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Kang Jung-min

By Kang Jung-min, former chairman of the Nuclear Safety and Security Commission

Thursday marked the passage of ten years since the nuclear disaster at Fukushima. It was an unprecedented meltdown that occurred in the cores of three nuclear reactors after a massive earthquake tsunami knocked out power within a power plant there and disabled the reactors’ cooling capabilities.

Massive amounts of radioactive materials leaked from the reactors in a hydrogen explosion, forcing the evacuation of over 100,000 people from the regions around the plant. Ten years later, around 13,000 remain unable to return to their homes due to radioactive contamination.

The 2011 Fukushima disaster followed in the wake of a partial core meltdown at Three Mile Island in 1979 and a meltdown and shell structure explosion at Chernobyl in the former Soviet Union in 1986. With it, the “safety myth” in the atomic energy community — the assertion that large-scale core meltdown incidents would only occur once in 100,000 to a million years — came crashing down.

Are South Korea’s nuclear power plants safe from the threat of massive nuclear accidents like those seen at Chernobyl or Fukushima?

In the wake of the Fukushima disaster, the South Korean government formulated 50 safety improvement measures for nuclear power. As of July 2020, 47 of them had entered effect.

Yet my personal view is that a major accident could happen at any time with South Korea’s nuclear power plants. The reason is that the government’s follow-up measures for plant safety are all basically premised on a scenario caused by a major natural disaster.

A nuclear incident like the one at Fukushima could happen even without a natural disaster as a precipitating cause. A similar outcome could be triggered by a military attack or act of terrorism or sabotage that disables a plant’s safety systems, including those related to cooling and power. One example that comes quickly to mind is an enemy missile attack against one of South Korea’s nuclear plants.

The containment building that protects the reactor would be directly vulnerable to a missile attack. In place to prevent the possible leaking of radioactive gas into the atmosphere from a nuclear incident, the containment building would lose its containment capabilities if a missile attack were to breach its walls or cause cracks.

Even if the reactor vessel inside that building is not damaged by the attack, there could be damage to the pumps, pipes and other components of the cooling system. A core meltdown could occur if pump or pipe damage prevents cooling water from circulating.

Disruption to an offsite power source from a missile attack could also compromise the emergency diesel generator within the site. Without electricity, it becomes impossible to operate the emergency core cooling system within the reactor — a situation that could lead to a core meltdown.

Another scenario is one where the same causes lead to direct or indirect damage to the spent nuclear fuel storage tanks or cooling system located in an ordinary concrete building next to the containment building, leading to a fire involving spent nuclear fuel. The amount of radiation leaked into the surrounding environment by a fire in the spent nuclear fuel storage tanks would far exceed the Fukushima disaster in scale.

In my own research presented before the American Nuclear Society last November, I found that an average of anywhere from 2.3 million to 12.9 million South Koreans would need to be evacuated in the scenario of a core meltdown incident at the Kori-3 reactor.

But in the scenario of a fire involving Kori-3’s spent nuclear fuel storage tanks, the average number of evacuees would range between 8.5 million and 50 million. In such an incident, the effects of radioactivity would also cause major damage in neighboring countries such as North Korea, Japan, China, Russia and Taiwan.

It’s difficult to prevent a nuclear power plant accident from happening. But there are things we can do to vastly reduce the potential ravages of radioactivity from a spent nuclear fuel storage tank fire.

In the case of South Korea’s light water reactor plants, we can adopt ordinary storage in place of the high-density storage currently used due to a lack of spent nuclear fuel storage tank capacity. We can also relocate spent nuclear fuel to safer metal/concrete dry storage facilities after they have cooled for five years and more in their tanks.

Major nuclear power plant disasters could happen at any time. We must not neglect our efforts to ensure safety. It’s a matter with direct bearing on national security.

Please direct comments or questions to [english@hani.co.kr]