In Situ Long-Term Measurements of pH and Redox Potential During Spent Fuel Leaching Under Stationary Conditions-The Method and Some Preliminary Results


In order to get a better understanding for the spent fuel corrosion process, the variations of important intensive parameters such as pH and the redox potential (Eh) of the bulk solution have been continuously measured during long term sequential leaching experiments. These data may be used together with standard chemical analytical data for modeling spent fuel corrosion, especially in anoxic or reducing conditions. In order to overcome difficulties caused by the strong radiation field and the long experiment times, a method for in-situ measurements of pH and Eh using a computer controlled system was worked out. The stability of the measuring system over long time periods was then tested; pH values stable within 0.05 pH units/year in buffered systems were measured. The variations of these parameters in a variety of conditions and solution compositions were followed continuously during the spent fuel leaching process.

A discussion of the results of spent fuel leaching in anoxic conditions is presented, pointing out the difficulties to realize in laboratory near field conditions. An interesting case of calcite co-precipitation/co-dissolution is also presented. Dissolution experiments show that the calcite precipitated previously during spent fuel leaching experiments in synthetic groundwater contained considerable amounts of actinides and fission products.

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  1. 1

    Johnson L. H. and Shoesmith, D. W. Spent fuel. In: Radioactive Waste Forms for the Future, Eds. Lutze W and R. C. Ewing, (North-Holland Physics Publishing, The Netherlands 1988).

  2. 2

    Oversby, V. M. Nuclear waste Materials, In.: Materials Science and Technology, Eds. R. W. Cahn, P. Haasen and E. J. Kramer, Vol. 10B, Nuclear Materials, Part 2, (edited by B. R. T. Frost, VCH Verlagsgesellschaft mbH, Federal republic of Germany 1994).

  3. 3

    Forsyth R. S. and Werme, L. O. J. Nucl. Mater. 190, 3 (1992).

    CAS  Article  Google Scholar 

  4. 4

    L.O. Werme, K. Spahiu, J. Alloys and Compounds, 271-273 194 (1998).

    CAS  Article  Google Scholar 

  5. 5

    D. Shoesmith and S. Sunder AECL Report- 10488, 1991.

    Google Scholar 

  6. 6

    D. W. Shoesmith, S. Sunder and W. H. Hocking, In The electrochemistry of novel materials, Eds. J. Lipkowski and P. N. Ross (VCH, New York, NY, 1994), pp. 297–337.

  7. 7

    R. S. Forsyth, SKB Technical Report 97-25, 1997.

    Google Scholar 

  8. 8

    A. S. Brown, J. Am. Chem. Soc. 56 646 (1934).

    CAS  Article  Google Scholar 

  9. 9

    G. Gran, Acta Chem. Scand. 4, 559 (1950).

    CAS  Article  Google Scholar 

  10. 10

    G. Gran, Analyst, 77 661(1952).

    CAS  Article  Google Scholar 

  11. 11

    R. S. Forsyth, SKB Technical Report 97-11, 1997.

    Google Scholar 

  12. 12

    R. S. Forsyth and U-B Eklund, SKB Technical Report 95-04, 1995.

    Google Scholar 

  13. 13

    T. Eriksen, U-B. Eklund, L. Werme, J. Bruno, J. Nucl. Mater., 227, 76 (1995).

    CAS  Article  Google Scholar 

  14. 14

    J. Bruno, E. Cera, U-B Eklund, T. Eriksen, M. Grive, K. Spahiu, presented at Migration 99, Lake Tahoe, Nevada, September 1999. To be published in Radiochimica Acta.

    Google Scholar 

  15. 15

    K. Spahiu, L. Werme, J. Low, U-B. Eklund, presented at 1998 Spent Fuel Workshop, May 18-20, Las Vegas, Nevada, 1998 (unpublished).

    Google Scholar 

  16. 16

    I. Grenthe, K. Spahiu. T. Eriksen, J. Chem.Soc. Faraday Trans. 88, 1267 (1992).

    CAS  Article  Google Scholar 

  17. 17

    D. K. Nordstrom, E. A. Jenne, J. W. Ball, In Chemical Modelling in Aqueous Systems, edited by E. A Jenne, ACS Advan. in Chem. Series 93, Am. Chem. Soc., Wasington D.C., 1979), pp. 51–79.

  18. 18

    M. Whitfield, Limnol. and Oceanog., 19 857 (1974).

    CAS  Article  Google Scholar 

  19. 19

    Garrels R.M. and Christ C.L.: Solutions, Minerals, and Equilibria, Harper & Row, New York 1965, 450 p.

    Google Scholar 

  20. 20

    K. A. I. Nararajan and I. Iwasaki, Minerals Sci. Eng. 6 35 (1974).

    Google Scholar 

  21. 21

    J. N. Butler and R. N. Roy, in: Activity coefficients in electrolyte solutions 2nd ed., edited by K. S. Pitzer CRC Press, Boca Raton, 1991), pp. 156–189.

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Spahiu, K., Werme, L., Low, J. et al. In Situ Long-Term Measurements of pH and Redox Potential During Spent Fuel Leaching Under Stationary Conditions-The Method and Some Preliminary Results. MRS Online Proceedings Library 608, 55 (1999).

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