Study of neutronic and creep properties of Kanthal APMT for advanced fuel cladding applications

Abstract

FeCrAl alloys have excellent oxidation resistance and exhibit slower reaction kinetics with steam. Kanthal APMT is an advanced powder metallurgical FeCrAl alloy that shows promise as accident tolerant fuel cladding material. The neutronic properties of APMT as a fuel cladding material were evaluated in a Light Water Reactor (LWR) core and compared with zirconium-based alloys through the help of Monte Carlo N-Particle Transport (MCNP) code. The results show that there is neutronic penalty associated with the use of APMT as a cladding component which can be compensated by either modification in the fuel-cladding geometry or enrichment in the fuel. Creep tests were performed at 823–973 K and at stresses ranging from 100 to 300 MPa. The creep rupture data was found to obey Larson-Miller and Monkman-Grant relationships. The hardness of the crept specimens, measured after the creep test, shows significant reduction of mechanical strength near the fractured tip. Two types of second phase particles, YFeCr-rich and YAlO-rich, were observed in the fractured surface of the crept specimen through energy dispersive spectroscopy.