Powder neutron diffractometer for testing of irradiation effects in nuclear fuels and materials

The exposure of materials to a nuclear reactor environment causes radiation damage, such as embrittlement, creating one of the most difficult problems facing nuclear reactors. Therefore, the NSUF Program calls for developing diagnostic equipment for embrittlement testing. Embrittlement is caused by irradiation-induced lattice defects, and neutron powder diffraction (NPD) is one of the most powerful techniques for studies of crystal lattice structures and their changes due to radiation damage. However, NSUF has extremely limited NPD capabilities, and virtually none for neutron-irradiated highly radioactive samples. Neutron research user facilities are oversubscribed due to the popularity of neutron methods. Given difficulties with handling radioactive samples, these facilities are virtually inaccessible to the NSUF community, preventing NPD of irradiated samples. Small research reactors at universities and National Labs, and laboratory-based neutron generators, are valuable additional resources. Building neutron powder diffractometers at such facilities will enable NPD methods for NSUF, especially for post-irradiation examination (PIE) of samples irradiated at these facilities, such as the MIT Reactor and Idaho National Lab, which lack NPD methods for PIE. This project will develop a commercial neutron powder diffractometer suitable for shielded spaces for studies of highly radioactive materials at INL, MIT, and elsewhere. We will design and demonstrate a compact neutron powder diffractometer capable of measuring highly radioactive samples. Our device will use off-the-shelf parts and fit inside a shielded room. Detectors and other hardware will be radiation-hard and remotely operated. The outcome of our project would be the demonstration of a compact neutron powder diffractometer with integrated software to characterize highly radioactive samples. Our proposed instrument could be installed at unused beamlines at national facilities or small neutron sources, where a shielded hutch can be installed. The development of our new instrument will take a step in bringing neutron scattering techniques to the NSUF community that has mostly relied on laboratory X-ray diffractometers, which are not well suited for studies of high-Z nuclear materials.