Study on inherent neutron sources in MSR

  • Rui-Min Ji
  • Cheng-Gang Yu
  • Ming-Hai Li
  • Rui Yan
  • Yang ZouEmail author
  • Gui-Min LiuEmail author


The molten salt reactor (MSR) has received much recent attention. The presence of beryllium and the mixing of actinides with light nuclei in the fuel salt result in a relatively strong neutron source that can affect the surveillance at subcritical and transient characteristics during operation. In this study, we predict the inherent neutron sources based on a MSR model. The calculation shows that in the fresh core, the inherent neutron sources are mainly from alpha-induced neutrons. After power operation, the inherent neutron sources become remarkably stronger due to photoneutrons. Although being an insignificant part in the total neutron population during operation, the inherent neutron sources can be used as the installed neutron source after shutdown. If the MSR has continuously operated at full power (2 MWt) for 10 days, then there would be no need for the installed source within 80 days after shutdown. After operating constantly for 500 days, the installed neutron source can be eliminated within 2 years after shutdown.


MSR Fuel salt Inherent neutron source Photoneutron Alpha-induced neutron 


  1. 1.
    Y.Q. Shi, Experimental methods in the nuclear reactor, 1st edn. (Atomic Energy Press, Beijing, 2011), pp. 46–64 (in Chinese)Google Scholar
  2. 2.
    M. Watanabe, A. Yamamoto, Y. Yamane, Measuring the photoneutron originating from D(γ, n)H reaction after the shutdown of an operational BWR. J. Nucl. Sci. Technol. 46, 1099–1112 (2009). CrossRefGoogle Scholar
  3. 3.
    F. Jatuff, A. Lüthi, M. Murphy et al., Measurement and interpretation of delayed photoneutrons effects in multizone criticals with partial D2O moderation. Ann. Nucl. Energy 30, 1731–1755 (2003). CrossRefGoogle Scholar
  4. 4.
    S. Li., L. Deng, H. B. Xu, et al., Usability analyses of source range detector after secondary neutron source canceled. At. Energy Sci. Technol. 45, 314–318 (2011) (in Chinese)Google Scholar
  5. 5.
    L.J. Fei., R. Le, Analyses on cancelling secondary neutron source in Changjiang NPP. Plant Maintenance Eng. z1, 13–16 (2015). (in Chinese)
  6. 6.
    M.S. Onegin, Delayed photoneutrons in the PIK reactor. At. Energy 107, 194–201 (2009). CrossRefGoogle Scholar
  7. 7.
    I. Khamis, Evaluation of the photo-neutron source in the syrian miniature neutron source reactor. Ann. Nucl. Energy 29, 1365–1371 (2002). CrossRefGoogle Scholar
  8. 8.
    S. Birikorang, E. Akaho, B. Nyarko et al., Feasibility study of photo-neutron flux in various irradiation channels of Ghana MNSR using a Monte Carlo code. Ann. Nucl. Energy 38, 1593–1597 (2011). CrossRefGoogle Scholar
  9. 9.
    P.N. Haubenreich, J.R. Engel, B.E. Prince, et al., MSRE design and operations report Part III. Nuclear analysis. ORNL, ORNL-TM-0730, USA (1969)Google Scholar
  10. 10.
    P.N. Haubenreich, Inherent neutron sources in clean MSRE fuel sal. ORNL, ORNL-TM-0611, USA (1963)Google Scholar
  11. 11.
    R.C. Steffy, Jr., Inherent neutron sources in MSRE with clean 233U fuel. ORNL, ORNL-TM-2685, USA (1969)Google Scholar
  12. 12.
    J.R. Engel, P.N. Haubenreich, B.E. Prince., MSRE neutron source requirements. ORNL, ORNL-TM-0935, USA (1964)Google Scholar
  13. 13.
    W.N. Powell., Reconsideration of inherent neutron sources in liquid fuel of molten salt reactors. Master’s thesis, The Ohio State University, 2013Google Scholar
  14. 14.
    W. Wilson, R. Perry, W. Charlton et al., Sources: a code for calculating (alpha, n), spontaneous fission, and delayed neutron sources and spectra. Prog. Nucl. Energy 51, 608–613 (2009). CrossRefGoogle Scholar
  15. 15.
    Z Dai, W Liu, Thorium-based Molten Salt Reactor (TMSR) project in China. Proceedings of the conference on molten salts in nuclear technology, Mumbai, India, 9–11 Feb 2013Google Scholar
  16. 16.
    TMSR group, Pre-conceptual design of the 2 MW liquid fueled molten salt reactor and pyroprocess demonstration facility (2014)Google Scholar
  17. 17.
    SCALE: A Comprehensive Modeling and Simulation Suite for Nuclear Safety Analysis and Design. ORNL, ORNL/TM-2005/39, USA (2011)Google Scholar
  18. 18.
    D.B. Pelowitz (ed.), MCNP6™ User’s Manual, Los Alamos National Laboratory, LA-CP-13-00634, USA (2013)Google Scholar
  19. 19.
    D.P. Heinrichs, E.M. Lent., Photonuclear benchmarks with a comparison of COG and MCNPX results. Brookhaven National Laboratory, UCRL-CONF-200552, USA (2003)Google Scholar
  20. 20.
    H. Kröhnert, G. Perreta, M.F. Murphy et al., Freshly induced short-lived gamma-ray activity as a measure of fission rates in lightly re-irradiated spent fuel. Nucl. Instrum. Methods Phys. Res. Sect. A 624, 101–108 (2010). CrossRefGoogle Scholar
  21. 21.
    M. Švadlenková, L. Heraltováb, V. Juříček et al., Gamma spectrometry of short living fission products in fuel pins. Nucl. Instrum. Methods Phys. Res. Sect. A 739, 55–62 (2014). CrossRefGoogle Scholar
  22. 22.
    G. 12789.1, Criteria for nuclear reactor instrumentation Part 1: General principles, 1991Google Scholar

Copyright information

© Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Chinese Nuclear Society, Science Press China and Springer Nature Singapore Pte Ltd. 2018

Authors and Affiliations

  1. 1.Shanghai Institute of Applied Physics, Chinese Academy of SciencesShanghaiChina
  2. 2.University of Chinese Academy of SciencesBeijingChina

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