Vermont Yankee engineers believe they have found source of tritium leak

first_imgNorthstar Vermont Yankee,Vermont Yankee engineers and technicians have identified a likely source of a tritium leak at the Vernon nuclear power station, according to a statement from Yankee released last night. As noted by Yankee on Saturday, workers were successful in inserting a conduit into the Advanced Off Gas pipe tunnel from the AOG Building side of the tunnel. This allowed an inspection of the tunnel using a boroscope. The inspection found standing water in the tunnel. The water was tested and found to contain tritium in a concentration of  2,400,000 pCi/L. A level of 200,000 pCi/L is considered by the EPA as the maximum safe level in drinking water. On Sunday, workers shut off flow from a drain line associated with one of the plant s hydrogen recombiner units and began moving the standing water out of the tunnel to be processed through the normal radiological waste treatment systems. The drain line appears to be a likely source for the water found in the tunnel, according to Yankee. Work continues to determine if and where the water from the tunnel could have been getting into the groundwater, and to verify that there are no other potential sources of tritiated water entering the tunnel.Meanwhile, the shoring and bracing work at the AOG building excavation is being reviewed by engineers and vendor experts. Over the weekend, workers attempted to set the I-beam shoring piers around the perimeter of the excavation site. Due to interferences found while excavating for the pier holes, there is a need to make changes to the shoring plan and these changes are being worked on. The actual size of the excavation area might have to be modified from the original size in order to place the piers or to accommodate different shoring options. Erection of the enclosure building over the excavation site continues.While this investigation continues, Vermont Yankee states that no tritium levels found in any samples taken from drinking water wells or the adjacent Connecticut River. Outside experts and Yankee have agreed that tritium probably is seeping into the river, but at levels that are undetectable given the amount leaked and the volume of the river.For more details on the tritium investigation, the Vermont Department of Health has a thorough status report on the investigation at this web link:…(link is external)Also helpful is the Nuclear Regulatory Commission web page on tritium monitoring:…(link is external)Source: Entergy Vermont Yankee. 2.16.2010last_img