The Radiological Health Program evaluates and manages the actual and potential public health impacts on Vermonters from activities at the Vermont Yankee Nuclear Power Station, located in the town of Vernon in Windham County.

Environmental Surveillance and Monitoring Reports

The Health Department continuously measures the radiation dose around Vermont Yankee, both at the site boundary as well as locations throughout Windham County. On a regular basis, samples are collected around the power station to test for radioactive contamination. Samples are taken from:

  • Air

  • Groundwater

  • Surface water

  • Soil

  • Vegetation

  • Connecticut River sediment

  • Fish from the Connecticut River

Local farms provide milk samples every month for testing to verify there are no radiological contaminants in the milk. Analysis of samples is done at the Health Department Laboratory.

Once every month, the Health Department Laboratory tests private drinking water supplies of selected locations near the Vermont Yankee site boundary. To date, none of these wells have shown contamination with tritium or other radionuclides that would be associated with a nuclear reactor.

Vermont Yankee surveillance reports

Environmental surveillance has been in effect since before Vermont Yankee began commercial operation in 1973. The Health Department publishes an annual report of its surveillance findings. See the reports in the table below.

In 2005, there was an investigation into whether the State’s radiation limit at the Vermont Yankee site boundary had been exceeded. A third party was brought in to conduct the investigation and found Vermont Yankee had not gone over the site boundary radiation dose limit. Read the investigation


Environmental surveillance monitoring reports
File Name
2006 Vermont Yankee Surveillance Report
2007 Vermont Yankee Surveillance Report
2008 Vermont Yankee Surveillance Report
2009 Vermont Yankee Surveillance Report
2010 Vermont Yankee Surveillance Report
2011 Vermont Yankee Surveillance Report
2012 Vermont Yankee Surveillance Report
2013 Vermont Yankee Surveillance Report
2014 Vermont Yankee Surveillance Report
2015 Vermont Yankee Surveillance Report
2016 Vermont Yankee Surveillance Report
2017 Vermont Yankee Surveillance Report
2018 Vermont Yankee Surveillance Report
2019 Vermont Yankee Surveillance Report
2020 Vermont Yankee Surveillance Report




Tritium Contamination Investigation

Tritium is a radioactive form of hydrogen. It is a byproduct of the nuclear fission process in a nuclear reactor and occurs naturally in the environment at very low concentrations. Most tritium in the environment is in the form of tritiated water, which easily moves about in the atmosphere, bodies of water, and in soil and rock.

On January 7, 2010, the Health Department was notified by Vermont Yankee Nuclear Power Station that samples taken from a groundwater monitoring well on site at the plant contained tritium. It ended up being an unintentional underground release of radioactive material. This also meant that other radioisotopes could have contaminated the environment, which soil testing confirmed. Although the soil at Vermont Yankee has been contaminated with radioactive materials, there is no known exposure or risk to the public.

More information on tritium

Testing private drinking water

If you are a Vernon resident or are interested in having your well water tested for tritium, the laboratories listed below can test private well water for tritium.

Labs that test drinking water for tritium

The State of Maine Health and Environmental Testing Lab
Phone: 207-287-2727
Contact person: Pat Boudreau

Test America Inc. – Richland Washington
Phone: 509-375-3131 ext. 164
Contact person: Christi Hayes
This is a private lab, not a public health lab.

Westchester County Department of Labs and Research
Phone: 914-231-1531
Contact person: Robert Hilbrandt, Jr.

Please contact the laboratories directly for information about sampling bottles, the quantity of water needed, turnaround times and cost.

Find out more about testing your private drinking water

Testing Soil for Radiation

Soil samples were taken from various locations and depths below the excavation area outside the Advanced Off-Gas (AOG) pipe tunnel that was found to have caused the leak reported on January 7, 2010. Strontium-90, cesium-137, zinc-65, manganese-54 and cobalt-60 were detected at greater concentrations and deeper in the ground than would be expected from nuclear fallout or weapons testing from long ago. This is evidence that radioisotopes, in addition to tritium, washed out of the AOG pipe tunnel into the environment with the leaking nuclear reactor water.

In the February 26, 2010 set of soil samples, strontium-90 and cesium-137 were measured at much greater concentrations than are found in surface soils in Vermont and around the world. See soil sample results for February 26, 2010

In the March 17 and 18, 2010 set of soil samples, cesium-137 was found at as much as 75 times what would be expected in surface soils. Analysis by Vermont Yankee of concrete mud and construction debris in the AOG pipe tunnel also confirmed the presence of cesium-137. See soil sample results for March 17, 2010

At the request of the Health Department, samples of mud and construction debris from within the tunnel were also taken for analysis. Split samples were analyzed by the Health Department Laboratory. Samples were also analyzed by an independent laboratory under contract with the Health Department for “hard to detect” radionuclides such as strontium-90, iron-55 and nickel-63.

Soil testing done immediately after another leak was discovered by Vermont Yankee on May 28, 2010 also detected these as well as several other radioisotopes that decay quickly and are no longer detectable within days or months: chromium-51, cobalt-58, barium-140 and lanthanum-140.

As part of its ongoing environmental surveillance, the Health Department has tested soil samples from two sites in the state not associated with Vermont Yankee and confirmed cesium-137 at concentrations consistent with past nuclear fallout. In 2008, cesium-137 was measured at 86 and at 168 picocuries per kilogram (pCi/kg).

Radioactive Elements Found in the Soil at Vermont Yankee

Strontium-90 and cesium-137

Strontium-90 and cesium-137 are both products of nuclear fission, and do not occur naturally in the environment. These isotopes give off radiation and decay over a long period of time. The “half-life” is the length of time it takes to decay to one-half of its original concentration. Strontium-90 has a half-life of 29 years, and cesium-137 has a half-life of 30 years.

Strontium-90 is considered one of the more hazardous of the radionuclides associated with nuclear reactors. It is a strong beta emitter. This means that its radiation can dose our skin, but it is stopped by a layer of wood, a sheet of aluminum, or sometimes clothing. It behaves chemically much like calcium, and tends to concentrate in the bones, teeth and bone marrow. Strontium-90 is linked to bone cancer, cancer of the soft tissue near bone, and leukemia.

Cesium-137 is a moderately strong gamma emitter. This means that its radiation can pass through the human body, stopped only by a lead shield or several feet of concrete.
diagram of alpha, beta and gamma radiation

Zinc-65, manganese-54 and cobalt-60

Zinc-65, manganese-54 and cobalt-60 are all corrosion products. They are produced when steel components in the nuclear reactor corrode. Tiny amounts of the corroded metals circulate in the reactor water and may be released during refueling or maintenance operations.

These isotopes give off radiation and decay over time. The “half-life” is the length of time it takes to decay to one-half of its original concentration. Zinc-65 has a half-life of 244 days. Manganese-54 has a half-life of 313 days. Cobalt-60 has a half-life of 5.3 years and is a strong gamma emitter. This means that its radiation can pass through the human body and is stopped only by a lead shield or several feet of concrete.
diagram of alpha, beta and gamma radiation

Last Updated: