Nuclear Science and Techniques

《核技术》(英文版) ISSN 1001-8042 CN 31-1559/TL     2019 Impact factor 1.556

Nuclear Science and Techniques ›› 2019, Vol. 30 ›› Issue (9): 140 doi: 10.1007/s41365-019-0666-3

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Research on the effect of the heavy nuclei amount on the temperature reactivity coefficient in a small modular molten salt reactor

Menglu Tan1,2 Guifeng Zhu1 Yang Zou1 Xiaohan Yu1 Ye Dai1   

  1. 1Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China
    2University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2018-12-27 Revised:2019-04-08 Accepted:2019-05-14
  • Contact: Gui-Feng Zhu
  • Supported by:
    This work is supported by the Chinese TMSR Strategic Pioneer Science and Technology Project (No. XDA02010000) and the Frontier Science Key Program of Chinese Academy of Sciences (No. QYZDY-SSW-JSC016).
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Menglu Tan, Guifeng Zhu, Yang Zou, Xiaohan Yu, Ye Dai. Research on the effect of the heavy nuclei amount on the temperature reactivity coefficient in a small modular molten salt reactor.Nuclear Science and Techniques, 2019, 30(9): 140     doi: 10.1007/s41365-019-0666-3

Abstract: Small modular thorium-based graphite-moderated molten salt reactors (smTMSRs), which combine the advantages of small modular reactors and molten salt reactors, are regarded as a wise development path to speed deployment time. In a smTMSR, low enriched uranium and thorium fuels are used in once-through mode, which makes a marked difference in their neutronic properties compared with the case when a conventional molten salt breeder reactor is used. This study investigated the temperature reactivity coefficient (TRC) in a smTMSR, which is mainly affected by the molten salt volume fraction (VF) and the heavy nuclei concentration in the fuel salt (HN). The fourfactor formula method and the reaction rate method were used to indicate the reasons for the TRC change, including the fuel density effect, the fuel Doppler effect, and the graphite thermal scattering effect. The results indicate that only the fuel density has a positive effect on the TRC in the undermoderated region. Thermal scattering from both salt and graphite has a significant negative influence on the TRC in the overmoderated region. The maximal effective multiplication factor, which shows the highest fuel utilization, is located at 10% VF and 12 mol% HN and is still located in the negative TRC region. In addition, on increasing the heavy nuclei amount from 2 mol% HN to 12 mol% HN (VF = 10%), the total TRC undergoes an obvious change from - 11 to - 3 pcm/K, which implies that the change in the HN caused by the fuel feed online should be small to avoid potential trouble in the reactivity control scheme.

Key words: Molten salt reactor, Temperature reactivity coefficient, Heavy nuclei amount