High Performance Fuel Design for Next Generation PWRs Appendices B-I to FY-02 Annual Report

Abstract

B.1.1 VIPRE modeling of PWR core with annular fuel: Optimization studies in the first year used an isolated channel and models for MDNBR analyses. These analyses provided sufficient knowledge of potential thermal hydraulic performance of annular fuels to select the 13x13 array as the most promising configuration. To obtain more realistic and accurate MDNBR, a whole core model is necessary. In particular, the major concern is correct representation of channel flow rate. The earlier models used the core-average mass flux, which does not account for flow rate reduction in the hot channels due to increased pressure drop in this channel as a result of higher subcooled, or possibly, saturated boiling. Therefore, it is expected that the MDNBR obtained from the full core VIPRE-01 model will be smaller than the values obtained from the isolated channel model.