Radiation Safety and ALARA

1. Radiation Safety and ALARA Cember, Ch 10

2. What is ALARA ALARA is an acronym for As Low As Reasonably Achievable. This is a radiation safety principle for minimizing radiation doses and releases of radioactive materials by employing all reasonable methods. ALARA is not only a sound safety principle, but is a regulatory requirement for all radiation safety programs.

3. What is the Basis for ALARA? Current radiation safety philosophy is based on the conservative assumption that radiation dose and its biological effects on living tissues are modeled by a relationship known as the �Linear Hypothesis�. The assertion is that every radiation dose of any magnitude can produce some level of detrimental effects which may be manifested as an increased risk of genetic mutations and cancer. Thus, radiation safety programs attempt to lower doses received by radiation workers by utilizing practical, cost effective measures.

4. How is ALARA Implemented? An effective ALARA program is only possible when a commitment to safety is made by all those involved. This includes management, and as appropriate for each facility: radiation safety staff, radiation safety committees, and all radiation workers. Typically Radiation Safety Manuals provide guidelines for the responsibilities and good practices which are consistent with both the ALARA concept and the appropriate state and Fedueral regulatory requirements. These guidelines and regulations require not only adherence to legal dose limits for regulatory compliance, but also ALARA investigation dose levels which serve as alert points for initiating a review of the work practices of a radiation worker.

5. As Low As Reasonably Achievable Taking into account: Social, Technical, Economic, Practical, and Public policy considerations.

6. NCRP 116 ALARA Guidance Justification The need to justify radiation dose on the basis of benefit Optimization the need to ensure that the benefits are maximized Limitation the need to apply dose limits

7. Six fundamental principlesshould be considered Eliminate or reduce the source of radiation, Contain the source, Minimize time in a radiation field, Maximize distance from a radioactive source, Use radiation shielding, and Optimize resources.

8. Hierarchy of Controls Engineered Controls Administrative controls Personnel protective measures

9. The first ALARA design principle is to eliminate or reduce the source  Removal of source or source elimination, Source reduction, or Radioactive decay.

10. The second ALARA design principle isto control and contain radioactivity

11. Methods to control and containradioactive sources include Containment leak-tight enclosures Ventilation circulation, exchange, and filtration of air Filtration circulation, exchange, processing, and filtration of water or air

12. Protective designsinclude such items as: Ventilated fume hoods, Gloveboxes, Exhaust systems, Water filtration systems, and Oversized ventilation cleanup systems.

13. The third ALARA design principle is to reduce the time in a radiation field

14. Design factors to reduce time spent in radiation fields include Install reliable equipment to reduce maintenance, Provide adequate clearance for maintenance and inspections, Utilize special tools to speed maintenance and access, Remove components from radiological area for repair and calibration, and Install permanent lighting and platforms.

15. The fourth ALARA design principle is to maximize distance from source

16. Design factors to maximize the distance from radioactive sources include: Remote operations, Locating instruments and readouts in low dose areas, Provision for removal of components to low dose areas for maintenance, and Use of remote handling tools for repair, maintenance, and operations.

17. Design factors, continued Use of cameras and microphones to perform remote surveillance and inspections, and Equipment should be laid out so as to maximize the distance between workers and the radiation source.

18. The fifth ALARA design principle is to use shielding between worker and the source

19. The sixth ALARA design principle is optimization Designing to ALARA uses the cost-benefit process of optimization to achieve ALARA.

20. Practical ALARA Examples for Small Facilities Pre Work: Order and use only the amount of radioactive material necessary to perform experiments. Dry-run: Try the experiment without radioactive material first to familiarize yourself with the experiment and equipment. Wear protective clothing: Laboratory Coat Gloves Protective Glasses/Goggles Do not wear open-toed sandals or shoes in the laboratory. Contamination Prevention: Work in designated radioactive materials areas on benches covered with an absorbent liner.

21. Practical ALARA Examples continued While Working: When working with liquids be aware of the potential for splashes, splatters or spills. Store stock solutions in secondary packing when not in use, such as the plastic container used for shipping. Clean loose and removable contamination. Minimize time spent near radioactive materials. Keep as much distance between yourself and the radiation source(s) as possible. Use shielding to maintain radiation exposures as low as possible. Consider shielding needs of others who may be behind or next to your experiment. Survey materials and equipment before removing it from the work area.

22. Practical ALARA Examples, continued Post-Work: Minimize and properly dispose of radioactive waste. Store radioactive material (stock material, waste) as far as practical from the working area and behind sufficient shielding. Secure all radioactive materials. Perform a comprehensive post experimental and personal survey. Wash hands before leaving the area.

23. Pop Quiz Increasing the distance from a radiation source from one foot to four feet will reduce the radiation levels to: a) One fourth of the original exposure rate. b) One sixteenth of the original exposure rate.

24. Summary Six fundamental principles discussed Eliminate or reduce the source of radiation, Contain the source, Minimize time in a radiation field, Maximize distance from a radioactive source, Use radiation shielding, and Optimize resources.