Selection and Classification of Abnormal Events

Since the function of the AFS is to keep the main coolant flow rate in the event of the unavailability of the RCPs, its actuation signals should be released by detecting an abnormality in the RCPs or a decrease in the main coolant flow rate. Reactor coolant pump trip and main coolant flow rate low are taken as the AFS signals. Loss of offsite power, condensate pump trip, turbine control valves quickly closed, main stop valves closure, and MSIV closure are also taken as the AFS signals because these abnormalities cause a trip of the RCPs. 

Abnormalities of LWRs are categorized as several types. Since the Super LWR is also a light water cooled reactor and the components are similar to those of LWRs, its abnormalities are taken from those of PWRs and BWRs. Reference is also made to sodium cooled reactors. Although many of the abnormalities in sodium cooled reactors are also considered in LWRs, there are some abnormalities that are not considered. However, these abnormalities are not possible in the Super LWR. Gas cooled reactors are also considered however, there are no abnormalities which are 

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The safety principle and safety system design are described in Sects. 6.2 and 6.3, respectively. Then, the deterministic approach to the Super LWR safety is described in Sects. 6.4-6.7 these describe safety analysis methods, selection and classification of abnormal events, the criteria for safety analyses, and the results of safety analyses. In addition, development of a transient subcharmel analysis code and its application to the flow decreasing events are described in Sect. 6.8. Based on the safety system design and the deterministic safety analyses, level-1 probabilistic safety assessment (PSA), which is also called level-1 probabilistic risk assessment (PRA), is presented. 

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