Third Quarter 2006
INL Quarterly Site Environmental Report
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Another potential pathway for contaminants to reach humans is through the food chain. The ESER Program samples multiple agricultural products and game animals from around the INL and Southeast Idaho. Specifically, milk, wheat, potatoes, garden lettuce, sheep, big game, waterfowl, and marmots are sampled. Milk is sampled throughout the year and large game animals are sampled whenever available. Sheep are sampled during the second quarter. Lettuce and wheat are sampled during the third quarter, while potatoes are collected during the fourth quarter. See Table A-1, Appendix A, for more details on agricultural product and wildlife sampling. This section discusses results from milk, lettuce, wheat, large game, and soil sampled during the third quarter of 2006.
Milk samples were collected weekly in Idaho Falls at Reed’s Dairy and monthly at eight other locations around the INL (Figure 11) during the third quarter of 2006. All samples were analyzed for gamma emitting radionuclides. Samples are analyzed for 90Sr and tritium during the second and fourth quarters.
Iodine-131 (131I) was not detected in any milk sample during the
third quarter. Cesium-137 was reported in one of the weekly Idaho Falls samples
near the detection limit. No 137Cs was detected when the sample was
recounted. Data for 131I and 137Cs in milk samples are
listed in Appendix C, Table C-7.
In 2004 the ESER Program tested two prototype self-contained lettuce planters at the sampling locations in Atomic City and at the EFS on the INL. These locations were relatively remote and had no access to water, requiring that a self-watering system be developed. This prototype method allows for the placement and collection of lettuce at areas previously unavailable to the public (i.e., on the INL). The planters are set out in the spring with the lettuce grown from seed. This new method also allows for the accumulation of deposited radionuclides on the plant surface throughout the growth cycle.
Six lettuce samples and one duplicate sample were collected from prototype planters. The lettuce crop failed in the planter located at the EFS in 2006. Each sample was analyzed for gamma-emitting radionuclides and 90Sr. No gamma results were measured above the 3s uncertainty value. Strontium-90 was reported in all samples except the Federal Aviation Administration (FAA) Tower. The quantities detected are consistent with those found in previous years, which are attributed to uptake of soil with residual 137Cs and 90Sr from nuclear weapons testing that took place between 1945 and 1980.
Data for 137Cs and 90Sr in
all lettuce samples taken during the third quarter are listed in Table C-8 (Appendix
C).
No large game animals were available for sampling during the third quarter of 2006.
A total of 12 wheat samples (including one duplicate) were collected from local grain growers. All samples were analyzed for gamma-emitting radionuclides and 90Sr. Strontium-90 was positively detected in one wheat sample, collected from Idaho Falls, at a concentration well within historical measurements. Data for 137Cs and 90Sr in all wheat samples taken during the third quarter are listed in Appendix C, Table C-9.
Thirteen soil samples (including one duplicate at Carey) were collected at boundary and offsite locations. All samples were analyzed for gamma-emitting radionuclides, 241Am. 238Pu, 239/240Pu, and 90Sr (Tables C-10 and C-11). Cesium-137 was detected in all samples except one (FAA Tower) at concentrations consistent with historical measurements and is most likely present from past atmospheric nuclear weapons testing fallout. Similarly 90Sr, another fallout radionuclide, was detected in all soil samples at levels within historical measurements.
Plutonium-238 was detected in one sample collected at Blackfoot at a concentration about three times higher than the maximum historic measurement. Americium-241 was also detected one sample (Carey) at a level about three times higher than the maximum historic measurement. The fact that the soil samples were collected offsite and, in the case of 241Am was not detected in a duplicate sample, indicate that the source(s) of these radionuclides is most likely not the INL and is probably environmental in origin.