Regulatory Actions Taken after Fukushima IAEA Technical Meeting on EVALUATION OF NUCLEAR POWER PLANT DESIGN SAFETY IN THE AFTERMATH OF THE FUKUSHIMA DAIICHI ACCIDENT 26 29 August 2103, Vienna, Austria Victor Manuel González Mercado CNSNS, México Comisión Nacional de Seguridad Nuclear y Salvaguardias 1
Mexican nuclear power plant Laguna Verde NPP is located at the State of Veracruz Laguna Verde (LVNPP) Two General Electric BWR-5 Thermal Power: 2027 MWt (~680 Mwe) 3.1% of total country s electrical power generation Licensee and operator: Comisión Federal de Electricidad (CFE) Started operation Unit 1 in 1990 Unit 2 in 1995 Comisión Nacional de Seguridad Nuclear y Salvaguardias 2
Mexican nuclear power plant Laguna Verde site is located far from the main earthquake epicenters in Mexico (Atlantic Coast) and with no important seismic events. Safe Shutdown Earthquake (SSE) is 0.26g of Peak Ground Acceleration. The period of return is 2000 years The maximum credible earthquake predicted for the area has a magnitude of 6.5 on the Richter Scale and could produce a tsunami of magnitude 1. Such a tsunami could cause an elevation of the sea level at the site in the order of 0.50 to 0.75m Laguna Verde site can be subjected to Hurricanes (Atlantic and Caribbean Sea). This event can be critical for Station Blackout Wind velocity Reactor Building 275 kph (Scale 5 Saffir-Simpson, > 249 kph) Comisión Nacional de Seguridad Nuclear y Salvaguardias 3
Initial Actions A review of the capacity of LVNPP to face an event similar to that occurred at Fukushima Daiichi NPP. was required to Licensee CNSNS Base Inspection Programme (PBI) for 2011 was reviewed and adjusted. Two special inspections were included to verify Results of required review Implementation of the SBO rule Special attention was put on related inspection areas (e. g. Emergency Plan, Operator Training Program, Fire protection) in the Base Inspection Program. Comisión Nacional de Seguridad Nuclear y Salvaguardias 4
Inspection results Procedures for verifying the status of the external and internal areas to cope with flood events need to be developed LVNPS is able to cope with a 4 hour SBO, coping time needs to be reviewed Vulnerabilities CNLV to natural events such as earthquakes, floods and adverse weather conditions, as well as the simultaneous occurrence of some of them need to be reviewed. Development of a External Events Probabilistic safety analysis (IPEEE) is recommended Comisión Nacional de Seguridad Nuclear y Salvaguardias 5
Inspection results (cont.) Hard containment emergency venting system discharge to reactor building has to be modified. Severe accident management guides need to be developed Comisión Nacional de Seguridad Nuclear y Salvaguardias 6
Stress tests Seismic and flood information and the calculation methodologies were updated. Seismic and flood (sea-land, land-sea) design basis remain valid. LVNPS is able to cope with a 4 hour SBO Containment hard pipe vent discharges to secondary containment Severe accident management guides have not been developed Comisión Nacional de Seguridad Nuclear y Salvaguardias 7
Regulatory Requirements Develop and implement guidance and strategies intended to maintain or restore core cooling, containment, and spent fuel pool cooling capabilities under the circumstances associated with loss of large areas of the plant due to explosions or fire (10CFR 50.54(hh)(2) ) Modify hard containment emergency venting system discharge. Develop Severe accident management guides Develop External Events Probabilistic safety analysis (IPEEE) Comisión Nacional de Seguridad Nuclear y Salvaguardias 8
Licensee Actions Post-Fukushima Daiichi (1F) Actions in Laguna Verde Nuclear Power Station Implementation of Diverse and flexible strategies (NEI-FLEX) to prevent fuel failure (reactor core and Spent Fuel Pool) and containment. Containment integrity: Construction of an emergency venting line with a rigid discharge duct to the atmosphere Improvements to provide alternative water sources to the ones made available from the original design Extending the SBO required coping time Comisión Nacional de Seguridad Nuclear y Salvaguardias 9
Thank you Comisión Nacional de Seguridad Nuclear y Salvaguardias 10