Issues of scale in nuclear graphite components

Holt, Matthew

July 2008

Thesis or dissertation

© 2008 Matthew Holt. All rights reserved. No part of this publication may be reproduced without the written permission of the copyright holder.

A conceptual model for the determination of the effect of specimen size on the strength of nuclear graphites was developed using abstraction techniques and finite element Analysis (FEA). The model was designed to be able to predict the response of nuclear graphites (primarily IM1-24 graphite) using fixed material properties under defined loading conditions and model constraints. Employing custom written C++ programs, randomly generated microstructural representations of IM1-24 graphite at a number of differing sizes were produced and subsequently had the stresses and strains through the model analysed using ANSYS FEA software.

In conjunction with the conceptual modelling, a comprehensive testing programme was designed and developed to gain a data set for the validation of the model outputs. Two types of graphite were selected for the testing programme. Logically, IM1-24 graphite and a control graphite R4340. A large number of varying sizes of specimen were tested to failure under compression, 3-point and 4-point flexural loading and all results recorded and analysed.

On completion of both programmes it was found that the modelling programme proved to be successful, in particular, the microstructural response of the virtual material when compared to the testing results. An issue of constant strain inherent in the models due to the loading conditions rendered the numerical results difficult to compare to the testing programme, but the data obtained for the testing programme has expanded the knowledge of the response of IM1-24 graphite at differing scales and loading conditions.

Department of Engineering, The University of Hull
Neighbour, Gareth B.
Sponsor (Organisation)
British Energy Generation Limited
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