Evaluation of scintillation probe profiles from 200 area crib monitoring wells. Volume I

Ground disposal of liquid radioactive waste from Hanford separations plants began on a limited basis in 1945. Small volumes of selected radioactive waste were initially discharged to the ground by means of subsurface structures or crib facilities. As more was learned about site geology and waste-sediment interactions, it was concluded that increased volumes of liquid effluent and increased quantities of radionuclides could be safely disposed of in the ground if properly controlled. Waste discharged to the ground was then greatly increased, reaching a peak of 8.34 x 105 Ci discharged in 1955. Thereafter, the volume and quantity of radioactive waste discharge were decreased as ground disposal of radionuclides was minimized and separation plants were shut down. The purpose of this study, as with two earlier studies conducted in 1964 and 1969, is to measure qualitatively the distribution, redistribution and decay of radionuclides beneath crib facilities. For this study, nearly 300 crib monitoring wells adjacent to approximately 100 crib facilities were logged with a scintillator, a device for measuring radioactivity. The profiles for each well were compared with selected profiles developed between 1954 and 1973. Volume II (Appendix A) and Volume III (Appendix B) contain selected scintillation probe profiles from crib monitoring wells, background information for cribs (waste description, waste inventory and service dates) and an evaluation of radionuclides in the ground, which are listed by crib facility for 200 East Area and 200 West Area, respectively. The distribution, redistribution and decay of radionuclides in the vadose zone are discussed in Volume I