The dynamic response of multi-layers AGR core brick arrays

Ahmed, K.M.

doi:10.1016/0029-5493(87)90303-7

Cited by 4 publications

(5 citation statements)

References 9 publications

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“…In order to capture such forces in the numerical models, a reasonable representation of viscous friction and Coulomb friction had to be sought. The older versions of GCORE modelled friction solely via viscous damping, while the current version of GCORE in ABAQUS includes a representation of the Coulomb kinetic friction law, 13 which leads to reasonable predictions of core behaviour that compare well with the MLA rig results 6 . This current GCORE model approximates the friction force as follows (Figure 14): At low velocities: friction force ( F T ) is the friction damping force (proportional to the relative velocity ( v ) of the contacting bodies). At higher velocity: friction force ( F T ) is the Coulomb friction, calculated as the elastic reaction force ( F N ) normal to the plane in which friction acts multiplied by the friction coefficient ( μ ). …”

Section: Numerical Modellingmentioning

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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Section: Numerical Modellingmentioning

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

View full text Add to dashboard Cite

show abstract

“…Early studies were limited to one‐ and two‐dimensional models of the high‐temperature gas‐cooled reactor cores (HTGR), which are simpler to treat numerically and experimentally as they involve only one major type of graphite bricks—as opposed to two in the AGR. The first method for predicting the seismic responses of AGR reactor cores was developed in the early 1980s using arrays of rigid bodies and nonlinear contact elements . This method was supported by an extensive set of dynamic excitation tests on small arrays of full‐size bricks and brick slices .…”

Section: Introductionmentioning

confidence: 99%

“…This method was supported by an extensive set of dynamic excitation tests on small arrays of full‐size bricks and brick slices . Seismic responses of AGR reactor cores are currently computed by GCORE, which uses representations of the arrays of graphite bricks similar to those used earlier …”

Section: Introductionmentioning

confidence: 99%

“…The first method for predicting the seismic responses of AGR reactor cores was developed in the early 1980s using arrays of rigid bodies and nonlinear contact elements. 37 This method was supported by an extensive set of dynamic excitation tests on small arrays of full-size bricks and brick slices. 38,39 Seismic responses of AGR reactor cores are currently computed by GCORE, 40 which uses representations of the arrays of graphite bricks similar to those used earlier.…”

Section: Introductionmentioning

confidence: 99%

“…38,39 Seismic responses of AGR reactor cores are currently computed by GCORE, 40 which uses representations of the arrays of graphite bricks similar to those used earlier. 37 The problem is both important and challenging because of its implications in the safe operation of the core and because it goes beyond the state of the art in the area of multiblock dynamics. This publication is a first attempt to understand the fundamental mechanics of the problem in order to explain and predict the dynamic response of this complex nonlinear system.…”

Section: Introductionmentioning

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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Numerical study of the dynamic characteristics of a single-layer graphite core in a thorium molten salt reactor

Yang

Ding

et al. 2018

NUCL SCI TECH

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The dynamic response of multi-layers AGR core brick arrays

Cited by 4 publications

References 9 publications

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

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

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

Numerical study of the dynamic characteristics of a single-layer graphite core in a thorium molten salt reactor

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