Gamma-Ray Imaging Spectrometers for Nuclear Materials Accounting and Control

The nuclear security and safeguards community does not have an effective tool to track the location and quantities of radioactive material within facilities. This effort will result in a sensor that can provide precise locations and quantities of radioisotopes in complex measurement environments. It is in the national interest to develop the best possible tools to monitor all aspects of the domestic and international nuclear industry. Current radiation detectors are relatively crude, lacking the ability to precisely identify, quantify, and locate radioisotopes. This makes it challenging to track and secure radioactive material in the complex radiation environments encountered throughout the nuclear fuel cycle. The proposed work will adapt an existing commercial product from H3D, Inc., the Polaris-H radiation imaging spectrometer, to operate in the demanding environments encountered in nuclear materials accounting and control. This device is capable of high resolution spectroscopy at room temperature and forms a 4-pi Compton image, thus it is an ideal instrument to provide the location, quantity and identity of radiation sources. However, it does not function effectively in the relatively high radiation environments encountered when monitoring various aspects of the nuclear fuel cycle. This work will address the issues that arise at high count rate in an effort to meet the requirements laid out in the proposal solicitation. The phase I effort will focus on preparing two different promising ASIC (application specific integrated circuit) readout systems to meet the operational requirements. One is the ASIC used in the existing product and the other is the next generation digital ASIC that provides more complete data for each event. After applying hardware and software modifications to these systems they will be tested in a well-calibrated high-count-rate environment to determine the effectiveness of the modifications and their suitability to meet the users needs. The effort will conclude by selecting a readout system for moving forward with commercialization. The Polaris-H system that will be adapted in this project has already realized success in the commercial nuclear reactor market. However, readout problems at high count rates have limited the market penetration of this system. If these problems are resolved through the proposed effort it will significantly expand the market for this technology amongst the commercial operators. More importantly, it will open up other markets, in the safeguards and security community, which had been out of reach. It will improve the overall safety of the nuclear industry, from uranium mining to long term fuel storage, by providing a unique and powerful tool to track the relevant radioisotopes.