Connecticut has one nuclear power plant. On Saturday, one of its reactors was shut down because the water in Long Island Sound was too hot.

Unit 2 of Millstone Power Plant near New London was shut down Sunday afternoon after temperatures in the sound exceeded 75 degrees for 24 hours, the maximum temperature at which the nuclear power plant has permits to extract cooling water for the unit, said Ken Holt, spokesman for plant operator Dominion.

We’ve mentioned the correlation between warmer water and electricity production before. In a nuclear plant, water plays a critical role in keeping the reactor core cool. Obviously warm water is not as effective at displacing that heat. And if the reactor core isn’t kept cool — well, let’s just say you want to keep it cool.

Temperatures in Long Island Sound (at left center). Click to embiggen. (Image courtesy of Weather Underground.)

Long Island Sound is not exactly a minor body of water. North of Long Island itself, the sound is connected directly to the Atlantic Ocean. As the Times notes, the water has never before been too warm to cool the reactor.

As for the facility’s other reactor:

Holt said that Millstone’s other reactor, Unit 3, pulls water from deeper in the sound than does Unit 2, and so far has not been affected by the warm waters. However, he said the unit has the same temperature limit under which it can operate. “If temperatures continue to rise, Unit 3 will be shut down as well,” he said. … Together, the two Millstone reactors produce about 16 million megawatt-hours of electricity per year –enough to power 500,000 homes.

If there were a … problem with either reactor, here’s a map of where you wouldn’t want to be (for a few centuries). And for what it’s worth, we hear there’s a Twinkie factory in nearby Natick.