PROCEDURES TO MEASURE MEAN AMBIENT DOSE EQUIVALENT RATES USING ELECTRET ION CHAMBERS.

The capabilities of electret ion chambers (EICs) to measure mean ambient dose equivalent rates were investigated by performing both laboratory and field studies of their properties. First, EICs were 'calibrated' to measure ambient gamma dose equivalent in the Ionizing Calibration Laboratory of the Greek Atomic Energy Commission. The EICs were irradiated with different gamma photon energies and from different angles. Calibration factors were deduced (electret's voltage drop due to irradiation in terms of ambient dose equivalent). In the field studies, EICs were installed at eight locations belonging to the Greek Early Warning System Network (which is based on Reuter-Stokes ionization chambers) for three periods, averaging 5 months each. In the same locations, in situ gamma spectrometry measurements were performed with portable germanium detectors. Gamma ambient dose equivalent rates were deduced by the in situ gamma spectrometry measurements and by soil sample analysis. The mean daily electret potential drop (in Volts) was compared with the mean daily ambient dose equivalent, measured with a portable HPGe detector and Reuter-Stokes high-pressure ionization chambers. From these measurements, 'field' calibration factors (electret's voltage drop due to gamma radiation in terms of ambient dose equivalent) were deduced and found in very good agreement with the values deduced in Laboratory. The influence of cosmic radiation and the intrinsic voltage loss when performing long-term environmental gamma measurements with EICs, was estimated.

A Holistic Approach to Assessment of Population Exposure to Radiation: Challenges and Initiatives of a Regulatory Authority.

A regulatory authority for radiation safety should continuously evaluate and improve the national safety framework, in line with current requirements and standards. In this context, the Greek Atomic Energy Commission initiated a series of concerted actions. The radiation dose to the population due to public and medical exposures was assessed. The assessment of dose due to public exposure was based on measurements of radon concentrations in dwellings, radionuclide concentrations in environmental samples, and air dose rates; the assessment of dose due to medical exposure was based on dose measurements for typical examinations or procedures and data on their frequency. The mean effective dose to a member of the population was found to be 4.5 mSv (1.8 mSv and 2.7 mSv from medical and public exposures, respectively). Regarding occupational exposure, aircrew dose assessment, eye lens monitoring, and the national dose registry were significantly improved. With respect to artificial tanning (sun beds), the ultraviolet radiation produced was assessed and the practices followed were observed. Results demonstrated exceedance of the 0.3 W m erythema effective irradiance limit set in European Union standards by 63.5% of the sun beds measured, along with general noncompliance with standards. An overarching activity was the upgrade of the Greek Atomic Energy Commission information system in order to collect and disseminate radiation data electronically, launch a networking strategy for interaction with stakeholders, and facilitate the process of regulatory control. In response to the above findings, regulatory actions have been initiated.

DETERMINATION OF THE INTERNAL EXPOSURE OF GREEK CITIZENS RETURNING FROM JAPAN IMMEDIATELY AFTER THE FUKUSHIMA ACCIDENT.

Following the nuclear accident at the Fukushima Daiichi Nuclear Power Plant on 11 March 2011, during the period 17 March to 25 October 2011, a total of 22 Greek citizens were measured after their return to Greece. Artificial radionuclides were detected in 5 of the 22 measured individuals by whole body counter measurements conducted 10 and 11 d after the commencement of the accident. Of the 5 contaminated individuals, 3 were adults and 2 children, aged 9 and 5 y, who stayed for a single day in Tokyo. Dose calculations were performed assuming that the sole exposure pathway was through inhalation that occurred on 14 March, according to the information provided by them, using the detected artificial radionuclides in the spectra ((134)Cs, (137)Cs, (131)I). The estimated total committed effective doses calculated were found to be in the range of 9-280 µSv.

Follow-up study of indoor radon in Greek buildings.

The Nuclear Technology Laboratory of the Aristotle University of Thessaloniki (NTL-AUTh) and the Greek Atomic Energy Commission (GAEC) have a continuous collaboration on indoor radon measurements in Greek buildings since 1999. In the present work, the existing database was enriched with 590 indoor radon measurements in 295 houses and 76 indoor radon measurements in 38 workplaces. In total in the present work, 1948 indoor radon measurements in 974 buildings performed by the NTL-AUTh and GAEC from 1999 to 2012 in 8 of the 13 administrative regions of Greece are presented and discussed.

Environmental measurements and inspections on imported foods and feedstuffs in Greece after the Fukushima accident.

The radionuclides released during the accident at the Fukushima Daichii nuclear power plant following the Tohoku earthquake and tsunami on 11 March 2011 were dispersed in the whole north hemisphere. Traces of (131)I, (134)Cs and (137)Cs reached Greece and were detected in air, grass, sheep milk, ground deposition, rainwater and drainage water. Members of Six Greek laboratories of the national network for environmental radioactivity monitoring have collaborated with the Greek Atomic Energy Commission (GAEC) and carried out measurements during the time period between 11 March 2011 and 10 May 2011 and reported their results to GAEC. These laboratories are sited in three Greek cities, Athens, Thessaloniki and Ioannina, covering a large part of the Greek territory. The concentrations of the radionuclides were studied as a function of time. The first indication for the arrival of the radionuclides in Greece originating from Fukushima accident took place on 24 March 2011. After 28 April 2011', concentrations of all the radionuclides were below the minimum detectable activities (<10 µBq m(-3) for (131)I). The range of concentration values in aerosol particles was 10-520 µBq m(-3) for (131)I, 10-200 µBq m(-3) for (134)Cs and 10-200 µBq m(-3) for (137)Cs and was 10-2200 µBq m(-3) for (131)I in gaseous phase. The ratios of (131)I/(137)Cs and (134)Cs/(137)Cs concentrations are also presented. For (131)I, the maximum concentration detected in grass was 2.2 Bq kg(-1). In the case of sheep milk, the maximum concentration detected for (131)I was 2 Bq l(-1). Furthermore, more than 200 samples of imported foodstuff have been measured in Greece, following the EC directives on the inspection of food and feeding stuffs.

Environmental radioactivity measurements in Greece following the Fukushima Daichi nuclear accident.

Since the double disaster of the 9.0 magnitude earthquake and tsunami that affected hundreds of thousands of people and seriously damaged the Fukushima Daichi power plant in Japan on 11 March 2011, traces of radioactive emissions from Fukushima have spread across the entire northern hemisphere. The radioactive isotope of iodine (131)I that was generated by the nuclear accident in Fukushima arrived in Greece on 24 March 2011. Radioactive iodine is present in the air either as gas or bound to particles (aerosols). The maximum (131)I concentrations were measured between 3 and 5 April 2011. In aerosols the maximum (131)I values measured in Southern Greece (Athens) and Northern Greece (Thessaloniki) were 585±70 and 408±61 µΒq m(-3), respectively. (131)I concentrations in gas were about 3.5 times higher than in aerosols. Since 29 April 2011, the (131)I concentration has been below detection limits. Traces of (137)Cs and (134)Cs were also measured in the air filters with an activity ratio of (137)Cs/(134)Cs equal to 1 and (131)I/(137)Cs activity ratio of about 3. Since 16 May 2011, the (137)Cs concentration in air has been determined to be about the same as before the Fukushima accident. Traces of (131)I were also measured in grass and milk. The maximum measured activity of (131)I in sheep milk was about 2 Bq l(-1) which is 5000 times less than that measured in Greece immediately after the Chernobyl accident. The measured activity concentrations of artificial radionuclides in Greece due to the Fukushima release, have been very low, with no impact on human health.

Hair analysis as an indicator of exposure to uranium.

Medical examinations performed on four monks of a monastery in the northern Greece revealed heavy metal contamination. Hair analysis, performed by a toxicological laboratory abroad, indicated, among other, the presence of uranium. The uranium concentrations determined in a laboratory of "Elemental Hair Analysis' indicated a uranium level that was about five times the maximum value of the reference range, which has been adopted by the measuring laboratory. After these diagnostic findings, on request of 10 monks, uranium determination in hair and urine samples was performed by means of alpha spectrometry in GAEC's laboratory. The measured uranium concentrations in hair varied from 0.15 to 2.10 mBq g(-1), which correspond to 12.1 and 170 ng g(-1), respectively. The uranium concentrations in urine were between 41 and 174 ng d(-1). For comparison purposes, urine and non-dyed hair samples from the staff of the laboratory were analysed. Because one of the major sources of uranium intake is through drinking water, water samples were also analysed. The mean value of the uranium concentration in the two drinking water samples collected from the residence area was found to be 2.35 µg l(-1).

Indoor radon measurements in areas of northern Greece with relatively high indoor radon concentrations.

Indoor radon concentrations were measured in 77 schools of the prefecture of Xanthi in northern Greece. The arithmetic mean radon concentration is 231 Bq m(-3) with a range between 45 and 958 Bq m(-3). Thirty five schools have mean radon concentration above 200 Bq m(-3) and nine schools have mean radon concentration above 400 Bq m(-3). From continuous radon gas measurements in the school with a relative higher radon concentration (958 Bq m(-3)) was deduced the 'true' radon concentration, defined as the radon concentration in the school during the hours of the presence of teachers and scholars. The mean 'true' radon concentration for a time period of about 2 weeks was 104 Bq m(-3). The mean radon concentration for the same 2 weeks was seven times higher (700 Bq m(-3)). Greek and International regulations for radon in workplaces refer to only the mean annual radon concentration. It would be preferable for schools to replace the mean annual radon concentration with the 'true' radon concentration.