IAEA International Atomic Energy Agency PART V: ASSESSMENT OF EXTERNAL AND INTERNAL EXPOSURES (OTHER THAN MEDICAL) Module V.1 - Assessment of occupational exposure due to external sources of radiation Lecture 1 – Individual monitoring programmes Postgraduate Educational Course in radiation protection and the Safety of Radiation sources

IAEA Lecture objectives The objective of this lecture is to outline the steps, principles and issues involved in designing an occupational exposure monitoring program. The lecture will include the basis for monitoring, elements of program design, use of operational levels and individual monitoring services. At the completion of this lecture, the student should understand the principles of occupational monitoring program design and how to approach establishing monitoring program elements. Module V.1 Lecture 1 - Individual monitoring programmes2

IAEA Occupational Exposure An Introduction Module V.1 Lecture 1 - Individual monitoring programmes3

IAEA Definition of Occupational Exposure ILO “The exposure of a worker received or committed during a period of work.” Module V.1 Lecture 1 - Individual monitoring programmes4

IAEA Definition of Occupational Exposure GSR “All exposure of workers incurred in the course of their work,”…… however:  Exposure due to natural sources is in general considered an existing exposure situation and is subject to the requirements stated in Section 5 of the GSR. Module V.1 Lecture 1 - Individual monitoring programmes5

IAEA Definition of Occupational Exposure However, the relevant requirements for planned exposure situations (occupational exposure) apply to: a) Exposure due to material in any practice specified in para. 3.1 of the GSR where the activity concentration in the material of any radionuclide in the uranium or thorium decay chains is greater than 1 Bq/g or the activity concentration of 40 K is greater than 10 Bq/g; b) Exposure due to 222 Rn and its progeny and 220 Rn and its progeny in workplaces in which occupational exposure due to other radionuclides in the uranium or thorium decay chains is controlled as a planned exposure situation; Module V.1 Lecture 1 - Individual monitoring programmes6

IAEA Definition of Occupational Exposure The relevant requirements for planned exposure situations (occupational exposure) also apply to:  (c) Exposure due to 222 Rn and 222 Rn progeny where the annual average activity concentration of 222 Rn in air in the workplace remains above the reference level established in accordance with para of the GSR after the fulfilment of the requirement stated in para Module V.1 Lecture 1 - Individual monitoring programmes7

IAEA Occupational Exposure – Existing exposure situations l Naturally Occurring Radioactive Materials - NORM l Air crew exposure to cosmic radiation l GSR Requirement 47: Responsibilities of the government specific to existing exposure situations The government shall ensure that existing exposure situations that have been identified are evaluated to determine which occupational exposures and public exposures are of concern from the point of view of radiation protection. Module V.1 Lecture 1 - Individual monitoring programmes8

IAEA Determination of Occupational Exposure Is the exposure received in the course of work and is the exposure amenable to control? GSR 1.42 Is the exposure a planned exposure situation with source or practice above the exemption limit (GSR Schedule 1)? The requirements for occupational exposure apply Is the exposure an emergency exposure situation and the actions to be taken do not include those listed in 4.15 of the GSR? Is the exposure an existing exposure situation where the Regulatory Authority deems that occupational exposure is a concern? GSR Reg. 47 Module V.1 Lecture 1 - Individual monitoring programmes9

IAEA Types of occupational exposure l Planned exposure situations: man made, predictable l Emergency exposure situations: intervention is needed. l Existing exposure situations: natural radioactivity or due to previous accidents. Module V.1 Lecture 1 - Individual monitoring programmes10

IAEA Occupational exposure assessment 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 the monitoring programs is to provide the assessment of workplace conditions and individual exposures Module V.1 Lecture 1 - Individual monitoring programmes11

IAEA Responsibility of occupational exposure assessment Occupational exposure assessment Employers, as well as self-employed persons, and registrants and licensees shall be responsible for making arrangements for assessment of the occupational exposure of workers, on the basis of individual monitoring where appropriate, and shall ensure that arrangements are made with authorized or approved dosimetry service providers that operate under a quality management system. Module V.1 Lecture 1 - Individual monitoring programmes12

IAEA Monitoring programs l Assessment of external exposure l Assessment of internal radiation exposure l Workplace monitoring l Individual dose assessment Module V.1 Lecture 1 - Individual monitoring programmes13

IAEA Monitoring is based on workplace area classification Controlled areas GSR Registrants and licensees shall designate as a controlled area any area in which specific measures for protection and safety are or could be required for: Controlling exposures or preventing the spread of contamination in normal operation; Preventing or limiting the likelihood and magnitude of exposures in anticipated operational occurrences and accident conditions. Module V.1 Lecture 1 - Individual monitoring programmes14

IAEA Monitoring is based on workplace area classification Supervised areas GSR Registrants and licensees shall designate as a supervised area any area not already designated as a controlled area but for which occupational exposure conditions need to be kept under review, even though specific measures for protection and safety are not normally needed Module V.1 Lecture 1 - Individual monitoring programmes15

IAEA Occupational monitoring requirements  GSR For any worker who usually works in a controlled area, or who occasionally works in a controlled area and may receive a significant dose from occupational exposure, individual monitoring shall be undertaken where appropriate, adequate and feasible. Module V.1 Lecture 1 - Individual monitoring programmes16

IAEA Occupational monitoring requirements l GSR 3.100: In cases where individual monitoring of the worker is inappropriate, inadequate or not feasible, the occupational exposure shall be assessed the basis of the results of workplace monitoring and information on the locations and durations of exposure of the worker. Module V.1 Lecture 1 - Individual monitoring programmes17

IAEA GRS For any worker who regularly works in a supervised area or who enters a controlled area only occasionally, the occupational exposure shall be assessed on the basis of the results of workplace monitoring or individual monitoring, as appropriate. Occupational monitoring requirements Module V.1 Lecture 1 - Individual monitoring programmes18

IAEA Occupational Exposure Monitoring and Assessment Module V.1 Lecture 1 - Individual monitoring programmes19

IAEA 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 management l Performance testing l Record keeping and reporting Module V.1 Lecture 1 - Individual monitoring programmes20

IAEA Assessment of occupational exposure l Assessment of occupational exposure involves assessment of both the external and internal exposure components. l The total effective dose, E is the sum of the external and internal exposure components. Module V.1 Lecture 1 - Individual monitoring programmes21

IAEA 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 Module V.1 Lecture 1 - Individual monitoring programmes22

IAEA 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 Module V.1 Lecture 1 - Individual monitoring programmes23

IAEA Monitoring for occupational exposure is made through; l Individual monitoring l Workplace monitoring Module V.1 Lecture 1 - Individual monitoring programmes24

IAEA 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 who 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. Module V.1 Lecture 1 - Individual monitoring programmes25

IAEA Objectives of 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. Module V.1 Lecture 1 - Individual monitoring programmes26

IAEA Objectives of 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. Module V.1 Lecture 1 - Individual monitoring programmes27

IAEA 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. Module V.1 Lecture 1 - Individual monitoring programmes28

IAEA Workers also 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. Module V.1 Lecture 1 - Individual monitoring programmes29

IAEA Monitoring program Types Module V.1 Lecture 1 - Individual monitoring programmes30

IAEA Monitoring types are related to objectives l Routine l Task-related l Special Module V.1 Lecture 1 - Individual monitoring programmes31

IAEA Routine monitoring (RS-G-1.1) 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 program Module V.1 Lecture 1 - Individual monitoring programmes32

IAEA Task-related monitoring (RS-G-1.1) 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. Module V.1 Lecture 1 - Individual monitoring programmes33

IAEA 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. Task-related monitoring (RS-G-1.1) Module V.1 Lecture 1 - Individual monitoring programmes34

IAEA Special Monitoring (RS-G-1.1) 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. Module V.1 Lecture 1 - Individual monitoring programmes35

IAEA 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. Special Monitoring (RS-G-1.1) Module V.1 Lecture 1 - Individual monitoring programmes36

IAEA Designing a monitoring program Module V.1 Lecture 1 - Individual monitoring programmes37

IAEA Designing a monitoring program 1.Determine program requirements: - Regulation - License requirements - Legal protection Module V.1 Lecture 1 - Individual monitoring programmes38

IAEA Designing a monitoring program 2.Evaluate the radiation environment: - Workplace hazard - Intensity of sealed sources - Type of radionuclides (Energy, T½, Activity) - Particle sizes - General metabolism Module V.1 Lecture 1 - Individual monitoring programmes39

IAEA Designing a monitoring program 3.Evaluate available monitoring capabilities: - Equipment available - Detection limits - Alternative resources Module V.1 Lecture 1 - Individual monitoring programmes40

IAEA Designing a monitoring program 4.Assess the need of different software and hardware: - Interface with equipment - Databases - Dose calculation algorithms Module V.1 Lecture 1 - Individual monitoring programmes41

IAEA Designing a monitoring program 5.Define the specific objective of the program or task: - Criteria for worker selection for monitoring 6.Define the programmatic elements for each radionuclide of interest: - Monitoring frequency - operational levels - Dose assessment methodology - Follow-up actions in case of overexposure Module V.1 Lecture 1 - Individual monitoring programmes42

IAEA Designing a monitoring program 7.Methods to be applied in case of radiological emergency 8.Determine QM requirements 9.Write standard operating procedures 10.Train employees in performing the standard operating procedures before they are implemented Module V.1 Lecture 1 - Individual monitoring programmes43

IAEA Designing a monitoring program 11.Implement the standard operating procedures 12.Perform periodic program re-assessment and adjustment Module V.1 Lecture 1 - Individual monitoring programmes44

IAEA 45 Designing a monitoring program 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 FacilitiesEquipmentStaffBudgetQM system Calibration Organization of the monitoring program Monitoring Assessment of the intakes and doses Module V.1 Lecture 1 - Individual monitoring programmes

IAEA Operational Levels Module V.1 Lecture 1 - Individual monitoring programmes46

IAEA Operational levels Operational level - predetermined value for any of the quantities which requires a certain course of action if the value of the level for a quantity is exceeded. Module V.1 Lecture 1 - Individual monitoring programmes47

IAEA Operational levels l Operational levels often refer to effective dose, but may apply to other quantities. These are called derived operational levels. l A operational level is not a limit in itself. l The operational level action may range from just recording the value to intervention. Module V.1 Lecture 1 - Individual monitoring programmes48

IAEA Operational levels l Recording level l Investigation level l Action level Module V.1 Lecture 1 - Individual monitoring programmes49

IAEA Recording level GSR: A level of dose, exposure or intake specified by the regulatory body at or above which values of dose to, exposure of or intake by workers are to be entered in their individual exposure records. 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 Module V.1 Lecture 1 - Individual monitoring programmes50

IAEA 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 unrealistic attention should not be given to exposures which result in very small doses. l It is suggested that the recording level is taken as the detection threshold of the dosimetry system Module V.1 Lecture 1 - Individual monitoring programmes51

IAEA Investigation levels l GSR: Investigation level - The value of a quantity such as effective dose, intake or contamination per unit area or volume at or above which an investigation would be conducted. 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. Module V.1 Lecture 1 - Individual monitoring programmes52

IAEA Investigation levels l For monthly monitoring or exchange periods, IL= 20 mSv x 0.3 / 12 = 0.5 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. Module V.1 Lecture 1 - Individual monitoring programmes53

IAEA Action level l Level for urgent remedial or protective action. l Applies to existing exposure or emergency exposure situations. l Action levels often serve to protect the public. l Have occupational exposure relevance in existing exposure situations. l Particularly relevant to workplace radon exposure. Module V.1 Lecture 1 - Individual monitoring programmes54

IAEA References GSR 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 External Sources of Radiation, Safety Guide RS-G-1.3 (1999). INTERNATIONAL COMMISSION ON RADIOLOGICAL PROTECTION, General Principles for the Radiation Protection of Workers, Publication No. 75, Pergamon Press, Oxford and New York (1997). Module V.1 Lecture 1 - Individual monitoring programmes55