Jellyfish vs. Nuclear plants: A New Existential Threat?

Polina A Bogomolova
Second-Year MA Candidate at SAIS Washington

Earlier this month a large colony of moon jellyfish jammed the Oskarshamn nuclear power plant’s cooling system pipes. The jellyfish blockage forced the plant, which is located in southeastern Sweden, to shut down its Unit 3—one of the largest boiling-water-type reactors in the world producing 14,000 MW in electricity output. According to plant representatives, workers scrubbed for three days before clearing the several tons of jellyfish that had blocked the pipes.

In 2005, the same problem forced Oskarshamn to shut down Unit 1 for several days. And Sweden is not the only country to have had jellyfish swarm nuclear plants. In 2011, two other plants—the Orot Rabin plant in Israel and the Torness nuclear facility in Scotland—had to be shut down due to jellyfish invasions. In 2012, the same fate fell upon the Diablo Canyon nuclear power plant in California.

Jellyfish can live in extreme conditions where no other species can. They need little oxygen, and they can withstand a wide range of ocean temperatures. According to Dr. Anthony Richardson, a scientist with the Commonwealth Scientific and Industrial Research Organization (CSIRO), due to global warming, overfishing, and sea pollution, marine ecosystems, especially in the highly industrialized and highly populated areas – like Baltic Sea where the Oskarshamn plant is built – are changing drastically. As a result, many of the jellyfish’s predators and competitors have either died off or migrated, which has allowed jellyfish populations to boom. Such places as Mediterranean Sea, Sea of Japan, Gulf of Mexico, the Caspian and Baltic Sea, and the Northeast and Far East US coastal waters report frequent and more severe year-to-year outbreaks of jellyfish overpopulation. Such a tendency not only harms marine biology and the global economy, but also creates dangerous conditions for many nuclear plants built at the above-mentioned coastal areas.

The most common technology used in nuclear plants to produce electricity is Boiling-Water-Reactors (BWRs). These reactors require plants to take in significant amounts of water daily for cooling, water usually drawn from large lakes, the sea, and/or the ocean. Jellyfish in the source waters flow with the pipes’ intake and accumulate on the pipes’ cleaning membranes. The result is an impenetrable jellyfish clog. When a nuclear plant is unable to access cooling water to operate its turbines safely, it must shutdown or risk malfunctioning.

According to Steve Haddock, of the Monterrey Bay Aquarium Research Institute, the jellyfish problem is not new for the nuclear-power industry. The first such jellyfish-clogging was recorded as early as in 1937. However, due to climate change and global warming, marine ecosystems are changing very rapidly, which is increasing the frequency of jellyfish overpopulation outbreaks. We have yet to determine how to prevent jellyfish overpopulation—or the resulting ecological, economic, and public health consequences. As of now, Oskarshamn Nuclear Plant and alike remain poorly prepared to face the next jellyfish invasion.

Polina A Bogomolova is a second-year graduate student at the Johns Hopkins School of Advanced International Studies (SAIS) concentrating in Energy, Resources, and Environment (ERE)

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