Tritium Contamination at Vermont Yankee 2010-12

Timeline • Summary of events

January 2010 – Health Department investigation begins

On January 7, Vermont Yankee Nuclear Power Station notified the Vermont Department of Health that samples taken in November 2009 from a ground water monitoring well (identified as GZ-3) on site contained tritium. This finding signaled an unintended release of radioactive material, and meant that other radioisotopes may have contaminated the environment.

PDF iconVermont Yankee Plant Site Map

On January 11 Vermont Yankee, with assistance from the Nuclear Regulatory Commission (NRC), began its own investigation to identify sources of the tritium and magnitude of the contamination.

February 2010 – Major source of leak is found

On February 14, the major source of the leak was found. A pair of stream pipes in the PDF iconAdvance Off-Gas (AOG) pipe tunnel were found to be badly corroded and leaking nuclear steam. The floor drain of this concrete tunnel was found to be clogged with construction debris and mud, which caused condensate from the steam pipes to pool inside the tunnel and leak out at a failed joint.

May 2010 – Plume of contamination defined, new leak detected

On May 14, soil testing in the area around the leak had measured concentrations of radioisotopes consistent with a leak of nuclear reactor water. Steadily decreasing tritium concentrations in samples taken from the ground water monitoring wells drilled since January showed the movement of tritium contamination in the ground water generally west to east into the Connecticut River.

On May 29, Vermont Yankee officials notified the Health Department that a new leak was identified and stopped at the AOG drain line. This occurred as the AOG system was being started up after its refueling outage.

June 2010 - 2012 – Ongoing investigation

Since the leak was first reported, the Health Department closely monitored and reported on the investigation. Investigation summary reports are available up until 2012.

PDF icon2010 Vermont Yankee Surveillance Report - This desribes the amount and types of radiation found on and near the Vermont Yankee Nuclear Power Station.

Investigation SUMMARY reports & Graphics

Title Date Type
2010 Summary - Vermont Yankee Tritium Investigation
2010 summary of the investigation into tritium contamination at Vermont Yankee Nuclear Power Station.
12/31/2010 PDF Download
2011 Summary – Vermont Yankee Tritium Investigation
2011 summary of the investigation into tritium contamination at Vermont Yankee Nuclear Power Station.
12/31/2011 PDF Download
2012 Summary – Vermont Yankee Tritium Investigation
2012 summary of the investigation into tritium contamination at Vermont Yankee Nuclear Power Station.
12/31/2012 PDF Download
Vermont Yankee Tritium Investigation Graphics
Maps and graphics used to track the plume of contamination during the course of the investigation into the tritium leak at Vermont Yankee Nuclear Power Station.
03/25/2017 PDF Download
Tritium Lab Testing & Results Summary
03/25/2017 PDF Download
2012-2013 Tritium Gamma Spectroscopy Results
12/31/2013 PDF Download
Tritium Soil Contamination Analysis
 Summary of soil sampling and analysis due to the tritium investigation.
03/25/2017 PDF Download
2010 Tritium Gamma Spectroscopy Test Results
12/31/2010 PDF Download
2011 Tritium Gamma Spectroscopy Results
12/31/2011 PDF Download