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NKS Programme Area:NKS-R
Research Area:Severe accidents and Reactor Physics
Report Number:NKS-246
Report Title:In-vessel Coolability and Steam Explosion in Nordic BWRs
Activity Acronym:INCOSE
Authors:Weimin Ma, Liangxing Li, Roberta Hansson, Walter Villanueva, Pavel Kudinov, Louis Manickam, Chi-Thanh Tran
Abstract:The objective of this research is to reduce the uncertainty in quantification of steam explosion risk and in-vessel coolability in the Nordic BWR plants which employ cavity flooding as severe accident management (SAM) strategy. To quantify the coolability of debris bed packed with irregular particles, the friction laws of fluid flow in particulate beds packed with non-spherical particles were investigated on the POMECO-FL test facility, and the experimental data suggest that the Ergun equation is applicable if the effective particle diameter of the particles is represented by the equivalent diameter of the particles, which is the product of Sauter mean diameter and shape factor of the particles. One-way coupling analysis between PECM model for melt pool heat transfer and ANSYS thermo-structural mechanics was performed to analyze the vessel creep, and the results revealed two different modes of vessel failure: a ‘ballooning’ of the vessel bottom and a ‘localized creep’ concentrated within the vicinity of the top surface of the melt pool. Single-droplet steam explosion experiments were carried out by using oxidic mixture of WO3-CaO, and the results show an apparent difference in steam explosion energetics between the eutectic and non-eutectic melts at low melt superheat (100 oC).
Keywords:severe accident, debris coolability, steam explosion
Publication date:01 May 2011
ISBN:ISBN 978-87-7893-318-8
Number of downloads:800
Download:pdf NKS-246.pdf
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