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Understanding the likelihood and consequences of post-closure criticality in a geological disposal facility

Published online by Cambridge University Press:  02 January 2018

R. J. Winsley ,
T. D. Baldwin ,
T. W. Hicks ,
R. M. Mason  and
P. N. Smith
R. J. Winsley*
Affiliation:
Radioactive Waste Management, Curie Avenue, Building 587, Harwell Oxford, Didcot OX11 0RH, UK
T. D. Baldwin
Affiliation:
Galson Sciences Limited, 5 Grosvenor House, Melton Road, Oakham, Rutland LE15 6AX, UK
T. W. Hicks
Affiliation:
Galson Sciences Limited, 5 Grosvenor House, Melton Road, Oakham, Rutland LE15 6AX, UK
R. M. Mason
Affiliation:
Amec Foster Wheeler, Kings Point House, Queen Mother Square, Poundbury, Dorchester, Dorset DT1 3BW, UK
P. N. Smith
Affiliation:
Amec Foster Wheeler, Kings Point House, Queen Mother Square, Poundbury, Dorchester, Dorset DT1 3BW, UK
*
*E-mail: robert.winsley@nda.gov.uk
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Abstract

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A geological disposal facility (GDF) will include fissile materials that could, under certain conditions, lead to criticality. Demonstration of criticality safety therefore forms an important part of a GDF's safety case.

Containment provided by the waste package will contribute to criticality safety during package transport and the GDF operational phase. The GDF multiple-barrier system will ensure that criticality is prevented for some time after facility closure. However, on longer post-closure timescales, conditions in the GDF will evolve and it is necessary to demonstrate: an understanding of the conditions under which criticality could occur; the likelihood of such conditions occurring; and the consequences of criticality should it occur.

Work has addressed disposal of all of the UK's higher-activity wastes in three illustrative geologies. This paper, however, focuses on presenting results to support safe disposal of spent fuel, plutonium and highlyenriched uranium in higher-strength rock.

The results support a safety case assertion that post-closure criticality is of low likelihood and, if it was to occur, the consequences would be tolerable.

Keywords

geological disposalpost-closurespent fuelnuclear materialscriticality safety
Type
Research Article
Information
Mineralogical Magazine , Volume 79 , Issue 6 , November 2015 , pp. 1551 - 1561
Creative Commons
Creative Common License - CCCreative Common License - BY
Copyright © The Mineralogical Society of Great Britain and Ireland 2015. This is an open access article, distributed under the terms of the Creative Commons Attribution (CC BY) license (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 2015

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