Review of Severe Accident Phenomena in LWR and Related Severe Accident Analysis Codes

Muhammad Hashim,Yang Ming,Azkar Saeed Ahmed

doi:10.19026/rjaset.5.4574

Abstract

Firstly, importance of severe accident provision is highlighted in view of Fukushima Daiichi accident. Then, extensive review of the past researches on severe accident phenomena in LWR is presented within this study. Various complexes, physicochemical and radiological phenomena take place during various stages of the severe accidents of Light Water Reactor (LWR) plants. The review deals with progression of the severe accidents phenomena by dividing into core degradation phenomena in reactor vessel and post core melt phenomena in the containment. The development of various computer codes to analyze these severe accidents phenomena is also summarized in the review. Lastly, the need of international activity is stressed to assemble various severe accidents related knowledge systematically from research organs and compile them on the open knowledge base via the internet to be available worldwide.

Highlights

There had been two big nuclear power plant accidents in the last century: TMI-2 accident in 1979 and Chernobyl accident in 1986
Why Fukushima Daiichi accident happened in Japan many researches on severe accident had conducted for almost three decades after the days of the TMI and Chernobyl accidents? From a series of update log on Fukushima Daiichi accident in Japan reported by (Shibutani, 2011a), it can be well recognized that the root cause of this recent big severe accident in Japan since Chernobyl accident comes from a biased group thinking shared by many experts of Japanese nuclear society that it is not necessary to introduce any safety measure against severe accident because Japanese technology is so reliable
If lower head of a Reactor Pressure Vessel (RPV) is failed molten core will release into a containment vessel and various severe accident phenomena such as steam explosion, hydrogen burn and Molten Core Concrete Interaction (MCCI), etc., will occur

Summary

INTRODUCTION

There had been two big nuclear power plant accidents in the last century: TMI-2 accident in 1979 and Chernobyl accident in 1986. It may or may not involve core degradation (IAEA, 2008) These accidents can neither be termed as DBAs (because of their low probability) nor severe accidents.These accidents are considered with specific attentionwith mitigation measures. If lower head of a Reactor Pressure Vessel (RPV) is failed molten core will release into a containment vessel and various severe accident phenomena such as steam explosion, hydrogen burn and Molten Core Concrete Interaction (MCCI), etc., will occur. These phenomena can threaten the integrity of the containment vessel (Akihide, year).which is the last barrier against the radiological risk to the environment. Core degradation stage (IRSN-CEA 83/351, 2007; William, 2005): progression of

10 Containment failure

CONCLUDING REMARKS