NRC has a performance indicator and inspection finding matrix webpage for each plant. There are separate pages for Unit 1 and Unit 2

January 14, 2012

Sequoyah tritium in groundwater update

On Friday, John Carlin, vice president at Sequoyah, also addressed the tritium found at spiked levels in a new monitoring well at the plant.

Tritium is a radioactive isotope of the element hydrogen. It is produced both naturally in the upper atmosphere when cosmic rays strike nitrogen molecules in the air, and during nuclear weapons explosions, or as a byproduct in reactors producing electricity.

The highest level found in the sampling on Dec. 16 was about 23,000 picocuries per liter in the new well drilled within about 25 yards of Sequoyah's cooling water discharge channel leading to the Tennessee River.

The Environmental Protection Agency's drinking water standard is 20,000 picocuries per liter. The nuclear industries "voluntary reporting level" also is 20,000 picocuries per liter. A "curie" is the standard measure for the intensity of radioactivity, and a picocurie is one trillionth of a curie.

"That was a hot spot when we notified the NRC of the finding," Simmons said. "We did the prudent thing. We notified and informed people what the conditions were.

He said regulations didn't require TVA to examine where the tritium came from, but the utility had some of the substance analyzed by independent experts who found with dating and tests that it "aligns with a spill that we had in the 1980s."

He said TVA investigated further and determined that there is no active leak now.

"That doesn't mean we've stopped looking," Carlin said. "And we'll keep people informed."

He said experts believe the tritium plume is stable and isn't going to move to the river.

"We do not in any way shape or form find that that tritium in the ground is acceptable," Carlin said. "Please do not go away thinking that we're saying that meets our standard. It doesn't meet our standard. It's unacceptable."