Year
2012
Abstract
In the present paper, reviewing the technologies applied to TMI-2, feasibility study of gamma spectroscopy of low-volatile fission products(FPs) for special nuclear material accountancy in molten core material or debris has been performed numerically, and the sensitivity of low-volatile FP nuclides on fuel contents, especially Pu-239, was studied with parameters of typical BWR fuel such as enrichment, burnup and neutron spectrum, power density. Comparing with TMI-2, a PWR with 1st irradiation cycle fuels loaded, broader neutron spectrum axial profile and irradiation cycle complexity of typical BWR fuel assemblies make more variance of inventory estimation, but the better calculation predictably can be expected by significant improvement of nuclear data and codes. As results, Pu-239 quantification by burnup dependent Eu-154/Pu-239 index has accuracy of 15-18% standard deviation (?) mainly affected by burnup uncertainty, and Pu-239 quantification by Ce-144/Pu-239 has accuracy of ? ~20 % as long as Ce-144/Pr-144 released photon could be observed before Ce-144 decays beyond the measurable level, within the scope of inventory survey except for measurement uncertainty. Finally systematic image of fuel quantification by passive gamma spectroscopy and, as future study, FPs quantification tests by mockup debris measurement are introduced