North Anna reports another elevated tritium sample
For the second time in 16 months, North Anna Power Station has reported an elevated level of tritium at a monitoring site at the plant. This one, reported to the Nuclear Regulatory Commission on Tuesday, was 53,300 picocuries per liter, above the voluntary threshold reporting level of 20,000 picocuries. A picocurie (pronounced PEE-ko curee) is one trillionth of a curie—a unit of radiological measurement. The sample, taken near a turbine building, was obtained as part of an ongoing study to determine the source of the tritium, previously reported to the agency in October 2010. The NRC report says hydrological studies at North Anna have determined that the ground water in that area migrates away from Lake Anna, built to cool the plant’s reactors in the 1970s. The report says there is “no increase in the projected annual [tritium] dose to the public,” and no sources of drinking water in the area. Eight ground water-monitoring sites outside the plant’s protected area showed no detectable levels of tritium, meaning there is no migration of the substance offsite. Tritium is a weakly radioactive hydrogen isotope that occurs naturally, and during the operation of nuclear power plants. In October 2010, a sample showed a tritium level of 16,500 picocuries per liter. Normal for that site is 3,000 to 4,000 picocuries. See my story tomorrow for more details.