Leach and EP (extraction procedure) toxicity tests on grouted waste from Tank 106-AN

Pacific Northwest Laboratory is conducting laboratory experiments to produce leach rate data for various waste species that will be contained in grout at Hanford. In the work reported here, grout made from Tank 106-AN liquid waste was used to produce empirical leach rate data for several radionuclides ({sup 60}Co, {sup 90}Sr, {99}Tc, {129}I, {137}Cs, and {sup 241}Am), stable major components (NO{sub 3}{sup {minus}}, NO{sub 2}{sup {minus}}, F, Cl, and Na), and trace metals (Cr, Mo, and Ni). Two types of tests were used to produce leach rate data: an intermittent replacement leach test (ANS 16.1 leach test) and a static leach test. Measured effective diffusivities of key species are as follows: 4 to 6 {times} 10{sup {minus}8} cm{sup 2}/sec for {sup 99}Tc, 3 to 7 {times} 10{sup {minus}8} cm{sup 2}/sec for {sup 129}I, 4 to 6 {times} 10{sup {minus}9} cm{sup 2}/sec for nitrate, and 6 to 7 {times} 10{sup {minus}9} cm{sup 2}/sec for nitrite. The leach indices of all species studied are above (more favorable than) the waste form criteria. The leach indices for {sup 99}Tc and {sup 129}I are 7.4 {plus minus} 1.2 and 7.6 {plus minus} 0.4, respectively, and are being further investigated in continuing studies of double-shellmore » slurry feed grouts. An Extraction Procedure (EP) toxicity test was also conducted and the grouted water is considered nontoxic per this test protocol. 19 refs., 9 figs., 8 tabs.« less