How Did Those Vermont Fish Get Radioactive?

"Hey, don't look at us" has been Entergy Corporation's response to the discovery of Strontium-90 in fish from the Connecticut River.
But the contamination, revealed this week by the Vermont Department of Health, promises to complicate the utility's effort to extend the license of its aging Vermont Yankee Nuclear Plant.
One of the most lethal by-products of nuclear fission, Strontium-90 was found in the bones of nine of 13 fish collected from the Connecticut River last summer, and for the first time, in the edible flesh of one fish.
That fish was collected nine miles upstream from the Connecticut Yankee Nuclear Power Plant, a distance that encouraged Entergy officials to cast doubt on the source of the contamination:
We are 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. 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.”
Vermont Gov. Peter Shumlin seemed to tie the contamination to the plant in a statement he released on Tuesday, but he backed off that claim on Wednesday after his own Health Department echoed Entergy:
"We cannot associate low levels of Sr-90 in fish in the Connecticut River with Vermont Yankee-related radioactive materials without other supporting evidence," the Vermont Department of Health said in its statement on the finding. The strontium-90 was only slightly above the lower limit of detection. The state's radiological health chief, Bill Irwin, told the Burlington Free Press he would eat the fish:
“It would not be of concern to me,” he said. “The risk is very small.”
Gov. Shumlin, however, said he would pass on eating the fish.
Shumlin wants Vermont Yankee shut down when its license expires in 2012. The Nuclear Regulatory Commission has approved a 20-year extension for the plant, but Entergy also needs approval from the state. Expecting denial, Entergy is preparing to sue Vermont.
Although no strontium has been found in groundwater samples taken at the plant, strontium-90 has been found in soil samples taken near a pipe that leaked tritium into groundwater, according to the Burlington Free Press.
A “bone-seeker,” strontium-90 is chemically similar to calcium, so the body deposits it in bone and marrow, where it is known to cause cancer. Radioactive isotopes of strontium are particularly dangerous to the growing bones of fetuses and children.
The finding has prompted Vermont to more closely scrutinize fish samples, which could result in more adverse publicity for Entergy while it fights for license renewal. According to the Health Department:
One finding of Sr-90 just above the lower limit of detection in one fish sample is notable because it is the first time Sr-90 has been detected in the edible portion of any of our fish samples.While the scientific literature includes evidence that edible portions of fish can retain Sr-90, this finding in the Connecticut River requires more sample data so we can better understand what it means. For this purpose, the Department of Health has asked that additional samples of fish obtained on June 9, 2010 be analyzed by our contract lab.
An isotope that didn't exist before the 1940s, Strontium-90 was distributed around the globe during above-ground atomic weapons testing in the 1950s. With a half-life of 29 years, much of that initial contamination has degraded.
The strontium found in the fish last summer was higher than current background levels, but within background levels measured in the Connecticut River in 1971. Strontium-90 continues to enter the environment from small releases associated with medical and industrial uses and from nuclear accidents such as Chernobyl and Fukushima.
The Vermont fish were taken from the river months before the Fukushima accident. Another dangerous isotope found in Hawaiian milk this Spring, strontium-89, has been associated with Fukushima.
Entergy also operates the Indian Point nuclear plant near New York City and has hired Rudy Giuliani to help that plant secure a license renewal.