Wyniki wyszukiwania - BazTech

1

Size distribution of ambient and radioactive aerosols formed by the shortlived radon progeny

Skubacz Krystian, Wołoszczuk Katarzyna

Journal of Sustainable Mining

|

2019

|

Vol. 18, iss. 2

61--66

EN

The survey of ambient airborne particle size distribution is important when the deposition of radioactive particles is considered in the human lung and the assessment of radiation hazard in occupational exposures or contaminated environments. CLOR (the Central Laboratory for Radiological Protection) in cooperation with CMI (the Central Mining Institute) performed simultaneous measurements of the activity size distribution of radon progeny and ambient aerosols using different types of aerosols. Measurements were performed in a radon chamber with a volume of 17m3, where radon was generated by a radium-226 open source, and ambient aerosols by an oil candle, vax candle, and incense sticks. Such measurements were also made in an aerosol depleted atmosphere after cleaning the chamber air by means of a high-efficiency pump and filters. The size distribution of radioactive aerosols containing radon progeny was measured by RPPSS (Radon Progeny Particle Size Spectrometer) with the measuring size ranging from 0.6 nm to approximately 2500 nm. The key parts of this device are the impaction plates and diffusion screen batteries, which collect aerosols of different sizes, and semiconductor alpha detectors which detect the activity of the collected particles. The SMPS (Scanning Mobility Particle Sizer Spectrometer) and APS (Aerodynamic Particle Sizer) were applied to evaluate the size distribution of all aerosols with sizes from approximately 3 nm to 20 μm. Based on the results obtained by these spectrometers, the activity size distributions and related dose conversion factors (DCF) were evaluated both for the exposed workers and the general population.

2

Deconvolution of alpha spectra from air filters applied for measurements of the short-lived radon progeny concentration

Skubacz K.

Nukleonika

|

2017

|

Vol. 62, No. 3

229--234

EN

The paper contains a description of a method for the analysis of the complex alpha spectra generated during the measurement of the activity of filters outside of a vacuum chamber under environmental conditions. The peaks corresponding to the energies of alpha particles emitted by the specific isotopes are particularly large on the low-energy side of the peak maximum, and the energy resolution strongly depended on the applied filters. The analysis was based on the non-linear regression to a function designed for four, six and eight parameters. Satisfactory results were obtained for each of these functions, and the best-fitting results were achieved for the eight-parameter function. In addition, the uncertainties related to the estimated parameters, as well as the signals corresponding to functions that describe the shape of the energy peak, have been evaluated. There are also examples of the implementation of the method with respect to short-lived radon progeny and thoron decay products.

3

The influence of air conditioning changes on the effective dose due to radon and its short-lived decay products

Grządziel A., Kozak K., Mazur J., Połednik B., Dudzińska M. R., Bilska I.

Nukleonika

|

2016

|

Vol. 61, No. 3

239--244

EN

Most people spend the majority of their time in indoor environments where the level of harmful pollutants is often significantly higher than outdoors. Radon (222Rn) and its decay products are the example of radioactive pollutants. These radioisotopes are the main source of ionizing radiation in non-industrial buildings. The aim of the study was to determine the impact of air-conditioning system on radon and its progeny concentrations and thus on the effective dose. The measurements were carried out in the auditorium at the Environmental Engineering Faculty (Lublin University of Technology, Poland). Measurements of radon and its progeny (in attached and unattached fractions) as well as measurements of the following indoor air parameters were performed in two air-conditioning (AC) operation modes: AC ON and AC ON/OFF. The air supply rate and air recirculation were taken into consideration. The separation of radon progeny into attached and unattached fractions allowed for determining, respectively, the dose conversion factor (DCF) and the inhalation dose for teachers and students in the auditorium. A considerable increase of the mean radon progeny concentrations from 1.2 Bq/m3 to 5.0 Bq/m3 was observed in the AC ON/OFF mode compared to the AC ON mode. This also resulted in the increase of the inhalation dose from 0.005 mSv/y to 0.016 mSv/y (for 200 h/year). Furthermore, the change of the air recirculation rate from 0% to 80% resulted in a decrease of the mean radon concentration from 30 Bq/m3 to 12 Bq/m3 and the reduction of the mean radon progeny concentration from 1.4 Bq/m3 to 0.8 Bq/m3. This resulted in the reduction of the inhalation dose from 0.006 mSv/y to 0.003 mSv/y.

4

Influence of aerosol concentration and multivariate processing on the indication of radon progeny concentration in air

Machaj B., Urbański P.

Nukleonika

|

2004

|

Vol. 49, nr 3

123-129

EN

Measurements of radon progeny concentration in air by a radon progeny monitor are sensitive to the concentration of particles suspended in air. Minimum detectable concentration and accuracy of the measurement are determined by random errors of the monitor. Multivariate data processing can be used to decrease these random errors. Influence of aerosol concentration on the measured results of radon progeny concentration in air, by an RGR-30 mining radiometer, operating on the principle of alpha radiation detection from radon progeny deposited on an air filter, were determined in a radon chamber experiment. The air suspended particle concentration and the radon concentration in the radon chamber were controlled and the corresponding radon progeny concentration was measured by the radon progeny monitor. Additionally, count rate from the monitor detector, originating from the alpha activity deposited on the air filter, was measured at intervals of one minute and was then used for the three-interval, and Principal Component Regression (PCR) data processing. It was found that for the aerosol concentration in air from 40 p/cm3 to approximately 9,000 p/cm3 indications of the radon progeny monitor depends considerably on the aerosol concentration. Radon daughter concentration normalized to the radon concentration against aerosol concentration varied from 0.3 to 0.9. In mines, where the aerosol concentration generally is high, this phenomenon has little effect on the indication of the radon progeny monitor. At low aerosols concentration, appropriate correction of radon progeny concentration has to be taken. Comparison of random errors when measured signal of the monitor (count rate against time) was processed employing the three-interval method and PCR data processing shows that PCR ensures a lower random error.