Severe accident management guidelines (SAMGs) increase focus on containment integrity after some progression in the course of a severe accident. This change in priorities is made according to criteria that vary depending on reactor type and specific procedures. Non challenging the priority given to containment integrity, trying to cool the degrading fuel and/or the corium within the reactor pressure vessel (RPV) is a way to slow down or stop the progression of an accident. This may also delay or avoid the RPV rupture that may subsequently endanger the containment integrity by dynamic loads [direct containment heating (DCH), ex-vessel steam explosion (SE)] and/or static loads [corium-concrete interaction (CCI)].
This issue, called “in-vessel coolability”, has been identified as most important by both the Committee on the Safety of Nuclear Installations (CSNI) Working Group on the Analysis and Management of Accidents (WGAMA) and EC-SARNET (see Severe Accident Research Priorities final report SARNET-SARP-D96).
This document presents the results of a workshop on this topic held in Paris, France on 12-14 October 2009.