Jellyfish Shut Down Diablo Canyon Power Plant

An unprecedented invasion of jellyfish earlier this week managed to accomplish what decades worth of activists have failed to do: Shut down San Luis Obispo County’s Diablo Canyon Nuclear Power Plant. Shortly before 9 p.m. Tuesday, alarms began to sound at the Pacific Gas and Electric’s Avila Beach facility. Water pressure readings for the power plant’s cooling system were skyrocketing and no one could figure out why. After a team of scuba divers surveyed the underwater scene of the bay that feeds the plant’s intake valves, they determined the culprit: Hundreds of moon jellyfish (Aurelia aurita) had jammed the pipes, prompting officials to power down the plant.

While no permanent damage was done, according to PG&E spokesperson Sharon Gavin, the two-reactor facility – which pumps out about 18,000 gigawatt hours of electricity a year – was severely hamstrung by the invasion with one reactor operating at half capacity and the other completely shut down for about two days. As of press time, the unit 1 reactor was back up to 97 percent of operating capacity while unit 2 remained totally shut down.

The moon jellyfish is no stranger to area waters, but the impact of this week’s swarm is unheard of, Gavin said. And while no PG&E customers have lost service as a result of the intake attack, the mess is far from an easy cleanup.

“Our divers are not seeing anymore jellyfish action right now, so that’s a good thing,” Gavin said.

But there is still work to be done before the plant will be fully operational. With hundreds of jellyfish “about the size of a basketball” caked on the filter screens found in the bowels of the intake pipes, divers have been working to scrape the jiggly invaders off in hopes of getting the second reactor back up to speed before the weekend.