Speaker
Description
Authors (affiliation): Ioana Lalau 1,2, Aurelian Luca 1, Claudia Olaru 1, Constantin Teodorescu 1, Mihail-Razvan Ioan 1
1 Horia Hulubei National Institute of Physics and Nuclear Engineering (IFIN-HH), Romania,
2 University of Bucharest, Faculty of Physics, Romania
Uranium decay series represent one of the most significant sources of naturally occurring radioactivity. Starting from 238U, the series decay consecutively by alpha emission into one of its daughters, 226Ra which decays into 222Rn a colorless, odorless and chemically inert radioactive gas.
Therefore, high concentrations of 222Rn can be found in dwellings, caves and other closed areas which require a careful monitoring of radon activity concentration, as lung cancer can occur when people are exposed to high levels of radon concentration. Accurate indoor determination of the radon 222Rn activity concentration in air is necessary in order to implement the European Council Directive No. 2013/59/EURATOM. The Romanian National Commission for Nuclear Activities Control (CNCAN) designated several Romanian testing laboratories for measurements of radon activity and/or radon activity concentration in air. Calibration of the equipment used by these laboratories is essential for assessing with high precision, the indoor levels of radon activity concentration. Starting from 2022, for the first time in Romania, the calibration of various radon monitors received from customers was performed at Horia Hulubei National Institute of Physics and Nuclear Engineering (IFIN-HH) by the Ionizing Radiation Metrology Laboratory (LMRI), designated by CNCAN as a calibration laboratory. The calibration was performed with the radon gas activity standards produced by LMRI and the radon chamber of IFIN-HH (1 m3 volume) and its accessories.
The method used to extract radon with an activity value suitable for the monitor calibration based on a 226Ra source (Pylon type, 250 kBq activity) is described. The radon is transferred in the radon chamber, which is then closed. A homogeneous radon atmosphere in the radon chamber is assured by two fans. Then, the calibration process starts, following the radon activity concentration decay,
measured with both the reference monitor and the customers monitor. The calibration range is (100 - 10,000) Bq/m3.
The purpose of the study was to analyze the radon monitors responses and their uncertainties, and finally compare their performance with the standard radon
monitor AlphaGuard in order to improve the calibration process in the future. Measurements results and the uncertainty budgets are presented in the paper.
A few recommendations for customers are provided. A new working procedure for the calibration of the systems using solid state nuclear track detectors will be developed and implemented in the near future by LMRI.
