In Situ Pu isotopic measurements using electromechanically cooled HPGe detectors at PFPF

A high-resolution gamma ray spectroscopy (HRGS) system has been installed at the Advanced Material Accountancy Glovebox Assay (AMAGB) System so that neutron and gamma ray measurements can occur simultaneously on material transfer containers. This equipment was installed in August 2000 at the Plutonium Fucl Production Facility (PFPF) in Japan. It is anticipated that placing the HRG6 system at the neutron assay station will save a few person-days per IAEA inspection because it will no longer be necessary to take samples from the transfer container for isotopic analysis at another assay station. The HRGS system consists of a 25% relative efficiency coaxial detector with electromechanical cooling and digital signal processing. The digital spectrometer has the benefit of increasing throughput, improving energy resolution, and extending the lifetime of neutron damaged HPGe detectors as compared to analog spectrometers. The gamma-ray system is used to verify the Pu isotopic composition and 241Am concentration in transfer containers of MOX. The 240Pueff action is calculated from the isotopic data and is used to convert the neutron assay data to total grams plutonium. The results of performance tests and calibration measurements using this system are reported in this paper.