Screening of advanced cladding materials and UN–U3Si5 fuel

Abstract

In the aftermath of Fukushima, a focus of the DOE-NE Advanced Fuels Campaign has been the development of advanced nuclear fuel and cladding options with the potential for improved performance in an accident. Uranium dioxide (UO 2) fuels with various advanced cladding materials were analyzed to provide a reference for cladding performance impacts. For advanced cladding options with UO 2 fuel, most of the cladding materials have some reactivity and discharge burn-up penalty (in GWd/t). Silicon carbide is one exception in that the reactor physics performance is predicted to be very similar to zirconium alloy cladding. Most candidate claddings performed similar to UO 2-Zr fuel-cladding in terms of safety coefficients. The clear exception is that Mobased materials were identified as potentially challenging from a reactor physics perspective due to high resonance absorption. This paper also includes evaluation of UN-U 3 Si 5 fuels with Kanthal AF or APMT cladding. The objective of the U 3 Si 5 phase in the UN-U 3 Si 5 fuel concept is to shield the nitride phase from water. It was shown that UN-U 3 Si 5 fuels with Kanthal AF or APMT cladding have similar reactor physics and fuel management performance over a wide parameter space of phase fractions when compared to UO 2-Zr fuel-cladding. There will be a marginal penalty in discharge burnup (in GWd/t) and the sensitivity to 14 N content in UN ceramic composites is high. Analysis of the rim effect due to self-shielding in the fuel shows that the UN-based ceramic fuels are not expected to have significantly different relative burn-up distributions at discharge relative to the UO 2 reference fuel. However, the overall harder spectrum in the UN ceramic composite fuels increases transuranic build-up, which will increase long-term activity in a once-thru fuel cycle but is expected to be a significant advantage in a fuel cycle with continuous recycling of transuranic material. It is recognized that the fuel and cladding properties assumed in these assessments are preliminary, and that additional data are necessary for these materials, most significantly under irradiation. After the Fukushima accident, a major focus of the AFC has been on fuels with enhanced accident tolerance, a.k.a. "Accident Tolerant Fuels (ATF)". The key objectives that an attractive and viable ATF must satisfy include: • "First do no harm" → at least comparable performance under all conditions, and improved performance in accident scenarios

Radial distributions of power and isotopic concentrations in candidate accident tolerant fuel U3Si2 and UO2/U3Si2 fuel pins with FeCrAl cladding

“…Due to the much higher thermal conductivity, the temperature in the U3Si2 fuel is expected to be flatter (and lower in center) than that in UO2 fuel. Quantitative results can be obtained with the empirical formulae (8) and (9), and the temperature at the surface of fuels. This conclusion is verified by multi-physics coupling analysis recently [33].…”

Severe Accident Analysis Of BWR Core Fueled With UO₂/FeCrAl with Updated Materials and Melt Properties From Experiments

“…These preliminary analyses were performed to provide initial insight into the possible improvements that ATF concepts could provide and to identify issues with respect to modeling ATF concepts. In addition to these scoping studies, screening studies were performed [10] and a common methodology and set of performance metrics were developed to compare and support prioritizing ATF concepts [11].…”

“…This resulted in the UO 2 mass increasing by 18.5%. The reduction in cladding thickness is based on previous reactor physics assessments of FeCrAl cladding in PWRs in which it was determined that maintaining operational cycle lengths was best accomplished through a small increase in batchaverage enrichment and reduction of the cladding thickness to about half of the nominal thickness [10,26,27]. Recent neutronics studies found similar results for BWRs as well; however, the studies suggest reducing both the cladding and channel box thicknesses by about 50% [28,29].…”

Neutronic Analysis on Potential Accident Tolerant Fuel-Cladding Combination U3Si2-FeCrAl

“…2 Science and Technology of Nuclear Installations However, UN chemically reacts with water [8], especially at high temperature. Additional shielding material UN/U 3 Si 5 has been studied to overcome the defect [9]. But a problem still exists, which is the determination of the percentage of U 3 Si 5 to prevent the fuel from reacting with water in an accident condition.…”