Year
1990
Abstract
A neutron coincidence counting system has been developed for assaying plutonium holdup in glove boxes at the automated mixed-oxide fuel fabrication facility, PFPF, in Japan. The time-correlated neutron emission rate arising from the spontaneous fission decay of plutonium isotopes is measured and converted to grams of plutonium contained in the glove box. Each detection system consists of a pair of polyethylene slabs containing ^He proportional counters and associated electronics. These slabs are placed on either side of the glove box that is to be measured for plutonium holdup. The detectors are moved by a portable lifter to map out the coincidence response from the entire glove box. Results of a design optimization study that considered detector efficiency, as well as overall size and weight and how these parameters interface with the procedure of mapping the glove box, are presented. The use of the Los Alamos transport code, MCNP, in the detector design optimization and in the aid of calibration is also discussed.