A Subcritical Testbed for Fast Neutron Irradiation of Novel Fuels and Cladding in Fast Reactors

Next generation reactor R&D aims to improve overall safety, efficiency, sustainability, and proliferation resistance for economically viable nuclear energy. New reactor design and fuel development rely on novel materials that are resistant to both radiation damage and corrosive environments. However, American nuclear fuel developers face a serious dilemma: there are no existing domestic fast reactors. Thus, the financial cost and time required to test novel fuels and advanced materials overseas prohibits many promising concepts from proceeding beyond early design stages. To overcome this problem, Niowave, Inc. proposes to develop a subcritical testbed that can bombard materials with fast neutrons in a fast reactor like environment, without a nuclear reactor. This would support experimentation and demonstration with novel fuels and materials, without the logistical and regulatory challenges of fast reactors. In this proposed system, a hybrid fast/thermal spectrum subcritical testbed is coupled to a superconducting electron linac through a lead-bismuth eutectic (LBE) neutron converter. This system will create a peak fast- spectrum neutron flux in excess of 1015 n/cm2s in a liquid metal environment for testing and demonstrating novel fuels and materials used in Generation-IV designs, where fast-spectrum reactors are prominent. The proposed subcritical testbed facility is not a reactor, and is simpler to license than a reactor. An initial proof-of-concept fast neutron source, driven by a superconducting linac and LBE neutron converter already exists at Niowave and is designed to produce a fast neutron flux in excess of 1014 n/cm2s. Additionally, Niowave is developing a subcritical LEU target assembly, licensed under 10 CFR 30/70, to provide the US with critical radioisotopes. Our fast neutron source and LEU-based subcritical radioisotope production facility serves as a starting point for the design of a subcritical testbed for fuel characterization. The equipment, experimental data, and expertise Niowave gained will be leveraged and applied to the subcritical testbed to advance novel fuel design and support reactor materials testing. Phase I and II will focus on design and prototype development and demonstration. Ultimately, we intend to build a materials testbed facility for the nuclear energy and reactor community.