SBIR-STTR Award

Advanced nuclear reactor systems utilize liquid metal coolants, which requires that reactor component materials be corrosion resistant while maintaining safety, reliability, and performance criteria in normal reactor operation as well as in accident scenarios. Niowave, in collaboration with Los Alamos National Laboratory and the University of Michigan, is currently developing a hybrid fast/thermal spectrum subcritical testbed, coupled to a superconducting electron linac, to provide peak fast-spectrum neutron fluxes greater than 1015 n/cm2s in heavy- liquid metal environment. The facility will be used to test novel fuels, materials, instruments and components, reactor safety designs, provide data for reactor code development, and support the regulatory process for licensing novel technology.An initial proof-of-concept fast neutron source, driven by a superconducting linac and lead-bismuth eutectic (LBE) neutron converter already exists at Niowave. Additionally, Niowave’s Radioisotope Program established both the facilities and the NRC license to operate a subcritical uranium assembly and perform nuclear fuel reprocessing. In the hybrid subcritical testbed, LBE is used as a neutron converter and coolant. To determine compatible materials with LBE, materials such as niobium, austenitic steel (i.e., 316L), ferritic/martensitic steel (i.e., HT9), and ODS (i.e., MA956) steel have been tested in stagnant LBE up to 700 °C at Niowave.Niowave has decided to expand this work and develop a corrosion test station (CTS) using LBE for improved characterization and examination of advanced nuclear reactor fuels and materials. In Phase I, a detailed engineering design along with all the various components of the station will be completed. The corrosion test station will be built from stainless steel and operated at temperature up to 500 °C. In Phase II, the CTS will be built with parts made of Nb or Nb-SS bimetal for the sample test section and operated at temperatures up to 700 °C with flow velocities capable of exceeding 5 m/s. The samples include novel cladding and reactor structural materials, and actual nuclear fuel specimens (i.e., U, U-Zr, U-TRU-Zr, and UO2) or surrogates that will be tested for extended amount of time. Ultimately, this station will support the nuclear energy community’s fuels and materials qualification program by providing means to develop, characterize, and examine promising materials for advanced reactors.

Liquid-metal coolants are one of the most promising solutions for the challenges of advanced high temperature nuclear reactor systems.They optimize heat transfer, neutronics, safety, and compactness of the reactor systems.Molten lead and lead-bismuth eutectic (LBE) are the primary coolant candidates due to their unique thermo-mechanical and neutronics properties.However, they are highly corrosive for the materials used in reactor components.The structural components of advanced reactors must be resistant to corrosion from the liquid metal coolant and compatible with other reactor component materials.There is a need in the community for a facility in which advanced materials can be tested in fast reactor environments of both normal and off-normal conditions to increase safety and operating efficiency of GEN-IV reactor designs.To address this need, Niowave proposes to develop a Corrosion Test Station (CTS) using LBE for improved characterization and examination of advanced nuclear reactor fuels and materials.In this proposed system, various reactor materials will be exposed to high-temperature, high-flow rate LBE environment.In Phase I, Niowave designed, constructed and operated a prototype flowing LBE corrosion test station.Several commissioning and benchmarking experiments made it possible to characterize LBE flow, evaluate pressure drop calculations, and gain operational experience in a flowing LBE experiment.Finally, a corrosion test demonstrated the capabilities of the system to operate steadily over an extended period and provided initial results showing the corrosion/erosion effects of high velocity LBE.In Phase II Niowave, in continuous collaboration with Los Alamos National Laboratory, proposes to design, construct, and operate a corrosion test station which can expose advanced alloys to LBE at temperatures up to 700 °C and an average velocity exceeding 5 m/s for extended periods.This system will provide a testbed for the fast reactor community to characterize and examine advanced alloys in extreme environments.In Phase III, the CTS facility will have the capacity to test numerous samples in parallel to qualify advanced reactors materials.Private industry, academic institutions, and the public sector are actively involved in thermal-hydraulics, instrumentation and control, and chemical testing of novel materials with LBE and would utilize the facility in a variety of research endeavors.