Nuclear graphite friction properties and the influence of friction properties on the pebble bed

Luo, Xianwu; Li, Xiaotian; Yu, Suyuan

doi:10.1016/j.nucengdes.2010.07.030

Cited by 34 publications

(7 citation statements)

References 28 publications

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“…As the static friction between the wall and the particles increases, there is significantly higher head independence of pressure and flow rate of granular flows in beds (McCabe et al, 1985;Luo et al, 2010). It was found that a bed-heightto-bed-diameter ratio (H/D ≥ 2) will yield long duration of radioactive particle tracking (RPT) experiments.…”

Section: Operational and Geometric Issuesmentioning

confidence: 99%

A review of pebble flow study for pebble bed high temperature gas-cooled reactor

Jiang

Yang

et al. 2019

Exp. Comput. Multiph. Flow

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The pebble bed high temperature gas-cooled reactor is a promising generation-IV reactor, which uses large fuel pebbles and helium gas as coolant. The pebble bed flow is a fundamental issue for both academic investigation and engineering application, e.g., reactor core design and safety analysis. This work performed a review of recent progress on pebble flow study, focusing on the important issues like pebble flow, gas phase hydrodynamics, and inter-phase heat transfer (thermal hydraulics). Our group's researches on pebble flow have also been reviewed through the aspects of phenomenological observation and measurement, voidage distribution, geometric and parameter optimization, pebble flow mechanisms, flow regime categorization, and fundamentals of modelings of pebble flow and radiation. Finally, the major problems or possible directions of research are concluded which would be some of our focuses on the pebble bed flow study.

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Section: Operational and Geometric Issuesmentioning

confidence: 99%

A review of pebble flow study for pebble bed high temperature gas-cooled reactor

Jiang

Yang

et al. 2019

Exp. Comput. Multiph. Flow

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“…non-monotonically on µ p , which can be explained by examining whether pebbles can spin, and slide on pebble-pebble contacts. A wide range of friction coefficients for graphite that have been reported in the literature (Luo et al, 2010), and there are additional uncertainties that are introduced by the extreme operating environment in a PBR core. We note that the friction values over which we observe the complex non-monotonic boundary layer behavior are within the realms of feasibility for friction values in a real reactor.…”

Section: Resultsmentioning

confidence: 99%

“…To understand this phenomenon in more detail we performed a suite of simulations where both µ p and µ w are varied. We focused on the range of friction coefficients from 0.01-0.5, which encompasses the bulk of experimental measurements presented by Luo et al (2010).…”

Section: Friction Effects On the Flow Regimesmentioning

confidence: 99%

“…In particular, the frictional properties of graphite are known to vary greatly on the conditions, and limited data is available in the high-pressure, high-temperature, helium gas environment within the core. In a review article by Luo et al (2010), friction coefficients ranging from 0.03-0.87 have been reported in the literature, with most lying in the range from 0.2-0.4. The effect of friction on granular flows has been addressed in a variety of previous modeling studies.…”

Section: Introductionmentioning

confidence: 99%

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Analysis of the pebble burnup profile in a pebble-bed nuclear reactor

Tang

Zhang

Guo

et al. 2019

Nuclear Engineering and Design

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In a pebble bed nuclear reactor, each fuel pebble draining through the core experiences a different amount of burnup depending on the precise trajectory that it follows. Understanding the burnup profile of pebbles is essential for reactor safety, as well as for fuel economy. Here, we introduce a method for constructing the burnup profile based on performing a discrete element simulation of the pebble drainage, followed by a burnup calculation in each individual pebble. This method is more accurate than previous approaches, and in particular it captures the extremal cases of pebble burnup. We demonstrate the method using the geometry, neutron flux data, and thermal characteristics from the HTR-10 reactor being developed at Tsinghua University. We examine pebble burnup during a single drainage cycle, and over multiple drainage cycles characteristic of normal reactor operation. Our results show that the presence of slow-moving boundary layers of pebbles near the reactor wall strongly influences the burnup profile. We perform a systematic study where the pebble-pebble and pebble-wall friction coefficients are independently varied, and we show that the strength of the boundary layers is a complex interplay of these two parameters.

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“…As the coefficient of static friction increases, significantly higher head independence of pressure and flow rate is observed (Luo et al 2010). Thus, a height-to-diameter ratio (H/D) of 1 is selected for this study.…”

Section: Methodsmentioning

confidence: 99%

Experimental investigation of the overall residence time of pebbles in a pebble bed reactor (PBR) using radioactive pebble

Khane

Taha

2016

Progress in Nuclear Energy

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The granular flow of pebbles in a pebble bed reactor (PBR) under the influence of gravity is a dense granular flow with long-lasting frictional contacts. The basic governing physics is not fully understood and hence the dynamic core of a PBR and non-idealities associated with pebbles flow inside the reactor core are of non-trivial significance from the point of view of safety analyses, licensing, and thermal hydraulics. In the current study, overall and zonal pebbles residence time investigation is carried out by implementing noninvasive radioisotope-based flow visualization measurement techniques such as residence time distribution (RTD) and radioactive particle tracking (RPT). The characteristics of overall pebble residence time/transient number, zonal residence time, and the z-component of average zonal velocities at different initial seeding positions of a tracer particle have been summarized. It is found that the overall pebbles residence time/transient number increases (the z-component of average zonal velocities decreases) from the center towards the reactor wall. Also, pebbles' zonal residence time results (the whole core is divided into three zones) which provide more insight and understanding about PBR core dynamics have been reported. The benchmark data provided could be used for assessment of commercial/in-house computational methodologies related to granular flow investigations.

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Nuclear graphite friction properties and the influence of friction properties on the pebble bed

Cited by 34 publications

References 28 publications

A review of pebble flow study for pebble bed high temperature gas-cooled reactor

A review of pebble flow study for pebble bed high temperature gas-cooled reactor

Analysis of the pebble burnup profile in a pebble-bed nuclear reactor

Experimental investigation of the overall residence time of pebbles in a pebble bed reactor (PBR) using radioactive pebble

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