APPLICATION OF A SCINTILLATION GAMMA-SPECTROMETER FOR DETERMINATION OF RADON CONTENT IN WATER

Experimental studies have been carried out to determine the sensitivity of a mobile scintillation gamma-spectrometer to radon-222 in mineral water samples for the selected measurement geometry and the minimum measurable activity of radon-222 in such samples. The measurement results of radon content in mineral water samples obtained using such gamma-spectrometer are presented too.

Determination of radon index on the test site “Botanical Garden − BAS”, Sofia

The study deals with pilot investigations of the radon index in Bulgaria. In situ measurements of the radon activity and soil permeability at 3 sites one over and two – close to fault zone have been performed. The results show that higher radon content is detected in the fault zone.

ON JUSTIFICATION OF CHANGES IN THE RADON CONTENT RATIONING IN INDOOR AIR

The deadline for the development of the final draft of the new radiation safety standards RSS-2019, harmonized with international recommendations, including the regulation of radon content in the indoor air of residential and public buildings is expected to be finished in 2019. We estimated the possibility and expediency for replacement of the hygienic standard established in RSS -99/2009 with the reference level recommended by the International Basic Safety Standards of IAEA GSR Part 3 on the basis of data analysis results on radon content levels in indoor air of residential and public buildings on the territory of subjects of the Russian Federation. An analysis of the array of measurements results for radon content with a volume of 680,301 measurements taken during the period from 2001 to 2017 in the subjects of the Russian Federation collected as part of Unified State System for Control of Individual Exposure Doses and stored in the Federal database of exposure doses of citizens of the Russian Federation due to the natural and man-made background radiation was carried out. Absolute and relative estimates of the number of radon EEVA values exceeding 200, 150 and 120 Bq/m3 were obtained, both for individual regions and for the country as a whole. The results show that the reduction of hygienic standard of radon EEVA will increase the share of the non-compliant regulatory instruments of residential and public buildings up to 150 Bq/m3 almost in 2 times, up to 120 Bq/m3 almost in 3 times on average in Russia. We formulated a number of proposals aimed at harmonizing the Russian standards of radon content in indoor air with the IAEA recommendations taking into account the economic feasibility and while maintaining the possibility of monitoring compliance with the requirements of radiation population safety.

HYDROGEOCHEMISTRY OF THE ZAELTSOVSKY-MOCHISHCHE FIELD OF RADON WATERS

Results of the studies into the features of the geochemistry of radon waters from the Zaeltovsky-Mochishche zone of Novosibirsk city are reported. Radon waters are fracture, cold with the temperature of 6-10 оC, they occur at a depth of 50-200 m. In the hydrogeological section, neutral and weakly alkaline waters are developed, with рН from 6,9 to 7,8, mainly with the calcium hydrocarbonate and calcium-sodium hydrocarbonate composition, with total mineralization from 322 to 895 mg/dm3. The concentrations of 222Rn in water-saturated zones of granites vary from 308 to 1521 Bq/dm3, while in the wells drilled into hornstones radon content varies within the range 37-241 Bq/dm3. The concentrations of 238U and 226Ra do not exceed 0.098 mg/dm3 and 3.5∙10-7 mg/dm3, respectively.

Relationship between Grain Size Distribution and Radon Content in Surficial Sediments of Wadi Arar, Saudi Arabia

Surficial sediments with low radon content are desirable materials in construction applications. In this study, the relationship between grain size and radon content was investigated in sediments collected from seven sites in Wadi Arar, Saudi Arabia, with the intent of determining whether grain size analysis could be used for rapidly assessing the suitability of potential construction materials. Thirty-five samples were collected (five per site) and the grain size distribution was determined using sieves. Radon contents were measured on composite samples with a RAD7 radon detector. Among the sediment types (gravel, coarse sand, medium sand, fine sand, and silt and clay), the best linear correlations between grain size and radon contents were found for the coarse sand (negative slope, r=0.82) and fine sand (positive slope, r=0.78). Polynomial relationships were also tested. A fourth-degree polynomial equation effectively described the correlation between grain size and radon content (R2 = 0.933). As shown by this model, the highest correlations with radon contents were detected at grain sizes smaller than 2.0 mm. Thus, grain size may be useful for preliminary site assessment work.