氘氚中子与Fe作用后泄漏γ能量沉积谱测量与计算

Measurement and Calculation of Leakage Gamma Energy Deposition Spectra from Fe Samples after Interaction of D-T Neutrons

  • 摘要: 评价核数据的质量直接影响各类核装置及产品的有效性、安全性、可靠性和经济性。Fe是核工业应用中屏蔽快中子的主要材料之一,其评价核数据的准确程度将会影响核装置的安全性和经济性,因此,针对natFe样品开展积分实验是非常重要的一项研究内容。本文基于中国原子能科学研究院研制的屏蔽积分实验装置,开展了脉冲D-T中子与板状natFe样品作用后的泄漏γ谱在液体探测器里产生的能量沉积谱测量研究。通过飞行时间法,分别测量获得了3种厚度natFe样品60°和120°方向的瞬发伽马在BC501-A型液体闪烁体探测器里产生的能量沉积谱;利用MCNP 4C程序开展了泄漏γ谱的模拟计算,分别采用CENDL-3.2库、ENDF/B-Ⅷ.0库、JENDL-5.0库和JEFF-3.3库中Fe同位素的评价数据,结合Geant4程序计算的探测器响应矩阵,获得了泄漏γ在探测器里产生的能量沉积谱的模拟结果;对模拟结果与实验结果进行了比较分析,结果表明,JENDL-5.0库模拟结果与实验结果总体符合较好;在低能区(<2 MeV),ENDF/B-Ⅷ.0和JEFF-3.3库模拟符合很好,而JENDL-5.0库稍有低估;在高能区(>2 MeV),CENDL-3.2和JENDL-5.0库符合很好,而ENDF/B-Ⅷ.0和JEFF-3.3库有高估现象。CENDL-3.2库中关于Fe的评价数据有待进一步改善。

     

    Abstract: The quality of nuclear data directly impacts the effectiveness, safety, reliability, and economy of various nuclear facilities and products. Fe is one of the primary materials used in the nuclear industry for shielding fast neutrons, and the accuracy of its nuclear data evaluation affects the safety and economy of nuclear installations significantly. Therefore, conducting integral experiments on natural iron (natFe) samples is an important research topic. This paper presents a study on the measurement of the energy deposition spectra generated in detectors by the leakage gamma spectra from slab natFe samples after the interaction of pulsed D-T neutrons, using the shielding integral experiment facility developed by the China Institute of Atomic Energy. The instantaneous gamma energy deposition spectra in the BC501-A liquid scintillator detector for three thicknesses of natFe samples at 60° and 120° were measured by using the time-of-flight method. Simulations of the leakage gamma spectra were carried out using the MCNP 4C program with evaluated data for iron isotopes from the CENDL-3.2, ENDF/B-Ⅷ.0, JENDL-5.0, and JEFF-3.3 libraries, and the detector response matrix calculated by the Geant4 program. A comparative analysis between the simulation results and experimental findings indicates that ENDF/B-Ⅷ.0 and JEFF-3.3 libraries provide a better match in the low energy region (<2 MeV), while CENDL-3.2 and JENDL-5.0 libraries show better agreement in the high energy region (>2 MeV). The evaluated data on Fe in the CENDL-3.2 library require further improvement.

     

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