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. 24/2002 H. 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. Studies on radiation exposure of workers
Corresponding to 0,7 – 7,6 mSv/a effective dose
1,7 – 37,8 Bq/a 232Th
Urine excretion analysis
Sternad, Kratzel, Forts. im Strahlensch. 1998
Main exposure from electrode sharpening
welding < 6 Bq/a, 4,5 mBq for each electrode sharpening
Air sampling welding sharpening
Ludwig, Seitz, IRPA9, 1996
1 of 3 cases increased Inhalation
welding to 3,6 Bq/a sharpening to 0,8 Bq/a
Tietze et al., Schweißen&Schneiden 1998
Possible risk exists (AC-TIG)
< 0,1 to 144 Bq/a 232Th incorporation
Ludwig et al., Health Phys. 1999

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 ratios 228Th/232Th Th/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
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 Rot 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!