Vermont Yankee reports trace amount of tritium in monitoring well

Vermont Yankee released a statement yesterday reporting that, for the first time, a small amount of tritium, a radioactive isotope, has been identified in a sample taken from a monitoring well at the plant. Tritium is a form of hydrogen that occurs naturally and is also a byproduct of nuclear plant operation. It is also used in illuminated products such as exit signs. Based on the experience of other US nuclear plants, Yankee has been specifically monitoring for tritium as part of an industry-wide monitoring program.
The level of 17,000 picocuries per liter found at the Vernon plant in one monitoring well is below (about one half) the federal regulatory reporting limit (30k/L), according to the Yankee statement. A picocurie is one trillionth of a curie, the standard unit of measure of radioactivity. Since 2007, Vermont Yankee and the rest of the industry have been taking a proactive approach in groundwater monitoring including communicating the results. So, while there are no regulatory requirements to report tritium at these low levels, notifications were proactively made to regulatory agencies and the public.
Vermont Yankee monitors 32 wells on the plant site and the results are analyzed by an independent laboratory. On Wednesday, according to Yankee, the independent lab forwarded the positive result from the one groundwater monitoring well to Vermont Yankee which confirmed the result Thursday. Vermont Yankee has assembled a multi-disciplined technical team to investigate the source of the elevated level. It is important to note that there has been no elevated tritium level found in any drinking water well samples or in Connecticut River water. (However, the tritium level found in the monitoring well was, in fact, below EPA drinking water standards.) The Yankee statement said that the existence of tritium in such low levels does not present a risk to public health or safety whatsoever.
Also, Yankee reported that Wednesday’s transmission line work that required a power reduction was completed Wednesday night by VELCO and the plant was authorized by ISO-New England to increase power. However, the plant output was held at 72-percent Thursday morning to allow checks of an oil level indication on one of two recirculating water pump motors. The recirc pumps are used to vary power level in the reactor. The indication was found to be related to the reduced speed of the pump during the power reduction. All other measurements (temperature, vibration) associated with the pump were normal. Yankee said operators are closely monitoring the pump as power was increased yesterday afternoon. At full power, the plant operates at about 630 megawatts of constant output.
Source: Vermont Yankee nuclear power plant, Vernon. 1.7.2010