The 27 gallons (102 liters) of condensate was released from a steam system overflow vent Feb. 3 and return pumps failed, causing a spill onto the ground at the plant 40 miles (64 kilometers) southeast of Minneapolis, Mary Sandok, a spokeswoman for Xcel, said in an e-mail. The 551-megawatt Unit 1 and the 545-megawatt Unit 2 are operating at full power.
The release contained 15,000 picocuries per liter of tritium, a low-level radioactive form of hydrogen, according to a filing with the Nuclear Regulatory Commission. The Environmental Protection Agency’s drinking water standard for tritium allows 20,000 picocuries per liter, the NRC says on its website.
“Plant management has shut down the steam heating system while it investigates the matter, identifies the cause of the pump failure and corrects the equipment deficiencies,” Sandok said. “The overflow did not impact operations at the plant and there was no risk to the public or employees.”
The condenser system turns steam, which is heated by the reactor to drive turbines that produce electricity, back into water. The incident, which occurred in a warehouse being heating by the steam, follows a leak of sodium hypochlorite and other chemicals at the plant Jan. 1. Bleach is a solution of sodium hypochlorite.
The release also included methoxypropylamine, ammonia and hydrazine, the filing showed. The plant near Red Wing generates enough to power nearly 1 million homes, according to Xcel.
Tritium is produced in the upper atmosphere and falls to the ground in rain water, according to the NRC. It is also a byproduct of nuclear plants, a weak type of radiation that doesn’t penetrate the skin, the federal agency said.
Critics of nuclear energy say tritium causes cancer and gets into drinking water from leaky pipes at nuclear plants.
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