HTGR Knowledge Base

Conference Article: The relation between irradiation induced dimensional change and the coefficient of thermal expansion: A new look

G. Hall, B. J. Marsden, A. Fok and J. Smart, Nuclear Graphite Technology Group, University of Manchester, United Kingdom

Abstract

In the 1960s, J.H.W. Simmons derived a theoretical relationship between the coefficient of thermal expansion (CTE) and dimensional changes in irradiated graphite. At low irradiation dose, the theory was shown to be consistent with experimental observations. However, at higher doses the results diverge. Despite this, modified versions of this theory have been used as the basis of the design and life prediction calculations for graphite-moderated reactors.

This paper revisits Simmons’s theory, summarising the assumptions made in its derivation. The paper then modifies and applies the theory to the dimensional change and CTE change behaviour in isotropic nuclear graphite, making use of trends in irradiated behaviour recently derived using finite element analyses.

The importance of these issues to present HTR technology is that the life of HTR graphite components is related to their irradiated dimensional change behaviour. A more in depth understanding of this behaviour will allow suitable graphite material to be selected or new graphite types to be developed.

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key words: Gas Cooled Reactor, Nuclear Technology
Reference:
Proceedings of the Conference on High Temperature Reactors, Petten, NL, April 22-24, 2002
Organized by HTR-TN in cooperation with the European Nucler Society (ENS) and the IAEA
International Atomic Energy Agency, Vienna (Austria)
HTR-2002, pp:1-5