Earthquake response of a multiblock nuclear reactor graphite core: Experimental model vs simulations

Elia Voyagaki*, Panos Kloukinas, Matt Dietz, Luiza Dihoru, Tony Horseman, Olafur Oddbjornsson, Adam J. Crewe, Colin A. Taylor, Alan Steer

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

11 Citations (Scopus)
125 Downloads (Pure)

Abstract

The complex dynamics of a quarter-scale model of a graphite nuclear reactor core, representative of the second generation of British advanced gas-cooled nuclear reactors, is investigated numerically and experimentally. Advanced gas-cooled nuclear reactor cores are polygonal, multilayer, arrays of graphite bricks, with each brick allowed to rock by design relative to each other in accordance with the boundary conditions. A 35 000 DOF, nonlinear finite element model of the core created by Atkins Nuclear, was analysed on a high performance computing facility at the University of Bristol, and a corresponding 8 t physical model, equipped with 3200 data acquisition channels, was built and tested on the University of Bristol 6-DOF shaking table. In this paper, the two models are subjected to a series of (1) synthetic earthquake and (2) idealised harmonic input motions. The experimental data are used to compare and verify the two models and explore the dynamics of the core. A kinematic model of the response is also developed based solely on geometric constraints. The results are presented in the form of response maps and graphs. Important conclusions are drawn as to the dynamics and earthquake response of such systems, which inform numerical model validation. It is found that contrary to the case of a small number of rocking blocks that exhibit highly complex response patterns, the behaviour of the model at hand is both smooth and repeatable. An analogy between the response of the core and that of dense granular matter exhibiting particle interlocking and dilatancy is highlighted.

Original languageEnglish
Pages (from-to)2601-2626
Number of pages26
JournalEarthquake Engineering and Structural Dynamics
Volume47
Issue number13
Early online date5 Aug 2018
DOIs
Publication statusPublished - 25 Oct 2018

Keywords

  • earthquake response
  • finite element model
  • granular medium
  • multibody rocking
  • nuclear core
  • shaking table experiment

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