Six Cases of Improper Welding Procedure in Hanbit Nuclear Power Plant Cooling System... 13 Years of Quality Control Lapses

Inappropriate WPS Application Identified in 6 Out of 14 Heat Exchanger Maintenance Cases for Units 1 and 2
Task Remains to Investigate Omission of Reporting and Prolonged Quality Management Lapses
Hanbit Nuclear Power Plant Explains, "It Took Time to Determine Nonconformity"

It was confirmed that six cases were reported where inappropriate Welding Procedure Specifications (WPS) were used during the maintenance of heat exchangers in the cooling systems of Hanbit Nuclear Power Plant Units 1 and 2. Since the first case in 2013, the same type of problem has been repeated over a period of 13 years up to this year, raising serious questions over whether the nuclear power plant's maintenance system and quality management procedures have functioned properly.

According to the Hanbit Nuclear Power Plant Environmental Safety Monitoring Center and other sources on September 3, it was discovered that maintenance work on the internal thinning sections of the Hanbit Unit 1 Component Cooling Water (CCW) Heat Exchanger A and Hanbit Unit 2 Heat Exchanger A and B was performed using WPS without impact testing applied.

Panoramic view of Hanbit Nuclear Power Plant.

A WPS defines the methods, materials, and operating conditions for welding, serving as a standard to ensure consistent weld quality. WPS and its related welding process technologies are used to ensure the integrity of major power plant facilities. Of the 14 maintenance tasks subject to this recent inspection, the Hanbit Nuclear Power Plant Environmental Safety Monitoring Center explained that improper application of the WPS was confirmed in 6 cases.

In detail, with regard to Hanbit Unit 1 CCW Heat Exchanger A, out of six inspected maintenance tasks, improper application of the WPS was found in three instances: October 2013, November 2016, and January of this year. For Unit 2, improper WPS application was found in two instances for Heat Exchanger A (March 2013 and November 2023) and one instance for Heat Exchanger B (February 2013). The same type of issue, therefore, has recurred from the first case confirmed in 2013 to this year, spanning a total of 13 years.

The reporting process to local monitoring organizations is also causing concern.

At the 94th Monitoring Committee meeting on August 21, issues with the heat exchanger due to rising seawater temperatures were discussed. However, it is known that Hanbit Nuclear Power Plant Headquarters did not report these WPS application issues at the time.

The Monitoring Center stated that it would review why Hanbit Headquarters did not report the matter at the time, and, if it is found that there was a deliberate omission, the monitoring body intends to respond at the organizational level.

An official from the monitoring body pointed out, "Given the nature of nuclear power plants, which are directly linked to the safety of local residents, any such problem should have been promptly shared. Rather than informing after an incident has occurred, it is necessary to disclose information from the moment any abnormalities or problems are identified."

In response, Hanbit Nuclear Power Plant explained that the notification to the local community was delayed because it took time to determine whether the issue constituted a nonconformity.

A representative from Hanbit Nuclear Power Plant said, "After discovering the issue during the planned preventive maintenance of Hanbit Unit 1 this year, we conducted a full investigation and expanded inspection, confirming a total of six cases across Units 1 and 2. We have been in constant consultation with the Nuclear Safety and Security Commission. Recently, after officially classifying the cases as nonconformities (NCR), we reported them to the regional office of the Commission. Subsequently, the relevant information was also conveyed to the Nuclear Safety Communication Council," he explained.

He added, "The notification to the local monitoring organizations was delayed by several months because we needed time to review and confirm whether the cases corresponded to nonconformities or discrepancies. We will provide additional details on the specific reasons for the final notification delay in a separate report."

The Hanbit Nuclear Power Plant plans to upload a detailed explanatory report on its website.

This content was produced with the assistance of AI translation services.