强中子本底辐射屏蔽体优化设计技术研究
Development of an Optimizing Design for the Radiation Shielding with Intense Neutron Extra-background
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摘要: 在国内首次采用高强度窄脉冲DPF中子源，采用直照法测量零功率堆瞬发中子时间常数α。由于外中子源本底太强，导致直照中子和散射中子产生的干扰信号比测量信号高三个量级。为有效地抑制外本底，针对不同能量的干扰中子，采用不同材料进行屏蔽。通过数值模拟的方法优化辐射屏蔽体设计，在屏蔽中子的同时也对散射γ 进行了有效屏蔽，使测量信噪比达到了7.5:1，并与实验结果相符合，实验中所采用的新型无机晶体也有效抑制了中子本底。The value of prompt neutron multiplication, α, is measured under the condition of using a denser plasma focus(DPF) neutron-source irradiating zero power assembly for the first time in China. The acquired signal is lower three orders of magnitudes than that of the noise caused by direct and scattered neutrons from the extra-high-intensity neutron-source. Using different kinds of material to decrease the noise caused by neutron with different kinds of energies, an optimized design for radiation shielding is developed by the method of numerical simulation to suppress noise signal. Both neutron and γ-ray are shielded simultaneously. The Signal/Noise Ratio (SNR) with the optimal design was up to 7.5:1 and was consistent with the experimental results. The noise of neutron is decreased effectively by the new kind of unorganic crystals used.Abstract: The value of prompt neutron multiplication, α, is measured under the condition of using a denser plasma focus(DPF) neutron-source irradiating zero power assembly for the first time in China. The acquired signal is lower three orders of magnitudes than that of the noise caused by direct and scattered neutrons from the extra-high-intensity neutron-source. Using different kinds of material to decrease the noise caused by neutron with different kinds of energies, an optimized design for radiation shielding is developed by the method of numerical simulation to suppress noise signal. Both neutron and γ-ray are shielded simultaneously. The Signal/Noise Ratio (SNR) with the optimal design was up to 7.5:1 and was consistent with the experimental results. The noise of neutron is decreased effectively by the new kind of unorganic crystals used.
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