Radiation workers are normally exposed to doses resulting from their day-to-day activities. Besides that, background radiation, such as radon, can contribute to the exposure rates. The radionuclide 222Rn is a noble gas belonging to the uranium series, and its indoor concentration in the air depends on the exhalation from surrounding soil and the exhalation from building materials. Radon exhaling from porous building materials containing high uranium concentrations can become a significant exposure factor in areas with limited ventilation. The objective of this study was to evaluate the 222Rn concentrations in the radiochemistry and radiometric laboratories in the nuclear reactor building of the Nuclear Reactor Center (CERPq) located in the Institute of Nuclear and Energy Research (IPEN), São Paulo, Brazil. Measurements were done using a Radon Gas Monitor, model RAD7, equipped with a solid-state alpha detector. A passive method (SSNTD) was also used, consisting of square pieces of CR-39 foils (2.5 cm × 2.5 cm) placed within small diffusion chambers. The CR-39 detectors were etched in KOH 30% solution at 80°C for 5.5 h in a constant-temperature bath. After etching, the detectors were washed, dried, and scanned using a microscope to obtain the track density measurements. The activity concentrations measured with both techniques varied from 52 to 103 Bq m-3 in the studied areas of the CERPq. These values may be compared to the reference level of 100 Bq m-3 established by the World Health Organization to ensure safety environments.

中文翻译：

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巴西核反应堆中心的氡浓度。

辐射工作人员通常会因日常活动而受到辐射剂量的影响。除此之外，背景辐射（例如氡气）也会影响暴露率。放射性核素222Rn是属于铀系的稀有气体，其在室内空气中的浓度取决于周围土壤的呼气和建筑材料的呼气。从含有高浓度铀的多孔建筑材料中呼出的氡可能成为通风有限的区域的重要暴露因素。本研究的目的是评估位于巴西圣保罗核与能源研究所 (IPEN) 核反应堆中心 (CERPq) 核反应堆大楼内放射化学和辐射测量实验室中的 222Rn 浓度。使用配备固态 α 探测器的 RAD7 型氡气监测仪进行测量。还使用了被动方法 (SSNTD)，该方法由放置在小型扩散室内的方形 CR-39 箔片 (2.5 cm × 2.5 cm) 组成。CR-39 探测器在 80°C 的 KOH 30% 溶液中在恒温槽中蚀刻 5.5 小时。蚀刻后，将探测器清洗、干燥并使用显微镜扫描以获得轨迹密度测量值。在 CERPq 的研究区域中，使用两种技术测量的活性浓度从 52 到 103 Bq m-3 不等。这些值可与世界卫生组织制定的 100 Bq m-3 参考水平进行比较，以确保环境安全。