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

    分类: 核科学技术 >> 裂变堆工程技术 提交时间: 2023-06-18 合作期刊: 《Nuclear Science and Techniques》

    摘要: 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; 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 difference of <0.18% with the source located at the system center.

  • The Integration and Horizontal Testing of CSNS-II Double Spoke Cavity Cryomodule

    分类: 物理学 >> 核物理学 提交时间: 2025-03-31

    摘要: The China Spallation Neutron Source (CSNS) is the fourth pulsed accelerator-driven neutron source in theworld, and it achieved its design target of 100 kW in 2020. The planned China Spallation Neutron Source PhaseII (CSNS-II) is set to commence in 2024. The CSNS-II Linac design mainly involves adding a Radio FrequencyIon Source and a section of a superconducting linear accelerator composed of two types of superconductingcavities, namely double-spoke cavities and 6-cell elliptical cavities, after the Drift Tube Linac (DTL) . Thedevelopment of the double-spoke superconducting cavity began in early 2021, and by January 2023, the welding,post-processing, and vertical tests of two 324 MHz double-spoke cavity prototypes had been completed, withvertical test gradients of 11.6 MV/m and 15 MV/m, and Q0 ≥ 3 × 1010 @ Eacc ≤10 MV/m. The RD of thecryomodule began in January 2022. In October 2023, the clean assembly of the double-spoke cavity string andthe cold mass installation of the cryomodule commenced,and it took two months to complete the installation ofthe cryomodule and valve box. In January 2024, the horizontal test of the cryomodule was completed, makingit the first double-spoke cavity module in China. The test results showed that the maximum gradients of the twosuperconducting cavities at a pulse width of 4 ms and a repetition frequency of 25 Hz were 12.8 MV/m and 15.2MV/m, respectively. This article provides a detailed introduction to the double-spoke superconducting cavity,tuner, coupler, and cryomodule, and elaborates on the clean assembly of cavity string and cold mass installationof the cryomodule, concluding with a detailed analysis of the horizontal test results.