HTGR Knowledge Base

Conference Article: Safety evaluation during a depressurization accident of the SFHTR

Abstract

High temperature gas-cooled reactor (HTGR) has many good characteristics that inherent safety is very high, high temperature heat of near 1000 deg. C is available, high heat efficiency and high fuel bum-up are expected, etc. To obtain a public acceptance for the HTGR having many good characteristics mentioned above, it is a crucial point to show and demonstrate the outstanding inherent safety, for example, the safety during a severe accident. The reactor transient during the depressurization accident without reactor scram (DAWS) has been analyzed for the severe accident free HTR (SFHTR) with 400MWt. The DAWS has a possibility to become the severe accident in the HTGR. To simulate the reactor dynamics and heat removal from the surface of reactor pressure vessel during the DAWS, the one point-approximation reactor dynamics code with single channel model representing the core was combined with the thermal analysis code with whole reactor model. The combined calculation code is able to calculate the reactivity balance due to xenon build up and reactor cool down during such accident. From the analytical result, it was found that no reactor meltdown occurs even in the worst scenario. The calculation code developed to simulate the DAWS is applicable to the evaluation of beyond design basis accidents for the SFHTR. Also this code is applicable to the simulation of the safety demonstration test planned in the High Temperature engineering Test Reactor under conducting a reactor physics test at present. This paper describes the reactor transient during the DAWS and the newly developed analytical code.

view the full text of this article (8 pages, format: PDF, size= 379kB)

Reference:

Proceedings of a Technical Committee Meeting held in Beijing, People's Republic of China, 2-4 November 1998

International Atomic Energy Agency, International Working Group on Gas-Cooled Reactors, Vienna (Austria)

IAEA-TECDOC--1210, pp:77-84