IMPACT EVALUATION OF SAFETY MARGINS IN THE LAGUNA VERDE NUCLEAR POWER PLANT USING A DETERMINISTIC AND PROBABILISTIC METHODOLOGY

摘要

Immersed in a climate of submittals for design and operational modifications for Nuclear Power Plants such as power up rates, life extension or increased fuel burn up, the Mexican Nuclear Regulatory Agency (CNSNS) is concerned with the impact and cumulative effects that theses changes may have over the original safety margins, even though all the regulatory requirements are being fulfilled. The use of Probabilistic Risk Analysis is increasing and it is important to address their integration with traditional deterministic analysis. The forthcoming second power up rate plans that will take place in short time in the Laguna Verde NPP gives a motivation to CNSNS to explore the benefits of evaluate the situation of safety margins with an integrated methodology. In the present paper, the application of a methodology for evaluation of Safety Margins is addressed for a safety issue for Laguna Verde. In this application the margin in peak cladding temperature has been evaluated through the event of Main Steam Isolation Valves closure as first approach. In this case, the safety margins impact of the first power up rate (5%) already accomplished in Laguna Verde is considered and analyzed as reference for the next planned and higher power up rate.