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Sodium Sulphate Activated GGBS/PFA and Its Potential as a Nuclear Waste Immobilisation Matrix

Published online by Cambridge University Press:  21 March 2011

Yun Bai ,
Neil B. Milestone  and
Changhui Yang
Yun Bai
Affiliation:
Immobilisation Science Laboratory (ISL), Department of Engineering Materials, University of Sheffield
Neil B. Milestone
Affiliation:
Immobilisation Science Laboratory (ISL), Department of Engineering Materials, University of Sheffield
Changhui Yang
Affiliation:
Department of Building Materials & Engineering, Chongqing University, P.R.China
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Abstract

The UK currently uses Portland cement composite blends to immobilise/encapsulate intermediate and low level radioactive wastes (ILW and LLW). However, among other things, the high pH of these systems causes the corrosion of some metals, which can lead to expansion and excess generation of hydrogen. Therefore, in order to immobilise nuclear waste where corrosion is an issue, a near neutral cementing system is desirable.

Among the activators which can be used in the alkali-activated slag (AAS) systems, a solution of Na2SO4 is near neutral but the ground granulated blast-furnace slag (GGBS) itself has a pH about 11, increasing the pH within the Na2SO4 activated AAS. As low calcium Pulverized Fuel Ash (PFA) only has a pH about 9, using a GGBS/PFA blend activated by Na2SO4 offers the potential to develop a near neutral cementing system for nuclear waste immobilisation purposes.

In this paper, the replacement of GGBS in the Na2SO4 activated AAS system with PFA at 0%, 10%, 20% and 30% by mass was examined. The pH and corrosion of Al were determined and used as primary criteria for judging the feasibility for further development of a Na2SO4 activated GGBS/PFA matrix for immobilising nuclear wastes. The microstructure of the matrices was studied by SEM. Leaching studies were carried out to examine the possibility of immobilising Cs+ within these Na2SO4 activated GGBS/PFA matrices. The potential of using Na2SO4 activated GGBS/PFA for immobilising nuclear wastes is discussed.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 932: Symposium – Scientific Basis for Nuclear Waste Management XXIX , 2006 , 38.1
Copyright
Copyright © Materials Research Society 2006

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References

REFERENCES

1. Department for Trade and Industry, U.K., Energy White Paper: our energy future – creating a low carbon economy, published by TSO (The Stationery Office), ISBN: 0-10-157612-9, February, 2003, 138pp.Google Scholar
2. Nirex, Radioactive Wastes in the UK: A summary of the 2001 inventory, Nirex Report N/041, October, 2002, 14pp.Google Scholar
3. Sharp, J. H., Milestone, N. B., Hill, J. and Miller, E. W., Cementitious systems for encapsulation of intermediate level waste, The 9th International Conference on Radioactive Waste Management and Environmental Remediation, September 21-25, 2003, Oxford, England, 10pp.Google Scholar
4. Hayes, M., RAT 0754: To Review Previous Experience with Respect to Corrosion Rates of Aluminium on Immobilisation in BFS/OPC grouts, BNFL reference, 2000.Google Scholar
5. Glukhovsky, V.D., Soil silicates, Gosstroiizdat, Kiev, 1959 (in Russian).Google Scholar
6. Shao-Dong, Wang, Xin-Cheng, Pu, Scrivener, K.L. and Pratt, P.L., Alkali-activated slag cement and concrete: a review of properties and problems, Advances in Cement Research, 1995, 7, No. 27, July, pp. 93–102.Google Scholar
7. Qian, G., Sun, D.D. and Tay, J.H., Characterization of mercury- and zinc-doped alkali-activated slag matrix, part I: mercury, Cement and Concrete Research 33 (2003), pp. 1251–1256.Google Scholar
8. Qian, G., Sun, D.D. and Tay, J.H., Characterization of mercury- and zinc-doped alkali-activated slag matrix, part II: zinc, Cement and Concrete Research 33 (2003), pp. 1257–1262.Google Scholar
9. Deja, J., Immobilization of Cr6+, Cd2+, Zn2+ and Pb2+ in alkali-activated slag binders, Cement and Concrete Research 32 (2002), pp. 1971–1979.Google Scholar
10. Qian, G., Li, Y., Yi, F. and Shi, R., Improvement of metakaolin on radioactive Sr and Cs immobilization of alkali-activated slag matrix, Journal of Hazardous Materials B92 (2002), pp. 289–300.Google Scholar
11. British Standards Institution, Characterisation of waste – leaching – compliance test for leaching of granular waste materials and sludges, Part 1: One stage batch test at a liquid to solid ratio of 2 l/kg for materials with high solid content and with particle size below 4 mm (without or with size reduction), BS EN 12457-1:2002, BSI, London.Google Scholar
12. Fraay, A.L.A., Bijen, J.M. and de Haan, Y. M., The reaction of fly ash in concrete: A critical examination, Cement and Concrete Research, Vol. 19, pp. 235–246, 1999.Google Scholar
13. Bai, Y., Yang, C. H. and Milestone, N. B., The potential use of low pH alkali salts activated GGBS to immobilise nuclear wastes containing reactive metals: Part II, pH, corrosion and leaching studies, Paper submitted to Nuclear Future for publication, 11pp.Google Scholar
14. Setiadi, A. and Milestone, N. B., Corrosion of aluminium in composite cements, 24th Cement and Concrete Science Conference, Warwick, September 16-17th, 2004, 4pp.Google Scholar