Neutron diagnostics using Compton suppression gamma-ray spectrometer for tritium breeding blanket experiments

To obtain tritium breeding ratio in tritium breeding blanket experiments, incident neutron flux measurement is essential. To develop high tritium breeding performance, the more precise neutron flux measurement is required. In this work, the Compton suppression gamma ray spectrometer, which can suppress the expected background noise signals from Compton scatterings, is used to detect the gamma rays from neutron activated indium foils for the purpose of reducing the measurement errors in the neutron activation system (NAS). The statistical error of the measured sample activity in the Compton suppressed system is estimated to be about 2.8% from the counting error (1.4%) and the detector efficiency error (2.4%), and the statistical error of the measured sample activity in the non-suppressed system was estimated to be about 4.7% (from the counting error 2.0% and the detector efficiency error 4.3%) in KSTAR experiment. This system can be applied to ITER TBM and future nuclear fusion devices. (C) 2016 Elsevier B.V. All rights reserved.