Hostname: page-component-76fb5796d-dfsvx Total loading time: 0 Render date: 2024-04-25T15:29:03.842Z Has data issue: false hasContentIssue false
  • English
  • Français

Spent Fuel Dissolution: An Examination of the Impacts of Alpha-Radiolysis

Published online by Cambridge University Press:  10 February 2011

P.A. Smith  and
L.H. Johnson
P.A. Smith
Affiliation:
Safety Assessment Management Ltd., 9 Penny Green, Settle, North Yorkshire, BD24 9BT, UK
L.H. Johnson
Affiliation:
Nagra, Hardstrasse 73, CH-5430, Wettingen, SWITZERLAND
Get access

Abstract

When spent fuel eventually comes into contact with groundwater, fuel matrix dissolution will be strongly influenced by redox conditions in the near field. The most significant factors influencing redox conditions at the fuel surface in a reducing environment are alpha-radiolysis of water and the presence of reductants such as Fe(II) and H2 arising principally from canister corrosion. The radiolytic yield (G) of molecular oxidants, generally considered to be ∼1 molecule of hydrogen peroxide per 100 eV for alpha-radiolysis, is expected to be considerably lower in the presence of reductants but the overall effect on the rate of matrix dissolution cannot yet be reliably quantified. We have attempted to estimate the effective yield of oxidants by examining the results from various studies of spent fuel and UO2 dissolution, including alpharadiolysis experiments. The analysis suggests that the effective yield (Geff) is likely to be no greater than 0.01 in the repository environment. The implications of low Geff values are discussed in relation to fuel dissolution rates. Some other aspects of radiolysis relevant to nearfield redox chemistry are also examined, including the potential significance of alpha emitters sorbed in the repository near field in producing radiolytic oxidants.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 608: Symposium QQ – Scientific Basis for Nuclear Waste Management XXIII , 1999 , 29
Copyright
Copyright © Materials Research Society 2000

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

1 Christensen, H. and Sunder, S., Current state of knowledge in radiolysis effects on spent fuel corrosion. Studsvik Report STUDSVIK/M-98/71 (1998).Google Scholar
2 Forsyth, R. and Werme, L.O., Spent fuel corrosion and dissolution, J. Nucl. Mat. 190, p. 3–19 (1992).Google Scholar
3 Johnson, L.H., The dissolution of irradiated U0 2 fuel in groundwater, Atomic Energy of Canada Limited Report, AECL-6837 (1982).Google Scholar
4 Christensen, H., Calculations simulating spent-fuel experiments, Nucl. Tech. 124 (1998), p. 165 Google Scholar
5 Tait, J.C. and Luht, J.L., Dissolution Rates of Uranium from Unirradiated UO2 and Uranium and Radionuclides from Used CANDU Fuel Using the Single-pass Flow-through Apparatus.Ontario Hydro Used Fuel Disposal Program Report 06819-REP-01200-0006 ROO (1997).Google Scholar
6 Eriksen, T.E,Eklund, U-B., Werme, L.O. and Bruno, J., Dissolution of irradiated fuel: A radiolytic mass balance study, J. Nucl. Mat. 227, p. 76–82 (1995).Google Scholar
7 Sunder, S., Shoesmith, D.W. and Miller, N. H.: Oxidation and dissolution of nuclear fuel (UO2) by the products of alpha radiolysis of water, J. Nucl. Mater. 244, p. 66–74 (1997).Google Scholar
8 Shoesmith, D.W. and Sunder, S.: The prediction of nuclear fuel (UO2) dissolution rates under waste disposal conditions. J. Nucl. Mat. 190, p. 20–35 (1992).Google Scholar
9 Horseman, S.T., Harrington, J.F. and Sellin, P., Gas migration in MX-80 buffer bentonite, in Scientific Basis for Nuclear Waste Management XX, edited by Gray, W.J. and Triay, I.R. (Mat.Res. Soc. Proc. 465, Pittsburgh, PA 1997). p. 1003–1010.Google Scholar
10 Tait, J.C. and Johnson, L.H.: Computer modelling of alpha radiolysis of aqueous solutions in contact with used UO2 fuel in Proceedings of the 2nd Int. Conf. on Radioactive Waste Management, Winnipeg, MB, Sept., 1986, Canadian Nuclear Society, Toronto, p. 611–615.Google Scholar
11 Christensen, H. and Bjergbakke, E., Alpha-radiolysis of aqueous solutions, in Scientific Basis for Nuclear Waste Management IX, edited by Werme, L.O., (Mat. Res. Soc. Proc. 50,Pittsburgh, PA 1985) p. 401–408.Google Scholar
12 Cramer, J.J. and Smellie, J.: Final report of the AECL/SKB Cigar Lake analog study.Atomic Energy of Canada Limited Report, AECL- 10851, COG-93-147. (1994).Google Scholar
13 Liu, J. and Neretnieks, I.: Some evidence of radiolysis in a uranium ore body - quantification and interpretation, in Scientific Basis for Nuclear Waste Management XVIII, edited by Murakami, T. and Ewing, R.C. (Mat. Res. Soc. Proc. 353, Pittsburgh, PA 1995). p. 1179–1186.Google Scholar
14 Stroes-Gascoyne, S., Johnson, L.H., Beeley, P.A. and Sellinger, D.M., Dissolution of used CANDU fuel at various temperatures and redox conditions, in Scientific Basis for Nuclear Waste Management IX, edited by Werme, L.O., (Mat. Res. Soc. Proc. 50, Pittsburgh, PA 1985), p. 317–326.Google Scholar
15 Wronkewiecz, D., Bates, J.K., Wolf, S.F. and Buck, E.C., Ten-year results from unsaturated drip tests with UO2 at 90°C: implications for the corrosion of spent nuclear fuel, J. Nucl. Mat. 238, p. 78–95 (1996).Google Scholar
16 Johnson, L.H. and Taylor, P., Alteration of spent Candu fuel in aerated steam at 150°C, Report prepared for the US DOE/YMSCO under the terms of Contract #DE-AC08-95NV 11784, AECL-12003, COG-98-364 (1999).Google Scholar
17 King, F. and Betteridge, J.S., Ex situ measurements of the porosity of precipitated corrosion products on oxidized UO2, Ontario Hydro Report No 06819-REP_01200-0059 ROO (1998).Google Scholar
18 Bruno, J., Cera, E., Pablo, J. De, Duro, L., Jordana, S. and Savage, D.. Determination of radionuclide solubility limits to be used in SR-97. Uncertainties associated to calculated solubilities. SKB Technical Report 97–33. (1997).Google Scholar
19 , Nagra: Kristallin-I Safety Assessment Report, Nagra Technical Report 93-22, Nagra, Wettingen, Switzerland (1994).Google Scholar
20 Eriksen, T.E. and Ndalamba, P.. On the formation of a moving redox-front by oa-radiolysis of compacted water saturated bentonite. SKB Technical Report 88-27 (1988).Google Scholar