Test results confirm a second radioactive isotope in soil around Vermont Yankee nuclear plant

Second radioactive substance at Vermont Yankee

MONTPELIER, Vt. — Test results have confirmed the presence of another, more dangerous, radioactive substance in the soil at Vermont’s only nuclear power plant, officials said Tuesday, five days after announcing they had found and stopped tritium leaks at Vermont Yankee.

The state Health Department said Tuesday that cesium-137 was found at the site. The substance has a half-life of 30 years, about 2½ times that of tritium, which was found in early January. A half-life is the time it can be expected to take for a substance to lose half its radioactivity. Unlike tritium, cesium-137 does not occur naturally in the environment; it is a product of nuclear fission.

Both radioactive substances can increase the chances of developing cancer depending on the intensity of exposure.

The presence of trace amounts of cesium-137 was first reported Feb. 24, but Vermont Yankee officials said it was “consistent with what would be found in soil” due to atmospheric testing of nuclear weapons in the 1950s and ’60s and the accident at the Chernobyl reactor in the Soviet Union in 1986.

The Health Department statement on Tuesday said the cesium-137 found in the Vermont Yankee soil samples was three to 12 times as high as the background levels attributed to the other causes, meaning it “appears likely the Cs-137 comes from Vermont Yankee reactor related sources.”

Vermont Yankee spokesman Larry Smith said he was not surprised by the finding, and that plant officials believe the cesium can be cleaned up as part of their already planned effort to remove some of the soil around plant buildings and ship it off for treatment as low-level radioactive waste.

Smith agreed with comments William Irwin, the Health Department’s radiological health chief, made in a recent interview with The Associated Press, in which Irwin said the cesium -37 likely resulted from leaking fuel rods that plagued Vermont Yankee and many other nuclear plants in the 1970s and 1980s.

The Health Department statement said it was unusual that the cesium-137 was found at a depth of 15 feet underground, because it usually stays on the surface. Smith said it was possible the material fell to that depth as plant technicians dug a trench between two buildings to hunt for the source of the tritium leak.

Tuesday’s announcement came as lawmakers began drafting new legislation to require that Vermont Yankee increase the amount of money it has set aside for decommissioning the plant — dismantling it when it shuts down.

Gov. Jim Douglas has vetoed two similar bills in recent years, but this one has a twist. It comes after the state Senate voted down a bill to give Vermont Yankee a green light to continue operating after 2012, meaning decommissioning could come sooner than Vermont Yankee, which has been seeking a 20-year license extension, wanted it to.