装饰建材放射性无损检测及评价方法研究

根据γ衰变纲图，研究将γ射线强度的测量问题转化为表面α射线的强度测量问题，从而实现建材的快速无损检测。进行了各类建材表面α、β辐射水平和其天然放射性核素γ比活度关系的研究和不同饰材表面β辐射水平的饱和厚度研究。结果发现：由于天然放射系中最大能量β粒子的射程大于单块饰材，不能用表面β辐射水平进行无损检测判断；花岗石的表面α辐射水平与外照射指数的拟合关系为：Iγ=0．38 49．84α 288．24α^2，拟合曲线和实测值的符合率为95％；抛光砖的表面α辐射水平与外照射指数的拟合关系为：Iγ=0．42 343．55α-32999．66α^2，拟合曲线和实测值的符合率为90％。积累更多的数据将进一步提高拟合曲线和实测值的符合率。

Non-destructive examination and estimation of radioactivity levels for decorative building materials

Measurement of gamma ray intensity from building materials can be substituted by measuring alpha rays following outline of a radionuclide decay. Exposure levels of alpha ray from the surface of decorative materials can be measured non-destructively by placing a detector on the surface of the materials. We have studied the relationship between gamma specific activities of natural radionuclides and alpha and beta ray level in building materials used in interior decoration, and the saturated thickness of beta ray from the surface of different materials. The results showed that the range of beta ray with the maximum energy in natural radioactive series is longer than thickness of a piece of decorative materials. So the exposure level of beta ray cannot be used to estimate the limit of external and internal indexes. The polynomial between exposure level of alpha ray from surface (a) and external index (Ig) for granite is: Ig= 0.38 + 49.84a+ 288.24a2. The measured values were in accordance with the values from the polynomial within 95%. The polynomial between exposure level of alpha ray from surface (a) and external index (Ig) for polishing tiles is: Ig = 0.42 + 343.55a32999.66a2. The measured values were in accordance with the values from the polynomial within 90%.