97-31
Issued March 27, 1997

BNL Contact: Mona S. Rowe 516/344-2345
DOE Contact: Jayne Brady 202/586-5806

 

MARCH 27 UPDATE ON UNDERGROUND COLLECTION TANK
AT BROOKHAVEN NATIONAL LABORATORY

 

UPTON, NY - MARCH 27 - Radioactive tritium has been found at detectable levels in the groundwater immediately south of an underground collection tank at the U.S. Department of Energy's Brookhaven National Laboratory. In addition, preliminary data indicate the presence of other radioactive elements. As noted on March 14, this tank was identified in December 1996 as part of an ongoing site-wide Superfund investigation.

The contaminants may have leaked from a non-watertight seal located approximately five feet above the bottom of the collection tank.

The tritium levels in groundwater near the tank are below the U.S. Environmental Protection Agency (EPA) drinking water standard, and no drinking water is contaminated.

The tank is located within the BNL site, about one and one-half miles north of the southern site boundary. Further groundwater testing is being performed to delineate the contamination's extent and depth. The contamination is not related to the tritium plume that has been found in groundwater south of BNL's High Flux Beam Reactor (HFBR).

Approximately 750 gallons of water were removed from the concrete-walled tank on March 12, after an analysis of the water in the tank showed high levels of tritium and radioactive strontium-90, radium-226 and cesium-137. Because the tank is now empty, there is no continuing source of contamination. Sludge at the bottom of the tank, which has also been removed, contained strontium-90, radium-226, cesium-137, americium-241 and cobalt-60.

Contamination originating from the tank will be remediated under the BNL's Superfund cleanup project.

Groundwater Testing

Groundwater testing results from seven temporary monitoring wells located 45 feet south of the tank show a peak concentration of 6,900 picocuries per liter (pCi/L), found at 82 feet below land surface. The EPA drinking water standard for tritium, a radioactive form of hydrogen, is 20,000 pCi/L.

Two samples were taken from each well, at depths of 76 and 82 feet below land surface. Six of the seven wells showed measurable tritium, all at levels below 2,000 pCi/L except for the one sample with the peak concentration of 6,900 pCi/L.

One of the seven wells also shows preliminary indications of other radioactive elements. Further analysis will be performed to determine the nature of these elements.

Two of the seven temporary wells will be resampled at greater depths, to further define the extent of the contamination. Testing results from these additional groundwater samples are expected shortly. Two additional temporary wells have been installed east of the seven monitoring wells.

Because groundwater in the area flows generally south, four additional temporary wells have been installed just north of the tank, to help confirm that the tank is indeed the source of the groundwater contamination.

Source Detection and Prevention

The collection tank was built to collect drainage from pipes connected to the base of the HFBR stack and the fan house for the former Brookhaven Graphite Research Reactor (BGRR), which was shut down in 1968. The HFBR has been shut down since December 1996 and will remain shut down until the tritium leak from the reactor's spent fuel storage pool is stopped.

Inspection of the tank's walls indicate that it may have leaked from a non-watertight seal between a stainless steel duct and one of its concrete walls. The seal is located above the tank's intended water level, but there are indications that water in the tank rose above the seal level.

The tank is currently empty and dry, and BNL has taken steps to monitor the tank and to ensure that water does not accumulate in it. BNL is reviewing modifications that will disconnect the HFBR drains from the collection tank.

Remediation Plans

BNL will include the tank-related contamination among the areas on site that will be cleaned up under the Superfund law. Remediation plans and schedules have not yet been determined.

BNL and DOE will continue to provide further information as it becomes available.

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