Padiolytically Induced Oxidation Reactions of Actinide Ions in Concentrated Salt Solutions

Abstract

The autoradiolytic oxidation of Pu(IV) and Am(III) has been investigated in saline solution of different NaCl concentrations, pH and specific α-activities. The high linear energy transfer (LET) property of α-radiation in solution enhances the oxidation of the Cl ion and thus increases the redox potential (Eh) of the NaCI solution system to a value of more than +1000 mV vs. NHE. Radiolytic reaction products are found as being comparable with those from the Cl2 saturated NaCl solution 'and create a metastable system consisting of C12/HCl0/Cl0−/Cl−. The oxidation of Pu(IV) and Am(III) in such solutions is dependent on the NaCl concentration, pH and specific a-activity involved. The quantitative oxidation to Pu(VI) and Am(V) is ob- served in the concentrated NaCl solution at pH > 7 with a moderately high specific activity (> 1 Ci/L).

Hydrolysis Reactions of Am (II I) and Am(V)

“…The oxidation becomes completed within a week [17][18][19]. Radiolysis reactions induced by α-radiation transfer the NaCl solution to a strongly oxidizing medium.…”

“…Radiolysis reactions induced by α-radiation transfer the NaCl solution to a strongly oxidizing medium. The process is depending on the specific α-activity, NaCl concentration and pH [18,19]. Experiment is conducted with 1 Ci/L 241 Am(III) in 3M NaCl solution at pH = 8.3…”

“…While carrying out experiment, it is found that a-radiation induced radiolysis reactions in concentrated Nad solutions become significant, resulting in the oxidation of Am (111) to Am(V) [17][18][19]. For this reason the hydrolysis reactions of Am(V) have been also investigated in a selected saline solution.…”

A Direct Speciation of Transuranium Elements in Natural Aquatic Systems by Laser-Induced Photoacoustic Spectroscopy

“…For this reason the occurance of Am hydroxide species in the solution of the first spectrum cannot be considered as possible. Making the solution alkaline with addition of Na 2 C03 to pH = 12, the absorption peak at 508 nm is observed, which may be a Am (III) carbonate species of higher degree complexation, probably Am(0H)(C03) 2 " or Am(C0 3 )3~ [12]. The solution is again neutralized to pH = 6.7 by addition of HC10 4 and then the absorption band is found at 506.6 nm, which is different from the 500 505 Wavelength 515 Fig.…”

Radiation-chemical effects in the near-field of a final disposal site: role of bromine on the radiolytic processes in NaCl-solutions

“…Such radiolytic compounds will influence the mobility of radionuclides via redox and complex formation reactions and the variation of the pH [1,2]. Radiation effects in chloride brines are therefore of fundamental importance for the safety of a final disposal.…”