Tritium detected in groundwater at Sequoyah Nuclear Plant

Tritium detected in groundwater at Sequoyah Nuclear Plant

December 21st, 2011 by Pam Sohn in News

Cooling towers let off steam at the Sequoyah Nuclear Plant.

Photo by Jake Daniels/Times Free Press.

TVA's nuclear troubles seem to be mounting.

The utility now has active safety concern flags from the U.S. Nuclear Regulatory Commission raised at all three of its operating nuclear plants.

Additionally, Tennessee Valley Authority officials acknowledged on Tuesday they have found elevated levels of tritium in a groundwater sample taken from a monitoring well at the Sequoyah Nuclear Plant.

TVA spokesman Ray Golden said there is no indication the radioactive material has migrated in groundwater beyond the Soddy-Daisy plant's property, which borders the Tennessee River.

Golden also said a new Watts Bar Nuclear Plant "white" safety finding was raised in September by NRC inspectors and TVA was notified last week. Golden said it was an equipment issue and is associated with the nuclear security division at Watts Bar, not the plant's operating system.

Under NRC's color-coded inspection findings, white is least serious, then yellow, then red. A plant operating with no safety problems is coded as green. Each increasing level concern calls for more NRC oversight. Each plant reactor is graded in several different disciplines, ranging from security to occupational radiation safety.

NRC spokesman Joey Ledford -- citing security -- would not confirm anything about the Watts Bar security issue, except that the NRC had sent a letter of concern to TVA.

"I won't say it's unprecedented, but it's not typical," Ledford said of TVA as a nuclear operator receiving flagged NRC safety concerns at every one of its operating plants at the same time.

Golden said, however, that it is the first time in TVA history that all three of its plants have been flagged for concerns resulting in enhanced inspections.

NRC gave Browns Ferry Nuclear Plant a "red," or highest safety concern flag, last summer after TVA and inspectors discovered one of the reactors had been operating for as much as 18 months with a dysfunctional cooling valve.

And this fall, NRC gave Sequoyah Nuclear Plant a white finding because one of its two reactors had four unplanned shutdowns in less than a year. The reactor since has had a fifth unplanned "scram."

Ledford and Golden said the immediate safety and security concerns have been dealt with and the plants are operating safely.

Ray Golden

Photo by Dan Henry/Times Free Press.

Tritium discovery

The tritium discovery in monitoring wells at Sequoyah will be monitored by NRC, but is not included in the plant's safety finding, Ledford said.

Golden and Sequoyah Plant Manager Paul Simmons said the elevated level of tritium, found in one of two new onsite monitoring wells at Sequoyah, poses no threat to the health and safety of the public.

Golden said the tritium may be left over from a spill in 2003 when an underground pipe leaked. That leak was found and fixed, he said.

Simmons pledged continued monitoring.

"The newly installed groundwater monitoring wells were placed in an area known to have contained tritium that was previously reported," He said in a prepared statement. "The health and safety of the public are our primary concern, which is why providing additional monitoring capability to the plant's groundwater wells is an important measure for protecting the community and the environment."

Tritium, a radioactive form of hydrogen, is a byproduct of making electricity at nuclear power plants. It also can naturally occur in the atmosphere.

The highest level found in the sampling on Dec. 16 was about 23,000 picocuries per liter.

Golden said 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, he said.

A "curie" is the standard measure for the intensity of radioactivity contained in a sample; a picocurie is one trillionth of a curie.

Golden said the tritium has been detected in groundwater, which is not used for drinking water or irrigation purposes, and no potable water wells are downstream of where the tritium was found. The plant borders the Tennessee River.

Additionally, TVA confirmed no detectable levels of tritium in any sampling of the Tennessee River where the plant discharges water, Golden said.

"It's a little like comparing apples and oranges, but we've still reported the finding to federal, state and local officials," Golden said.

Golden said TVA "voluntarily" reported the tritium findings to the Tennessee Department of Environment and Conservation, the Chattanooga-Hamilton County Health Department and the Nuclear Regulatory Commission.

TDEC spokeswoman Tisha Calabrese-Benton said NRC is the regulator, not the state.

Adena Williams, spokeswoman for the Chattanooga-Hamilton County Health Department, said well water monitoring no longer is part of the health department's work. Instead it now falls under the Hamilton County Public Works Department.

To put the detection numbers into perspective, Golden said if a person drank two liters of water every day with this amount of tritium for a year, he or she would receive a radiation dose of about 4 millirems. In comparison, one X-ray from a dental exam will have a radiation dose of about 10 millirems. On average, Americans receive about 620 millirems of background exposure annually from natural and manmade radioactive sources, according to TVA.

Simmons said TVA is "reviewing the new monitoring well sample results, determining the cause of these elevated levels and how they relate to the previously reported releases of tritium."

In 2003, TVA discovered a significant leak in underground piping carrying tritium-laced water. That underground piping was abandoned and TVA installed new underground pipe to fix the problem, Golden said.

Under normal operating circumstances, the tritium contaminated water is held in holding tanks and gradually mixed with clean water until it is low enough in radiation to be safety released to the river. Those releases are permitted by the state and federal authorities, Golden said.

Golden said Sequoyah now has a total of 16 groundwater monitoring wells on the Sequoyah site. He said TVA also monitors private wells near the plant and no tritium has been detected off the plant site.

Watts Bar Security

Golden said the Watts Bar security problem "was identified during a recent inspection of the plant's physical security -- fences, cameras, detection and intrusion systems."

TVA took immediate action to fix the problem, he said.

"TVA takes its responsibilities to physically protect the nuclear plant very seriously," he said. "TVA is in the process of conducting a root cause analysis to determine the cause of the NRC finding within security and will implement a series of corrective actions."

Ledford said the problems pointed up by NRC's color-coded findings don't appear to be related.

"There is no indication there is a fleetwide problem, but we are going to keep monitoring," he said.

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