The Severe Accident Analysis Of IRIS Reactor

There are many research on SMR at home and abroad, but the research on severe accident are few, since the integral SMR has many differences with the conventional Loop-PWR, the severe accident research of integral SMR will be helpful to understand the characteristics of integral SMR under severe accident, and have important meaning to the SAMG and decrease the CDF.The IRIS reactor’s RELAP5/SCDAP model was built in this thesis, the analytic model includes the primary and secondary loop, the emergency heat removal system (EHRS). The8steam generator and4EHRS are modeled. The SCDAP model of core and the COUPLE model of the lower head are built. The containment is modeled with Contempt-lt/028program. The steady-state results are very close to the target values. For the accident of Turbine Trip, the power decline fast after the SCRAW, the pressure and temperature of primary declined quickly after the EHRS activated, the simulation results are accord with the accident procession, the variation trend of parameters are also accord with the reference, this justified the model.The analytic results of Turbine Trip show that with the large inventory and lower power, nearly7hours later the core begin uncovered, and12hours later the core became damaged. For the case with no interference, the vessel will dry out, there will be steam natural circulation in the vessel, the control rods will meltdown and cause the creep rupture of the lower head. For the case with no depressurization, a charging pump injection will mitigate the severe accident. For the case with depressurization, the flash vaporization of the coolant will cause the core expose quickly, the two charging pump injection couldn’t mitigate the accident, by increasing the injection flow to35kg/s, the accident could be mitigated.The DVI lines break accident will leads the reactor loss more coolant, and quicken the progression, the time of into the severe accident state is5.4hours earlier than the CVCS lines break accident. For the CVCS lines break accident, two charging pumps injection could mitigate the accident. For the DVI lines break accidents, one charging pump injection could mitigate the accident. Based on analyses of the mitigation measures of severe accidents induced by Turbine Trip and LOCA accidents, the severe accident entry temperature of IRIS reactor is703K.