# 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 ›› 2014, Vol. 25 ›› Issue (2): 020602

• NUCLEAR ENERGY SCIENCE AND ENGINEERING •

### Measurement of keff with an improved neutron source multiplication method based on numerical analysis

YE Bin, ZENG Li-Na, YIN Yan-Peng, YANG Chao-Wen, ZHENG Chun

1. 1Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900, China
2College of Physical Science and Technology, Sichuan University, Chengdu 610064, China
• Contact: ZHENG Chun E-mail:zhengchun@caep.cn
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YE Bin, ZENG Li-Na, YIN Yan-Peng, YANG Chao-Wen, ZHENG Chun. Measurement of keff with an improved neutron source multiplication method based on numerical analysis.Nuclear Science and Techniques, 2014, 25(2): 020602

Abstract:

In this work, we developed a numerical analysis-associated experiment method to determine the effective multiplication factor keff, which is difficult to obtain directly from conventional neutron source multiplication (NSM) method. The method is based on the relationship between keff, subcritical multiplication factor ks and external neutron source efficiency  in the subcritical system. On basis of the theoretical analysis, the dependence of ks and  on subcriticality and source position was investigated at the Chinese Fast Burst Reactor-II (CFBR-II). A series of ks were measured by NSM experiments at four subcritical states (keff = 0:996, 0:994, 0:991 and 0:986) with the 252Cf neutron source located at different positions (from the system center to outside) at each subcritical states. The  was obtained by Monte-Carlo simulation for each condition. With the measured ks and calculated , keff of the subcritical system was evaluated with a relative difference of < 1% between values obtained by the improved method and by positive period method. Especially, the relative deference of < 0:18% with the source located at the system center.