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Ph. D. thesis

Zsolt Kasztovszky

Supervisor: Prof. Dr. György Marx

Eötvös Loránd University, Department of Atomic Physics, Budapest, 1997

SUMMARY

It is well known that half of the radiation burden is due to the presence of radon (²²²Rn) in the human environment. Different estimations for the doses originating from inhalation of air and ingestion of water with high radon concentration have been published (ICRP-65). The Environmental Protection Agency of US has introduced an Alternative Maximum Contaminant Level of 150 Bq l^-1 for radon in drinking water [V.].

In 1992 a high level radon exhalation was observed in the region of Mátraderecske, Hungary, occassionally accompanied with CO₂ exhalation. The intensity of radon flow seemed to be randomly varying in time and space. In 1994 the influenting factors were not known. I have carried out regular observation of the well-waters’ radioactivity and other geological and meteorological factors, to determine the main causes of variation of radon concentration. In addition - based on international recommandations - I calculated the health risks due to the consumption of these high radon concentration waters.

To measure the water samples’ activity I found the liquid scintillation method to be the most reliable. The method was calibrated a standard RaCl₂ solution set. The radon concentrations of waters in Mátraderecske has been found to be in the range of 30- 350 Bq l^-1. This is the same order of the activity of waters in Rudas spa, known to show the highest activity concentration in Hungary [II]. According to the simplest model, the radon content of waters are determined by the relative position of the ²³⁸U-rich soil layer and the level of ground-water [IV.]. In some cases this model had to be modified. The radon concentration of waters may vary by an order of magnitude during a year. I found significant correlation between radon concentration and rainfall. The radon levels are strongly influenced also by other meteorological factors [V].

The additional effective dose rate is about 1 mSv year^-1, due to the daily consumption of water with 150 Bq l^{-1 222}Rn concentration. It means, that the consumption of well-waters with highest radon level in Hungary induces 1- 3 mSv year^-1 additional effective dose rate [II].

PUBLICATIONS

RELATING TO THE THESIS

[I.] L. Sajó-Bohus, G. Marx, Á. Hováth, Zs. Kasztovszky, E. Tóth: On environmental radon concentration mapping, Proceedings of the Workshop on Harmonization of East-West Radioactive Pollutant Measurements, Budapest, 1994. aug. 28- szept. 2. (p. 115-126)

[II.] Zs. Kasztovszky, P. Szerbin, R. Kuczi: On the natural radioactivity of waters in Hungary, Central European Journal of Occupational and Environmental Medicine, 1996; 2 (4) 335-347

[III.] E. Tóth, F. Deák, Cs. Gyurkócza, Zs. Kasztovszky, R. Kuczi, G. Marx, B. Nagy, S. Oberstedt, L. Sajó-Bohus, Cs. Sükösd, G. Tóth, N. Vajda: Peculiar radon spot in Hungary, Journal of Radioanalytical and Nuclear Chemistry Letters, 213 (5) 1996 317-330

[IV.] E. Tóth, F. Deák, Cs. Gyurkócza, Zs. Kasztovszky, R. Kuczi, G. Marx, B. Nagy, S. Oberstedt, L. Sajó-Bohus, Cs. Sükösd, G. Tóth, N. Vajda: Radon variations in a Hungarian village, Environmental Geology, 28 (2) 1996 123-127

[V.] Zs. Kasztovszky, L. Sajó-Bohus, B. Fazekas: Parametric changes of radon (²²²Rn) concentration in ground water in Northeastern Hungary, Journal of Environmental Radioactivity 49 (2000) 171-180

CONFERENCES

RELATING TO THE THESIS

[VI.] Kasztovszky Zs.: Vizek radioaktivitásának mérése, ELTE Atomfizikai Tanszék, Tanszéki Tea, Budapest, 1994. május (in Hungarian)

[VII.] Zs. Kasztovszky, G. Marx, E. Tóth: Radon measurements in well-waters in Hungary, RIO FOLLOWUP International Conference on Science Education, Eger, 1994. aug.

[VIII.] L. Sajó-Bohus, G. Marx, Á. Hováth, Zs. Kasztovszky, E. Tóth: Radon measurements in well-waters in Hungary, Workshop on Harmonization of East-West Radioactive Pollutant Measurements, Budapest, 1994. aug. 28-szept. 2.

[IX.] Kasztovszky Zs., Marx Gy., Tóth E.: Mátraderecskei kutak vizének radioaktivitása, XX. Sugárvédelmi Továbbképz? Tanfolyam, Balatonkenese, 1995. máj. 17-19. (in Hungarian)

[X.] L. Sajó-Bohus, G. Marx, Á. Hováth, Zs. Kasztovszky, E. Tóth: In-Situ Potential Risk Dependence of Environmental Radon Concentration Mapping (poszter), III. Congresso Peruano de Protección Radiológica (Regional IRPA), Cusco, 1995. okt. 23-27.

[XI.] Kasztovszky Zs., Szerbin P., Kuczi R.: Magyarországi vizek természetes radioaktivitása, Õszi Radiokémiai Napok, Balatonkenese, 1996. okt. 16-18. (in Hungarian)