# 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 (2): 34

• NUCLEAR ENERGY SCIENCE AND ENGINEERING •

### Application of Monte Carlo method to calculate the effective delayed neutron fraction in molten salt reactor

Gui-Feng Zhu1 • Rui Yan1 • Hong-Hua Peng1 • Rui-Min Ji1 • Shi-He Yu1 • Ya-Fen Liu1 • Jian Tian1 • Bo Xu1

1. 1 Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China
• Received:2018-06-07 Revised:2018-09-04 Accepted:2018-09-06
• Contact: Rui Yan E-mail:yanrui@sinap.ac.cn
• Supported by:
This study was supported by the Chinese TMSR Strategic Pioneer Science and Technology Project (No. XDA02010000) and the Frontier Science Key Program of the Chinese Academy of Sciences (No. QYZDY-SSW-JSC016).
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Gui-Feng Zhu, Rui Yan, Hong-Hua Peng, Rui-Min Ji, Shi-He Yu, Ya-Fen Liu, Jian Tian, Bo Xu. Application of Monte Carlo method to calculate the effective delayed neutron fraction in molten salt reactor.Nuclear Science and Techniques, 2019, 30(2): 34

Abstract: Delayed neutron loss is an important parameter in the safety analysis of molten salt reactors. In this study, to obtain the effective delayed neutron fraction under flow condition, a delayed neutron precursor transport was implemented in the Monte Carlo code MCNP. The moltensalt reactor experiment (MSRE) model was used to analyze the reliability of this method. The obtained flow losses of reactivity for 235U and 233U fuels in the MSRE are 223 pcm and 100.8 pcm, respectively, which are in good agreement with the experimental values (212 pcm and 100.5 pcm, respectively). Then, six groups of effective delayed neutron fractions in a small molten salt reactor were calculated under different mass flow rates. The flow loss of reactivity at full power operation is approximately 105.6 pcm, which is significantly lower than that of the MSRE due to the longer residence time inside the active core. The sensitivity of the reactivity loss to other factors, such as the residence time inside or outside the core and flow distribution, was evaluated as well. As a conclusion, the sensitivity of the reactivity loss to the residence time inside the core is greater than to other parameters.