(10/P134) TRENTON - Concentrations of radioactive tritium in the aquifers directly below the Oyster Creek nuclear power plant in Lacey Township, Ocean County, have decreased substantially in recent weeks, according to samples of groundwater taken from test wells on the site, DEP Commissioner Bob Martin announced today.

The groundwater remediation system set up to address a tritium leak at the power plant, which is owned and operated by the Exelon Corp., has been running continuously for almost two weeks, said Commissioner Martin. Tritium levels in the extracted ground water from the specially drilled recovery well are registering at well below the federally accepted limits.

While the Commissioner is pleased with the initial results, he stressed the DEP will continue aggressive efforts to have the radioactive material pumped from the aquifers and prevent any migration of that material towards potable water supplies in the region.

"This is good news but there is still plenty of work to do on this matter,'' said Commissioner Martin. "We have a continuing obligation to protect the public health and welfare of our residents. So far, there is no evidence that tritium is threatening any public water supply, and we intend to make sure that never occurs.''

The Commissioner said he is pleased with cooperation being provided to the DEP by Exelon to clean up tritium that leaked from the nuclear power plant in 2009. He pledged the DEP will continue to diligently monitor that effort.

In May, Commissioner Martin announced a State investigation into the 2009 leak into the aquifers below Oyster Creek. The DEP issued a Spill Act directive to Exelon, requiring the company to cooperate with the DEP's investigation and to take action to prevent the radioactive substance from ever reaching the region's potable water supplies.

Earlier this year, documented levels of tritium in some monitoring wells located in the Cohansey aquifer exceeded 4 million picocuries per liter (pCi/L), compared with an EPA health-based standard of 20,000 pCi/L. Those levels have since declined markedly. Recent sampling found levels of 258,000 pCi/L from groundwater in the lower Cape May Aquifer and down to 341,000 pCi/L from a well drilled into the Cohansey Aquifer.

In addition, independent testing done for the DEP has shown that the tritium contamination seems to be contained on the site of the nuclear plant and has not migrated away from the plant. Early results from groundwater monitoring wells indicate tritium has not reached the clay bottom of the lower portion of the Cohansey Aquifer and has not been detected in any of the wells in the deeper Kirkwood Aquifer.

Exelon started groundwater pumping operations in September at two small monitoring wells drilled into the Cape May and upper Cohansey aquifers. Exelon also added a third and larger recovery well on the south side of the plant's discharge structure.

Sampling of groundwater pumped from the new recovery well has found low levels of tritium, at 5,800 pCi/L, which is far below the acceptable federal standard. The current plan calls for pumping groundwater from the Cohansey Aquifer, measuring the concentration of tritium in the water, discharging it into the Oyster Creek cooling-water intake structure, allowing the tritium to mix with the cooling water throughout the plant and then letting it flow into the discharge canal. Tests of that discharged water so far are showing no detectable tritium levels.

The DEP will evaluate the effectiveness of the remediation in January, when more water quality information and hydraulic data will be available to ensure the site is being cleaned up, said Commissioner Martin.

Tritium is a mildly radioactive isotope of the element hydrogen that occurs both naturally and as a by-product of nuclear power plant operations, according to the federal Nuclear Regulatory Commission.

Information on the tritium testing and results is available at:
http://www.state.nj.us/dep/rpp/bne/octritium.htm

Previous DEP press releases on tritium release at Oyster Creek:
http://www.nj.gov/dep/newsrel/tritium.html