According to a Sept 9th report by the Massachusetts Department of Public Health (MDPH), tritium levels from one of the groundwater sampling wells at Pilgrim is trending higher than other wells on the site. In August, 4,882-5,307 picocuries per liter (pCi/L) of tritium was detected in monitoring well #216. Furthermore, the September report once more shows historically consistent levels of tritium in several of the sampling wells near Pilgrim.
The report references several potential sources of the tritium near well #216, including a radwaste discharge line, a previous spill in that area, or a leak resulting from a separated “neutralization sump discharge line.” Back in April, an underground line leading to the discharge canal (AKA “neutralizing sump pump discharge line”) had separated and begun to leak, and tritium was detected. The leak was accidentally discovered when water was seen leaking out of an electrical junction box at the plant.
Since sampling began in 2007, tritium has been detected at various concentrations in all 21 sampling wells on the property (including well #3, located up-gradient at the property boundary; intended to serve as a comparison well). Since tritium is highly soluble, it flows easily with groundwater. Groundwater flow on the property is believed to flow north and east toward Cape Cod Bay.
This most recent report of a high concentration of tritium is not isolated, nor is it the worst case. In July 2010, the tritium level in well #205 was reported to be 25,552 pCi/L. This is above the Environmental Protection Agency’s (EPA) maximum threshold for safe drinking water, which is 20,000 pCi/L. It’s important to keep in mind, however, that even low doses of radiation exposure are unsafe.
The National Academies of Science developed a report in 2005 called “Health Risks from Exposure to Low Levels of Ionizing Radiation,” which found that there is no safe level of exposure to radiation; even low doses can cause cancer. To address this, the EPA set a Maximum Contaminant Level Goal (MCLG) for all radionuclides (including tritium) as ZERO. The EPA defines MCLG as the “level of a contaminant in drinking water below which there is no known or expected risk to health.”
According to the MDPH report, Entergy will continue to evaluate whether the “neutralization sump discharge line” problem can explain some of the historical tritium levels detected in monitoring wells.
 Reported by Massachusetts Environmental Radiation Laboratory (MERL)