Use of Risk-Informed Technique to Evaluate the Balance of Technical Specifications Events

Risk-informed Technique, combining Deterministic analysis with Probabilistic Risk analysis, could evaluate the whole risk of Nuclear Power Plant, which is more and more deeply used in different areas in NPP, such as Technical Specifications, In-service inspection, GQA and so on. In Risk-informed Technical Specifications Optimization, a three-tiered approach for licensees to evaluate risk associated with proposed TS changes: Probabilistic Risk Assessment Capability and insights, Avoidance of Risk-Significant Plant Configuration, and Risk-Informed Configuration risk management. The Avoidance of Risk-Significant Plant Configuration is one of the essential links, which is also the chief content of Risk-informed Technical Specifications Optimization, so identifying the risk-signification configurations is particularly important for evaluating risk impact. This paper takes one proposed Spray isolation valve TS item change of Containment Spray System in some NPP as an example, to illustrate the method and process of Identifying Risk-significant Configuration from importance analysis result, and gives management suggestions based on the Risk-significant Configuration result, which gives a special way to analysis avoidance of risk-significant configuration, and a well practical lesson for Risk-informed application..