Detailed study of the γ-radiolysis of nitrilotriacetic acid in a simulated, mixed nuclear waste

Abstract

Gamma radiolysis of a simulant of an actual mixed waste, composed of nitrilotriacetic acid (NTA) and an inorgamc matrix, at y-doses ranging from 0-7.5-106+10% R in a 6~ resulted in total NTA degradation,, but I0.8% of the simulant's original organic content remained. Radiolysis yielded 4 chelator fragments and 2 carboxylic acids, all formed at different rates. The chelator fragment N-(Methylamine)iminodiacetic acid (MAIDA) dominated at low y-doses, while N-[N'-amino(2-iminoethyl)]iminodiacetic acid (AIEIDA) dominated at high y-doses. Chemical degradation control studies revealed that the harsh chemistry of the inorganic matrix caused only 20.7% NTA degradation and formation of only 2 chelator fragments, while the heat generated by the ~ (95 ~ had little additional impact.

Thermodynamical and Structural Study of Protactinium(V) Oxalate Complexes in Solution

“…In the present work, oxalic acid was chosen since it is expected to behave as a strong ligand toward Pa(V). Moreover oxalic acid, produced by fungi or exsuded by roots of plants, may be initially present in groundwater or may form in course of radiation damage of more complex polycarboxylic acids. , Literature devoted to the behavior of protactinium in presence of oxalate is rather scarce and controversial. Ion exchange and solvent extraction experiments, performed at tracer scale, have led to the observation of various oxalate complexes, ranging from (1,1) to (1,4), with or without oxo or/and hydroxo groups. ,, The corresponding formation constants have been determined but can hardly be compared among each other because of differences in experimental conditions and complexes formulations.…”

A Review of Sodium Oxalate Solubility in Water

“…Oxalate is found in these wastes in both the liquid and as solid disodium oxalate. − Oxalate was generated as a reaction product of a nitric acid destruction process using sugar . Oxalate was also generated from the degradation of larger organics in the waste. − Oxalic acid was used to clean out nearly empty tanks in the past, where the subsequent neutralization created disodium oxalate. , Given that oxalate occurs in both the solid and liquid phases in nuclear waste, the solubility of disodium oxalate is of interest …”

Strontium/strontium‐90 removal from c helate‐bearing Hanford tank waste using crystalline silicotitanate

“…Gluconate and HEDTA were below the detection limits even though both species were added to the waste during processing at Hanford's B Plant. 2,32 All of the chelates slowly degrade via hydrolysis and radiolysis over time, [33][34][35][36][37][38] which likely explains why gluconate and HEDTA were not detected by Urie et al 25 Organic degradation products oxalate and the carbonate have accumulated in the solids at the bottom of tank AN-102. 39 There has likely been additional chelate degradation since the year 2002, but still significant quantities remain given the large concentration of dissolved 90 Sr recently observed in tank AN-102 supernatant.…”