Nuclear Techniques ›› 2017, Vol. 40 ›› Issue (2): 20601-020601.doi: 10.11889/j.0253-3219.2017.hjs.40.020601

• NUCLEAR ENERGY SCIENCE AND ENGINEERING • Previous Articles     Next Articles

A mono-sized sphere packing algorithm in cylindrical container with two-phase gravity-based method

LIU Fengrui1,2, HUANG Jianping1, LI Zhong1, WANG Naxiu1   

  1. 1. Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Jiading Campus, Shanghai 201800, China;
    2. University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2016-09-26 Revised:2016-11-29 Online:2017-02-10 Published:2017-01-24
  • Supported by:

    Supported by Strategic Priority Program of Chinese Academy of Sciences (No.XD02001002)

Abstract:

Background: The Pebble-bed Fluoride-salt-cooled High-temperature Reactor (PB-FHR) is one type of next generation IV nuclear power plants. It combines two existing technologies to create a new reactor option:graphite-matrix, coated-particle fuels developed for helium-cooled high-temperature reactors and liquid-fluoride-salt coolant used in molten salt reactors. To proceed thermal-hydraulic analysis of the core of PB-FHR such as online refuelling, randomly packed bed with different porosity is usually required firstly. Purpose: In this study, an efficient algorithm to produce randomly packed pebble bed with mono-sized spheres and variable packing factor in cylindrical containers is proposed. Methods: The packing of the pebble bed is initially constructed by free falling of soft particles (Young's module much less than the real value) under the gravity environment using the discrete element method (DEM). During the free-falling process, different Young's modules and friction factors are used to control the overlaps of the packing. Then the packing expands with specific large Young's module and friction factor to eliminate the unrealistic large overlaps. In the expanding process, the time step is limited and the strategy of dissipating elastic energy is introduced to constrain the speed of expansion. Results: Low friction factor in two processes tends to produce the dense packing or vice versa. The computational burden depends on the Young's module in the free-falling process significantly. Conclusion: Through adjusting the friction factor and the Young's module in the free-falling process and the friction factor in the expansion process, the packing algorithm can generate the pebble bed with wide range of porosity and higher computational efficiency.

Key words: PB-FHR, Pebble fuel, Packing algorithm, DEM

CLC Number: 

  • TL339