Multi-cycle analysis on OPR1000 type reactor using multi-physics coupled calculation of RAST-K and FRAPCON

Abstract

A nodal diffusion reactor core analysis code, RAST-K v2.0, which developed at Ulsan National Institute of Science and Technology (UNIST) has been coupled with steady-state fuel analysis code, FRAPCON4.0. In the coupled system, RAST-K and FRAPCON exchanges power distribution and thermal properties which are determined by each other. Because two source codes are fully coupled, data exchange is performed via memory. Pin-wise whole core coupled calculation is achieved by applying pin power reconstruction method in RAST-K and performing FRAPCON calculation for every fuel rod in the model. To improve multi-physics coupled calculation efficiency, FRAPCON has been modified to be able to do restart calculation. The Cycle 1-4 of OPR1000 type commercial reactor has been analyzed by the coupled system. The coupled calculation results were compared with that of RAST-K standalone with embedded simple 1-dimensional thermal-hydraulics solver for the same reactor, and the analysis showed insignificant changes in nuclear reactor design parameters observed due to limitation of cross section feedback, while radial power distribution changes were observed.