Code Analysis on the Loss of Flow Scenario for a Small Modular Reactor

Abstract

Based on the accumulated pool type sodium cooled fast reactors technology the SALUS reactor is being conceptually designed by KAERI to maximize the utilization of u r anium resources using fast neutrons. The GAMMA code has been developed to predict the physical phenomena expected following the anticipated as well as postulated accidents in a high temperature gas cooled reactor and further updated and extended to non LWR (light water reactor) such as liquid metal reactor and molten salt reactor. The major results from the analysis on both passive decay heat removal system (PDHRS) performance and unprotected loss of flow (ULOF) scenario for the SALUS were summarized as a part of the development and assessment of the GAMMA+ code. First of all, a modeling on the PDHRS of SALUS was performed using the GAMMA+ code to analyze the design values of DHX and AHX heat exchangers. Second, modeling and safety analysis utilizing the GAMMA+ code for the accident scenario of ULOF has been conducted in order to assess the applicability of the code to the SALUS reactor. In analyzing safety for the ULOF scenario, evaluations were conducted for two scenarios of the power loss of two primary heat transfer system (PHTS) pumps and the pseudo trip of one PHTS pump. This verified that the GAMMA+ code could be used to the safety analysis on the sodium cooled fast reactors such as SALUS with the similar accuracy to the MARS LMR code.