Using MCNP for success criteria evaluation of reactor trip function in probabilistic modeling of ATWS upon LOOP

In this study, MCNP and SAPHIRE are employed together, to probabilistically model ATWS sequences upon loss of offsite power (LOOP); the former to evaluate the success criteria of trip function and the latter to estimate the ATWS induced core damage frequency, regarding the evaluated success criteria. MCNP outcomes will reveal the least requisite number of control rods which is enough to insert adequate negative reactivity, and SAPHIRE is used to develop Probabilistic Safety Assessment (PSA) model and estimate the induced core damage frequency (CDF). Sensitivity cases are also defined regarding the variation of core parameters to study different situations.