Radiation safety level 5

1. Radiation safetylevel 5 Frits Pleiter radiation safety - level 5

2. Contents • atomic and nuclear physics (1) • interaction with matter (3) • sources and x-ray equipment (2) • shielding (3) • detection (4) • radiobiology (6) • objective risk of radiation (6) • subjective risk acceptation (6) • quantities and units (5) • regulations (7) • practical health physics (8 - 10) • waste (11) radiation safety - level 5

3. Dosimetrysource constant and inverse square law dose is proportional to the activity and to the irradiation time dose decreases with the square of the distance from the source D =   A  t / r2 the constant  in this equation is called "source constant" it makes it possible to convert activity to external dose   E / 7 Gy m2 MBq-1 h-1 (E in MeV) radiation safety - level 5

4. Dosimetrysource constant and inverse square law nuclide  (Gy m2 MBq-1 h-1) T½ 22Na 0.33 2.6 j 60Co 0.36 5.3 j 99mTc 0.023 6.0 h 125I 0.034 60 d 131I 0.066 8.0 d 137Cs 0.093 30 j 192Ir 0.14 74 d 201Tl 0.017 73 h 241Am 0.017 430 j radiation safety - level 5

5. Dosimetryrules of thumb at 1 m from a -source of 1 MBq  dose rate  10 µGy/h at 1 m from a -source of 1 MBq  dose rate  E / 7 µGy/h at 1 m from an x-ray tube  dose rate  10 mGy/min a -contamination of 1 kBq per cm2  skin dose rate rate  2 mGy/h radiation safety - level 5

6. Dosimetryeffective dose coefficient E(50) = e(50)  A the "effective dose coefficient" e(50) depends on radiotoxicity of the nuclide chemical composition of the radioactive substance contamination route (ingestion, inhalation, injection, wound, skin) it makes it possible to convert activity to internal dose especially tritiated water can penetrate skin and even gloves radiation safety - level 5

7. Dosimetryeffective dose coefficient nuclide e(50)inh (Sv/Bq) T½ 3H (H2O) 1.810-11 12.3 j 14C (CO2) 6.510-12 5730 j 22Na 2.010-9 2.6 j 32P 2.910-9 14.3 d 35S 1.210-10 87.5 d 45Ca 2.310-9 163 d 99mTc 2.910-11 6.0 h 125I 7.310-9 60 d 131I 1.110-8 8.0 d 226Ra 1.210-5 1600 j natural Th 6.210-5 1.41010 j natural U 5.710-5 4.5109 j radiation safety - level 5

8. Safety measuresnominal working hours 8 hours per day 5 days per week  40 hours per week 50 weeks per year  2000 hours per year radiation safety - level 5

9. Safety measuresorganisational measures maintain a correct administration system for sources and devices mark each source and device with a warning sign when in use store unused sources in a vault remove the key of an x-ray device when not in use radiation safety - level 5

10. Safety measuressealed sources protection against external radiation use as little activity as possible (ALARA) reduce exposure time increase working distance (inverse square law) apply shielding (lead, lucite) measure the dose rate periodic leak test take regular smear tests (limit is 185 Bq) direct activity measurent with a contamination monitor is pointless radiation safety - level 5

11. Safety measuresx-ray devices protection against external radiation do not irradiate more often than necessary (ALARA) reduce exposure time increase working distance (inverse square law) apply shielding (lead apron) use a dose rate meter that is sensitive at low energy check the equipment periodically check filter and leakage radiation leave maintenance to the supplier of the equipment watch out for scattered radiation reduce exposed area (diaphragm, light visor) radiation safety - level 5

12. Safety measuresopen radioactive substances protection against external radiation see sealed sources protection against internal contamination use as little activity as possible (ALARA) prevent spreading (containment, splash tray) remove air born activity (ventilation, fume hood) prevent intake of activity (work discipline, protocol) check for contamination by periodic laboratory surveys immediately warn responsible radiation expert evacuate laboratory and check workers when leaving determine extent of contamination (dose rate meter is useless) decontaminated surface (limit is 4 Bq/cm2) radiation safety - level 5

13. Safety measuresopen radioactive substances principle of "containment" glas tube, beaker glas, splash tray, fume hood, radionuclide laboratory radiation safety - level 5

14. Safety measuresopen radioactive substances avoid oral uptake don't eat at the work place don't drink at the work place don't smoke at the work place don't apply make-up at the work place radiation safety - level 5

15. Safety measuresopen radioactive substances avoid uptake via lungs risk of aerosol formation while shaking and vortexing centrifuging opening bottles sanding risk of tritium vapour tritium in condens is released when defrosting a refrigerator risk of iodine vapour avoid formation of iodine vapour (keep pH > 4) iodine in condens is released when warming up a "cold room" keep lid on waste bin radiation safety - level 5

16. Safety measuresopen radioactive substances avoid direct uptake in blood system don't work with open wounds avoid uptake of 3H via skin (use double gloves) radiation safety - level 5

17. Radionuclide laboratoryregulations work with open radioactive substances is only permitted in a radionuclide laboratory there are B-, C- en D-laboratories building requirements are most stringent for a B-laboratory building requirements are least stringent for a D-laboratory maximum allowed activity is largest in a B-laboratory maximum allowed activity is smallest in a D-laboratory radiation safety - level 5

18. Radionuclide laboratoryguideline radionuclide laboratories there are two different opinions • the risk is determined by regular uptake of small quantities of radioactive substances (National Health Council, 1985) • the risk is determined by incidents (HARAS-report, 1997) the Guideline Radionuclide Laboratories is based on opinion 1 radiation safety - level 5

19. Radionuclide laboratoryguideline radionuclide laboratories Amax = 0.02  10 p+q+r / e(50)inh Amax = maximum allowed activity in Bq p = dispersion parameter q = laboratory parameter r = local ventilation parameter (note that r  q) e(50) = dose conversion coefficient in Sv/Bq radiation safety - level 5

20. Radionuclide laboratoryguideline radionuclide laboratories radiation safety - level 5

21. Radionuclide laboratoryguideline radionuclide laboratories radiation safety - level 5

22. Radionuclide laboratoryguideline radionuclide laboratories radiation safety - level 5

23. Regulationsradioactive waste radioactive waste is waste in which both the activity concentration exceeds the exemption level and the activity exceeds the exemption level radioactive waste is also waste that looks like radioactive waste  no radioactivity stickers in normal industrial waste disposal is expensive (in 2005 about € 1300 per 100 liter) only COVRA is allowed to collect radioactive waste radiation safety - level 5

24. Regulationsradioactive waste avoid waste production use as little activity as possible use short-lived nuclides if not active, dispose as normal industrial waste separate waste dry and liquid waste organic and inorganic waste long-lived and short-lived waste counting vials cadavers sealed sources hand waste over to COVRA in standard drums radiation safety - level 5

25. Regulationsradioactive waste radioactive substances may be handed over to another person provided either the activitity concentration is less than the exemption level or the activity is less than the exemption level radiation safety - level 5

26. Regulationsradioactive waste nuclide concentration (Bq/g) activity (Bq) 3H 106 109 14C 104 107 32P 103 106 35S 105 108 99mTc 102 107 125I 103 106 131I 102 106 226Ra 1 104 238U 10 104 radiation safety - level 5

27. Regulationsdisposal there are strict rules for discharge to air discharge to sewer dose rate at border of the location knowledge of these rules is not required for the course level 5 radiation safety - level 5