Analytical considerations in assessment of workplaces exposed to NORM

1. Analytical considerations in assessment of workplaces exposed to NORM Erich Hrnecek, ARC Seibersorf research GmbH 9th European ALARA Network workshop on „Occupational Exposure to Natural Radiation“

2. Overview: • Current legal situation in Austria • Studies • Radon • NORM • TIG – welding: Analytical Strategy • Conclusions

3. Current legal situation in Austria • Council Directive 96/29 EURATOM • Strahlenschutz-EU-Anpassungsgesetz BGBl. Teil I Nr. 146, 20th August 2002 • § 36d Maximum exposition of workers from 222Rn, U, Th, cosmic radiation according to dose limit category A • § 36f Fields of work, where increased exposition 222Rn, U, Th can be expected have to be defined by regulatory authority In these fields of work, it will be obligatory to evaluate the potential exposure of workers and to report the results to the authorities • Fields of work have to be defined in Radiation Protection Ordinance

4. Studies: Radon • 1991 – 2001: Austrian National Radon Project (ÖNRAP) • Investigation of Radon exposure distribution in Austrian homes • Map of Radon potential for Austrian standard dwellings H. Friedmann, BfS Ber. 24/2002H. Friedmann et al, Env. Int 22, S 677 (1996)

5. Studies: Radon • 1997 – 1999: Radon concentrations in drinking water • Map of Rn concentrations • Cat. 1: 85% < 100 Bq/l • Cat. 2: 85% < 300 Bq/l • Cat. 3: >15% > 300 Bq/l • Areas with enhanced Radon concentrations in drinking water can be identified • Workers in waterworks H. Friedmann, BfS Ber. 24/2002

6. Studies: Radon • Thermal spas: • Radon galleries for medical treatment • Badgastein • 222Rn: 44 kBq/m³, up to 350 kBq/m² • Aerosol composition varies with ventilation conditions: G. Wallner, Rad. Env. 7, 397 (2005). • ~1.8 mSv during treatment

7. Studies: NORM • No comprehensive survey on NORM exposure in Austria exists • Potential exposure: • Rare earth industry • Mining • Oil and gas industry • Use of Th in industrial processes • Current study on TIG – welding

8. Motivation: Welding • Project from Austrian Social Insurance for Occupational Risks to assess exposure of workers during welding • Exposure to UV - radiation • Exposure to electromagnetic fields • Exposure to Th during TIG - welding

9. Motivation • Tungsten Inert Gas shielded welding with thoriated Tungsten electrodes • containing 1% (WT10) to 4% (WT40) ThO2 • Inkorporation by Inhalation • during welding • during sharpening of electrodes

10. Ludwig et al.,Health Phys. 1999 Air samplingweldingsharpening < 0,1 to 144 Bq/a 232Th incorporation Possible risk exists (AC-TIG) Tietze et al., Schweißen&Schneiden 1998 Air samplingweldingsharpening welding to 3,6 Bq/asharpening to 0,8 Bq/a 1 of 3 cases increased Inhalation Ludwig, Seitz, IRPA9, 1996 Air samplingweldingsharpening welding < 6 Bq/a, 4,5 mBq for each electrode sharpening Main exposure from electrode sharpening Sternad, Kratzel, Forts. im Strahlensch. 1998 Urine excretion analysis 1,7 – 37,8 Bq/a 232Th Corresponding to 0,7 – 7,6 mSv/a effective dose Studies on radiation exposure of workers

11. Analytical Strategy • Analysis of welding electrodes • Inhalation of airborne welding fumes • Inhalation of dust from electrode sharpening • Excretion analysis of workers • Particle analysis

12. Analytical Strategy • Analysis of welding electrodes • WT10, WT20, WT30, WT40 • 1,0 - 4,0 % Thorium • Alpha Spectrometry • charakteristic isotope ratios228Th/232Th 230Th/232Th • Isotopic signature of electrodes

13. Analytical Strategy • Inhalation of airborne welding fumes • study of TIG welding during instruction courses for welders (standardized working environment) • Stationary air sampler: Gravikon PM4: 4 m³/h • Personal air sampler: Gilian Instr. Corp.: 3,5 l/h • mg/m³ air concentration of dust • Thorium: Alpha Spectrometry

14. Analytical Strategy

15. Analytical Strategy • Exposure to welding fumes • Personal air sampler: 0,2 – 1,0 mg/m³ • Stationary air sampler: 0,1 – 0,5 mg/m³ • Welding fumes contain ~ 3 % electrode material • Air concentration depends on worker and ventilation conditions

16. Analytical Strategy • Inhalation of dust from electrode sharpening • Electrode grinding machines with / without suction system • Stationary air sampler • Personal air sampler • ~ 90 mg / Electrode sharpening • 1 – 6 mg/m³ air concentration of dust • Thorium: Alpha Spectrometry

17. Analytical Strategy • Excretion analysis of workers • instruction courses for TIG welders at Austrian Institute for Welding Technology • Sampling during courses • 48 h urine sample, feces sample • Sampling after vacation • 48 h urine sample, feces sample • Alpha Spectrometry • Distinction of exposure from electrodes and natural background (food) by isotope vector

18. Analytical Strategy: Particle analysis • Welding robot • DC - TIG welding (Steel) • AC - TIG (Aluminium) • Measurements with impactor and stationary air sampler

19. Analytical Strategy: Particle analysis

20. Analytical Strategy: Particle analysis • Cascade Impactor • Berner - Impactor LPI Rot25 10 Stages 25 l/min • Measuring range: 0,016 µm - 16 µm • Determination of particle size distribution • Maximum concentration: 0,03 – 0,06 µm • Th - analysis: Alpha Spectrometry • Particle Analysis: SIMS

21. Conclusions • Current situation in Austria • Radon: Survey on Radon in water and houses exist • Radon: Additionally, some data are available on thermal spas • NORM: Fields of work have to be defined by legislation • Study on Th-exposure from TIG welding in progress

22. Thank you for your attention!