Influence of Dose Conversions, Equilibrium Factors, and Unattached Fractions on Radon Risk Assessment in Operating and Show Underground Mines.

This paper compares the results of measurements taken in the underground workings of active and tourist mines. In these facilities, the aerosol size distributions of ambient aerosols at key workplaces and the distributions of radioactive aerosols containing radon decay products were determined. Based on these studies, dose conversions used for dose assessment and unattached fractions were determined. In addition, radon activity concentrations and potential alpha energy concentrations of short-lived progeny were also measured in the mines to determine the equilibrium factor. The dose conversions varied between 2-7 mSv/(mJ × h × m-3). The unattached fraction measured in active coal mines ranged from 0.01-0.23, in tourist mines from 0.09-0.44, and in the tourist cave it was 0.43. The results showed significant discrepancies between the effective doses determined from current recommendations and legal regulations and those determined from direct measurements of parameters affecting exposure.

Radon Exposure in the Underground Tourist Route-Historic Silver Mine in Tarnowskie Góry, Poland.

An assessment of the exposure of workers and tourists to radon in the underground tourist route of the Historic Silver Mine in Tarnowskie Góry was carried out. The study was conducted over a one-year period to capture seasonal variations in radon concentrations. CR-39 track detectors were used to measure radon concentrations, which were exposed in the mine during the following periods: 9 February 2021-19 May 2021, 19 May 2021-26 August 2021, 26 August 2021-25 November 2021 and 25 November 2021-3 March 2022. The annual average radon concentration along the tourist route was 1021 Bq m-3. The highest measured concentration was 2280 Bq m-3 and the lowest concentration was 80 Bq m-3. Based on the measured concentrations, effective doses were calculated, assuming that employees spend 1350 h a year in underground areas and that the time of visiting the mine by tourists is ca. 1 h. The average annual effective dose a worker would receive is approximately 2.5 mSv, and a tourist below 2 µSv. The dose limit expressed as the annual effective dose is 1 mSv for members of the general public and 20 mSv for occupational exposure.

The Determination of Radon/Thoron Exhalation Rate in an Underground Coal Mine-Preliminary Results.

The objective of this work was to perform a series of measurements of radon and thoron exhalation in the underground workings of an experimental coal mine. In the years 2012-2015, experiments on underground coal gasification were carried out in a coal mine, which caused, among other effects, damage to rock mass. Afterward, periodic increases in the concentration of potential alpha energy (PAEC) of radon decay products in the air were found, which could pose a hazard to miners. The question posed was whether the gasification experiment resulted in the increased migration of radon and thoron. If so, did it increase the radiation hazard to miners? The adaptation of the existing instrumentation to the specific conditions was conducted, and a series of measurements were made. It was found that the measured values of radon and thoron exhalation rates ranged from 3.0 up to 38 Bq·m-2·h-1 for radon and from 500 up to 2000 Bq·m-2·h-1 for thoron.

Application of TLD devices for radon and thoron PAEC measurements in air is the concept of "total PAEC" useful?

The calibration of monitors of radon decay products is a difficult task, and even more so in the case of monitors detecting the products of thoron decay. An important issue here is the lack of primary standards, both in relation to the products of radon as well as thoron decay. In Poland, for many years, measurements of potential alpha energy concentration (PAEC) were carried out with the application of special devices, called ALFA probes. These in turn featured thermo-luminescent detectors (TLD), the readout of which provided information about the potential alpha energy, with no dependence on equilibrium or other factors alike. In this paper, we propose modifying this technique, which had been used only for measurements of products of radon decay. We specifically examine how it can be used to allow simultaneous measurements of radon and thoron PAECs. In employing the method, the idea is to use two sets of TL detectors in the same device during and after sampling. The first set of detectors is used to store the energy of alpha particles during the course and for a short while after the sampling, up to 5 h after its end. Using this method, the first set of detectors holds respectively the full and partial PAECs of products of radon and thoron decay. After that, the first set of TLDs is replaced with a second one. These are then left in the device for another 55-60 h. This set contains only the PAEC from thoron decay products. Afterwards, it is necessary to subtract thoron PAEC from the first set result and add it to the result provided by the second set in order to estimate the PAEC for the products of thoron decay. On a practical level, using such a procedure can potentially difficult during underground or field monitoring nevertheless. This is why another approach can be adopted as well. This is specifically to leave the device for 60 h after sampling without any changes, the original set of TLDs providing a "total" PAEC readout - this being a sum of radon and thoron PAECs. In this paper, we will explore the value of using such a readout for the measurement that is carried out.

The correction factors for UD802 dosimeters irradiated with different radiation energies and at different incidence angles.

Many laboratories around the world work on the issue of protection against ionising radiation. It is a very broad topic, covering both the protection of members of the public and workers exposed to ionising radiation, based on personal or environmental monitoring. Thermoluminescence detectors are commonly used for this purpose, which is accepted in most countries. The entire process of dose evaluation with such dosimeters can be divided into several steps. Undoubtedly, one of the most important steps is the calibration procedure. The calibration should be performed in conditions as similar as possible to those experienced during the exposure. Moreover, the calibration is performed using only the Cs-137 source. This article presents results of Panasonic UD-802 irradiation dosimeters in different radiation fields generated by Cs-137, Kr-85, Sr-90/Y-90 and an x-ray tube, series N, and at different angles such as 0°, 30°, 60°, 90°. On the basis of the obtained results, the calibration coefficients and correction factors were determined in relation to calibration based on Cs-137 or Sr-90/Y-90 irradiated at 0°.