NUCLEAR POWER PLANT EVALUATION SYSTEM AND METHOD

PROBLEM TO BE SOLVED: To respond to the necessity of highly precisely evaluating safety of a plant in a nuclear power plant evaluation system.SOLUTION: A nuclear power plant evaluation system includes: a plant system analysis part 21 which calculates a reactor pressure, a reactor core inlet enthalpy, a reactor core inlet flow rate and a reactor core inlet boron concentration as reactor core boundary conditions for a reactor core consisting of a plurality of fuel rods; a three-dimensional reactor core kinetics analysis part 22 which calculates reactor core output and a reactor core output distribution on the basis of the reactor core boundary conditions; a three-dimensional reactor core heat flow kinetics analysis part 23 which calculates distributions of fuel temperatures, coolant densities and boron concentrations on the basis of the reactor core boundary conditions and the reactor core output distribution; a first correction part 31 which calculates a corrected reactor core output distribution by increasingly correcting an uncertainty at the time of transition for the reactor core output distribution; and a second correction part 32 which calculates a corrected fuel rod output distribution by increasingly correcting an uncertainty at the time of transition for the fuel rod output distribution. The three-dimensional reactor core heat flow kinetics analysis part 23 calculates a minimum DNBR, a fuel center temperature and a cladding tube maximum temperature on the basis of the boundary conditions, the corrected reactor core output distribution and the corrected fuel rod output distribution.SELECTED DRAWING: Figure 2 【課題】原子力プラントの評価システムにおいて、プラントの安全性を高精度に評価することが必要である。【解決手段】複数の燃料棒からなる炉心に対し炉心境界条件としての原子炉圧力、炉心入口エンタルピ、炉心入口流量、炉心入口ほう素濃度を算出するプラントシステム解析部２１と、炉心境界条件に基づいて炉心出力及び炉心出力分布を算出する３次元炉心動特性解析部２２と、炉心境界条件と炉心出力分布に基づいて燃料温度、冷却材密度、ほう素濃度の分布を算出する３次元炉心熱流動特性解析部２３と、炉心出力分布に対して過渡時の不確かさを増量補正して補正炉心出力分布を算出する第１補正部３１と、燃料棒出力分布に対して過渡時の不確かさを増量補正して補正燃料棒出力分布を算出する第２補正部３２を備え、３次元炉心熱流動特性解析部２３は、境界条件と補正炉心出力分布及び補正燃料棒出力分布に基づいて最小ＤＮＢＲ、燃料中心温度、被覆管最高温度を算出する。【選択図】図２