核部件缓发γ能谱时间演化行为模拟

在分析无外中子源照射条件下核部件中裂变产物的来源及其释放缓发γ射线机理基础上，提出了应用CINDER90程序计算核部件中裂变产物活度的方法，计算并分析了裂变产物的种类、活度及其随辐照时间和冷却时间的变化规律，继而根据裂变产物β^-衰变释放的特征γ射线的能量与分支比数据，计算得到了核部件中裂变产物缓发γ射线源项，并应用蒙特卡罗方法计算了核部件释放的缓发γ能谱随辐照时间和冷却时间的变化，分析了缓发γ能谱的时间演化行为。结果表明：核部件缓发γ能谱中强度最大的γ射线是裂变核素¹⁴⁰La β^-衰变发射的1 596 keV射线，且该γ射线的强度在部件组装一定时间后保持稳定，该结果与文献结果符合一致。本文提出的裂变产物缓发γ能谱模拟计算方法和结果可为核部件γ能谱的测量与分析提供参考。

Numerical Simulation of Time Evolution Behavior of Delayed γ-ray Spectrum from Nuclear Component

Based on analysis of the production mechanism of fission products in the nuclear component without exterior neutron radiation and the delayed γ-rays released from the products, a simulation method for calculating the fission product activities and their variations with time was proposed using CINDER90 program. According to energy and branch ratios of the delayed γ-rays released from β^- decay of the fission products, the intensities of the different γ-rays were calculated. Then, the variations of the delayed γ-ray spectra of the nuclear component with radiation time and cooling time were calculated by Monte Carlo method, and the time evolution behaviors of the delayed γ-ray spectra were analyzed. The results show that the maximum intensity ray in the delayed γ spectra from nuclear component is released from ¹⁴⁰La β^- decay, the γ-ray energy is 1596 keV, and its intensity remains stable after the component is assembled for a certain time. These results agree well with the ones in the literature. The simulation method and the calculation results presented in this paper can be used as a reference for the spectrum measurement and analysis of nuclear components.