Tm. Beasley et al., Tc-99, U-236, and Np-237 in the Snake River Plain aquifer at the Idaho National Engineering and Environmental Laboratory, Idaho Falls, Idaho, ENV SCI TEC, 32(24), 1998, pp. 3875-3881
Citations number
24
Categorie Soggetti
Environment/Ecology,"Environmental Engineering & Energy
The Idaho National Engineering and Environmental Laboratory (INEEL) is loca
ted on the eastern Snake River Plain in southeastern Idaho; it is a multipu
rpose complex operated by the U.S. Department of Energy. Among its installa
tions is the Idaho Chemical Processing Plant (ICPP), a facility designed pr
incipally to recover highly enriched uranium (greater than or equal to 93%
U-235) from different nuclear fuel types used in naval propulsion, research
, and test reactors. Starting in 1952 and continuing until 1984, low-level
radioactive waste was discharged from the ICPP directly to the Snake River
Plain aquifer by means of an injection well and seepage ponds. Over time, a
suite of radionuclides have been measured in the aquifer including H-3, Cl
-36, Sr-90, Cs-137, I-129, and Pu isotopes. Reported here are the first mea
surements of the long-lived radionuclides Tc-99, U-236, and Np-237 in the a
quifer and their downgradient concentration changes during water transport
through fractured basalt. Like Cl-36, 99Tc behaves conservatively during tr
ansport while I-129, U-236, and Np-237 indicate retardation.