Organic chemical aging mechanisms: An annotated bibliography. Waste Tank Safety Program

Abstract

An annotated bibliography has been compiled of the potential chemical and radiological aging mechanisms of the organic constituents (non-ferrocyanide) that would likely be found in the UST at Hanford. The majority of the work that has been conducted on the aging of organic chemicals used for extraction and processing of nuclear materials has been in conjunction with the acid or PUREX type processes. At Hanford the waste being stored in the UST has been stabilized with caustic. The aging factors that were used in this work were radiolysis, hydrolysis, and nitrite/nitrate oxidation. The purpose of this work was twofold: to determine whether or not research had been or is currently being conducted on the species associated with the Hanford UST waste, either as a mixture or as individual chemicals or chemical functionalities, and to determine what areas of chemical aging need to be addressed by further research. The findings of this search are: • Reported work has encompassed neither the chemical complexity of the tank waste nor the scope of issues necessary to determine the mechanisms or products from aging. • The search revealed relevant studies on two major waste components: two studies on the alkaline hydrolysis (Burger 1955) of TBP and one example of radiolysis of NPH under alkaline (Shcherbak 1960) conditions. • Pathways are enumerated for destruction of the organic compounds, but vagaries due to lack of detailed information about the actual past and present conditions in the tanks (i.e., NO x and oxygen gas contents) and interfacial effects limit our ability to make conclusions about the degree of degradation and their on associated safety issues. • Additional research directed towards elucidating the effects of radiolysis on organic constituents in alkaline conditions as well as the synergistic and inhibitory effects of oxide surface-interactions, metal ion catalysis, mass transfer, solid-liquid interfaces, high concentrations of nitrate and nitrite would be helpful in addressing safety concerns. Most useful would be knowledge of the current state of tank contents obtained by thorough sampling of the problematic tanks.

Organic Tanks Safety Program: Waste aging studies

“…Prompted by specific questions concerning aging pathways and products, the chemical literature was searched for relevant prior work that might address the questions directly or provide insight to possible answers. Thls section summarizes these literature reviews which were performed this year on topics not covered in the annotated bibliography prepared in the previous year (Sarnuels et al 1993).…”

Project plan for resolution of the organic waste tank safety issues at the Hanford Site

“…The effort to understand the potential for aging or decomposition of the organic solvents in tank wastes was initiated by work at WHC (Babad et al 1993) and work at the Pacific Northwest National Laboratory (Samuels et al 1993;Camaioni et al 1994 andCamaioni et al 1996). Samuels and coworkers reviewed the literature on the base-catalyzed hydrolysis and radiation chemistry of TBP and related compounds (Samuels et al 1993). It was found that although TBP is only slightly soluble in water, it undergoes hydrolysis rather rapidly in alkaline solution to form sodium dibutylphosphate.…”