The International Atomic Energy Agency (IAEA) on 18 August concluded a five-day Site and External Events Design (SEED) mission to South Korea to review methods and criteria for evaluating seismic safety at the Wolsong and Shin Wolsong NPPs, operated by Korea Hydro and Nuclear Power (KHNP). Wolsong NPP comprises four Candu 6 heavy water units Shin-Wolsong operates two Korean OPR-1000 pressurised water reactor units.
The two plants are located at the same site, where an earthquake measuring 5.8 on the Richter scale struck in September 2016. The SEED team examined the results of inspections carried out after the earthquake as well as the technical basis of hazard assessments and risk analyses. It also reviewed KHNP's mid-term action plans established in response to the earthquake. Shin Morita, head of the IAEA's External Events Safety Section, said: "The team was impressed by the positive attitude and concrete actions, taken by KHNP and partly coordinated with the government, to continuously improve safety against natural external events."
The team identified good practices, including the fact the government has a nationwide plan for assessing seismic hazards, enabling KHNP to update parameters of site-specific external natural hazards. KNHP has established a new organization, the Seismic Engineering Office, "aimed at continuously improving safety against seismic hazards at all nuclear sites in the country, leveraging lessons and knowledge gained at the Wolsong and Shin Wolsong plants", the IAEA said. The team also recommended on-going, comprehensive seismic hazard assessment measures to strengthen alignment with IAEA safety standards. The final mission report will be delivered to the government within three months.