Insights into developing a systematic approach to safety analysis for advanced (non water-cooled) reactors and SMRs

To meet the regulatory expectations in REGDOC-2.4.1 for deterministic safety analysis, limit-of operating envelope (LOE) and realistic operating envelope (ROE) approaches have been implemented by the Canadian CANDU industry. The LOE approach is consistent with international practice. In the LOE approach, key parameters that characterize the plant operating condition at the time of the accident, as well as equipment response to the accident, are assumed to be at their operating limits, so as to maximize the consequences of the accident. The objective of the LOE approach is to calculate margins to the established acceptance criteria and safety limits during postulated reactor accidents in a conservative way and is applicable to design basis accidents (DBAs). The ROE approach analyzed the event in a realistic manner and is used for Anticipated Operating Occurrences (AOOs). This paper presents some lessons learned from performing deterministic safety analyses for the Canadian CANDU industry for consideration in developing safety analysis methods for advanced (non water-cooled) reactors and small modular reactors. (author)