Study of the consequences of secondary water radiolysis surrounding a defective canister
2003 (English)In: Nuclear Technology, ISSN 0029-5450, Vol. 142, no 3, 294-305 p.Article in journal (Refereed) Published
In the concept of deep geological disposal of spent nuclear fuel, a chemically reducing environment in the near field of a repository is favorable for retaining the radionuclides in the fuel. Water radiolysis can possibly change a reducing environment in the near field to an oxidizing environment. In this paper, the consequences of secondary water radiolysis, caused by radionuclides released from the spent nuclear fuel and dispersed in the bentonite buffer surrounding a canister, have been studied. The canister is assumed to be initially defective with a hole of a few millimeters on its wall. The small hole will considerably restrict the transport of oxidants through the canister wall and the release of radionuclides to the outside of the canister. The spent fuel dissolution is assumed to be controlled by chemical kinetics at rates extrapolated from experimental studies. Two cases are considered. In the first case it is assumed that secondary phases of radionuclides [such as amorphous Pu(OH)(4) and AmOHCO3] do not precipitate inside the canister. The model results show that a relatively large domain of the near field can be oxidized by the oxidants of secondary radiolysis. In the second case it is assumed that secondary phases of radionuclides precipitate inside the canister, and the radionuclide concentration within the canister is controlled by its respective solubility limit. The amount of radionuclides released out of the canister will then be limited by the solubility of the secondary phases. The effect of the secondary radiolysis outside the canister on the rate of spent fuel oxidation inside a defective canister will be quite limited and can be neglected for any practical purposes in this case.
Place, publisher, year, edition, pages
2003. Vol. 142, no 3, 294-305 p.
secondary water radiolysis, spent fuel dissolution, mathematical modeling, spent fuel, oxidative dissolution, model
IdentifiersURN: urn:nbn:se:kth:diva-22511ISI: 000182948800008OAI: oai:DiVA.org:kth-22511DiVA: diva2:341209
QC 201005252010-08-102010-08-10Bibliographically approved