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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

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