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Experimental study to evaluate the effect of polymeric encapsulants on the corrosion resistance of intermediate-level radioactive waste packages

Published online by Cambridge University Press:  05 July 2018

R. J. Winsley ,
N. R. Smart  and
C. Padovani
R. J. Winsley
Affiliation:
AMEC, Building 150, Harwell Oxford, Didcot, Oxfordshire OX11 0QB, UK
N. R. Smart*
Affiliation:
AMEC, Building 150, Harwell Oxford, Didcot, Oxfordshire OX11 0QB, UK
C. Padovani
Affiliation:
Nuclear Decommissioning Authority, Radioactive Waste Management Directorate, Curie Avenue, Harwell, Didcot, Oxfordshire OX11 0RH, UK
*
*E-mail: nick.smart@amec.com
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Abstract

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Intermediate-level radioactive waste is normally encapsulated in cementitious grout. However, for some wastes, grout may not be suitable and polymeric encapsulants are being considered as an alternative. One concern with such encapsulants is their long-term chemical stability and the possibility that release of aggressive degradation products could cause corrosion.

This paper evaluates the potential for three polymeric encapsulants: two epoxy resins (the APS polymer system, (APS) and Alchemix 4760 (ALC)) and a vinyl-ester styrene (VES); to cause internal corrosion of stainless steel waste containers. The corrosion behaviour of stainless steel 316L in contact with each encapsulant was studied in saturated Ca(OH)2 solutions and deionized (DI) water, at 80°C, under non-irradiated and γ-irradiated conditions.

In aerated, alkaline conditions, 316L was resistant to corrosion in all the conditions tested. However, in DI water, the pH fell to values as low as three due to release of acidic species from the polymers. The two epoxy materials (particularly APS) also released significant levels of chloride; VES did not. Chloride release appeared to be increased by γ-irradiation. As a result of the low pH chloride-containing environment created by the APS encapsulant, 316L experienced localized corrosion, whereas coupons in Alchemix 4760 and VES did not. Weight loss measurements correlated with visual observations. γ-irradiation appeared to increase the degree of corrosion.

Keywords

nuclear waste storagepolymeric encapsulationpitting corrosion316Lstainless steelγ-irradiation
Type
Research Article
Information
Mineralogical Magazine , Volume 76 , Issue 8 , December 2012 , pp. 2957 - 2967
Creative Commons
Creative Common License - CCCreative Common License - BY
© [2012] The Mineralogical Society of Great Britain and Ireland. This is an open access article distributed under the terms of the Creative Commons Attribution (CC BY) licence (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2012

Footnotes

†

Current address: NDA, RWMD, Curie Avenue, Harwell, Didcot, Oxfordshire OX11 0RH, UK

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