Power shortage prompts Kori 1 restart

07 August 2012

The South Korean government announced that unit 1 of the Kori nuclear power plant is being restarted as the country faces a power shortage due to high summer temperatures.

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The Kori plant (Image: KHNP)

An alert was recently issued warning that South Korea faces power shortages due to the high summer temperatures it is currently experiencing. This prompted the Ministry of Knowledge Management to declare on 6 August that Kori 1 was being restarted after several months offline.

Knowledge economy minister Hong Suk-woo was quoted by the Korea Times as saying, "Despite the approval from the safety commission, the government delayed the restart of the reactor for over a month, considering concerns held by residents from near the Kori plant." He added, "I believe there is no problem with the (reactor's) safety. From the beginning, it was a matter of how safe people felt."

In February, during a month-long maintenance shutdown, Kori 1 had been receiving power from one of its three grid connections while the other two were undergoing maintenance. One of the two diesel generators was also under maintenance while the other was on standby and a third was available for manual start.

However, a worker who had not been following proper procedure accidentally broke the connection to the grid and caused a 12-minute station black-out at the reactor. This meant that the reactor had no power for safety-related functions including cooling of the core and used fuel pond. Plant staff quickly and reconnected to the grid, however, the manager of the reactor decided to conceal the incident, despite a legal obligation to notify the Nuclear Safety and Security Commission (NSSC) of the technical emergency situation.

After details of the black-out came to light about a month later, the NSSC ordered Kori 1 to remain offline for safety inspections. In early July, the NSSC approved the restart of the unit. A month earlier, a mission from the International Atomic Energy Agency inspected the plant and confirmed it safe to restart. However, the plant's owner, Korea Hydro and Nuclear Power (KHNP), delayed its restart in order to gain the support of local residents.

Hong stressed, "We are not restarting the reactor in haste. If we wanted to restart it quickly, we would have done so a month ago." But, he added, "We are relieved the Kori reactor was restarted."

The unit - a 567 MWe pressurized water reactor - is expected to reach full generating capacity by as early as 10 August.

The circumstances of the safety-related incident and its cover-up were the subject of investigation by the NSSC. The reactor manager was dismissed after admitting his actions. The incident also led to the resignation of the head of KHNP, Jong-shin Kim, in April.

The NSSC said that the incident may have highlighted apparent safety culture issues. The regulator noted that a factor in the manager's decision not to report was pressure to have a perfectly clean operational record because the reactor had recently been given a licence extension - the first time this had happened in South Korea.

Researched and written
by World Nuclear News