Analysis of a Pump trip in a Typical Research Reactor by RELAP5/MOD3.3

摘要

In this paper, results obtained for the safety analysis of a typical MTR fuel type Research Reactor are presented. The considered case is originated by a trip of the main cooling pump. During the transient the core flow decreases exponentially, and when it reaches a certain fixed level, the natural circulation valve opens to allow passive decay heat removal. This phenomenon involves three heat transfer modes; forced, mixed, and natural convection. In this framework the analysis were performed using an advanced computational tool, namely RELAP5/MOD3.3 code. In fact, previous work using RELAP5/MOD2 code was not able to simulate adequately the lost of flow that involves transition from a downward forced flow to an upward natural circulation flow. For this purpose a detailed investigation of the new code features in this field was carried out based upon the former nodalization of the reactor coolant loop. The obtained results agree with the former steady state calculations using the aforementioned older RELAP5 version.