EDN: KIYYVN
Authors & Affiliations
Arkhangelsky D.M., Daichenkova Yu.S., Kalugin M.A., Shkarovsky D.A.
National research center “Kurchatov institute”, Moscow, Russia
Arkhangelsky D.M. – Junior Researcher. Contacts: 1, pl. Akademika Kurchatova, Moscow, Russia, 123182. Tel.: +7 (961) 643-61-95; e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it..
Daichenkova Yu.S. – Researcher.
Kalugin A.M. – Deputy Head of Complex for Scientific Work, Dr. Sci. (Tech.).
Shkarovsky D.A. – Head of Department, Cand. Sci. (Phys.-Math.).
Abstract
In reactors with circulating fuel (molten-salt reactors), the effect of fuel circulation on neutron physics is significant. A decrease in the effective fraction of delayed neutrons in comparison with the steady-state modes without circulation is a notable consequence of fuel circulation. This phenomenon is attributed to the transfer of delayed neutron emitters, which results in their generation within the circulation loop, outside of the reactor core.
The assessment of this effect can be facilitated through the utilization of both deterministic and stochastic methodologies, for which two primary implementation schemes can be identified. The first scheme involves shifting the birth points of delayed neutrons on the basis of a velocity field data. A different, less computationally demanding approach based on the estimation of the circulation correction for each group of delayed neutrons was chosen for implementation in the MCU code.
To verify the methodology, the reactivity effect due to fuel circulation has been calculated for experiments conducted at the MSRE reactor. Two fuel salt configurations were considered: uranium-235 and uranium-233.
The reactivity loss from fuel circulation was calculated using MCU in two steps. Initially, the effective fraction of delayed neutrons for the steady state was calculated. Subsequently, a set of parameters was set for each fissile isotope to determine the fraction of delayed neutrons born in the reactor core for each group. Utilizing the acquired parameters, the effective fraction of delayed neutrons was calculated, incorporating fuel circulation. The results obtained are in satisfactory agreement with the experimental data.
Keywords
molten-salt reactor, MSR, MSRE, reactivity effect, delayed neutrons, Monte Carlo method, MCU
Article Text (PDF, in Russian)
References
- Lapenta G., Ravetto P. Basic reactor physics problems in fluid-fuel recirculated reactors. Kerntechnik, 2000, vol. 65, pp. 250–252.
- Guerrieri C., Cammi A., Luzzi L. An approach to the MSR dynamics and stability analysis. Progress in Nuclear Energy, 2013, vol. 67, pp. 56–73. DOI: https://doi.org/10.1016/j.pnucene.2013.03.020.
- Guerrieri C., Aufiero M., Cammi A., Fiorina C., Luzzi L. A Preliminary Study of the MSFR Dynamics. Proc. of 20th International Conference on Nuclear Engineering collocated With the ASME 2012 Power Conference. Anaheim, California, 2012. Available at: https://re.public.polimi.it/handle/11311/675546 (accessed 29.07.2025).
- Jaradat M., Park H., Yang W., Changho L. Development and validation of PROTEUS-NODAL transient analyses capabilities for molten salt reactors. Annals of Nuclear Energy, 2021, no. 160, p. 108402. DOI: https://doi.org/10.1016/j.pnucene.2024.105392.
- Aufiero M. et al. Calculating the effective delayed neutron fraction in the Molten Salt Fast Reactor: analytical, deterministic and Monte Carlo approaches. Annals of Nuclear Energy, 2014, no. 65, pp. 78–90. DOI: https://doi.org/10.1016/j.anucene.2013.10.015.
- Kupriyanov K.S., Feynberg O.S., Ignatiev V.V. Effektivnaya dolya zapazdyvayushchikh neytronov v reaktore s tsirkuliruyushchim zhidkosolevym toplivom [Effective Fraction of Delayed Neutrons in Molten Salt Reactor with Circulating Fuel]. Voprosy atomnoy nauki i tekhniki. Seriya: Fizika yadernykh reaktorov – Problems of Atomic Science and Technology. Series: Physics of Nuclear Reactors, 2022, no. 2, pp. 97–106.
- Kophazi J., Szieberth M., Feher S., Czifrus S., de Leege P. Monte Carlo calculation of the effects of delayed neutron precursor transport in molten salt reactors. Proceedings of the PHYSOR 2004: The Physics of Fuel Cycles and Advanced Nuclear Systems – Global Developments. Chicago, Illinois, 2004, pp. 1919–1927.
- Laureau A., Heuer D., Merle-Lucotte E., Rubiolo P., Allibert M., Aufiero M. Transient coupled calculations of the Molten Salt Fast Reactor using the Transient Fission Matrix approach. Nuclear Engineering and Design, 2017, vol. 316, pp. 112–24. DOI: https://doi.org/10.1016/j.nucengdes.2017.02.022.
- Nguyen T., Chen Y. Extended development of the Monte Carlo code MCNP for effective delayed neutron fraction in molten salt reactors. Progress in Nuclear Energy, 2024, vol. 176, p. 105392. DOI: https://doi.org/10.1016/j.pnucene.2024.105392.
- Kalugin M.A., Oleynik D.S., Shkarovsky D.A. Overview of the MCU Monte Carlo Software Package. Annals of Nuclear Energy, 2015, vol. 82, pp. 54–62. DOI: https://doi.org/10.1016/j.anucene.2014.08.032.
- Haubenreich P.N. Prediction of Effective Yields of Delayed Neutrons in MSRE. USAEC Report ORNL-TM-380. Oak Ridge National Laboratory, October 13, 1962.
- Weinberg A.M. Preface: Molten-Salt Reactors. Nuclear Applications and Technology, 1970, vol. 8, issue 2, p. 105. DOI: https://doi.org/10.13182/NT70-A28617.
- Prince В.Е. et al. Zero-Power Physics Experiments on the Molten-Salt Reactor Experiment. ORNL-4233. Oak Ridge National Laboratory, Oak Ridge, Tennessee, 1968.
- Robertson, R.C. MSRE Design and Operations Report Part I: Description of Reactor Design. ORNL-TM-0728. Oak Ridge National Laboratory, Oak Ridge, Tennessee, 1965.
- Shen D., Fratoni M., Aufiero M., Bidaud A., Powers J., Ilas G. Zero-power criticality benchmark evaluation of the molten salt reactor experiment. Proc. of PHYSOR 2018: Reactor Physics paving the way towards more efficient systems. Cancun, Mexico, 2018. DOI: https://doi.org/10.1051/epjconf/202124710012.
- Gomin E.A. Status MCU-4 [MCU-4 Status]. Voprosy atomnoy nauki i tekhniki. Seriya: Fizika yadernykh reaktorov – Problems of Atomic Science and Technology. Series: Physics of Nuclear Reactors, 2006, no. 1, pp. 6–32.
- Prince B.E. Period measurements on the molten salt reactor experiment during fuel circulation: theory and experiment. ORNL-TM-1626. Oak Ridge National Laboratory, Oak Ridge, Tennessee, 1966.
UDC 621.039.51
Problems of Atomic Science and Technology. Series: Nuclear and Reactor Constants, 2025, no. 3, 3:9
