Sensitivity Studies on Lead Isotope Compositions and Geometry Effects for a LSDT Spectrometer

A lead slowing-down-time spectrometer has been investigated as a potential nondestructive assay technique for fissile materials in irradiated fuel elements. The correlation of the mean energy of the neutron spectrum and the slowing-down time is very important for a lead slowing-down-time spectrometer operation. It is one of the most important factors to reduce the impurity of the lead used as a spectrometer. This paper focuses on the sensitivity research depending on the isotope composition such as Ag, Cu, As, Sb, Zn, Fe, and Bi in the lead spectrometer. As well as, because the spectrometer consists of several cubical lead bulks, the gap between the bulks provides unexpected results coming from the capture cross section of the hydrogen in the air. Therefore, a geometrical investigation is also performed by the MCNPX simulation code