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The ESER program samples precipitation, surface water, and drinking water. Monthly composite precipitation samples are collected from Idaho Falls and the Central Facilities Area (CFA) on the INEEL. Weekly precipitation samples are collected from the Experimental Field Station (EFS) on the INEEL. Surface and/or drinking water are sampled twice each year at 19 locations around the INEEL. This occurs during the second and fourth quarters and is therefore not reported here. A summary of approximate minimum detectable concentrations (MDCs) for radiological analyses and DOE Derived Concentration Guide (DCG) (DOE 1993) values is provided in Appendix B.
Precipitation samples are gathered when sufficient precipitation occurs to allow for the collection of the minimum sample volume of approximately 20 mL. Samples are taken of a monthly composite from Idaho Falls and CFA, and weekly from the EFS. Precipitation samples are analyzed for tritium. Storm events in the first quarter of 2003 produced enough precipitation for a total of 13 samples – two from Idaho Falls, three from CFA, and five and three duplicates from the EFS.
Tritium was measured above the sample’s 3s value in seven samples: the three from CFA and four from the EFS collected in February and March. While there is no regulatory limit for tritium in precipitation, the DOE DCG and maximum contaminant level set by EPA for tritium in drinking water can be used as a measure. The highest tritium concentration, 184.0 ± 109.0 pCi/L (3.5 ± 2.3 Bq/L), was measured in a sample collected from the EFS on March 19. This value is many times lower than the DCG value (2 x 106 pCi/L) and the Safe Drinking Water Act limit (20,000 pCi/L) for tritium in drinking water.
Low levels of tritium exist in the environment at all times as a
result of cosmic ray reactions with water molecules in the upper atmosphere.
Tritium measured in first quarter ESER samples were within the range of values
measured elsewhere. The EPA’s ERAMS program collects precipitation samples from
across the United States. From 1996 through 2002, tritium measured in Region 10
(Alaska, Idaho, Oregon, and Washington) samples ranged from 0 to 1953 ± 71pCi/L
(72.53 ± 2.63 Bq/L) (EPA 2004). Data for all first quarter 2003 precipitation
samples collected by the ESER Program are listed in
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