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Where did the Strontium-90 come from?

Contamination found in fish in Connecticut River raises questions about its source

BRATTLEBORO—Routine tests of fish caught in the Connecticut River near the Vermont Yankee nuclear power station in Vernon have revealed traces of strontium-90, according to the Vermont Department of Health.

The department said the results require further investigation because although “the scientific literature includes evidence that edible portions of fish can retain strontium-90, this finding in the Connecticut River requires more sample data so we can better understand what it means.”

Entergy, the plant’s owner, issued a statement last week saying officials had “absolutely no evidence” that the radioactive isotope came from the nuclear plant, which has been plagued by tritium leaks over the past year.

While scientists agree that the origin of the radiation cannot be pinpointed, David Lochbaum, director of the Union of Concerned Scientists’ Nuclear Safety Project, called the absolute denial “galling,” in light of Entergy’s own reported emissions of the radionuclide to the Nuclear Regulatory Commission.

According to its website, the Health Department Laboratory routinely tests samples of fish and other environmental samples like air, water, milk, soil, and vegetation for “most radionuclides” as part of the department’s environmental surveillance surrounding Vermont Yankee.

The department also sends samples to a commercial laboratory, which tests for “hard to detect” radionuclides such as strontium-90 (Sr-90), iron-55, and nickel-63.

According to the department’s website, the Wadsworth Center Laboratory, operated by the New York State Department of Environmental Conservation, and the department’s own contract laboratory conducted the tests.

Health department tests showed Sr-90 in 13 samples of fish collected from the Connecticut River between February and June 2010.

The labs tested for hard-to-detect radionuclides in the edible portions (flesh) and inedible portions (bones, head, scales, and guts) of the fish collected both upstream of the nuclear plant, and near the plant in Vernon Pond, where the plant releases water from its discharge canal and the contaminated groundwater on site.

The department reported on its website that four of the 13 inedible portion samples did not reveal Sr-90 above the test’s lower level of detection. The other nine samples, however, contained levels ranging from 28 picocuries per kilogram (pCi/kg) to 255 pCi/kg.

“The fish in this sample were caught on June 9, 2010, about nine miles upstream of Vermont Yankee. This fish sample also had the highest Sr-90 concentration in inedible portions (255 pCi/kg),” stated the department on its website.

The department said the Sr-90 in this sample is “notable because it is the first time strontium-90 has been detected in the edible portion of any of our fish samples.”

The department “has asked that additional samples of fish obtained on June 9, 2010 be analyzed by our contract lab.”

Strontium, in addition to the radioactive forms, occurs naturally in the environment as a non-radioactive element, says the Environmental Protection Agency. The agency’s fact sheet calls strontium-90 a “bone seeker” because the isotope mimics calcium and can lodge in the bones and marrow.

Side effects of strontium-90 exposure include leukemia.

Responding to the news

Gov. Peter Shumlin was first out of the gate last week issuing a statement to the press before the Department of Health had released its report.

“Today’s troubling news from the Vermont Department of Health is another example of Entergy Louisiana putting their shareholders’ profits above the welfare of Vermonters,” he said.

“This is further evidence of the need for extraction wells that I repeatedly called on Entergy Louisiana to set up and keep running last fall. I am asking my Health Department to keep a close eye on test results moving forward to determine the extent of any contamination that has reached the environment,” said Gov. Shumlin.

Entergy retorted through spokesperson Larry Smith, who said in a written statement that the company was “aware that the Vermont Department of Health may have detected strontium-90 in some fish from the Connecticut River.”

“There is absolutely no evidence to suggest that Vermont Yankee is the source for the strontium-90,” said Smith. “We have 31 monitoring wells on site that are tested regularly. No groundwater sample from any well at Vermont Yankee has ever indicated the presence of strontium-90, or any other isotope other than tritium. We do not know why the Governor would suggest Vermont Yankee is the source, but there is no factual basis for that suggestion.”

Smith told The Commons last year that plant tests revealed strontium-90 as well as cobalt-60, and cesium-137 in soils surrounding the January 2010 tritium leak. Smith added that strontium-90, unlike tritium, does not move easily through the soil.

In an interview with Dave Gram of The Associated Press, Paul Gunter, director of reactor oversight for the Maryland-based anti-nuclear group Beyond Nuclear, said that Entergy itself reported strontium-90 releases “in each of the first four years” it owned Vermont Yankee.

Gunter also accused Entergy of “hiding behind” the theory that the strontium-90 in the fish originated in 1950s and 1960s bomb testing fallout.

At the source?

The health department agrees that recent fish samples do not conclusively reveal the strontium-90’s source.

“The human-made radionuclides [like Sr-90 or cobalt-60] come from the fairly constant release of very low quantities from medical and industrial users of radioactive materials, and from infrequent releases such as above-ground nuclear weapons testing in the 1950s, and the nuclear reactor accidents at Chernobyl in 1986 and Fukushima in 2011,” said the health department.

And Lochbaum, of the Union of Concerned Scientists’ Nuclear Safety Project, agreed that the Sr-90 may not originate with the nuclear plant.

“It’s nearly impossible to differentiate between strontium released from atomic bomb testing and that released from Vermont Yankee and other nuclear power plants,” said Lochbaum.

Lochbaum added that one way to distinguish “old” and “new” releases is to study “other radioactive byproducts that have different half-lives.”

Strontium-90 has a half-life of 30 years, he said. But looking at radioactive byproducts doesn’t work with fish that, like people, collect some radioisotopes while discharging others.

Lochbaum said a possible way to determine the source of the Sr-90 is to move away from a “snapshot” of one data collection and look at samples collected over many years.

“If the source is largely atomic bomb testing, the strontium levels would decline as the legacy material decayed. If the source were from nuclear power plants, the continuing releases of strontium might tend to [level], or even increase, the strontium levels in fish,” he said.

According to the health department, to date, it has “not measured other nuclear-power-plant-related radionuclides in fish or groundwater samples.”

Still, Entergy’s response to the test results does not wash with Lochbaum.

In Lochbaum’s opinion, the health department’s results might not pinpoint Vermont Yankee as the strontium-90’s source.

But the results do not exonerate the plant, either.

“I find Entergy’s statement to be patently false, as has so often been found in the past. Entergy generates electricity, not truth. That’s sad and unacceptable,” he said.

He described Entergy’s statement that there’s “no evidence” that Vermont Yankee leaked the radioactive isotope and cited its strontium-90-free monitoring wells as proof as “galling.”

“By its [Entergy’s] own admission, it [Vermont Yankee] is releasing strontium-90 into the environment” and therefore cannot rule itself out of the fish equation, said Lochbaum.

According to the company’s 2010 Radioactive Effluent Release Report for Vermont Yankee filed annually with the Nuclear Regulatory Commission, the plant released 31,800 picocuries of Sr-90 (at ground level not through the exhaust stack) in the first quarter.

The NRC requires all plant owners to file annual effluent release reports, said Lochbaum. The releases can go into the water, into the air, and shipped offsite as solid materials.

Lochbaum said that the Sr-90 released by Vermont Yankee in 2010 fell within federal limits.

But, he said, “For Entergy to omit this known release path and to only mention the monitoring wells is deceitful.”

“They are only telling part of the truth, and by doing so are telling a lie. Their statement on this matter is a shameless distortion of the facts. It would be unacceptable as an isolated case. Since it’s part of a long pattern of shameless distortions, it’s pathological — the company seems incapable of telling the truth.”

Calls to the Vermont Department of Health, Vermont Department of Fish and Wildlife and the Environmental Protection Agency to obtain long-term environmental data on strontium-90 were not returned by press time.

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Originally published in The Commons issue #113 (Wednesday, August 10, 2011).

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