Building management and effect evaluation of high radon in geothermal field

Objective To explore the source and control of radon in high radon houses in geothermal fields; Methods Radon concentration in indoor and soil was measured by ATD detector in winter and summer; radionuclides in building materials were measured by gamma-ray spectrometry; radionuclides dose rates of building materials were measured by 6150 A D/6H X-γ ray detector; and radon reduction technology was applied to one of the houses; Results The average radon concentrations in 32 rooms were (106.4 ± 63.7) Bq/m 3 (summer) and (421.3 ± 138.2) Bq/m 3 (winter), and the concentrations in 12.5% (summer) and 96.9% (winter) of the rooms exceed 150 Bq/m 3. The average radon concentration in soil around buildings was 12 890 Bq/m 3 ( n = 24), which is 1.7 times of the typical soil radon concentration in Beijing (7 600 Bq/m 3). After soil decompression, the radon concentration in the house could be reduced to less than 100 Bq/m 3. The radon reduction rates of active decompression and passive decompression were 94.6% and 71.4%, respectively. Conclusion The effect of soil decompression on reducing radon concentration in the bottom rooms is obvious. Attention should be paid to the radon in residential environment of geothermal field. 摘要： 目的 探讨地热田高氡房屋氡的来源与治理。 方法 α 径迹探测器 (ATD) 分冬夏两个季节测量室内和土壤中 的氡浓度。采用 γ 能谱法测量房屋主体建材放射性核素含量;采用 6150 A D/6H X-γ 剂量率仪测量房屋主体建材的外 照射剂量率；对其中一栋房屋实施土壤减压技术的降氡改造。 结果 夏冬季 32 个房间氡浓度均值分别为 (106.4 ± 63.7) Bq/m 3 和 (421.3 ± 138.2) Bq/m 3, 分别有 12.5% 和 96.9% 的房间超过 150 Bq/m 3。建筑物周围土壤氡浓度均值为 12890 Bq/m 3 (检测点 n = 24), 是北京市土壤氡浓度典型值 (7 600 Bq/m 3) 的 1.7 倍。实施土壤减压改造后冬夏季房屋中 氡浓度均可降至 < 100 Bq/m 3, 主动减压法降氡率为 94.6%, 被动减压法降氡率为 71.4%。 结论 土壤减压法对降低底 层房间氡浓度效果明显, 地热田居住环境中氡的问题应引起关注。