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Comparative modeling of stochastic versus regular arrangement of TRISO particles in HTTR

Torabi Ardakani, A ; Sharif University of Technology | 2015

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  1. Type of Document: Article
  2. DOI: 10.1016/j.pnucene.2014.09.017
  3. Publisher: Elsevier Ltd , 2015
  4. Abstract:
  5. TRISO particles are the specific features of HTTR and generally HTGR reactors. Their heterogeneity and random arrangement in graphite matrix of these reactors create a significant modeling challenge. In this study, an algorithm is proposed for modeling random arrangement of TRISO particles in the fuel compacts of HTTR. The effect of this arrangement on criticality calculations, i.e. effective multiplication factor and critical position of control rods, is then compared with regular arrangement. Regular arrangement was modeled by positioning each TRISO as a fixed sphere in the center of a cubic lattice and subsequently, each fuel compact was filled with around 13,000 (approximate number of TRISOs in fuel compact) of these cubic lattices, depending on its packing factor. Stochastic arrangement was modeled by our algorithm, via distributing definite number of TRISOs in a cubic lattice and each fuel compact was then filled with this cubic lattice. The calculations have been carried out using MCNPX version 2.6 for three core configurations: thin annular core, thick annular core and fully loaded core. The comparison of criticality calculations between these two arrangements in different core configurations showed approximately 60-250 pcm difference. All simulations were benchmarked with different simulation results presented in the IAEA-Technical Document No.1382. It was observed that our estimation of critical heights of control rods was more consistent with the experimental data
  6. Keywords:
  7. Control rods ; Criticality (nuclear fission) ; Fuels ; Criticality calculations ; HTTR ; MCNPX ; Regular arrangement ; Stochastic arrangement ; TRISO ; Stochastic systems
  8. Source: Progress in Nuclear Energy ; Volume 78 , January , 2015 , Pages 291-296 ; 01491970 (ISSN)
  9. URL: http://www.sciencedirect.com/science/article/pii/S0149197014002625