Wyniki wyszukiwania - BazTech

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Radon levels after restoration of the U-mine disposal site

Križman M. J., Rojc J., Jovanovič P.

Nukleonika

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2010

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Vol. 55, No. 4

523-527

EN

After cessation of the underground mining of uranium ore and production of uranium concentrate at Žirovski Vrh (Slovenia) in the period 1985–1990, two permanent surface disposal sites remained, namely, tailings pile and mine waste rock pile. Both disposal sites were of equal size of 4 hectares and were significant sources of radon. Their final restoration was designed in compliance with the condition of dose constraint for the public and authorized limits for radon exhalation from the remediated piles. In the late summer of 2008, a restoration of the mine waste pile was finished. Radon releases were reduced significantly by constructing an effective radon barrier of well compacted clayey material and a thick complex protective cover layer constructed over it. Radon exhalation rate from the mine waste area was lowered from primary level of 0.7 Bq/m2źs to natural levels (0.01 Bq/m2źs), and consequently, ambient radon levels also decreased on the site and nearby environment. The average radon contribution from the remaining U-mine sources was estimated on the basis of the environmental measurements of radon concentrations; they dropped from initial 7–9 Bq/m3 to approximately 3 Bq/m3. Further reduction of outdoor radon concentrations is expected after 2010, since the restoration of another disposal site will have been completed by the end of this year. Public exposure due to industrial radon after the first phase of restoration satisfactorily meets the dose constraint level of 0.3 mSv/y, since it decreased to less than 0.1 mSv/y.

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Radon events in the U-mine environment and related radiation exposure

Križman M. J., Rojc J., Peter J. E.

Nukleonika

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2010

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Vol. 55, No. 4

529-533

EN

The term �gradon event�h indicates here a sudden appearance of enhanced radon concentrations, observed like well expressed peaks in time series of radon concentrations. The peaks are superimposed on normal diurnal periodical curves. The characteristics of radon events are high peak values, a rather short duration and a low radon equilibrium factor. Since radon events appear only in the environment near significant radon emission sources, they were investigated in more detail in the case of the former .irovski Vrh uranium mine (Slovenia), using the existing network of continuous radon progeny measuring devices. Eight different types of radon events were identified in the vicinity of the U-mine disposal sites, lasting for some hours and with the range of their peak levels of equilibrium equivalent concentrations (EEC) of radon from a few Bq�Em.3 to over 200 Bq�Em.3. Exposures to radon events in units of Bq�Eh�Em.3 were estimated for adult individuals of the reference group. They resulted in relatively high effective doses of the range 1.5 �ĘSv per a single event, thus exceeding, e.g. the total effective dose for the public due to radioactive discharges from most nuclear facilities during the whole year.

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Test of the material for radon seal layer at the mine waste disposal site Jazbec

Rojc J., Jovanovic P.

Prace Naukowe GIG. Górnictwo i Środowisko / Główny Instytut Górnictwa

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2004

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nr 1

101-102