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Natural activity and inhalation problems

Electro-thermal elemental phosphorus production and workplace related affairs with natural radionuclides. Natural activity and inhalation problems Wim Erkens (Thermphos). Overview. Process Enrichment and surface contamination

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Natural activity and inhalation problems

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  1. Electro-thermal elemental phosphorus production and workplace related affairs with natural radionuclides Natural activity and inhalation problems Wim Erkens (Thermphos) wim erkens

  2. Overview • Process • Enrichment and surface contamination • Measurement technique (inhalation) • Measurement results • Classification as exposed workers • Risk communication • Conclusions wim erkens

  3. wim erkens

  4. Use of elemental phosphorus and derivates wim erkens

  5. Phosphorus slag leaving the furnace into a pan wim erkens

  6. The pan is being emptied wim erkens

  7. The pan is being emptied wim erkens

  8. The material is being removed from the slag beds after cooling and elaborated wim erkens

  9. , Thehydraulic slag mixture is used in road construction wim erkens

  10. The hydraulic slag mixture is being spread wim erkens

  11. A top layer is being applied wim erkens

  12. Surface contamination inside equipment • Up to hundreds of Bq per cm2 surface contamination inside equipment • Work which disperses this contamination can cause a dose rate of approximately 1 mSv per hour • Breathing air protection measures are necessary wim erkens

  13. Safety procedures • Entering process vessels, furnaces etc: • < 0.25 Bq per cm2 : no measures • > 0.25 < 10 Bq per cm2 : half mask (PF10) • > 10 Bq per cm2 : full face mask (PF 100-500) wim erkens

  14. Mask with a sturdy construction and broad flexible sealing edge wim erkens

  15. Protection factor: PF: laboratory conditions 50 PF: BS 20 PF: Dutch Labor inspectorate 10 wim erkens

  16. Full face mask with remote air supply wim erkens

  17. Improvements (dose reduction) • New floors which can be cleaned easily • Central vacuum cleaner • Process automation • Continuous cleaning operations • Slag beds removed from furnace building • Improved ventilation (iron beds) • Measurement programs • Breathing air protection measures (procedures) wim erkens

  18. Measurement technique • Air sampling: 120 litre per h through filter • Activity on filter is measured • Calculation of the activity in the air Bq/m3 • Dose estimation: • breathing rate : 1.2 m3 per h • activity in the air • DCC: Sv per inhaled Bq (particle size dependent) • Annual dose based on 1600 hours wim erkens

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  20. Air pump and IOM filter holder with filter wim erkens

  21. Monodisperse approach with LUDEP (GSD 1, no distribution): No AMAD Aerodynamic Median Activity Diameter Geometrical Standard Deviation wim erkens

  22. A joint measurement setup comprising various measuring devices wim erkens

  23. Industrial hygienic approach wim erkens

  24. The inside of a cyclone wim erkens

  25. Cascade-impactor wim erkens

  26. Collection efficiency % Cascade impactor wim erkens

  27. wim erkens

  28. Cascade-impactor: the first separation stage wim erkens

  29. Cascade-impactor: the third separation stage wim erkens

  30. Cascade-impactor: the seventh separation stage Dust that can reach the deepest parts of the lung wim erkens

  31. Dust producing for tests wim erkens

  32. Dust producing for tests wim erkens

  33. The thoracic cyclone approach wim erkens

  34. Conclusions measurement technique • Determination of dust distribution is a prerequisite for correct inhalation dose assessment • However: not simple: cascade impactor • Thoracic cyclone as a practical approach wim erkens

  35. Measurement results • Comparison ICRP30 ICRP66 lung models with IOM filter holder and with thoracic cyclone • Between brackets: cleaning operator wim erkens

  36. Exposed workers legislation • Based on directive 96/29/EURATOM and Dutch law. • Above 1 mSv per year Category B • Above 6 mSv per year Category A • Based on this law and the result of the dose measurements Thermphos classified the workers to exposed workers (300 people involved in phosphorus production) wim erkens

  37. Consequences classification • No extra medical examination • Dose monitoring system • Reporting the dose to NDRIS • National Dose Registration and Information system • Dose is reported to the workers (they knew about the radioactivity approximately 15 years) wim erkens

  38. Workers information • They received comprehensive information on dose and risk on their home address. • A risk comparison is given to them • Going to work • Working activities • Smoking cigarettes (the greatest risk) • Dose risk in perspective accepted risks wim erkens

  39. Workers reaction • None (no unrest), • But 1 person told me: • “We know this whole issue of radioactivity for more then 15 years, but if you forgot to tell it to your wife, you have to explain something to her if she opens your letter with dose information” wim erkens

  40. Summary • Enrichment and surface contamination • Procedures and breathing air protection measures • Continuous cleaning • Process improvements • Measurement technique • Continues study to improve the measurements • Measurement results • Classification as Exposed workers • Risk communication • To put RA-risk in perspective with “accepted risks” wim erkens

  41. Conclusion • Natural radioactivity in processes like our Elemental Phosphorus production cause problems in the workplace. • You cannot ignore these problems from a dose point of view. • However: These problems are manageable. wim erkens

  42. For more information on the measurement technique a comprehensive (free) paper in PDF format is available: Erkens@thermphos.com wim erkens

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