Tc Reductant Chemistry and Crucible Melting Studies with Simulated Hanford Low-Activity Waste

Kim, Dong-Sang ; Soderquist, Chuck Z. ; Icenhower, Jonathan P. ; McGrail, B PETER. ; Scheele, Randall D. ; McNamara, Bruce K. ; Bagaasen, Larry M. ; Schweiger, Michael J. ; Crum, Jarrod V. ; Yeager, John D. ; Matyas, Josef ; Darnell, Lori P. ; Schaef, Herbert T. ; Owen, Antionette T. ; Kozelisky, Anne E. ; Snow, Lanee A. ; Steele, Marilyn J.

Pacific Northwest National Laboratory (U.S.)

关键词: Volatilization;    Redox;    Crucibles;    Rhenium;    Melting;   

DOI  :  10.2172/15020035
RP-ID  :  PNNL-15131
RP-ID  :  AC05-76RL01830
RP-ID  :  15020035

美国|英语

来源: UNT Digital Library

【 摘 要 】

The FY 2003 risk assessment (RA) of bulk vitrification (BV) waste packages used 0.3 wt% of the technetium (Tc) inventory as a leachable salt and found it sufficient to create a significant peak in the groundwater concentration in a 100-meter down-gradient well. Although this peak met regulatory limits, considering uncertainty in the actual Tc salt fraction, peak concentrations could exceed the maximum concentration limit (MCL) under some scenarios so reducing the leachable salt inventory is desirable. The main objective of this study was to reduce the mobile Tc species available within a BV disposal package by reducing the oxidation state of the Tc in the waste feed and/or during melting because Tc in its reduced form of Tc(IV) has a much lower volatility than Tc(VII). Reduced Tc volatility has a secondary benefit of increasing the Tc retention in glass.