中子辐射屏蔽材料PVA/PEO水凝胶的制备及其作用研究

为研究一种新型中子辐射屏蔽材料水凝胶的制备及其对中子辐射的防护作用,应用物理交联法制备不同厚度的单纯和含有金属离子的PVA/PEO水凝胶;利用基于Monte Carlo模拟的SHIELD程序计算不同组分水凝胶对中子输运的影响,以期在理论上证实PVA/PEO水凝胶材料对2.45MeV中子辐射的屏蔽作用;采用BF3中子辐射探测器测量了K-400型高压倍加器发射的2.45MeV中子经过不同水凝胶后的中子通量变化。模拟计算结果显示,随着水凝胶厚度的增加,中子通量和能量逐渐减少;与单纯组比较,相同厚度含金属组中子数和能量减少更明显。BF3探测器测量结果显示,厚度为6—10cm的含金属组的中子通量计数减少的百分率显著高于单纯水凝胶组,辐射屏蔽效率与水凝胶厚度符合线性方程y=-4.51x+86.23,10m厚的含金属离子水凝胶中子通量计数的百分率可减低61.3?。结果表明,高分子聚合物PVA/PEO水凝胶对快中子辐射具有良好的屏蔽作用,含金属组的中子屏蔽效果明显优于单纯组。

Study on preparation and neutron radiation shielding effect of PVA/PEO hydrogel

The effects of neutron radiation shielding were studied by use of a new hydrogel. A simple PVA / PEO hydrogel and the hydrogel containing metal ions were prepared by physical cross-linking method. The effects of hy-drogels to 2.45 MeV neutron radiation shielding were theoretically analyzed by SHIELD procedure which is based on Monte Carlo simulation to calculate the neutron transport situation in different hydrogels. The flux counts of 2.45 MeV neutron through different thicknesses of hydrogels were measured by a BF3 neutron detector using a K-400 type high-voltage multiplier. The Monte Carlo simulation results show that neutron flux and energy decrease gradu-ally with increment of hydrogel thickness. Compared with simple group,the neutron flux and energy through the same thickness of group containing metal ions decrease more obviously. The results measured by BF3 neutron detector show that the percentage change of neutron flux count through 6—10 cm thickness of hydrogel containing metal ions to 2.45 MeV neutron increase significantly compared to simple hydrogel,and it comes to 61.3% at 10 cm thickness of the hydrogel,and its radiation shielding linear equation is y=-4.5103x ＋86.229. It can be concluded that PVA / PEO hydrogel has a better neutron irradiation shielding effect,especially for the PVA / PEO hydrogel containing metal ions.