Roles of analytical simulation in validation of a severe accident management program

Canadian Nuclear Safety Commission (CNSC) had led a task group of 'Informing Severe Accident Management Guidance (SAMG) and Actions through Analytical Simulation' under the Working Group on Analysis and Management of Accidents (WGAMA) of Nuclear Energy Agency (NEA) and complied a state-of-the-art report on this topic. This presentation will focus on Canadian approach to validate a fully-developed, plant-specific SAMG and identify areas for strengthening and improvement. Various methods are used to assess the effectiveness of severe accident management (SAM), including the use of SAMG and other post-Fukushima guidelines such as Emergency Mitigating Equipment Guidelines (EMEG). In this presentation, emphasis is given on how analytical simulation can play an important role in SAMG validation. The presentation will promote a discussion on the following aspects: • An overview of a SAM program, in which SAMG is a key component. A SAM program evaluation takes consideration of many aspects and activities. Assessing SAMG strategies and actions through analytical simulation is only one of these activities. • Methods of SAMG verification and validation. Analytical simulation is one of the means to inform the effectiveness of SAM. • Focusing areas for assessing SAMG actions through simulation. Questions may be asked such as what is the impact of an earlier or later initiation of a prevention or mitigation action? What are the environmental conditions associated with the expectation of the action? What are the positive and negative outcomes from the action? • Roles of severe accident analysis codes to support SAM. • Use of severe accident analysis codes to inform the adequacy and completeness of a plant-specific SAMG. • Examples of analytical simulation of the SAMG-specified actions and how the results or messages derived from such a simulation could be useful. (author)