Tiny Sea Creatures Plague South Korean Nuclear Plant Operations

Sea salps -- gelantinous, marine organisms that look like jellyfish -- may be small, typically measuring less than 10 centimeters tall. But the tiny creatures are turning out to be a major pest to South Korea’s nuclear industry.

The organisms have clogged water systems used to cool Korea Hydro & Nuclear Power Co.’s Hanul No. 1 and No. 2 reactors, forcing them to shut Tuesday, the second time in less than three weeks the units were taken offline due to sea salps. The reactors, which each have a capacity of 950-megawatts, were offline for about a week in late March.

The shutdowns could get costly the longer they continue. If the amount of lost power from the initial eight-day disruption was offset with generation from liquefied natural gas, it would require a 60,000-ton cargo of the supercooled fuel, costing roughly $21.8 million, according to BloombergNEF analyst Olympe Mattei.

South Korea has 24 operable nuclear plants with a combined capacity of more than 23 gigawatts.

Sea salps can link up into chains several meters in length and have been said to resemble a crystal chandelier drifting through the ocean. The organisms typically increase in number in June but that appears to have happened in March this year due to earlier-than-normal warm currents, said Yu Ok Hwan, a deputy director at Korea Institute of Ocean Science and Technology.

“We can’t say yet if the surge in salps is due to the changing climate or other factors,” said Youn Seok-hyun, a research scientist at National Institute of Fisheries Science. “It should be regarded as a temporary phenomenon unless we see a continuous increase over the next decade.”

More on how marine life impacts energy markets:

The number of sea salps has been gradually rising in recent years, according to Chae Jinho, the head of Marine Environment Research & Information Laboratory. “Given the current trend, there’s a possibility we may see more of these shutdowns at reactors in the coming years,” he said.

The country isn’t the only one to have been forced to halt nuclear generation temporarily after sea life clogged water cooling systems. Electricite de France SA in January had to disconnect all four reactors at its Paluel nuclear plant on France’s north coast after fish got stuck in the filter drums of the pumping station.

©2021 Bloomberg L.P.

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