Radon in Brazilian underground mines

Abstract

Radon is a chemically inert noble radioactive gas found in several radioactive decay chains. In underground mines, especially those that contain or have contained ores associated with uranium-bearing minerals, workers might be exposed to high levels of radon and its decay products (RDP). This work aims to investigate whether the exposure of workers to radon gas and its progeny has been evaluated in Brazilian non-uranium and non-thorium underground mines. Any such results and control measures undertaken or recommended to maintain concentrations under Brazilian occupational exposure limits (OELs) are documented. The methodology we adopted consists of three main phases. The first was an extensive bibliographical survey of the concentration levels of radon and RDP, as well as the radiation dose estimates, considering measurements made heretofore by various Brazilian researchers and exhibiting original measurement work undertaken by the one of the authors (mine O). In the second phase, the values obtained were compared with OELs. In the third phase, any control measures undertaken in mines with high exposure of workers to radon and its progeny were verified, and the adopted controls were determined. Radon concentration data obtained from 52 campaigns in 40 underground mines were analyzed. The results show that assessment of the exposure of workers to radon and its progeny was undertaken in many mines at least once, and that radon levels in 62.5% of the mines, when visited for the first time, were below the Brazilian OELs. As expected, the main control measure adopted or recommended was improvement of the ventilation system.

Radon Measurement and Radiological Dose Assessment From Terrestrial Rocks Using Solid-State Nuclear Track Detectors

“…In all European nations, the allowable effective dosage from occupational radiation dose is 20 mSvy -1 , whereas, in the United States, it is 50 mSvy -1 . In this regard, the obtained results are in agreement with the literature published data for the similar environment of different countries [3,13,[26][27][28][29][30][31][32][33][34][35][36]. Figure (4) shows a comparison between radon concentration results for NTD, sample (N3) that has a high value of radon concentration due to increasing content of 238 U and 226 Ra activity concentration; on the other hand, sample coded (S1) has a low value of radon concentration due to low level of 238 U. R* = Reference of permissible limit dose volume of the container, the surface area of the sample, and the radon decay constant.…”

Evaluation of Radon Radioactivity and Radiological Impact by Using Solid-State Nuclear Track Detector for Erediya younger granites of Central Eastern Desert in Egypt

“…The permissible dose of occupational radiation exposure is 20 mSvy -1 in all European countries and 50 mSvy -1 in the USA. The obtained results compatible with the literature work for similar environments [13,18,29,[49][50][51][52][53][54] in addition Table (3) present the recorded measurements in different countries. Fig.…”

Surface identification of undermined spaces with the use of soil radon emanometry

“…The formation and existence of large underground airy spaces, either as a result of natural tectonic and weathering processes (cracks, canals, caves), or anthropogenic activities (mining works, cellars, storages), can create good preconditions for accumulation of radon by its emanation from surrounding solid structural rock materials. It is documented by a number of scientific studies that deal with the evaluation of radiation load from radon exposure in tourist and healing-oriented caves (Szerbin, 1996;Thinová and Burian, 2008;Smetanová et al, 2014Smetanová et al, , 2020 or in operating mining works (Ayres da Silva et al, 2018), alternatively also in mining works which are in the state of activity suppression or liquidation (Wysocka et al, 2018). Health affecting radon accumulation occurs in these spaces mostly under the conditions of sufficient amount of uranium concentration in the surrounding geological materials (rocks) and media (underground water) and sufficient hermeticity of the underground space.…”