D. LaBrier, M. Mashal, M. Acharya, M. Benson, B. Sosa Aispuro
Idaho State University,
United States
Keywords: concrete, improved corrosion resistance, ductility, radiation resilient
Summary:
Ultra-High-Performance Concrete (UHPC) is an advanced cementitious composite material. It has high strength and stiffness, exceptional durability, internal steel fiber reinforcement for added ductility, and is self-consolidating. UHPC utilizes supplementary cementitious materials such as silica fume and fly ash, which are byproducts that considerably reduce the cement consumption in the mix. As a results, the carbon footprint of the cement, the largest source of emissions in concrete, is significantly reduced in UHPC when compared to conventional concrete. Recently, UHPC has been gained popularity for applications in civil infrastructure as a means for retrofitting existing facilities, as well as in the construction of new ones. However, little research has been conducted on applications of UHPC in critical infrastructure, in particular in the context of nuclear energy. Given the exceptional mechanical properties of UHPC, when compared to normal concrete, there is potential for applications as construction material for containment structures of microreactors, batteries or commercial fusion facilities. More traditional uses of concrete in the nuclear industry, including transportation and storage packaging of nuclear fuels, shielding, retrofitting of an existing nuclear reactor fleet, spent fuel management applications, and nuclear waste storage are also options for implementation of UHPC technology. Structural components made of UHPC can be prefabricated, and are lighter in self-weight compared to conventional concrete, resulting in cost savings for transportation and further carbon footprint reduction. In addition, UHPC can eliminate the need for shear/transverse reinforcement. Regulatory standard ANSI/ANS 6.4.2 provides information on the physical and chemical properties that are required for shielding materials prior to approved use in nuclear facilities. Initial tests of UHPC focused on compressive strength in comparison to normal concrete. Results from these tests demonstrate superior compressive strength for UHPC by a factor of two, when compared to normal concrete. After thermal load testing, the compressive strength of the UHPC increases by a factor of three to four than that of traditional concrete. A second set of samples was exposed to intense fields of gamma irradiation, followed by further thermal load testing. For these samples, the strength of the UHPC regressed somewhat from thermal load-only tests but still performed at strength levels slightly higher than pre-test evaluations and higher than those for normal concrete. Use of novel materials to support the development and qualification of advanced nuclear systems, such as commercial fusion facilities, has become a recent thrust of research within the nuclear industry. Materials such as UHPC may provide superior performance in the areas of thermal and radiation resistance from radiological sources, and even water impenetrability and reduction of hydrogen migration throughout shielding materials. Novel shielding technologies for fusion facilities are areas of significant research interest for the nuclear community. In this paper, researchers from Idaho State University discuss the viability of UHPC in advanced nuclear applications, and their proposed path forward for producing the data needed for the eventual qualification of such materials, including tests involving combined neutron-gamma doses, water infiltration and hydrogen migration studies.