Year
2003
Abstract
In this paper the neutron detector system (NDS) developed for the Californium-252 (252Cf) neutron source measurements of the fissile mass flow monitor (FMFM) will be presented. The FMFM measures the 235U fissile mass flow of the UF6 gas streams. The FMFM uses 252Cf neutron sources for the fission activation of the UF6 gas. These 252Cf sources are replaced about every two years due to their relatively short half-life (~2.65 years). During the source replacement the new 252Cf sources are calibrated with the previously installed sources (i.e., a relative source measurements) to insure proper and seamless FMFM performance. The NDS is developed as a possible alternative for the FMFM 252Cf relative source measurements. The NDS consists of a neutron detector (commercially available high efficiency 3He proportional counter), and the electronics, which are commercial NIM modules. During the measurements the 252Cf source is placed into its FMFM source plug and is then inserted into a polyethylene source plug holder that contains the detector. The source plug holder and the NIM, that contains the electronics, are separated by an 18-meter long cable. The NDS expected measurement time is 10-sec for each. The NDS measurement repeatability is good (