Environmental Research Institute of the Supervising Scientist (ERISS), GPO Box 461, Darwin, NT, 0801, Australia.
Safe Radiation Pty Ltd, Unit 19, 8 St. Jude Court, Browns Plains, QLD, 4118, Australia.
J Environ Radioact. 2020 May;216:106186. doi: 10.1016/j.jenvrad.2020.106186. Epub 2020 Feb 5.
The diffusion length of Rn in uraniferous waste rock was determined through a novel experiment. Large PVC columns were filled to different depths in the range from 0.5 m to 3.0 m with waste rock material from the Ranger uranium mine and the build-up of Rn activity concentration in the column headspace above the material was measured after closing the columns with a lid. Measurements were made approximately one month after filling the columns and again after approximately one and two years. The average Rn diffusion length derived from the measurements was 1.9 ± 0.2 m in the dry material. The corresponding diffusion coefficient was (7.3 ± 0.7) × 10 m s. For an infinitely thick layer of the dry material, the average value of the Rn exhalation flux density relative to the Ra activity concentration was estimated as (5.3 ± 0.3) × 10 Bq m s per Bq kg. From the diffusion length, the waste rock material was characterised as both a source and attenuator of Rn for its proposed use as the surface cover on the final landform of the remediated Ranger uranium mine.
通过一项新的实验，确定了镭矿石废物中Rn 的扩散长度。用 Ranger 铀矿的废物矿石将大型 PVC 柱填充到 0.5m 到 3.0m 的不同深度，并在关闭柱子的盖子后测量柱头顶空处的 Rn 活性浓度的积累。在填充柱子后大约一个月进行测量，然后再大约一年和两年后进行测量。从测量中得出的 Rn 平均扩散长度在干燥材料中为 1.9±0.2m。相应的扩散系数为(7.3±0.7)×10 m s。对于无限厚的干燥材料层，Rn 逸出通量密度相对于 Ra 活度浓度的平均值估计为每 Bq kg 5.3±0.3 Bq m s。从扩散长度来看，拟议将该废物矿石材料用作经修复的 Ranger 铀矿最终地貌的表面覆盖层，其既可以作为 Rn 的源，也可以作为 Rn 的衰减剂。
