talk, a review of the non-destructive assay techniques that were used in safeguarding the spent nuclear fuel from the BN-350 fast-breeder reactor will be presented with an emphasis placed on the maintenance of COK throughout the process of packaging the spent fuel into sealed containers. In addition to reviewing previous safeguards measurements at the BN-350 facility, the recent development of a safeguards measurement system to indirectly verify the presence of the spent fuel in dry storage casks by measuring signature “fingerprints” for each dry storage cask will be discussed.