Occupational Radiation Protection during High Exposure Operations

1. IAEA Training Material on Occupational Radiation Protection Occupational Radiation Protectionduring High Exposure Operations Lecture 7 Basic Concepts of Occupational Radiation Protection with High Exposure

2. Contents • Occupational exposure of emergency workers • Emergency planning and responsibilities • Justification • Optimization • Arrangement for the protection of emergency workers • Management of high occupational exposures • Assessment of high occupational exposures

3. 1. Occupational exposure of emergency workers Emergency Workers Emergency workers are workers who work for emergency exposure situations in the operating organization (registrant, licensee) or in one of the emergency response organizations. The exposure they receive is occupational exposure and the IAEA BSS (GSR Part 3) specifies the requirements. Helpers The IAEA GSR Part 7 identifies that others, called “helpers in an emergency”, may volunteer as emergency workers and integrated in the emergency response. The helpers in an emergency exposure situation are treated and protected as same as for emergency workers. 3

4. 1. Occupational exposure of emergency workers The fundamental difference between members of the public and emergency workers in an emergency exposure situation is that member of the public may receive doses unless some action is taken to prevent them, whereas emergency workers will receive doses due to specified duties assigned to them. The exposure of emergency workers starts with the assignment to undertake a particular action and finishes with completion of the assigned task or declaration of termination of the emergency. 4

5. 2. Emergency planning and responsibilities The arrangements for the protection of workers in an emergency should be a part of the emergency plan that is prepared on the basis of the hazard assessment. The emergency plan should include: • The persons or organizations responsible for ensuring compliance with requirements for protection and safety of workers in a nuclear or radiological emergency including those for controlling the exposure of emergency workers; • Defined roles and responsibilities of all workers involved in the response to a nuclear or radiological emergency; • Details of adequate self-protective actions to be taken, protective equipment and monitoring equipment to be used, and dosimetry arrangements; • Consideration and provision of access facilities and access control for the emergency workers on the site, including. 5

6. 3. Justification At the preparedness stage, the protective actions and other response actions to be taken in a nuclear or radiological emergency should be justified. Due consideration should be given to the detriment associated with doses received by the emergency workers implementing those actions. There should be a commitment to the justification process by all stakeholders. 6

7. 4. Optimization At the preparedness stage, the process of optimization, including the use of reference levels, should be applied to the protection of workers as well. There should be a commitment to the optimization process by all stakeholders. As part of the process of optimization, reference levels should be established. A reference level should represent the level of dose above which it is judged to be inappropriate to plan to allow exposures to occur and for which protective actions should therefore be planned and optimized. The initial phase is characterized by a lack of information about the event and the need for urgency in implementing protective actions with involvement of emergency workers Effort should be aimed at reducing any exposure as far as practicable taking into account the difficult conditions of the evolving emergency. 7

8. 4. Optimization When implementing protective actions during the late phase and at the transition from an emergency exposure situation to an existing exposure situation, the optimization process should be applied to the protection of emergency workers in the same way as for workers in planned exposure situations. 8

9. 5. Arrangements for the protection of emergency workers Protection of emergency workers should include, as a minimum: • Training of emergency workers designated as such in advance • Providing instructions immediately before their use to those emergency workers not designated as such in advance on how to perform their specified duties under emergency conditions and how to protect themselves (“just in time training”) • Managing, controlling and recording the doses received • Provision of appropriate specialized protective equipment and monitoring equipment • Medical follow-up and psychological counselling, as appropriate • Obtaining informed consent to perform specified duties, when appropriate 9

10. 5. Arrangements for the protection of emergency workers Emergency workers who are not designated as such at preparedness stage should be registered and integrated in into the emergency response operations in line with GSR Part 7. It is also good practice to limit the number of workers receiving emergency exposures by evacuating all unnecessary people from the vicinity of the accident. At the same time it may well be necessary to plan for 24-hour working and to have such workers available for shift work. 10

11. 5. Arrangements for the protection of emergency workers Because the exposure of emergency workers is deliberate and controlled, the dose limits for workers should be assumed to apply unless there are overriding reasons not apply them. Response organizations and employers have to ensure that no emergency worker is subject to an exposure in an emergency in excess of 50 mSv other than: • For the purpose of saving life or preventing serious injury • When undertaking actions to prevent severe deterministic effects and actions to prevent the development of catastrophic conditions that could significantly affect people and the environment • When undertaking actions to avert a large collective dose 11

12. 5. Arrangements for the protection of emergency workers Reference levels expressed as guidance values for restricting the exposure of emergency workers should be defined in accordance with the assigned task. Where lifesaving actions are concerned, every effort should be made to keep individual doses of emergency workers below 500 mSv for exposure to external penetrating radiation, while other types of exposure need to be prevented by all possible means. However, while estimating dose to emergency workers, the exposure from all pathways, external and internal, should be assessed and included in the total. Regardless of the circumstances, response organizations and employers should make all reasonable efforts to keep the doses received by emergency workers below the values of criteria for preventing and minimizing severe deterministic effects. 12

13. 5. Arrangements for the protection of emergency workers 13

14. 6. Management of high occupational exposures The government needs to establish a programme for managing, controlling the doses received by emergency workers in a nuclear or radiological emergency. Response organizations and employers should implement this programme. The group of emergency workers may be further divided into 3 categories of emergency worker: • Category 1 • Category 2 • Category 3 14

15. 6. Management of high occupational exposures Category of emergency worker Category 1 Emergency workers undertaking mitigatory actions and urgent protective actions on the site – include life-saving actions or to prevent serious injury or actions to prevent development of catastrophic conditions that could significantly affect people and the environment, actions to prevent serious deterministic effects and actions to avert large collective dose. Category 2 Emergency workers undertaking urgent protective actions off the site to avert a large collective dose (e.g. evacuation, sheltering, radiation monitoring, etc.). Category 3 Emergency workers undertaking early protective actions and other response actions off site (e.g. relocation, decontamination, environmental monitoring, etc.) as well as other actions aimed to enable the termination of the emergency. 15

16. 6. Management of high occupational exposures Any limit in duration of work undertaken by emergency workers and conditions by which they will conduct the work should be implemented by planning the emergency work driven by dose guidance values. Task should be assigned depending on the category of emergency worker: • Category 1emergency workers should carry out actions to save life or prevent serious injury and actions to prevent severe deterministic effects and actions to prevent the development of catastrophic conditions that could significantly affect people and the environment. • Category 2 emergency workers should not be the first choice for taking life-saving actions. • Category 1 and 2 emergency workers should carry out actions to avert a large collective dose • Category 3 emergency workers should carry out those actions in which they will not receive a dose of more than 50 mSv. 16

17. 6. Management of high occupational exposures Female workers who are aware that they are pregnant or breast-feeding should, in order to provide adequate protection for the embryo or foetus, notify the appropriate authority and should be excluded from emergency tasks and/or the infant are afforded the level of protection as required for members of the public. Emergency workers who undertake actions in which the doses received might exceed 50 mSv do so voluntarily and should have been clearly and comprehensively informed in advance of the associated health risks, as well as of available protective measures, and should be trained, to the extent possible, in the actions they are required to take. 17

18. 6. Management of high occupational exposures The operational guidance provided to emergency workers should be based on measurements of penetrating radiation. The dose from intakes, skin contamination and exposure of the lens of the eye should be prevented by all possible means for instance by the use of protective equipment, iodine thyroid blocking and the provision of instructions concerning operations in potentially hazardous radiological conditions. Such instructions should cover the application of the time, distance and shielding principles, the prevention of ingestion of radioactive material and the use of respiratory protection (including how to take off such protection equipment). 18

19. 7. Assessment of high occupational exposures Response organizations and employers should take all reasonable steps to assess and record the exposures received by workers in an emergency. The exposures of emergency workers in an emergency response and of workers who are accidently exposed should, if possible, be recorded separately from those incurred during routine work, but should be noted on the workers’ records of occupational exposure. The degree of accuracy required for any exposure assessment should increase with the level of exposure likely to have been received by the worker. The exposures of emergency workers should be monitored on an individual basis, using means appropriate to the situation, such as direct reading or alarm dosimeters. Depending on the nature of the accident, it may well be appropriate to use a Whole Body Counter for internal exposure assessment of workers. 19

20. 7. Assessment of high occupational exposures Records of occupational exposure should be generated and maintained in a simplified standard format by all response organizations and employers to avoid confusion. The information on the doses received and the associated health risk should be communicated to the emergency workers involved. Workers should not normally be precluded from incurring further occupational exposure because of doses received in an emergency exposure situation. 20

21. 7. Assessment of high occupational exposures Health surveillance Emergency workers and accidentally exposed employees should receive medical attention appropriate for the dose they may have received. Screening based on equivalent doses to specific radiosensitive organs as a basis for medical follow-up and counselling should be provided if an emergency worker or accidentally exposed employee has received an effective dose of 100 mSv over a period of a month or if the worker so requests. An emergency worker or an accidentally exposed employee who receives doses in nuclear or radiological emergency should normally not be precluded from incurring further occupational exposure. However, qualified medical advice should be obtained before any further occupational exposure if an emergency worker or accidentally exposed employee has received and effective dose exceeding 200 mSv or at the request of the worker. 21

22. 7. Assessment of high occupational exposures Health surveillance A particular concern should be whether a worker has received a dose sufficient to cause serious deterministic effects. Protective actions and other response actions should be taken in accordance with GSR Part 7. Such actions may include: • Performing immediate medical examination, consultation and indicated treatment • Carrying out contamination control • Carrying out immediate decorporation (if applicable) • Carrying out registration for long term health monitoring (medical follow-up) • Providing comprehensive psychological counselling 22