Safety Analysis Of A Small Modular Reactor Using Accident Tolerant Fuel

Using Accident Tolerant Fuel(ATF)is one of the effective ways to improve the safety of nuclear power plants.ATF can withstand longer and better sustain radioactive fission products in extreme environment of severe accidents.It effectively delays the process of severe accidents and reduces the damage.Small Modular Reactors(SMR)have characteristics of good design and low power density,.with good inherent safety.Combining the two has the potential to improve reactor safety dramatically.At present,there have been a lot of studies on ATF and SMR,and some people try to apply ATF to SMR.But the safety analysis of SMR using ATF is still no one did it.In this paper,the Westinghouse Small Modular Reactor(WSMR)is referred to build a small reactor model in MELOCR.The complete physical property model was written into MELCOR,and the rate of cladding oxidation in MELCOR was modified to obtain the ATF model.Combined with the SMR model,a SMR model using ATF is obtained.Based on this model,the temperature distribution of ATF during the steady state operation of the reactor was analyzed.Then,we analyze the process of SMR using ATF in the accidents of Station Blackout(SBO)combined with safety facilities failure and Loss of Coolant Accident(LOCA)combined with safety facilities failure.The results show that SMR has good security characteristics.With the input of safety facilities,the residual heat can be effectively removed to ensure the safety of the reactor.It can last for a long time if all the safety facilities fail.FCM fuel can reduce the fuel temperature during steady operation of the reactor and being able to heat up more slowly in an accident.It can effectively extend the core meltdown time.But it cannot reduce hydrogen production effectively.Finally,FeCrAl cladding,surface coating zircally cladding and SiC cladding are selected for analysis.The results show that these three kinds of cladding can effectively slow down the production of hydrogen.But FeCrAl cannot extend the core melting time because of its low melting point.The other two cladding materials can effectively prolong the core melting time.SiC has the longest core meltdown delay time.SiC cladding has excellent performance in inhibiting hydrogen generation and delaying core meltdown.