"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 2 1/2 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."

Dave Gram reports for the Associated Press March 30, 2010. [2]