High Count Rate, High Temperature Neutron/Gamma Detector for Advanced Reactors

One of the goals of DOE’s MPACT program is to develop nuclear material accounting NMA methods for next generation, advanced fuel cycles such as Molten Salt Reactors MSR. There are several challenges for NMA of MSR, for example, the high temperature and high dose rates, at which the measurements need to be performed. The goal of the proposed research is to develop highcountrate, high temperature neutron/gammaray detectors that can operate in an MSR environment. We will utilize dualmode sensors developed at RMD that provide excellent gamma spectroscopic capabilities and high sensitivity to neutrons. A robust detector using an advanced scintillation material integrated within a hightemperature design and interfaced with custom, digital readout electronics to perform pulse shape discrimination PSD for independent gamma ray spectroscopy and neutron detection under high radiation fields will support NMA at MSR. In Phase I of the research, we demonstrated the feasibility of the detector by studying the effect of the event rate and temperature on the gammaray spectral energy resolution and gamma/neutron discrimination for dual mode scintillation materials. Based on our findings we have down selected to one of the materials for building the prototype instruments in Phase II. The goal of Phase II is to construct the prototype instrument for MSR monitoring. The effort will consist of developing 1 scintillatorPMT assemblies to operate at temperatures exceeding 150 C; 2 the FPGAbased readout electronics and firmware for gamma ray spectroscopy and neutron detection at event rates exceeding 1 million counts per second; 3 the mechanics and system assembly for field testing. A radiation detection system capable of simultaneous detection of gammarays and neutrons at high count rates and temperatures, with good gammaray resolution and neutron efficiency will easily find its application in nuclear power plant management, well logging, nuclear plant decommissioning, dosimetry, homeland security, and nuclear physics.