NRF-based NDA of nuclear material using monochromatic -ray beam

Shizuma, Toshiyuki; Hayakawa, Takehito; Angell, C.; Hajima, Ryoichi; Minato, Futoshi   ; Suyama, Kenya; Seya, Michio; Johnson, M.*; McNabb, D.*

One of the urgent issues for NDA is to establish a reliable technique for the assay of nuclear materials in spent nuclear fuel. The system performance such as counting precision for the NRF-based NDA, would be affected by radiation backgrounds from spent fuel. Generally, the -ray spectrum of radiation backgrounds from spent fuel has characteristic shape with an exponential fall-off as a function of -ray energy. Therefore, the NRF measurement at higher energies is preferable to obtain a better signal-to-noise ratio. The counting precision is also affected by backgrounds from the coherent scattering. In order to minimize the Coherent scattering contribution, we propose a method in which NRF transitions to the first excited state is measured. Assuming various cross sections for NRF in the range of 3 to 100 eV barn at excitation energies of 2 to 5 MeV, we have estimated the statistical uncertainties of the proposed NDA system.