Stress Analysis&Design Optimization Of Multi-Layered SiC Based Fuel Cladding For LWR

During a loss of coolant accident(LOCA)or under high temperature,the current zircalloy cladding will react with the coolant then form hydrogen.The hydrogen build-up is dangerous because it could cause explosion and easily expose the radioactive materials to the environment.As one of the important candidates cladding materials for accident tolerant fuel(ATF).multi-layered SiC based cladding has been a hot topic recently.The conceptual design of multi-layered SiC cladding has been investigated to meet the fuel requirements of both the strength and impermeability.In this paper,a stress distribution model of the multi-layered SiC was developed on the basis of the theory of thermo-elasticity mechanics,taking radial temperature gradient and swelling effects into account as well.The heat transferring behaviour of the cladding is investigated by analyzing the temperature distribution under steady conditions.Finite Element Analysis(FEA)model of duplex SiC cladding was then built by ANSYS software to obtain the stress and temperature distribution under simulated PWR steady conditions.Also,a MATLAB model was provided to verify the numerical simulation result of FEA model during BOL and EOL burnup condition.Then,failure probability of each scenario was calculated using the modified Weibull modulus.Furthermore,the need to find the optimum design for the multi-layered cladding is still there.A total of 7 design points were studied starting from 20%Monolithic SiC to 80%.Each design point was studied for stress distribution during a cycle of PWR.Then failure probability was calculated for each of the design point.This failure probability gives a picture of how the cladding can fail and during which time in 1 operation cycle of PWRs.It is found that the best design to sustain the stresses and radiation and contains the fission gases as well would be 40%SiCf/SiC as inner layer and 60%Monolithic SiC as outer layer.