New 3He Replacement Sensors for DOE Material Control and Accountability

Nuclear material control and accountability (MC & amp;A) programs at DOE facilities require new techniques that maximize material loss detection sensitivity, increase the quality of accountability measurements, minimize material holdup, and reduce the magnitude of inventory differences. Similarly, new methods and technologies are needed to address key issues affecting future deployments of nuclear energy, while reducing the risk of nuclear proliferation. Successfully undertaking MC & amp;A requires new detectors that circumvent the current shortage of 3He. We propose to develop a high-efficiency, low- noise, solid-state neutron detector with intrinsic pulse shape and pulse height discrimination capabilities that allows effective real-time separation of neutron signals from gamma events. At the heart of the proposed detector are novel scintillators, incorporating heavy concentration of 6Li ions, synthesized in a structured form using a specialized technique that permits large-volume synthesis of high-quality material in hours and allows creation of unconventional compositions. Resulting sensors will be coupled to photodetectors to realize high-efficiency thermal neutron detectors with high gamma/neutron discrimination for effective operation in mixed radiation fields anticipated in measurements of spent nuclear fuels. Two families of novel neutron sensitive scintillators demonstrating excellent pulse shape and pulse height discrimination were discovered during this highly successful Phase I. These materials demonstrated neutron/gamma separation, count-rate and efficiency rivaling, and in some respects exceeding, that of current state-of-the-art scintillators. Experimental data and Monte-Carlo simulations both demonstrated their suitability for the desired MC & amp;A operations. Phase I also demonstrated unique ability of our synthesis method to create large structures suitable for portal imaging and/or neutron diffraction/radiography applications. We plan to develop, evaluate, and deliver to DOE fully functional detectors based on the scintillators discovered in Phase I, and demonstrate their performance in terms of neutron detection efficiency, high gamma rejection ratios, and ability to perform in the presence of intense gamma backgrounds. We will primarily focus on developing handheld instruments useful for neutron counting and spectroscopy. Specific areas of research will include material synthesis and characterizations, and Monte-Carlo simulations to optimize the detector and moderator geometries. Commercial Applications and Other Benefits: Besides safeguarding nuclear facilities, ensuring effective MC & amp;A in facilities, and allowing radiography/tomography in new approaches for spent-fuel storage and processing, improved scintillators and non-3He detectors are critically important to homeland security, nuclear and high-energy physics research, nuclear waste cleanup, nuclear treaty verification, geological exploration and development of new sources to effectively address our nations future energy needs. Proposed detectors will also permit scientific research enabling development of new drugs, materials, and systems that directly impact healthcare and quality of life.