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A discrete element method study on the evolution of thermomechanics of a pebble bed experiencing pebble failure |
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| Affiliation: | 1. Scientific Technical Center SINTEZ, D.V. Efremov Institute, 196641 St. Petersburg, Russia;2. I.I. Polzunov Scientific & Development Association on Research and Design of Power Equipment, 191167 St. Petersburg, Russia;1. Korea Atomic Energy Research Institute, Daejeon, Republic of Korea;2. National Fusion Research Institute, Daejeon, Republic of Korea;1. Institute of Nuclear and New Energy Technology of Tsinghua University, and The Key Laboratory of Advanced Reactor Engineering and Safety, Ministry of Education, Beijing 100084, China;2. College of Mechanical and Transportation Engineering, China University of Petroleum, Beijing 102249, China;3. School of Aerospace, Mechanical & Manufacturing Engineering, RMIT University, Melbourne, VIC 3083, Australia;1. Energy and Environment Science & Technology, Idaho National Laboratory, Idaho Falls, ID, USA;2. Fuels Modeling & Simulation, Idaho National Laboratory, Idaho Falls, ID, USA |
| Abstract: | The discrete element method (DEM) is used to study the thermal effects of pebble failure in an ensemble of lithium ceramic spheres. Some pebbles crushing in a large system is unavoidable and this study provides correlations between the extent of pebble failure and the reduction in effective thermal conductivity of the bed. In the model, we homogeneously induced failure and applied nuclear heating until dynamic and thermal steady-state. Conduction between pebbles and from pebbles to the boundary is the only mode of heat transfer presently modeled. The effective thermal conductivity was found to decrease rapidly as a function of the percent of failed pebbles in the bed. It was found that the dominant contributor to the reduction was the drop in inter-particle forces as pebbles fail; implying the extent of failure induced may not occur in real pebble beds. The results are meant to assist designers in the fusion energy community who are planning to use packed beds of ceramic pebbles. The evolution away from experimentally measured thermomechanical properties as pebbles fail is necessary for proper operation of fusion reactors. |
| Keywords: | Pebble bed thermomechanics DEM Discrete element method Pebble failure Effective thermal conductivity |
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