New component issues idle Korean reactors

Two South Korean power reactors have been ordered offline and another two must remain out of operation until uncertified cabling has been replaced. The government is worried about possible power shortages over the coming months as a result.

Two South Korean power reactors have been ordered offline and another two must remain out of operation until uncertified cabling has been replaced. The government is worried about possible power shortages over the coming months as a result.

Shin Kori units 1 and 2 (Image: KHNP)

In an investigation unrelated to the falsely-certified parts discovered last year, safety-related control cabling with forged documentation was found to have been installed at the four reactors. In the event of an accident, the cables send signals from the reactor operating systems, such as cooling, to the control room.

Korea's Nuclear Safety and Security Commission (NSSC) ordered Korea Hydro and Nuclear Power (KHNP) to immediately stop operation of its Shin Kori 2 and Shin Wolsong 1 units. It also said that Shin Kori 1, which has been offline for scheduled maintenance, must remain out of operation. In addition, the newly-constructed Shin Wolsong 2, which is awaiting approval to start commercial operation, will not be permitted to start up.

Power shortages

The Ministry of Trade, Industry and Energy said, "The unprecedented power shortage this summer is a concern." The ministry expects supply capacity of 80,000 MWe during the summer, when demand is projected to be 79,000 MWe. However, generating capacity is now only likely to be around 77,000 MWe.

It warned that the worst shortages could occur in August. It said it would consider various measures - including rolling blackouts - to help meet demand.

The NSSC has told KHNP that the four units will not be allowed to operateto until the cabling has been replaced. This, it said, is expected to take about four months to complete.

Korean authorities began an investigation into forged safety certificates for the cabling in April after a tip-off. NSSC chairman Lee Un-chul said, "We found fabrication in some graphs and test results of the cable parts used in Shin Kori units 1 and 2 and Shin Wolsong units 1 and 2. We also confirmed that these parts have been used for the Shin Kori units 3 and 4, which are nearing completion."

Lee told The Korea Times that a member of staff of a Korean testing institute produced a forged test result claiming it was from an overseas institute. He said, "The Korean institute asked a Canadian institute to conduct part of the test. The foreign institute said some of the cable parts did not pass its test, but the staff member altered the result."

The latest discovery of forged quality documentation is said to be unrelated to the case announced last November in which KHNP had allegedly been supplied with falsely-certified non-safety-critical parts for at least five power reactors. The utility told the ministry that eight unnamed suppliers - reportedly seven domestic companies and one US company - forged some 60 quality control certificates covering 7682 components delivered between 2003 and 2012.

The majority of the parts were installed at Hanbit (Yonggwang) units 5 and 6, while the rest were used at Hanbit units 3 and 4 and Hanul (Ulchin) unit 3. Hanbit 5 and 6 were taken offline while the parts were replaced.

A review of safety at all 23 of South Korea's nuclear power reactors has started. The review, being undertaken by Germany's TUV SUD, will include an examination of each unit's inspection results over the past three years. It will also check that operating procedures comply with international standards. The review is expected to be completed by the end of July.

Researched and written
by World Nuclear News