The development of a physical model of an Advanced Gas Cooled Reactor core: Outline of the feasibility study

Dihoru, Luiza; Oddbjornsson, Olafur; Kloukinas, Panos; Dietz, Martin; Horseman, Tony R; Voyagaki, Elia; Crewe, Adam J; Taylor, Colin Anthony; Steer, Alan

doi:10.1016/j.nucengdes.2017.01.012

Cited by 14 publications

(22 citation statements)

References 1 publication

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“…Instead of graphite, which is brittle, difficult to manufacture, dirty to handle, and subject to dust production through wear during shaking, an engineering plastic called Acetal was selected for the physical model components as it offers increased resilience, and its properties are well matched to that of graphite. A detailed presentation of the design process of the experiment is available in Dihoru et al The rig is an octagonal array of bricks and keys spanning eight layers as shown in plan and side views in Figure . Three types of bricks exist in the array: Lattice bricks (LBs), the larger array parts, which are multifaceted with a cylindrical bore (Figure C and Figure A).…”

Section: Agr Core Physical Model Descriptionmentioning

confidence: 99%

“…When testing, the restraint frame is bolted directly to the underlying platform of the University of Bristol shaking table. More information on the restraint system is available in Dihoru et al…”

Section: Agr Core Physical Model Descriptionmentioning

confidence: 99%

“…More information on the restraint system is available in Dihoru et al 43,44 The instrumentation involves in-house probes and measurement procedures, tailored data acquisition hardware and post-processing software, a high-speed vision system, a network of Hall effect transducers, accelerometers and potentiometric transducers installed in selected instrumented interstitial and lattice columns. A bespoke distributed microdata acquisition system (μDAQ) was developed by the authors, which allows the monitoring of displacements and accelerations of the instrumented components.…”

Section: Agr Core Physical Model Descriptionmentioning

confidence: 99%

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

Voyagaki

Kloukinas

Dietz

et al. 2018

Earthq Engng Struct Dyn

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Summary 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.

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Section: Agr Core Physical Model Descriptionmentioning

confidence: 99%

Section: Agr Core Physical Model Descriptionmentioning

confidence: 99%

Section: Agr Core Physical Model Descriptionmentioning

confidence: 99%

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

Voyagaki

Kloukinas

Dietz

et al. 2018

Earthq Engng Struct Dyn

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“…Several enhanced analytical methods and physical models for static and dynamic behaviour have been reported in the last decade 2,3 . Between 2008 and 2012, a quarter‐scale near‐full single layer 20‐rings array model (“the single‐layer array (SLA)”) was developed at UOB 4 to explore the basic mechanics of the core system as a precursor for a more sophisticated modelling tool: the quarter‐scale 8‐layer‐20‐bricks‐across AGR core model (“the multilayer array (MLA)”) 5 …”

Section: Introductionmentioning

confidence: 99%

Experimental and computational synergy for modelling an advanced gas‐cooled reactor core under seismic excitation

Dihoru

Oddbjornsson²,

Cannell

et al. 2020

Earthq Engng Struct Dyn

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Summary The advanced gas‐cooled reactors (AGRs) are the backbone of the United Kingdom's nuclear generation fleet, producing approximately 17% of the country's electricity. Their safety cases are supported by thorough inspection and monitoring of their graphite cores and extensive theoretical, analytical, and experimental studies. This paper presents a unique, highly innovative and technically challenging earthquake engineering project that has provided vital evidence to underpin the seismic safety assessments of the AGRs. Two modelling approaches, one experimental (a multilayer array physical model), and one numerical (a SOLFEC nonsmooth contact dynamics computational model) have been developed to investigate the seismic behaviour of an aged graphite core. The synergetic relationship between the two approaches is a product of insightful collaborative learning between the University of Bristol and Atkins, with the experiments providing material parameters and validation data and the computer simulations feeding array design and test schedule recommendations to the physical model. The predictive capabilities of the physical and the numerical models are tested by direct comparison and the good agreement between the results has increased the confidence in both. The model's versatility allows a variety of core scenarios to be tested that can explore in detail the AGR core behaviour in seismic conditions.

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“…The model components are made from a rigid engineering plastic (acetal). Details of model design, build and testing have been published (Dihoru et al 2015, Dihoru et al 2016. The rigs were tested extensively on the earthquake simulator, while computer model simulations were run in parallel.…”

Section: Introductionmentioning

confidence: 99%

A computer vision approach for dynamic tracking of components in a nuclear reactor core model

Dihoru

Crewe

Horseman³

et al. 2019

Nuclear Engineering and Design

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The Advanced Gas Cooled Reactors (AGRs) are a vital component of the UK's electricity supply system. Their continued reliable operation is supported by safety cases that include assessments of their seismic resilience to their ultimate lifetimes. These assessments are developed via a complex programme of numerical simulations, physical modelling and shaking table testing. A quarter sized physical model representing a single layer of an AGR graphite core was developed at the University of Bristol (UOB) to test the dynamic response for various core array configurations and seismic excitations. The dynamic displacement response is significant, as displaced components may cause local or general distortions that could theoretically affect the channel shapes and the keying system of an AGR core, with implications on the fundamental functions of the reactor. This paper presents a computer vision approach for component displacement mapping. An infrared vision system and a highresolution video system were employed to track all the components in the model core during a seismic event. The systems have proven to be fit for purpose, being able to map the position of the array components at a resolution of 0.1mm and to reveal features of response that are useful for understanding the core dynamics. The employed hardware and tracking algorithms are general in nature, hence they are transferrable to other case studies involving multi-body assemblies under dynamic loading.

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The development of a physical model of an Advanced Gas Cooled Reactor core: Outline of the feasibility study

Cited by 14 publications

References 1 publication

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

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

Experimental and computational synergy for modelling an advanced gas‐cooled reactor core under seismic excitation

A computer vision approach for dynamic tracking of components in a nuclear reactor core model

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