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The Internal Radiation Hazard Ionising Radiation Regulations 1999 Dose Limits and Unsealed Isotopes

The Internal Radiation Hazard Ionising Radiation Regulations 1999 Dose Limits and Unsealed Isotopes. Brief History :. 1895 - Roentgen discovers X-rays 1896 - Becquerel announces discovery of ‘other’ rays 1896 - Thompson deliberately overexposes finger

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The Internal Radiation Hazard Ionising Radiation Regulations 1999 Dose Limits and Unsealed Isotopes

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  1. The Internal Radiation Hazard Ionising Radiation Regulations 1999 Dose Limits and Unsealed Isotopes Janice Brock University RPO

  2. Brief History : • 1895 - Roentgen discovers X-rays • 1896 - Becquerel announces discovery of ‘other’ rays • 1896 - Thompson deliberately overexposes finger • 1900 - Generally excepted that frequent/intensive use causes burns • 1904 - Rollins demonstrates that X-rays can kill guinea pigs Janice Brock University RPO

  3. 1915 - British Roentgen Society issues ‘advice’ to X-ray users 1925 - Mutscheller proposes ‘permissible exposure limit’of 1/100 of dose producing skin burn (equivalent to 2 mSv/day) 1928 - Roentgen (R) adopted as the unit for measuring dose 1930 - Formation of International X-ray and Radium Protection Committee Janice Brock University RPO

  4. 1936 - ACXRP recommend tolerance dose of 0.1 R/day ~250 mSv/yr 1942 - Wollan appointed first ‘health physicist’ by Manhattan Group 1946 - Nobel Prize awarded to Muller for work on the genetic effects 1950 - International Committee on Radiological Protection Janice Brock University RPO

  5. Uses for ionising radiation Shoe-Fitting Fluoroscope (ca. 1930-1940) Janice Brock University RPO

  6. Janice Brock University RPO

  7. The Lifestone Cigarette Holder (ca. 1964) Janice Brock University RPO

  8. Fuel Saving Device (ca.2005) Janice Brock University RPO

  9. Radon Health Mine (Present Day) Janice Brock University RPO

  10. Current UK Legislation • International Commission on Radiological Protection (ICRP). • Radioactive Substances Act 1993 (RSA93). • Ionising Radiation Regulations 1999 (IRR99). Janice Brock University RPO

  11. ICRP - Independent registered UK charity 1. Justification 2. Optimisation (ALARP principle) 3. Dose limitations Janice Brock University RPO

  12. Radioactive Substances Act 1993 : Registration : all sources accounted for Authorisation : radioactive waste minimization Accountability : cradle to grave Governing Body : SEPA Justification : next slide Janice Brock University RPO

  13. Justification: Radioactive Substances Act 1993is a legal requirement for applications to use ionising radiation. No practice involving the use of ionising radiation shall be allowed unless its introduction produces a net benefit – trivial uses not allowed. Janice Brock University RPO

  14. When formulating a justification take into account the following: Appropriateness of the procedure Risk versus benefit Radiological assessment Safety considerations Possible environmental impact Dose limitations – set by UK government Optimisation – next slide Janice Brock University RPO

  15. Optimisation: • Radioactive Substances Act 1993 • Suitable controls are in place to address all significant hazards • Risks are kept as low as reasonably practicable (ALARP) • Procedures to continually review risk controls • Accurate record keeping Janice Brock University RPO

  16. Ionising Radiation Regulations 1999 Health and safety – all radiation employers must fully comply Emphasis is on dose limitation – National limits Comprehensive Approved Code of Practice Dose Assessment Governing body – Health and Safety Executive (HSE) Janice Brock University RPO

  17. Dose Limitation: IRR99 Radiation dose limits for each population group must not be exceeded. Dose assessments – do not include exposures received from medical treatments or natural sources. Dose records must be kept for each employee. Dose monitoring and record keeping provided by an Independent body – e.g. University uses Landaur. Janice Brock University RPO

  18. ICRP 60 (1983) - Dose limit recommendations Incorporated into IRR 1999 Stochastic effects Radiation worker > 18 yrs - 20 mSv (effective) / yr. Janice Brock University RPO

  19. Members of the Public Average annual dose of 1 mSv/yr averaging over 5 years Dose in any one year not exceeding 5 mSv. UK further restricts that contributions from discharges from nuclear installations must not exceed 0.5 mSv/yr Janice Brock University RPO

  20. Deterministic effects : No need for separate organ dose limit if 20 mSv/yr adopted Skin, hands, forearms 500mSv/yr Feet and ankles 500 mSv/yr Lens of eye 150 mSv/yr Janice Brock University RPO

  21. Radiation Dose Limits & ICRP 60 • Background Radiation : • Gamma - from rock and soil, Glasgow ~ 0.3 mSv/yr • Cosmic - high energy particles from space bombard • atmosphere producing mu mesons and neutrons resulting in ~ 0.3 mSv/yr Janice Brock University RPO

  22. 40K - naturally occurring isotopes of potassium, uranium, thorium and carbon ~ 0.2 mSv/yr Radon - gaseous decay product of uranium, can contribute an effective maximum annual dose of ~ 1.2 mSv Depending on where you live you could receive a background dose of up to 2 mSv/yr Janice Brock University RPO

  23. Dose Assessment: Absorbed dose DT is measure of dissipated energy/unit mass Unit is the 1Gy 1Gy = Dissipation of 1 Joule/kg Equivalent dose HT = DT x WR Measured in Seiverts 1 Gy = 1 Sv for beta and 20 Sv for alpha. Effective dose E = HT x WT, Measured in Seiverts Janice Brock University RPO

  24. The Effects on Health : Deterministic effect : An effect which is known to occur above a threshold limit, severity increases with increasing dose. Stochastic effect : Effect is not certain to occur but there is a probability of occurrence. Janice Brock University RPO

  25. Dose Assessment: IRR99 Annual Limit on Intake (ALI) Intake (of radioisotope) which would give an effective dose equal to the annual dose of a radiation worker when we calculate the accumulated dose over a period of 50 years. Janice Brock University RPO

  26. The value of ALI for a particular isotope depends on : The route of entry The chemical properties of the isotope The particle size (especially in the case of inhalation) The types and energies of the radiation and the physical and biological half-life Concentration in particular organs, etc E.g. 125I is given as 2.7 MBq (inhalation) and 1.3 MBq (ingestion) Janice Brock University RPO

  27. Dose Assessment: Committed effective dose per unit intake, expressed in Sv/Bq More information given than for ALI e.g. - age of exposed individuals - status (public or occupational) - gut transfer factors - three default lung absorptions -1 E.g. 125I - 1.5E-8 Sv/Bq (ingestion) 5.3E-9 Sv/Bq (inhalation) Janice Brock University RPO

  28. Dose Assessment: By measurement • Whole body monitor • Liquid scintillation • Gamma spectroscopy • Portable scintillation counter • Personal dosimeter Janice Brock University RPO

  29. e.g. Thyroid monitoring for 125I intakes 125I accumulates in the Thyroid gland A type 5.42 probe held at Adams apple ~ 10 cps for 1 kBq intake 1 kBq intake = 1.35 mSv equivalent dose = 70 Sv effective Janice Brock University RPO

  30. Working with Unsealed Isotopes – The Dangers Internal contamination with radioisotopes can happen through various routes: 1. Inhalation 2. Ingestion 3. Injection 4. Absorption Janice Brock University RPO

  31. Dangers in the Use of Unsealed Radioactive Materials • Most hazardous activities: • Opening a vial in close proximity - high dose rate • Dispensing from stock solutions – vapour, droplets, aerosols Janice Brock University RPO

  32. Use personal protection : E.g. lab coat, safety glasses/face shield, disposable gloves, disposable apron, appropriate radiation shield. Additionally : Personal dosimeter, consider finger badge for some isotopes e.g. P32, contamination monitor. Janice Brock University RPO

  33. Precautions in the Use of Unsealed Radioactive Materials Setting up the experiment : Use the least radiotoxic isotope Use the minimum activity required Know the physical and chemical properties of the isotope Use ‘dummy’ run experiments without radioisotopes Janice Brock University RPO

  34. Working Procedures : Laboratory coats must be worn at all times. Eating, drinking, smoking or applying cosmetics are prohibited. No mouth pipetting. Work must not be carried out by a person with an undressed cut or abrasion below the wrist. Gloves must be worn. Monitor for contamination radiation levels must be carried out routinely. Gloves and clothing must be monitored after handling radioactive materials. Janice Brock University RPO

  35. Working Procedures Continued : Hands must be washed before leaving the laboratory after handling radioactive materials. Work should be carried out in lined trays. All apparatus used for radioactive materials must be labelled with radioactive warning tape. Radioactive waste must be placed in an appropriate container and its radioactivity recorded, along with the relevant date. Containers for radioactive materials must not be directly held in the hand if this would cause significant doses to fingers. Particular attention must be paid to this possibility. Radionuclides emitting penetrating radiations must be adequately shielded. In the laboratory, records must be kept of all stocks and radioactive waste Contamination must be cleared up without delay. Janice Brock University RPO

  36. Radioactive Waste Three routes for disposal : 1. Liquid waste, via disposal sink. 2. Solid waste to authorised contractor, via RPS. 3. Gaseous disposal, via authorised fume cupboard. Janice Brock University RPO

  37. Radioactive Liquid Waste: Aqueous waste should be diluted before disposal Use only marked disposal sinks Run water through sink to disperse waste (avoid splashes) Log all activity discharged – very important SEPA will ask you to justify your disposal figures Do not exceed your monthly disposal limits expensive! No organic solvents Janice Brock University RPO

  38. Radioactive Solid Waste : Segregate the waste into 3H/14C; 32P; others. Dispose to marked bins only. Do not put non-radioactive waste into these bins. Do not put biohazard waste into these bins. Do not put radioactive waste into ‘normal’ waste bins. Contents of bins must be labelled. Units must be in Bq, kBq, MBq etc – legal document. Janice Brock University RPO

  39. Radioactive Waste Label Janice Brock University RPO

  40. Precautions in the Use of Unsealed Radioactive Materials No pipetting by mouth. No eating, drinking, smoking or applying cosmetics. Use disposable handkerchiefs. Wear labcoat (buttoned up). Wear radiation dosimeter (chest height). Wear gloves. Wear plastic apron for high activity solutions Work in fume cupboard Janice Brock University RPO

  41. Contamination Monitoring Janice Brock University RPO

  42. Decontamination Areas Decontaminate areas with Decon and work out to in ‘Safe’ level is about 3 Bq/cm2 ‘Fixed’ contamination must not exceed 3.5 Svhr-1 Janice Brock University RPO

  43. Skin Contamination : Wash (not scrub) skin with soap and running water Do not use Decon on skin Do not break the skin Report all accidents and spillage's immediately to your dept. RPS. If they are not available contact the University Radiation Protection Service (4471/5878) for advice Janice Brock University RPO

  44. Summary : The internal hazard is the principal hazard encountered in the use of unsealed radioactive materials. There is NO shielding from an internal intake. There is NO distance protection from an internal intake. Irradiation occurs 24 hours/day. Emissions will be dissipated in the cells of the body. Certain isotopes will concentrate in particular organs. Janice Brock University RPO

  45. Optimisation: Suitable controls are in place to address all significant hazards Risks are kept as low as reasonably practicable (ALARP) Procedures to continually review risk controls Dose Limitation: Radiation dose limits for each population group must not be exceeded. When calculating dose limits – do not include exposures received from medical treatments or natural sources. Dose records must be kept for each employee. Dose monitoring and record keeping provided by an Independent body – e.g. University uses Landaur. Janice Brock University RPO

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