慢化球探测器组合法测试中子屏蔽性能应用

Neutron shielding property test with combination detection method based on moderation sphere detectors

随着核技术在各领域的应用推广,中子屏蔽材料得到越来越广泛的应用,而目前国内外还没有测试中子屏蔽性能的统一标准。为了探索一种简单可行、能够在较宽中子能量范围内测试材料屏蔽性能的方法,本文对3He正比计数管、计数管外包镉及计数管外包不同直径的聚乙烯(Polyethylene,PE)慢化球共12个模型进行了MCNP(Monte Carlo N Particle Transport Code)模拟计算,得到一种慢化球探测器组合测试方法,使测试能够在1×10-5-1.25 Me V能量范围内有较一致的响应。利用这种方法测试了2 cm和4 cm厚PE对252Cf中子的透射率,与多球谱仪解谱法得到的结果在±1.0%内相吻合,对几种材料的测试结果也符合不同类型材料对中子的屏蔽规律,证实了这种简易组合测试方法的可行性。

Background： With the development of nuclear technique, neutron shielding materials have been used widely in many fields. Up to now, there is still no standard test method for neutron shielding property both at home and abroad.Purpose： This study aims to find an easy and feasible way to test the shielding effectiveness of materials in a wide range of neutron energy.Methods： Models for3He proportional counter cooperating together with polyethylene （PE） moderating spheres of different diameters were calculated using MCNP （Monte Carlo N Particle Transport Code） and the neutron transmittance of some materials was tested.Results： The combination detection method by using moderating sphere detectors has consistent response in a wide range of neutron energy from 1×10^5MeV to 1.25MeV. The article tested the neutron transmittance of 2cm- and 4cm-thick PE plates for252Cf neutrons. The results coincide with multi-sphere spectrometer within ±1.0% and the ordinary shielding rules of different type materials for neutrons.Conclusion： The method is validated to be feasible and simple to neutron shielding.