1. International Atomic Energy Agency ASSESSMENT OF OCCUPATIONAL EXPOSURE DUE TO INTAKE OF RADIONUCLIDES Designing a Programme for Monitoring Occupational Exposure

2. International Atomic Energy Agency Designing a Programme for Monitoring Occupational Exposure - Unit objectives The objective of this unit is to outline the steps principles and issues involved in designing an occupational exposure monitoring programme. The module will include the basis for monitoring, elements of programme design, use of reference levels and individual monitoring services. At the completion of this module, the student should understand the principles of occupational monitoring programme design and how to approach establishing programme elements.

3. International Atomic Energy Agency Designing a Programme for Monitoring Occupational Exposure - Module Outline Occupational Exposure: An Introduction Occupational Exposure Monitoring and Assessment Monitoring Programme Types Designing a Monitoring Programme Reference Levels Individual Monitoring Service Customer Related Issues

4. International Atomic Energy Agency Occupational Exposure: An Introduction

5. International Atomic Energy Agency Definition of Occupational Exposure ILO “The exposure of a worker received or committed during a period of work.” BSS “All exposure of workers incurred in the course of their work, with the exception of exposure excluded from BSS and exposure from practices or sources exempted by the BSS” (K-40, Schedule I - BSS).

6. International Atomic Energy Agency Occupational Exposure - Natural radiation l Naturally Occurring Radioactive Materials - NORM l Air crew exposure to cosmic radiation l IAEA programme of work to address these issues l Information on radioactivity levels, exposure conditions, and chemical and physical characteristics of airborne pollutants l Assessment of air crew exposure

7. International Atomic Energy Agency Determination of Occupational Exposure

8. International Atomic Energy Agency Types of occupational exposure l Normal exposure: man made, predictable and controlled. l Potential exposure: may occur but controlled. l Emergency exposure: intervention is needed. l Chronic exposure: elevated environmental radiation (radon, etc.), remedial action is needed.

9. International Atomic Energy Agency Need to monitor occupational exposure BSS, Appendix I : Occupational Exposure, ¶ I.32. “The employer of any worker, as well as self- employed individuals, and the registrants and licensees shall be responsible for arranging for assessment of the occupational exposure of workers, on the basis of individual monitoring where appropriate, and shall ensure that adequate arrangements be made with appropriate dosimetry services under an adequate Quality Assurance Programme.”

10. International Atomic Energy Agency Operational monitoring l The range of activities involved in dose assessment, including individual and workplace monitoring l Assessment of occupational exposure is a key element in achieving effective optimization and dose limitation l The general objective of operational monitoring programmes is to provide the assessment of workplace conditions and individual exposures

11. International Atomic Energy Agency Operational monitoring l Assessment of internal radiation exposure l Assessment of external exposure l Individual dose assessment

12. International Atomic Energy Agency Monitoring is based on workplace area classification Controlled Area “Any area in which specific protection measures and safety provisions are or could be required for: (a) controlling normal exposures or preventing the spread of contamination during normal working conditions; and (b) preventing or limiting the extent of potential exposures.” BSS I.21

13. International Atomic Energy Agency Monitoring is based on workplace area classification is crucial Supervised Area “Any area not designated as a controlled area but for which occupational exposure conditions are kept under review even though specific protective measures and safety provisions are not normally needed.” BSS I.24

14. International Atomic Energy Agency Occupational monitoring requirements l Any worker normally working in a controlled area, or l who occasionally works in a controlled area, and l may receive significant occupational exposure, l shall be provided individual monitoring where u appropriate, u adequate and u feasible

15. International Atomic Energy Agency Occupational monitoring requirements l When individual monitoring is, u inappropriate, u inadequate or u not feasible, l Occupational exposure assessment should be based on, u workplace monitoring, and u information about locations and durations of worker exposure

16. International Atomic Energy Agency Individual monitoring is not required for workers regularly employed in a supervised area or who enters a controlled area only occasionally, however, u Occupational exposure worker shall be assessed. u Assessment is to be based on workplace or individual monitoring results. Occupational monitoring requirements

17. International Atomic Energy Agency Occupational Exposure Monitoring and Assessment

18. International Atomic Energy Agency Assessment of exposure includes, l Individual monitoring l Workplace monitoring l Interpretation of results and dose assessment l Accuracy requirements l Dosimeter type testing l Quality Assurance and Quality Control l Performance testing l Record keeping and reporting

19. International Atomic Energy Agency Assessment of occupational exposure l Assessment of occupational exposure involves assessment of both the external and internal exposure components. l Total effective dose, E t, at any time, t, is the sum of the external and internal exposure components.

20. International Atomic Energy Agency Assessment of occupational exposure The following equation is used for assessment of occupational exposure and demonstration of compliance with dose limits: Where, H P (10) is the personal dose equivalent, e(g) j, ing is the dose coefficient for ingestion, I j,ing is the intake from ingestion, e(g) j,inh is the dose coefficient for inhalation, and I j,inh is the intake from inhalation

21. International Atomic Energy Agency Monitoring includes, Measurements related to the assessment or control of exposure to radiation and radioactive material Interpretation of the measurement results including those for the individual and those made in the workplace Assessment of measurement results and interpretation

22. International Atomic Energy Agency Monitoring for occupational exposure is done through; l Individual monitoring l Workplace monitoring

23. International Atomic Energy Agency General requirements for individual monitoring Assessment of the occupational exposure of workers on the basis of individual monitoring. l Any worker normally employed in a controlled area, or occasionally works in a controlled area and may receive significant exposure. l The nature, frequency and precision of individual monitoring is based on the magnitude and possible fluctuations of exposure levels, and the likelihood and magnitude of potential exposure.

24. International Atomic Energy Agency Objectives for individual monitoring 1.Demonstration of good working practices which indicate the adequacy of supervision, training and engineering standards. 2.Estimation of the actual radiation exposure of workers, to demonstrate compliance with legal requirements. 3.Evaluation and development of operating procedures.

25. International Atomic Energy Agency Objectives for individual monitoring 4.Provision of information which can be used to motivate workers to reduce their exposure. 5.Provision of information for the evaluation of dose in the event of accidental exposure. 6.Risk benefit analysis. 7.Medical records and epidemiological studies.

26. International Atomic Energy Agency Workplace monitoring l Depends on the levels of ambient dose equivalent and activity concentration. l Should be sufficient for u evaluation of the radiological conditions in all workplaces; u exposure assessment in controlled areas and supervised areas; and u review of the classification of controlled and supervised areas.

27. International Atomic Energy Agency Workers have responsibilities l Follow any applicable rules and procedures for protection and safety l Use properly the monitoring devices and the protective equipment and clothing provided l Provide the employer such information on their past and current work as is relevant to ensure effective and comprehensive protection and safety l Accept such information, instructions and training concerning protection and safety

28. International Atomic Energy Agency Monitoring Programme Types

29. International Atomic Energy Agency Monitoring types are related to objectives l Routine l Task-related l Special

30. International Atomic Energy Agency Routine monitoring l Associated with continuing operations l Intended to demonstrate that the working conditions, including the levels of individual dose, remain satisfactory, and meet regulatory requirements. l Largely confirmatory in nature, but underpins the overall operational monitoring programme

31. International Atomic Energy Agency Task-related monitoring l Applies to a specific operation. l Provides data to support the immediate decisions on the management of the operation. l May also support the optimization of protection.

32. International Atomic Energy Agency Task-related monitoring If radiation fields remain constant throughout the operations, l preliminary surveys are usually sufficient, l but repeated surveys before each series of operations are recommended. l Continued measurements are needed throughout the operation, l if the operations influence the dose equivalent rates or if the radiation fields may be variable.

33. International Atomic Energy Agency Special Monitoring l Investigative in nature. l Typically for a situation in the workplace where insufficient information is available to demonstrate adequate control. l Intended to provide detailed information in order to detect problems and to define future procedures.

34. International Atomic Energy Agency Special Monitoring Should normally be undertaken, l at the commissioning stage of new facilities, l following major modifications either to facilities or procedures, or l when operations are being carried out under abnormal circumstances, such as an accident.

35. International Atomic Energy Agency Designing a Monitoring Programme

36. International Atomic Energy Agency Designing a monitoring programme 1.Determine programme requirements: - Regulation - License requirements - Legal protection 2.Evaluate the radiation environment: - Workplace hazard - Intensity of sealed sources - Type of radionuclides (Energy, T½, Activity) - Particle sizes - General metabolism - Dosimetric properties of the radionuclides

37. International Atomic Energy Agency Designing a monitoring programme 3.Evaluate available monitoring capabilities: - Equipment available - Detection limits - Alternative resources 4.Assess the need of different software and hardware: - Interface with equipment - Databases - Dose calculation algorithms

38. International Atomic Energy Agency Designing a monitoring programme 5.Define the specific objective of the programme or task: - Criteria for worker selection for monitoring 6.Define the programmatic elements for each radionuclide of interest: - Monitoring frequency - Reference levels - Dose assessment methodology - Follow-up actions in case of overexposure

39. International Atomic Energy Agency Designing a monitoring programme 7.Methods to be applied in case of radiological emergency 8.Determine QA requirements 9.Write standard operating procedures 10.Train employees in performing the standard operating procedures before they are implemented

40. International Atomic Energy Agency Designing a monitoring programme 11.Implement the standard operating procedures 12.Perform periodic programme re-assessment and adjustment

41. International Atomic Energy Agency 41 Designing a monitoring programme Assess working conditions Workplace characteristics Activity characteristics Source characteristics Selection of the workers to be monitored Selection of the monitoring techniques Selection of the monitoring frequency Management approval Established conditions FacilitiesEquipmentStaffBudgetQA system Calibration Organization of the monitoring programme Monitoring Assessment of the intakes and doses

42. International Atomic Energy Agency Reference Levels

43. International Atomic Energy Agency Reference levels Reference level - predetermined value for: l any of the quantities, l which requires a certain course of action if, l the value of the level for a quantity is exceeded

44. International Atomic Energy Agency Reference levels l Reference levels often refer to effective dose, but may apply to other quantities These are called derived reference levels l A reference level is not a limit in itself. l The reference level action may range from just recording the value to intervention.

45. International Atomic Energy Agency Reference levels l Recording level l Investigation level l Action level

46. International Atomic Energy Agency Recording level Value of dose equivalent, intake or detected activity above which a result should be retained The recording level should be based on: 1/10 of the fraction of the annual limit, corresponding to the period of time of which the individual monitoring measurement refers about 0.17 mSv for monthly monitoring periods A result smaller than the recording level may be discarded and treated as zero in assessing the dose or intake

47. International Atomic Energy Agency Recording level l Discarding low doses may not help motivate the worker and the management to improve radiation protection and strive for lower exposure of the individual. l So, it may be useful to record all doses above the limit of detection, however, l Unrealistic attention should not be given to exposures which result in very small. l Therefore, it is suggested that the recording level is taken as the detection threshold of the dosimetry system

48. International Atomic Energy Agency Investigation levels l Investigation level - a value of dose equivalent or intake, usually for a single measurement, above which the result justifies further investigation l It is often appropriate to set the investigation level at 3/10 of the fraction of the relevant annual limit corresponding to the individual monitoring period

49. International Atomic Energy Agency Investigation levels l For monthly monitoring or exchange periods, IL= 20 mSv x 0.3 / 12 = 0.54 mSv l Below the investigation level, further review is not needed. l It may will be necessary to change investigation levels, for example as conditions in a workplace change.

50. International Atomic Energy Agency Action level l Level that for remedial or protective action. l Applies to chronic exposure or emergency exposure situations. l Action levels often serve to protect the public. l Have occupational exposure relevance in chronic exposure situations. l Particularly relevant to workplace radon exposure.

51. International Atomic Energy Agency Individual Monitoring Service

52. International Atomic Energy Agency Individual Monitoring Service (IMS) l Individual monitoring is carried out by an IMS. l IMS may be: u Component of licensee organization, u Commercial dosimetry service, u Service provided by regulatory authority, or u Service shared jointly by multiple licensees

53. International Atomic Energy Agency Individual Monitoring Service (IMS) l Several factors effect IMS selection: u Scope of radiation protection programme, u Number of workers to be monitored, u Financial resources, u Available IMS outside resources l Example of a small practise using commercial service is a dentist office

54. International Atomic Energy Agency Objectives of an Individual Monitoring Service l Supply customers with appropriate dose determination techniques : u with a high degree of reliability u with adequate accuracy; and u at an acceptable cost l Provide results within a reasonable timescale l Store the results in a secure dose record keeping system

55. International Atomic Energy Agency Elements of an IMS l System for unique sample identification l Facilities for assessment of intakes l An administrative system which includes a database containing details of customers l A secure dose record keeping system suitable for preserving and updating records for individual users l Means for ensuring calibration traceability

56. International Atomic Energy Agency IMS Basic Organisational Structure l Routine dosimetry. l Administration and finances. l Calibration section. l Record keeping. l Quality Management System

57. International Atomic Energy Agency IMS Basic Organisational Structure l Desirable to have a capability for investigation, development and research l Mailing center l Workshop l Customer relations section

58. International Atomic Energy Agency IMS Management, Organisation and Administration l Related to national legislation and are obviously dependent on local circumstances l Number of measurements to be carried out l Number of customers served

59. International Atomic Energy Agency Sequence of an IMS service order l Receipt of an order from a customer l Preparation of an invoice for the service and the offer of a contract giving details of the service and the terms and conditions involved l Receipt of payment from the customer (if applicable)

60. International Atomic Energy Agency Sequence of an IMS service order l Registration of the customer and employees into the system and the record keeping system l Preparation of the sample containers to be supplied for each issue period l Sample container dispatch to the customer

61. International Atomic Energy Agency Sequence of an IMS service order l Sample return to the IMS by the customer at the end of the wear period l Sample evaluation within the time scale prescribed by regulators l Entry of the sample analysis results in the data base

62. International Atomic Energy Agency Sequence of an IMS service order l Report of the results to the customer and, if required, to the regulators or their appointees, within the timescale laid down by the regulators. l Issue of a Termination Report. l Storage of personnel dosimetry records in a form approved by and for the time required by the regulators.

63. International Atomic Energy Agency Customer Related Issues

64. International Atomic Energy Agency Customer Related Issues l Several operational issues need to be resolved and agreed with the “customer” l Customers are organizational elements that require dosimetry services u Individuals within the dosimetry service u Other sections within the dosimetry service organization u Other organizations under the same employer u Outside companies or employers

65. International Atomic Energy Agency Customer related issues l Radionuclides to be assayed l Monitoring frequency l Measurement or analytical method(s) to be used l System of identification for those to be monitored l Dose record keeping l Reporting of results l Accessibility, privacy

66. International Atomic Energy Agency Customer related issues l Interpretation of results u quantities u dose limits u natural background u net dose u lower- and upper limits of detection l Information needed from the customer

67. International Atomic Energy Agency Customer related issues l Fee for service l Immediate reporting in case of unusually high doses (Telephone, Fax, Email, etc.) l Emergency processing l Technical, scientific, legal advice and/or assistance (when and how to deal with authorities)

68. International Atomic Energy Agency References FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS, INTERNATIONAL ATOMIC ENERGY AGENCY, INTERNATIONAL LABOUR ORGANISATION, OECD NUCLEAR ENERGY AGENCY, PAN AMERICAN HEALTH ORGANIZATION, WORLD HEALTH ORGANIZATION, International Basic Safety Standards for Protection against Ionizing Radiation and for the Safety of Radiation Sources, Safety Series No. 115, IAEA, Vienna (1996). INTERNATIONAL ATOMIC ENERGY AGENCY, INTERNATIONAL LABOUR OFFICE, Occupational Radiation Protection, Safety Standards Series No. RS-G-1.1, IAEA, Vienna (1999). INTERNATIONAL ATOMIC ENERGY AGENCY, Assessment of Occupational Exposure Due to Intakes of Radionuclides, Safety Guide No. RS-G-1.2, ISBN 92-0-101999-8 (1999). INTERNATIONAL COMMISSION ON RADIOLOGICAL PROTECTION, General Principles for the Radiation Protection of Workers, Publication No. 75, Pergamon Press, Oxford and New York (1997). INTERNATIONAL ATOMIC ENERGY AGENCY, Indirect Methods for Assessing Intakes of Radionuclides Causing Occupational Exposure, Safety Guide, Safety Reports Series No. 18, ISBN 92-0-100600-4 (2002).