Severe accident approach - final report. Evaluation of design measures for severe accident prevention and consequence mitigation.

Tentner, Adrian; Parma, Edward J.; Wei, Thomas Y. C.; Wigeland, R. A.

doi:10.2172/973483

Cited by 34 publications

(21 citation statements)

References 17 publications

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“…In the ERANOS model, we considered an axial thermal expansion coefficient of 1.00566 (driven by the clad assuming ΔT from 20 °C to average coolant temperature, 470 °C) and a radial expansion coefficient of 1.00666 (driven by the diagrid assuming ΔT from 20 °C to inlet coolant temperature, 395 °C). In the present study, the negative feedback effect due to control rod drive line expansion is not included along with design features and measures that might mitigate transients and facilitate passive reactor shut-down, like self-actuated shutdown systems (SASSs), such as flow levitated absorbers, Curie-point latches or gas expansion modules (GEMs) as indicated e.g., in [32], have not been considered in the present study because they are beyond the aim of the project [25].…”

Section: Model Descriptionmentioning

confidence: 99%

Safety-Related Optimization and Analyses of an Innovative Fast Reactor Concept

et al. 2012

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Abstract:Since a fast reactor core with uranium-plutonium fuel is not in its most reactive configuration under operating conditions, redistribution of the core materials (fuel, steel, sodium) during a core disruptive accident (CDA) may lead to recriticalities and as a consequence to severe nuclear power excursions. The prevention, or at least the mitigation, of core disruption is therefore of the utmost importance. In the current paper, we analyze an innovative fast reactor concept developed within the CP-ESFR European project, focusing on the phenomena affecting the initiation and the transition phases of an unprotected loss of flow (ULOF) accident. Key phenomena for the initiation phase are coolant boiling onset and further voiding of the core that lead to a reactivity increase in the case of a positive void reactivity effect. Therefore, the first level of optimization involves the reduction, by design, of the positive void effect in order to avoid entering a severe accident. If the core disruption cannot be avoided, the accident enters into the transition phase, characterized by the progression of core melting and recriticalities due to fuel compaction. Dedicated features that enhance and guarantee a sufficient and timely fuel discharge are considered for the optimization of this phase.

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Section: Model Descriptionmentioning

confidence: 99%

Safety-Related Optimization and Analyses of an Innovative Fast Reactor Concept

et al. 2012

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“…In the PAMR phase of SFRs, it is considered that one of the typical melt relocation paths from the disrupted core to the lower plenum is the control-rod guide tube (CRGT), which has relatively large potential of fuel removal from the core because of its large hydraulic diameter ∼10 cm [1]. After the melt discharge to the plenum, FCIs lead to solidification and fragmentation of the melt with very small particles.…”

Section: Experimental Conditions and Geometriesmentioning

confidence: 99%

“…In the course of melt relocation, melt-sodium contact leads to solidification and fragmentation of molten core materials with very small particles. Such fragmentation may increase the lateral spreading of the fragmented core materials once the materials have moved into more open areas [1]. This lateral spreading is likely to have an impact on the debris sedimentation behavior while forming a debris bed on the core-support structure or in the lower plenum of the reactor vessel.…”

Section: Introductionmentioning

confidence: 99%

Numerical study on sedimentation behavior of solid particles used as simulant fuel debris

Shamsuzzaman

Zhang

Horie

et al. 2014

Journal of Nuclear Science and Technology

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This paper presents numerical simulations using the discrete element method (DEM) to model sedimentation behavior of solid debris particles, which is significant for estimates of the coolability of debris beds. A series of experiments of gravity driven discharge of solid particles into a quiescent water pool was used to validate the DEM simulation method. We evaluated the effects of three crucial factors: particle density, particle diameter, and nozzle diameter on three key quantitative parameters: particle dispersion angle, particle fall time in the pool, and the height of the deposited particle bed to express the particle sedimentation behavior. The three crucial factors play a significant role in the particle sedimentation behavior. We compared the experimental and simulated results of the particle dispersion angle and particle fall time in the pool, and the height and shape of the deposited particle bed. The general trend of the simulation results indicates a reasonable agreement with the experimental observations. The simulations exhibit the potential applicability of the DEM-based simulation technique for the prediction of particle sedimentation behavior.

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“…In a postulated core disruptive accident (CDA) of a sodium-cooled fast reactor, core debris might settle on the core support structure and/or in the lower inlet plenum of the reactor vessel (as illustrated in Figure 1) because of rapid quenching and fragmentation of molten core materials in the subcooled sodium plenum [1,2]. Typically, the debris bed will form roughly conically shaped mounds.…”

Section: Introductionmentioning

confidence: 99%

“…To prevent the penetration of the reactor vessel by molten fuel and distribute molten fuel or core debris formed in a CDA into non-critical configurations, invessel retention devices are used in some sodium-cooled fast reactor (SFR) designs [1]. A multi-layered debris tray installed in the bottom region of the vessel is one of such devices [4].…”

Section: Introductionmentioning

confidence: 99%

An investigation on debris bed self-leveling behavior with non-spherical particles

Cheng

Tagami

Yamano

et al. 2014

Journal of Nuclear Science and Technology

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Studies on debris bed self-leveling behavior with non-spherical particles are crucial in the assessment of actual leveling behavior that could occur in core disruptive accident of sodium-cooled fast reactors. Although in our previous publications, a simple empirical model (based model), with its wide applicability confirmed over various experimental conditions, has been successfully advanced to predict the transient leveling behavior, up until now this model is restricted to calculations of debris bed of spherical particles. Focusing on this aspect, in this study a series of experiments using non-spherical particles was performed within a recently developed comparatively larger scale experimental facility. Based on the knowledge and data obtained, an extension scheme was suggested with the intention to extend the base model to cover the particle-shape influence. The proposed scheme principally consists of two parts -with one part for correcting the terminal velocity of a single non-spherical particle, which is the key parameter in our base model, and the other for representing the additional particle-particle interactions caused by the shaperelated parameters. Through detailed analyses, it is found that by coupling this scheme, good agreement between experimental and predicted results can be achieved for both spherical and non-spherical particles given current range of experimental conditions.

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Severe accident approach - final report. Evaluation of design measures for severe accident prevention and consequence mitigation.

Cited by 34 publications

References 17 publications

Safety-Related Optimization and Analyses of an Innovative Fast Reactor Concept

Safety-Related Optimization and Analyses of an Innovative Fast Reactor Concept

Numerical study on sedimentation behavior of solid particles used as simulant fuel debris

An investigation on debris bed self-leveling behavior with non-spherical particles

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