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| NKS Programme Area: | NKS-R | | Research Area: | Severe accidents and Reactor Physics | | Report Number: | NKS-112 | | Report Title: | Ex-Vessel Coolability and Energetics of Steam Explosions in Nordic Light Water Reactors - EXCOOLSE Project Report 2004 | | Activity Acronym: | EXCoolSE | | Authors: | H. S. Park, A. K. Nayak, R. C. Hansson & B. R. Sehgal | | Abstract: | Beyond-the-design-basis accidents, i.e. severe accidents, involve melting of the nuclear reactor core and release of radioactivity. Intensive research has been performed for years to evaluate the consequence of the postulated severe accidents.
Severe accidents posed, to the reactor researchers, a most interesting and most difficult set of phenomena to understand, and to predict the consequences, for the various scenarios that could be contemplated. The complexity of the interactions, occurring at such high temperatures (~2500ºC), between different materials, which are changing phases and undergoing chemical reactions, is simply indescribable with the accuracy that one may desire. Thus, it is a wise approach to pursue research on SA phenomena until the remaining uncertainty in the predicted consequence, or the residual risk, can be tolerated.
In the PRE-DELI-MELT project (Sehgal and Park, 2004) at NKS, several critical issues on the core melt loadings in the BWR and PWR reactor containments were identified.
Many of Nordic nuclear power plants, particularly in boiling water reactors, adopted the Severe Accident Management Strategy (SAMS) which employed the deep subcooled water pool in lower dry-well. The success of this SAMS largely depends on the issues of steam explosions and formation of debris bed and its coolability.
From the suggestions of the PRE-DELI-MELT project, a series of research plan was proposed to investigate the remaining issues specifically on the ex-vessel coolability of corium during severe accidents;
(a) ex-vessel coolability of the melt or particulate debris, and
(b) energetics and debris characteristics of fuel-coolant interactions endangering the integrity of the reactor containments. | | Keywords: | Severe accidents; melt coolability; ex-vessel; debris characteristics | | Publication date: | 01 Oct 2005 | | ISBN: | ISBN: 87-7893-173-8 | | Number of downloads: | 2471 | | Download: |  NKS-112.pdf |
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