A mercury complexant, L-cysteine hydrochloride, was tested for use in separ
ating Hg(II) from actinides during transuranic extraction (TRUEX) processin
g of wastes at the Idaho National Engineering and Environmental Laboratory
(INEEL). Mercury, americium, plutonium, and uranyl distributions for the TR
UEX solvent were characterized over a nitric acid concentration range of 0.
01 to 2M with and without cysteine. The applicability of cysteine was evalu
ated for selective Hg(II) complexation in an INEEL sodium-bearing waste sim
ulant. A test was also conducted to evaluate the applicability of cysteine
to separate Hg(II) from Sr in the strontium extraction (SREX) process with
Sr Resin used as a stand-in for the SREX process solvent. In all cases, the
use of L-cysteine HCl retained Hg in the aqueous phase while causing no or
little perturbation in the actinide and Sr distribution behavior.