CALIBRATION OF AN NDA NEUTRON MONITOR FOR DETERMINING PROCESS HOLDUP

Material holdup in chemical processing lines and equipment creates problems for special nuclear material accountability. A prototype neutron monitor has been built at Los Alamos National Laboratory (Los Alamos) to criteria provided by Rockwell Hanford Operations (Rockwell). The design of this prototype neutron monitor is based on the existing High-Level Neutron Coincidence Counter (HLNCC) technology developed at Los Alamos for use in the nuclear industry. In the present Rockwell application the HLNCC has been adapted for use as an NDA monitor for end-of-campaign calciner holdup measurements within a reprocessing facility. The design and theory of operation of the monitor are briefly discussed. The operating characteristics of the neutron monitor have been observed in detail and are described. Results of in-place calibration of the neutron monitor and the expected quality of NDA measurements that will be made with the monitor are presented.