A HYBRID MONTE-CARLO-DETERMINISTIC METHOD FOR AP1000 EX-CORE DETECTOR RESPONSE SIMULATION

The ex-core detector-response calculation is a typical deep-penetration problem, which challenging for the Monte Carlo method. response of detector an important parameter safe operation nuclear power plants. Meanwhile, evaluation during each step fuel-loading used to guide sequence. can also be reconstruct core-power distribution online monitoring long-term power. source-range sensitive thermal neutrons. For shielding above response, flux under 0.625eV needed, too small tallied by traditional simulations. In practice, tally results are close zero in region direct calculation. Even if number particles increased significant amount, statistical variance still very large. high along with time leads Figure Of Merit (FOM). order solve this problem and improve efficiency hybrid Monte-Carlo-deterministic method employed study, in-house particle transport code, NECP-MCX, developed paper. takes space-energy-dependent adjoint fluxes generate importance parameters mesh-based weight window Simultaneously, source biasing performed consistent make starting neutrons matching survival windows. As mesh superimposed, will not affected complex geometry model. obtained efficient S N multi-group cross-section data. whole toolset convenient use single set modelling data both deterministic Compared simulation, has higher such as AP1000 simulation.