, former director, Nuclear Safety Project

Disaster by Design/Safety by Intent #15

Disaster by Design

You probably have noticed by now there’s no shortage of acronyms and abbreviations in the nuclear industry. There are so many that the Nuclear Regulatory Commission (sometimes called the NRC) published a report chock-a-block with many of them. Because one can never have too many acronyms, I’ll unveil another one: ROSS, for Race of Safety Snails. Read more >

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Fission Stories #127: Helicopter Attack on Point Beach?

, former director, Nuclear Safety Project

At 10 pm on November 6, 1987, security guards at the Point Beach nuclear plant in Wisconsin spotted helicopters coming in low and fast. The helicopters zipped by so close that they rattled windows in the plant. Read more >

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Fission Stories #122: Monkey Business at Point Beach

, former director, Nuclear Safety Project

On May 28, 1996, workers were welding the shield lid onto a dry storage cask at the Point Beach nuclear plant in Wisconsin. The cask had been loaded with irradiated fuel assemblies and then lifted out of the spent fuel pool and placed on the refueling floor beside the pool. The workers triggered what the NRC artfully called “an unanticipated hydrogen gas ignition” (i.e., an explosion) inside the cask. The explosion lifted the 6,400 pound lid up about three inches and left it cocked at a slight angle on the cask. There were no measurable radioactive releases from the cask as a result of the event. Read more >

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Fission Stories #27: Jellyfish Put Nuclear Plant in a Jam

, former director, Nuclear Safety Project

Jellyfish appear harmless. Despite an occasional tale about swimmers being stung by jellyfish, Hollywood movies always feature shark attacks. No National Geographic special has featured cameramen being lowered into the sea in heavy steel cages to film voracious jellyfish. The Discovery Channel hosts a Shark Week each year but lacks a Jellyfish Day or even a Jellyfish Hour.

Nevertheless, a flotilla of jellyfish attacked the Turkey Point nuclear plant in Florida on September 3, 1984. They stormed the plant in such numbers and with such ferocity that they clogged the flow of cooling water to the plant’s main condensers. A metal screen designed to keep debris from being pumped into the plant was bent inward nearly two feet during the assault. Both of the nuclear reactors at Turkey Point had to be shut down. The clogged screens prevented the waste heat produced by the reactors from being dissipated to the environment. The reactors remained shut down for 11 days until Hurricane Diana swept the jellyfish back out to sea.

It was neither the first nor the last time that jellyfish put a nuclear plant in a jam. A year earlier, the operators manually tripped the Unit 1 reactor at the St. Lucie nuclear plant in Florida due to jellyfish blocking the cooling water supply. A month before the September 3 attack, the operators manually tripped the Unit 2 reactor at St. Lucie when the jellyfish returned en masse.

On September 18, 1993, the operators tripped the Unit 1 reactor at St. Lucie, again due to jellyfish intrusion. Two days later as the operators attempted to restore Unit 1 to full power, the jellyfish made another sneak attack. The operators had to trip the reactor again. On September 20, 1993, while making another attempt to restore the reactor to full power, the operators again had to trip the reactor because of the jellyfish.

Jellyfish also caused the operators to reduce the power level of the Unit 1 reactor at the Calvert Cliffs nuclear plant in Maryland on July 7, 2006.

On October 21, 2008, Moon Jellyfish forced the operators to trip the Unit 2 reactor and reduce the power level of the Unit 1 reactor at the Diablo Canyon nuclear plant in California.

The operators tripped the Unit 2 reactor at the Point Beach nuclear plant in Wisconsin on May 15, 2004. Workers lost sight of a diver performing underwater work at the intake structure where the plant draws water from the lake. As a precautionary measure, or as the first step in the recovery effort, the operators shut down the reactor. After the operators turned off the pumps at the intake structure, a second diver entered the water and was able to find the first diver and free his snagged air/communication line. No jellyfish were involved, but it shows that human swimmers can match what jellyfish can accomplish.

Our Takeaway

Nuclear plants draw vast amounts of water from nearby lakes, rivers, and oceans. Large quantities of fish larvae and other aquatic wildlife in that water perish along the way. The jellyfish got some revenge.

The toll paid by aquatic environments around nuclear plants is not insignificant and must be factored into the environmental assessments of nuclear plant operation. The aquatic environment can also take its toll on power plants, and that must also be factored in.

Postscript – Don’t dive near the intake structures for nuclear power plants. You might get in the way of the next jellyfish swarm.

“Fission Stories” is a weekly feature by Dave Lochbaum. For more information on nuclear power safety, see the nuclear safety section of UCS’s website and our interactive map, the Nuclear Power Information Tracker.

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