A Note from Larry Smith at Vermont Yankee
February 16, 2010
Vermont Yankee engineers and technicians continue their investigation into the source of tritium in the plant’s groundwater.
As noted 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. 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 a likely source for the water found in the tunnel. 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 today. 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, it is important to note that there has been no tritium levels found in any samples taken from drinking water wells or 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: https://email.entergy.com/exchweb/bin/redir.asp?URL=http://healthvermont.gov/enviro/rad/yankee/tritium.aspxhttp://healthvermont.gov/enviro/rad/yankee/tritium.aspx
Also helpful is the Nuclear Regulatory Commission web page on tritium monitoring: https://email.entergy.com/exchweb/bin/redir.asp?URL=https://email.entergy.com/exchweb/bin/redir.asp?URL=http://www.nrc.gov/reactors/operating/ops-experience/grndwtr-contam-tritium.htmlhttp://www.nrc.gov/reactors/operating/ops-experience/grndwtr-contam-tritium.html
Laurence M. Smith
Manager of Communications
Entergy Nuclear Vermont Yankee 802-258-4118
lsmit14@entergy.com
