An International Atomic Energy Agency (IAEA) team of experts has concluded a five-day Site and External Events Design (SEED) mission to the Republic of Korea.
The SEED team reviewed methods and criteria for evaluating seismic safety at the Wolsong Nuclear Power Plant and Shin Wolsong Nuclear Power Plant (NPP), operated by Korea Hydro and Nuclear Power Company (KHNP). Both facilities are located at the same site on the south-eastern coast, where an earthquake measuring 5.8 on the Richter scale struck in September 2016.
The mission, concluded on 18 August, was requested by the Government of the Republic of Korea. In particular, the 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 2016 earthquake.
“The IAEA team received information on the process and results that KHNP has conducted and obtained over the last four decades for assessing seismic hazards and safety at Wolsong and Shin Wolsong,” said Shin Morita, Head of the IAEA’s External Events Safety Section. “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.”
SEED missions are designed to assist Member States at different stages in the development of a nuclear power programme. The SEED safety review service offers a choice of modules on which to focus the review, such as site selection and assessment, and the design of structures, systems and components against site external hazards.
The SEED team was made up of three experts from Argentina, Switzerland and the United States of America as well as two IAEA staff. The team held talks with managers and experts at both KHNP’s headquarters in the city of Gyeongju and at the site.
“We will develop a detailed plan for implementing, in a timely manner, the IAEA’s recommendations,” KHNP Executive Vice President Mr Cheong-ro Yoon said. “KHNP will expand upon the experiences and knowledge it has gained to all nuclear power plants including the Kori, Hanbit and Hanul sites.”
The team identified good practices, including:
- 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 NPPs.
The team also provided suggestions and recommendations for further enhancements, including:
- On-going, comprehensive seismic hazard assessment measures should enhance alignment with IAEA safety standards.
- When assessing the impact of actual earthquakes on safe NPP operation, the Cumulative Absolute Velocity should be used in the decision criteria, so that the operators are able to determine the absence of potential damages with high confidence.
In accordance with IAEA practice, the final mission report will be delivered to the Government within three months.