Preliminary calibration curves for the ACP nuclear material accounting during the early stage of ACPF hot operation

The ACP Safeguards Neutron Counter (ASNC) is a kind of neutron coincidence counter for the Non-Destructive Assay (NDA) of ACP's nuclear materials. It was developed for the nuclear material accounting in the ACPF hot cell of ACP's process materials such as spent fuel rod cuts, UO2 pellet, U3O8 powder, uranium metal ingot, and waste materials including hulls and salt waste. The performance test of the ASNC was done by using a 252Cf neutron source which was cross-checked by the safeguards group of the Los Alamos National Lab. (LANL). The measured values of ASNC's main parameters such as neutron detection efficiency, neutron die-away time, and deadtime coefficient are satisfactory to get doubles rate for the spontaneous fission neutrons of 244Cm element. Preliminary calibration curves for main ACP nuclear materials such as metal ingot, UO2 powder and salt waste are also generated by using MCNPX and ORIGEN codes. We can see the obvious neutron multiplication influence on the increase of doubles rate for metal ingot and UO2 powder. However, there is almost no multiplication for salt waste there because there is not much enough of plutonium content in it. These calibration curves will be modified and complemented when hot calibration samples are prepared. To verify this calibration curve, DUPIC SFS measurement and DA will also be conducted