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More technical problems at nuclear reactors

Nuclear power plant fears, already stoked by last year’s Fukushima disaster in Japan and a power outage with a subsequent cover-up at Busan’s Kori No. 1 Nuclear Power Plant, were fanned further by technical problems October 2 that led to shutdowns at the Shin-Kori No. 1 and Yeonggwang No. 5 power stations.

Troubled by the recurrence of control rod incidents that could lead to safety issues, as well as the increased accident rate at the so-called “Korean-standard” reactors, observers are now saying Korea Hydro and Nuclear Power (KHNP) and the Nuclear Safety and Security Commission (NSSC), which respectively operate and regulate the plants, need to look into the cause of the problem and take appropriate action.

On October 2, KHNP announced a technical problem with the control system for the rods that adjust reactor output at Shin-Kori No. 1. This comes after similar incidents at Yeonggwang No. 6 on July 30 and Shin-Wolseong No. 1 on August 19, where the reactors were also shut down due to rod control system problems.

Control rods are used to control the fission chain reaction in nuclear fuel. They play an important role as a means of preventing accidents at operating reactors.

According to KHNP, the recent problems were all assigned an International Atomic Energy Agency risk level of zero, since the control rod issues would not immediately lead to an accident involving the release of radiation.

But if coupled with a natural disaster scenario such as the earthquake that struck Fukushima, or an explosion like the one at Chernobyl, a rod control failure could lead to a devastating accident.

Also drawing attention is the fact that all three reactors, as well as Yeonggwang No. 5, which was also recently shut down over a technical problem, are Korean-model designs.

Yeonggwang No. 5, which began commercial operation in 2002, is a Korean Standard Nuclear Power Plant (KSNP), which Shin-Kori No. 1, which went on line in February 2011, has an improved KSNP design called the OPR1000.

Of the 105 accidents and technical problems that occurred at South Korean nuclear power plants between 2000 and last month, thirty-nine, or 37 per cent, occurred at Korean-standard reactors. The percentage is especially high given that nine of them have gone online since the first one built, Uljin No. 3, went into operation in 1998.

Seoul National University nuclear engineering professor Hwang Il-soon cautioned against reading too much into the numbers. “There’s no obvious correlation between the Korean-model designs and the frequency of problems, and there tend to be more problems early in their operation anyway,” he said.

“The problem seems to be more that the plant operations have lost trust than that the actual risk is greater,” he added.

Indeed, sixty-two of the 86 problems reported between 2002 and 2011, or 72 per cent, were determined to be the result of human error. Popular distrust appears to stem from a lack of trust in power plant safety management more than anything else.

At the same time, neither KHNP nor the NSSC has made any plans for special investigations of the frequent shutdowns.

Yoo Kook-hee, the NSSC’s safety policy bureau chief, said, “If you consider that we added another two reactors this year, there hasn’t been a huge increase in power plant shutdowns, nor is there any commonality in the places and causes of the technical problems.”

Yoo added that independent examinations were under way to determine whether the problems might be associated with some shared vulnerability.

But Yang-Lee Won-young, head of Korean Federation for Environment Movement’s bureau for post-nuclear energy, said that if the reactors are put back into operation with only the problematic parts replaced, the likelihood of continued accidents, possibly major, increases.

“KHNP and the NSSC need to take this opportunity to uncover the root cause and allay the public’s fears,” Yang-Lee said.

Lee Heon-seok, an aide to lawmaker Kim Je-nam of the Preparatory Committee for a New Progressive Party, noted the approach adopted with nuclear power plants in Europe.

“They’re conducting three-stage inspections for all power plants, with crosschecking by operators, safety regulators, and regulators in other countries,” Lee said. “They extend the deadlines and conduct careful examinations to earn the trust of citizens, publicly disclosing everything they find.”

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