Radiation Protection and Safety in High-Energy Physics

1. Radiation Protection and Safety in High-Energy Physics Kenneth R. Kase, Ph.D. Associate Director, Environment, Safety and Health (Retired) Stanford Linear Accelerator Center & Senior Vice President National Council on Radiation Protection and Measurements 5th International High-Energy Physics Technical Safety Forum

2. Outline • Brief Overview of Radiation Protection Standards • Relationship of Radiation Safety to Other Safety Concerns • Current and Future Issues in Radiation Protection Related to High-Energy Physics 5th International High-Energy Physics Technical Safety Forum

3. 1925 Erythema Limit • Mutscheller: 1/100 erythema dose in 30 days • Sievert: 1/10 erythema dose in 1 year • Threshold concept 5th International High-Energy Physics Technical Safety Forum

4. ICRU • Formed by the International Congress of Radiology (ICR) • X-Ray Units Committee • Physical measurement required 5th International High-Energy Physics Technical Safety Forum

5. 1928 “Roentgen” Defined • “Roentgen”: Proposed by the “Units” Committee in 1925 • Adopted by the ICR in 1928 • “the exposure when the x-ray or gamma-ray field produces 1 e.s.u. of negative charge in 0.00129 gram of air” • ICRP and NCRP were formed 5th International High-Energy Physics Technical Safety Forum

6. 1933-1934 Dose LimitsEstablished • ICRP 0.2 R/day • NCRP 0.1 R/day 5th International High-Energy Physics Technical Safety Forum

7. 1941 New Information • Excessive radium use by the public via patent medicines • Radium dial painters exhibit damage • 0.1 g Radium Body Burden accepted 5th International High-Energy Physics Technical Safety Forum

8. 1949–1954 ICRP and NCRP • New Set of Weekly Dose Limits • 300 mR — blood forming organs lens, gonads • 600 mR — skin • 300 – 600 mR — other organs • 1,500 mR — extremities (x rays) • 1/10 these values for minors 5th International High-Energy Physics Technical Safety Forum

9. Public Concern • BEAR Committee (US National Academy of Sciences) • MRC Committee (UK Medical Radiation Council) • UNSCEAR (United Nations) 5th International High-Energy Physics Technical Safety Forum

10. 1957–1958 ICRP and NCRP • New Age-Related Worker Limits • 5 x (age – 18) rem/year, • 3 rem/13 weeks (head, trunk, active blood forming organs, lens, and gonads) 5th International High-Energy Physics Technical Safety Forum

11. 1957–1958 ICRP and NCRP • New Population Limit • 5 rem/30 years (170 mrem/year) • Small groups — 0.5 rem/year 5th International High-Energy Physics Technical Safety Forum

12. 1977 ICRP • Examine need for new limits • Greatly expanded use • New risk estimates • Risk-Based Approach 5th International High-Energy Physics Technical Safety Forum

13. 1977 ICRP Risk Estimates • D + D2, i.e., linear at low doses • Fatal cancer risk coefficient 1 x 10-2 per Sv (1 x 10-4 per rem) • Hereditary risk 0.4 x 10-2 per Sv (0.4 x 10-4 per rem) [Note: 1 Sv = 100 rem] 5th International High-Energy Physics Technical Safety Forum

14. Approach to Worker Limit(Stochastic) • Is 50 mSv/year acceptable? • Fatal accident rate in safe industries was 1 x 10-4/year • Average dose to workers will be <10 mSv/year (risk of 10-4/year) • 50 mSv/year limit provides same level of risk as safe industries 5th International High-Energy Physics Technical Safety Forum

15. 1990–1993 ICRP and NCRP • New Dose Limits for Workers • ICRP • 50 mSv/year maximum • 100 mSv/5 year (20 mSv/year) • NCRP • 50 mSv/year maximum • Age in 10’s of mSv 5th International High-Energy Physics Technical Safety Forum

16. Maximum Radiation Risks at HEP Facilities • Annual exposures to almost all workers are less than 5 mSv • This results in an annual added risk for a fatal cancer less than 3x10-4 • And an added lifetime cancer risk of 1% or less 5th International High-Energy Physics Technical Safety Forum

17. Relationship of Radiation Safety to Other Safety Concerns • Is it just another occupational hazard like electricity, construction, high pressure, vacuum, toxic chemicals and gases ? • Does it need to be treated differently? 5th International High-Energy Physics Technical Safety Forum

18. Relationship of Radiation Safety to Other Safety Concerns • Engineering and design • Shielding • Access control • Compare with electrical 5th International High-Energy Physics Technical Safety Forum

19. Current and Future Issues in Radiation Protection • Radiation is a hazard that presents risks similar to other industrial hazards at high energy physics facilities • It need not be treated differently from other hazards. • But, perhaps some of the principles used for radiation protection could be applied to the mitigation of other hazards 5th International High-Energy Physics Technical Safety Forum

20. Current and Future Issues in Radiation Protection • Control of Natural and Accelerator-produced Radioactive Material (NARM) • Issue in U.S. because of classification of material • Legislation before Congress to give responsibility to the Nuclear Regulatory Commission • Probably not an issue internationally 5th International High-Energy Physics Technical Safety Forum

21. Current and Future Issues in Radiation Protection • Clearance of material that may be slightly radioactive • Removal of radioactive materials from regulatory control • IAEA Basic Safety Standards and Safety Guide No. RS-G-1.7 make recommendations internationally • NCRP Report No. 141 makes recommendations for the U.S. 5th International High-Energy Physics Technical Safety Forum

22. Current and Future Issues in Radiation Protection • Future changes in regulations controlling: • Exposure of workers & public • ICRP proposal for 2005 • Exposure of ecological species • ICRP Committee 5 • Decommissioning & disposition of waste material • NCRP Annual Meeting 2005 5th International High-Energy Physics Technical Safety Forum

23. Current and Future Issues in Radiation Protection • Disposition of low activity radioactive material • Risk informed • Systems approach using Probabilistic Risk or Performance Analysis • IAEA Guidance • NCRP Report No. 139 • Single regulator • Cost effective disposal, not necessarily recycling or reuse 5th International High-Energy Physics Technical Safety Forum

24. Summary • Radiation dose recommendations for occupational exposures have evolved as more information is gathered on the effects of radiation on humans. • Current recommendations offer protection at a risk level of a few x 10-4 annually and 1 % lifetime. • Radiation presents a risk to workers that is similar to other industrial hazards. • The control of other hazards might benefit from the application of principles applied to the control of radiation hazards. 5th International High-Energy Physics Technical Safety Forum

25. Summary • Exposure guidance for people and species in the environment is not likely to change in the next few years. • There is a need for international acceptance of clearance levels and risk informed disposition regulations for potentially radioactive material. 5th International High-Energy Physics Technical Safety Forum