On the Effectiveness of CRGT Cooling as a Severe Accident Management Measure for BWRs
2009 (English)In: Proceedings of OECD/NEA Workshop on Implementation of Severe Accident Management Measures, 2009Conference paper (Refereed)
To quantify the effectiveness of control rod guide tubes (CRGT) cooling as a potential severe accident management (SAM) measure in BWRs, two analysis methods are adopted at KTH: alumped-parameter analysis of accident sequences performed by the MELCOR code at system level;and a mechanistic multi-dimensional analysis of heat transfer in the corium-filled lower head by theEffective Convective Model (ECM) developed for modeling of corium behavior in a complex geometry as the BWR's lower plenum with a forest of CRGTs. The dual approach leverages on the strength of the two methods (MELCOR/ECM), and therefore increases the reliability of the assessment.The current paper is focused on the MELCOR calculations. The first-cut results show that the nomina lflowrate (10.5kg/s) of CRGT cooling is sufficient to maintain the integrity of the vessel in a BWR of 3900 MWth, if the water injection is activated no later than 1 hour after scram. For late recovery of the CRGT cooling (later than 1 hour after scram), a higher flowrate rather than the nominal is needed to contain the melt in the vessel. For instance, if water injection through CRGTs is activated after 2 hours following scram, much higher flowrate (~40kg/s) is required for in-vessel retention (IVR).
Place, publisher, year, edition, pages
severe accident, in-vessel retention, coolability
IdentifiersURN: urn:nbn:se:kth:diva-57693OAI: oai:DiVA.org:kth-57693DiVA: diva2:472469
OECD/NEA Workshop on Implementation of Severe Accident Management Measures, Schloss Böttstein, Villigen, Switzerland, October 26 - 28, 2009
QC 201201122012-01-032012-01-032012-01-12Bibliographically approved