Jellyfish cause nuclear shutdown

Swedish nuclear reactor shut down after pipes clogged with jellyfish

In late September, tons of jellyfish clogging the cool-water pipes of one of the reactors at Sweden’s Oskarshamn nuclear plant forced the reactor to shut down for several days until the jellyfish could be cleared out.

The Oskarshamn reactor—reactor No. 3—is the largest boiling-water reactor in the world, according to; like the other two reactors at the plant, it uses the same technology as Japan’s Fukushima plant, which was crippled by a tsunami in March 2011.

The common moon jellyfish (pictured)—the culprit in the Oskarshamn incident—is “one of the species that can bloom in extreme areas that … are overfished or have bad conditions,” said Lene Moller, a researcher at the Swedish Institute for the Marine Environment.