Department of Geology, National Museum of Natural Sciences (MNCN-CSIC), 28006 Madrid, Spain.
Department of Geology, National Museum of Natural Sciences (MNCN-CSIC), 28006 Madrid, Spain.
J Environ Radioact. 2015 Jul;145:19-29. doi: 10.1016/j.jenvrad.2015.03.024. Epub 2015 Apr 6.
Castañar cave contains the highest radon gas ((222)Rn) concentration in Spain with an annual average of 31.9 kBq m(-)(3). Seasonal variations with summer minimums and maximum values in fall were recorded. The reduction of air-filled porosity of soil and rock by condensation or rainfalls hides the radon exchange by gas diffusion, determining this seasonal stair-step pattern of the radon activity concentration in underground air. The effective total dose and the maximum hours permitted have been evaluated for the guides and public safety with a highly detailed radon measurement along 2011 and 2012. A network of 12 passive detectors (kodalphas) has been installed, as well as, two radon continuous monitoring in the most interesting geological sites of the subterranean environment. A follow up of the recommended time (max. 50 min) inside the underground environment has been analysed since the reopen to public visitors for not surpassing the legal maximum effective dose for tourists and guides. Results shown that public visitors would receive in fall a 12.1% of the total effective dose permitted per visit, whereas in summer it is reduced to 8.6%, while the cave guide received a total effective dose of 6.41 mSv in four months. The spatial radon maps allow defining the most suitable touristic paths according to the radon concentration distribution and therefore, appropriate fall and summer touristic paths are recommended.
卡斯塔纳尔洞穴的氡气（^(222)Rn）浓度居西班牙之首，年平均浓度为 31.9 kBq m(-)(3)。记录到了夏季最低、秋季最高的季节性变化。土壤和岩石的充气孔隙率因冷凝或降雨而减少，从而掩盖了气体扩散引起的氡交换，这决定了地下空气中氡活度浓度的季节性阶梯式模式。根据 2011 年和 2012 年的氡详细测量结果，对导游和公众安全进行了有效总剂量和最大允许小时数的评估。已安装了 12 个被动探测器（kodalphas）网络，以及两个在地下环境最有趣地质地点的连续氡监测仪。在重新向公众开放后，一直对在地下环境中推荐的时间（最长 50 分钟）进行了分析，以免超过游客和导游的法定最大有效剂量。结果表明，在秋季，游客将接受的有效剂量为每次参观允许的总有效剂量的 12.1%，而在夏季则减少到 8.6%，而洞穴导游在四个月内接受的总有效剂量为 6.41 mSv。氡的空间分布图允许根据氡浓度分布来确定最适合的旅游路径，因此，推荐秋季和夏季的旅游路径。
