1. NCSR “DEMOKRITOS” INSTITUTE OF NUCLEAR AND RADIOLOGICAL SCIENCES & TECHNOLOGY, ENERGY & SAFETY (I.N.RA.S.T.E.S.) ENVIRONMENTAL RADIOACTIVITY LABORATORY

2. A survey on the radioactivity of mineral springs in Greece*
G. Kuburas, E. Tzempelikou and H. Florou
Measuring natural radioactivity by means of γ-spectrometry
Studying activity concentrations of Rn-222, Ra-226, U-238
Decision of the Greek Ministry of Tourism (Greek Official Gazette 2215/B/ ) on the identification process of thermal natural resources
* The authors acknowledge funding from the Greek General Secretariat for Research and Technology and the European Regional Development Fund under the Action “Development Grant for Research Institutions – KRIPIS” of OPCE II

3. Why should we measure the activity concentrations of these radionuclides?
Rn-222 (T1/2 = 3.82 d)
A radioactive gas that emanates from rocks and soils and tends to concentrate in enclosed spaces
It is the second cause of lung cancer in general population, after smoking
Epidemiological studies have provided convincing evidence of an association between indoor radon exposure and lung cancer
Natural springs supplied by underground aquifers quite often contain radon

4. Why should we measure the activity concentrations of these radionuclides?
Ra-226 (T1/2 = 1600 y)
Accumulates preferentially in the bones
Inhaled or ingested radium increases the risk of developing such diseases as lymphoma, bone cancer, and diseases that affect the formation of blood, such as leukemia
U-238 (T1/2 = 4.5E9 y)
Long term chronic intakes of uranium isotopes in food, water, or air can lead to internal irradiation and/or chemical toxicity
Intakes of uranium can lead to increased cancer risk, liver damage, or both

5. How do we measure the activity concentrations of these radionuclides?
Thermal springs water samples are collected in air tightly sealed Marinelli beakers
3 samples are collected in the same day in order to evaluate the daily radon fluctuation

6. How do we measure the activity concentrations of these radionuclides?
Samples are measured by means of γ-spectrometry to evaluate the Rn-222 activity concentrations
The Pb-214 (295.2 keV and keV) and Bi-214 (609.4 keV) photopeaks are used for the calculation of the Rn-222 activity concentrations (corrected to the collection date)

7. How do we measure the activity concentrations of these radionuclides?
After the first measurement the beakers are vented to let the radon gas escape
They are then sealed and re-measured after a 24 days’ period when secular equilibrium between Ra-226 and Rn-222 has been reached
In this way the activity concentration of any inherently present Ra-226 in the sample can be estimated
At the same time a separate quantity of the spring water is being submitted to mild evaporation and the remaining sediment is placed in a pillbox and is examined for the presence of U-238 by observing the Th-234 photopeaks at 63.3 keV and 92.6 keV

8. What equipment do we use?
3 HPGe detectors
Relative efficiency: 20%
Resolution: 2.0 keV at 1.33 MeV
Energy calibration: 0.5 keV/channel
2) Relative efficiency: 30%
Resolution: 1.95 keV at 1.33 MeV
3) Relative efficiency: 90%
Energy calibration: 0.25 keV/channel

9. In total, 75 water samples coming from 60 mineral springs located in 30 Regional Units of Greece have been surveyed during the 2014 to 2016 period
In case that the activity concentration of Rn-222 exceeds the value of 100 Bq/L, a resumptive water sampling must take place in the same hydrological year to cover both wet and dry periods
The method used for the determination of the activity concentrations of Rn-222, Ra-226 and U-238 is simple and cost effective

10. Activity concentrations of Rn-222, Ra-226 and U-238 in thermo-mineral springs water samples in the Regions of Greece
Region
Thermo-mineral springs water samples surveyed
Activity concentrations (Bq/L) per No of samples
Rn-222
Ra-226
U-238
< 10
> 100
< 0.1
> 0.1
< 0.5
> 0.5
Attica 1
Central Greece 13 3 8 2 6 7
Central Macedonia 9 5
Crete
East Macedonia and Thrace 4
Epirus
Ionian Islands
North Aegean 22 12 10
Peloponnese
South Aegean
Thessaly
West Greece
West Macedonia
Total 75 29 25 21 49 26 74

11. Summary
Thermo-mineral springs have been surveyed for natural radioactivity in 11 out of the 13 Regions of Greece
40% of the estimated 150 springs that can be commercially developed have been sampled during the 2014 to 2016 period
Elevated Rn-222 and Ra-226 activity concentrations are mainly observed in Ikaria Island (Eastern Aegean Sea)
Elevated Ra-226 activity concentrations characterize the mineral springs situated in and around the city of Loutra Edipsou (northern part of Euboea Island)
The U-238 activity concentrations, with a single exception (Glyfada, Attica), do not exceed in mineral springs of Greece the value of 0.5 Bq/L
Mineral springs water samples are currently being collected in a number of Greek Regional Units

12. Thank you for your attention!