Determination of dissolution rates of spent fuel in carbonate solutions under different redox conditions with a flow-through experiment

• Published in: Journal of nuclear materials Vol. 297; no. 3; pp. 231 - 243
• Main Authors: Röllin, S, Spahiu, K, Eklund, U.-B
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.09.2001; Elsevier
• Subjects: Applied sciences; Earth sciences; Earth, ocean, space; Energy; Engineering and environment geology. Geothermics; Exact sciences and technology; Fuels; Nuclear fuels; Pollution; Pollution, environment geology; Preparation and processing of nuclear fuels; Radioactive wastes; Wastes; W01; F05; A02; F07; Spent fuels; Nuclear industry; Radioactive pollution; Pollutant behavior; Underground storage; Carbon dioxide; Nuclear fuel; Radioisotope; Dissolution; Medium effect; Test method; pH; Lixiviation; Radioactive waste storage; Water pollution; Kinetics; Redox potential; Aqueous solution; Uranium dioxide; Irradiated nuclear fuel; Ground water
• ISSN: 0022-3115; 1873-4820
• DOI: 10.1016/S0022-3115(01)00645-6

Dissolution rates of spent UO 2 fuel have been investigated using flow-through experiments under oxidizing, anoxic and reducing conditions. For oxidizing conditions, approximately congruent dissolution rates were obtained in the pH range 3–9.3 for U, Np, Ba, Tc, Cs, Sr and Rb. For these elements, steady-state conditions were obtained in the flow rate range 0.02–0.3 ml min −1 . The dissolution rates were about 3 mg d −1 m −2 for pH>6. For pH<6, dissolution rates were strongly increasing for decreasing pH. Incongruent dissolution was found for Zr, Mo, Ru, Rh, Pd, Am and the lanthanides. The dissolution rates with H 2(g) saturated solutions dropped by up to four orders of magnitude as compared to oxidizing conditions. Because of the very low concentrations, only U, Pu, Am, Mo, Tc and Cs could be measured. For anoxic conditions, both the redox potential and dissolution rates increased approaching the same values as under oxidizing conditions.