Leachability of Actinides and Fission Products from Spent HTR Fuel

Brodda, B.-G.; Merz, E.

doi:10.1524/ract.1988.4445.1.3

Cited by 3 publications

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“…Determinations of the solid surface using XPS measurements gave an average composition of U02. 7 . No treatment of the solid to diminish the oxidized surface before starting the experiments was performed.…”

Section: Resultsmentioning

confidence: 99%

“…In NaCl-brines, Wang and Katayama [6] discussed the formation of a thin layer on the unirradiated U0 2 that passivates the dissolution, while Brodda and Merz [7] indicated that Q-brine is very aggressive in leaching experiments of spent HTR fuel. Recently, Casas et al [8] have studied the dissolution of unirradiated U0 2 in Q-brine, showing a similar behavior as a function of the oxygen partial pressure to those reported in diluted leachants [4].…”

Section: Introductionmentioning

confidence: 99%

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Mechanism of Unirradiated UO₂ (S) Dissolution in Nacl and Mgcl₂ Brines at 25°C

et al. 1994

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The dissolution of unirradiated U0 2 (s) has been studied in NaCI and MgCI 2 brines under both reducing and oxidizing conditions.The initial uranium release under reducing conditions has been attributed to the dissolution of an initial oxidized layer. The final uranium concentrations have been modeled by using the PHRQPITZ computer program giving the solubility of the solid phase U0 2 (s).Under oxidizing conditions, the initial release is the sum of the oxidized layer dissolution and the oxidation/dissolution of the U0 2 . The release rates calculated are 1.4-10-5 mol d-1 m-2 in NaCI-brine and 3.6 -10-5 mol d-1 m-2 in MgCI 2 -brine. After the initial release, uranium concentration in the NaCI-brine reaches a constant value, which has been attributed to the formation of a secondary solid phase. In MgCI 2 -brine, the uranium concentration increases slowly indicating, in this case, no control by secondary phase formation.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Mechanism of Unirradiated UO₂ (S) Dissolution in Nacl and Mgcl₂ Brines at 25°C

et al. 1994

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Dissolution of UO₂(s) in MgCl₂-Brines Under Different Redox Conditions.

et al. 1992

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The dissolution of unirradiated UO2(s), with a particle size of 1 mm, has been studied in MgCl2 brines at 298 K under both reducing and oxidizing conditions. Results obtained under reducing conditions (H atmosphere in the presence of a palladium catalyst) show an initial increase of the total uranium concentration in solution and a subsequent decrease until equilibrium (or steady state) values are reached. Results obtained under oxidizing conditions (nominal oxygen partial pressures of 0.05, 0.21 and 1 atm) show two different trends. A relatively fast initial dissolution rate and, after approximately two or three weeks, a slower dissolution rate. X-Ray Photoelectron Spectroscopy (XPS) has shown that the UO2 surface composition changes during the experiment.

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Leaching behaviour of non-irradiated and irradiated HTR UO₂-ThO₂fuel particles under reducing conditions

Alliot

Grambow

2006

MRS Proc.

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The dissolution of irradiated HTR UO2-ThO2 fuel particle under reducing conditions was studied using a continuous flow-through reactor and compared to the dissolution of unirradiated fuel particle in the same condition. The irradiated fuel particle was leached for more than eight months. A fast 137Cs release was observed, corresponding to a labile fraction (“instant release fraction”). Then, a congruent leaching of 137Cs and 90Sr was measured corresponding to a matrix dissolution rate equal to 1.7 mg/m2/d. A slower release of 238Pu probably due to sorption phenomena is observed. Dissolution rates are 100-2000 times higher than for unirradiated material. We can conclude that alpha-radiolysis is responsible for this increase due to local oxic conditions. However we cannot exclude that due to irradiation the accessible surface area has been increased as well.The coating of this irradiated particle was equally studied to determine the presence of different radionuclides and their leaching properties of leaching

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Leachability of Actinides and Fission Products from Spent HTR Fuel

Cited by 3 publications

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Mechanism of Unirradiated UO₂ (S) Dissolution in Nacl and Mgcl₂ Brines at 25°C

Mechanism of Unirradiated UO₂ (S) Dissolution in Nacl and Mgcl₂ Brines at 25°C

Dissolution of UO₂(s) in MgCl₂-Brines Under Different Redox Conditions.

Leaching behaviour of non-irradiated and irradiated HTR UO₂-ThO₂fuel particles under reducing conditions

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Leachability of Actinides and Fission Products from Spent HTR Fuel

Cited by 3 publications

References 0 publications

Mechanism of Unirradiated UO2 (S) Dissolution in Nacl and Mgcl2 Brines at 25°C

Mechanism of Unirradiated UO2 (S) Dissolution in Nacl and Mgcl2 Brines at 25°C

Dissolution of UO2(s) in MgCl2-Brines Under Different Redox Conditions.

Leaching behaviour of non-irradiated and irradiated HTR UO2-ThO2fuel particles under reducing conditions

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Mechanism of Unirradiated UO₂ (S) Dissolution in Nacl and Mgcl₂ Brines at 25°C

Mechanism of Unirradiated UO₂ (S) Dissolution in Nacl and Mgcl₂ Brines at 25°C

Dissolution of UO₂(s) in MgCl₂-Brines Under Different Redox Conditions.

Leaching behaviour of non-irradiated and irradiated HTR UO₂-ThO₂fuel particles under reducing conditions