Mitsubishi Heavy Industries, Ltd. (MHI) has been working on the development of codes for core design (nuclear and thermal-hydraulic) and safety evaluation with the aim of advancing the operation of PWR (Pressurized Water Reactor) plants in terms of long cycle operations, power uprate, the adoption of high burnup fuel, etc. This report explains firstly model advancement in the nuclear and thermal-hydraulic design codes, and then explains how those advanced models have been incorporated into the non-LOCA (Loss of Coolant Accident) analysis technique. This report also describes the large break LOCA analysis method that statistically evaluates the effect of uncertainty in safety analysis inputs. Development of the CFD (Computational Fluid Dynamics) -based evaluation technology is also described, which deals with the core melt spreading behavior important in the field of severe accident, including a comparison between experiments and calculation results. This report introduces the advanced core and safety evaluation codes of MHI which incorporate high accuracy for evaluation, in addition to their applicability to core design and safety evaluation.
