VII-13.
Best practices for the distribution, use and disposal of thoriated tungsten electrodes are described in Ref. [VII–1] and briefly summarized in the following.
VII-14.
While the risks from the distribution, use and disposal of thoriated tungsten electrodes are extremely low, it is still advisable to follow best practices at all times. It is advisable that those who need to handle or work with thoriated tungsten electrodes adopt the following practices:
Keep the number of thoriated tungsten electrodes in stock to the minimum necessary for those welding applications that require thoriated tungsten electrodes.
Store thoriated tungsten electrodes that are not in use in their boxes in a secure location that is accessible only to authorized persons.
Avoid carrying thoriated tungsten electrodes on the person.
Be familiar with safety procedures governing welding operations including those relating to grinding the tips of thoriated tungsten electrodes.
Keep non-essential personnel clear of welding and grinding operations at all times.
Wear a dust mask while carrying out grinding operations.
Work in a dedicated, well ventilated area that is fitted with a dust extraction system or local exhaust ventilation wherever possible.
Use a dedicated grinding wheel, fitted with a protective viewing screen, for grinding thoriated tungsten electrodes.
Grinding of thoriated tungsten electrodes is conducted by each individual welder whenever this is feasible.
Cleanup and remove deposited dust particles from thoriated tungsten electrodes with a vacuum system. If a vacuum system is not practicable, damp down the dust prior to collection.
Collect disused thoriated tungsten electrodes and dust resulting from welding and grinding operations on a daily basis and disperse in waste intended for landfill.
Do not dispose of disused thoriated tungsten electrodes and dust with scrap metal destined for recycling.
Where possible, replace thoriated tungsten electrodes with non-radioactive electrodes incorporating oxides such as cerium oxide or lanthanum oxide.
REFERENCES TO ANNEX VII
[VII–1] BURGESS, W.A., Recognition of Health Hazards in Industry: A Review of Materials and Processes, John Wiley and Sons, New York (1981).
[VII–2] RADIOLOGICAL PROTECTION INSTITUTE OF IRELAND, Guidance Notes for Welding Companies Using Thoriated Tungsten Electrodes, RPII, Dublin (2008).
[VII–3] JANKOVIC, J.T., UNDERWOOD, W.S., GOODWIN, G.M., Exposures from thorium contained in thoriated tungsten welding electrodes, Am. Ind. Hyg. Assoc. J. 60 3 (1999) 384–389.
[VII–4] NIEBOER, E., THOMASSEN, Y., CHASHCHIN, V., ODLAND, J.Ø., Occupational exposure assessment of metals, J. Environ. Monit. 7 (2005) 412.
[VII–5] INTERNATIONAL ATOMIC ENERGY AGENCY, IAEA Safety Glossary: Terminology Used in Nuclear Safety and Radiation Protection, 2007 Edition, IAEA, Vienna (2007).
[VII–6] NUCLEAR REGULATORY COMMISSION, Systematic Radiological Assessment of Exemptions for Source and Byproduct Materials, Rep. NUREG-1717, Office of Nuclear Regulatory Research, Washington, DC (2001).
[VII–7] US DEPARTMENT OF ENERGY, Safety Bulletin No. 2007-04, June 2007, Office of Health, Safety and Security, US DOE, Washington DC (2007).
[VII–8] OAK RIDGE ASSOCIATED UNIVERSITIES, Thorium Containing Welding Rod (1990s) (1999), https://www.orau.org/ptp/collection/consumer%20products/weldingrod.htm
[VII–9] McDOWELL-BOYER, L.M., Estimated Radiation Doses from Thorium and Daughters Contained in Thoriated Welding Electrodes, Rep. NUREG/CR-1039, ORNL/NUREG/TM–344, Oak Ridge Natl Lab., Washington, DC (1979).
[VII–10] SAITO, H., HISANAGA, N., OKADA, Y., HIRAI, S., ARITO, H., Thorium-232 exposure during tungsten inert gas arc welding and electrode sharpening, Ind. Health 41 3 (2003) 273–278.
[VII–11] EUROPEAN COMMISSION, FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS, INTERNATIONAL ATOMIC ENERGY AGENCY, INTERNATIONAL LABOUR ORGANIZATION, OECD NUCLEAR ENERGY AGENCY, PAN AMERICAN HEALTH ORGANIZATION, UNITED NATIONS ENVIRONMENT PROGRAMME, WORLD HEALTH ORGANIZATION, Radiation Protection and Safety of Radiation Sources: International Basic Safety Standards, IAEA Safety Standards Series No. GSR Part 3, IAEA, Vienna (2014).