MODELING PRISMATIC HTGRs WITH U.S. N.R.C ADVANCED GAS REACTOR EVALUATOR (AGREE)

摘要

A core fluids and heat transfer model has been developed for the prismatic high temperature gas reactor in support of the US NRC Next Generation Nuclear Plant (NGNP) evaluation model. The core fluids modeling relies on a subchannel approach in which the primary coolant flowpath through the core region and vertical in-core and ex-core gaps can be modeled as individual subchannels. These subchannels are connected together to represent a three dimensional reactor. An initial validation calculation for the core fluids model has been performed using data available in literature for bypass flow. The predicted bypass flow was within 2.6% of the value reported in the literature. The core level heat transfer model is based on a triangular finite volume method, where the base triangle is one sixth of the prismatic block. In order to improve the spatial accuracy at this level, a triangular refinement method was also implemented. The fuel compact temperature is calculated by a cylindrical conduction model which is implicitly coupled to the triangular core level model. The preliminary verification of the model was performed by comparing AGREE to a finite element code COMSOL by analyzing the MHTGR core heat transfer. Further verification and validation is currently an ongoing effort.