An array of thermoluminescent dosimeters (TLDs) is distributed throughout the Eastern Snake River Plain to monitor for environmental radiation (Figure 14). TLDs are changed out in May and again in November after six months in the field. The results of the spring sampling of TLDs exposed from November 2001 to May 2002 are discussed below.
Dosimeter locations are divided into Boundary and Distant groupings. Boundary average exposure rates ranged from a low of 0.30 mR/day at Reno Ranch/Birch Creek and Blue Dome to a high of 0.38 mR/day at Mud Lake. The overall Boundary average was 0.33 mR/day. The Distant group had a high of 0.41 mR/day at Aberdeen and a low of 0.30 mR/day at the Minidoka location. The overall average Distant value was 0.34 mR/day. There was no statistical difference between Boundary and Distant locations. Furthermore, all values are consistent with past readings. Table 4 lists the range and average for both groups over a six-month period. All results are listed in Appendix C, Table C-11.
Table 4. TLD Exposures from November 2001 to May 2002.