Presenter Name School of Drafting Regulations for Borehole Disposal of DSRS 2016 Vienna, Austria

1. Characterization and Categorization of DSRS Inventory Presenter Name School of Drafting Regulations for Borehole Disposal of DSRS 2016 Vienna, Austria

2. Outline of Presentation • Presentation resources • Regulatory Framework for Cat I/2 SRS • Characterization of DSRS • Categorization of DSRS • Compare and Contrast • Summary 2

3. Presentation Resources • International Atomic Energy Agency, Management of Disused Long Lived Sealed Radioactive Sources (LLSRS), IAEA-TECDOC-1357., Vienna (2003). • International Atomic Energy Agency, Code of Conduct on the Safety and Security of Radioactive Sources, IAEA, Vienna (2004). • International Atomic Energy Agency, Categorization of Radioactive Sources., Safety Guide No. RS-G-1.9, Vienna (2005). 3

4. Regulatory Framework • Basis in national statues • May be based upon IAEA documents • Many countries have national regulations for controlling SRS in higher activity categories. • Protection of the public and the environment • Examples of typical regulations governing licensing: • Public dose • Worker dose – conditioning/hot cell • Training • Isotope limits due to site safety assessment • Code of Conduct limits for SRS

5. Definitions Categorization – to provide a simple means to rank (into categories) radioactive sources with respect to their potential to cause harm to human health. The rankings/categories provide an internationally harmonized basis for risk informed decision making. Characterization – a list of physical, chemical and radiological properties of the SRS.

6. Characterization of DSRS’s Minimum radiological properties needed: • Isotope and radiation type • Activity with manufacture date • Status of source integrity (e.g., leaking?) • Physical properties (e.g., size, shape) • Source/device manufacturer • Model number • Serial number • Design specs • Traceability of source to documentation • IAEA’s International Catalogue of Sealed Sources

7. Characterization of DSRS’s Additional helpful radiological properties: • Isotope half-life, energy, & dose conversion factors • Neutron flux (for neutron sources) Non-radiological parameters: • Geometrical (e.g., long rods, spheres, strips) • Chemical & physical form (solid, liquid, or gas) • Liquid sources have a higher potential to leak

8. Characterization of DSRS’s Common classification of SRS is by type: • Alpha • Beta • Gamma/X-ray • Neutron sources Rule of thumb is SRS emit more than one type of radiation: • Alpha decay has a gamma with it. • Daughters are often beta emitters • Beta conversion during absorption results in Bremsstrahlung.

9. Example of DSRS Characterization Common SRS used in industry – Cs-137 Type of source: beta – gamma Strength: variable (e.g., 3700 GBq) w/date Physical property: solid salt in capsule Chemical property: CsCl is common Radiological half-life: 30.17 years Energy: gamma energy is 0.662 MeV Source integrity: leak check of shield date Dose conversion factor: 4.6 E-9 Sv/Bq

10. Categorization of DSRS’s Purpose of categorizing DSRS is to provide an internationally harmonized basis for risk informed decision making. System is based upon the concept of “dangerous sources” as measured by “D” values. Originally derived for emergency preparedness use D value is the radionuclide specific activity which, if not controlled, could cause severe deterministic effects for a range of scenarios creating external and/or internal exposures

11. Categorization of DSRS’s • For many isotopes, source strength can vary over several orders of magnitude. D values serve to normalize this range of activities for comparing risk. • A/D ratio is commonly used • provide initial rankings, • Rankings modified by other factors such as physical & chemical form, type of shielding or containment, supposed use, and accident case history, • Other factors are subjective and largely based on international consensus. See Appendix I of SG No. RS-G-1.9

12. Categorization of DSRS’s • Categorization System has five categories • Cat I is the most dangerous (fatal exposure in minutes) • Cat 5 is the least dangerous (can exceed dose limits if not controlled). • Subdividing categories is NOT recommended as system is not that precise and would lead to a loss of international harmonization. • RS-G-1.9 contains list of common sources. • Can’t find your source in the listing, obtain D factor for your isotope from table in 1.9 • Calculate A/D and compare to table. • Other factors may tweak result.

13. Categorization of DSRS’s • Categorization System has five categories • Cat 1 A/D≥1000 • RTG’s, teletherapy, gamma knifes • Cat 2 1000>A/D≥10 • Industrial radiography, HD brachytherapy • Cat 3 10>A/D≥1 • Fixed gages (high activity), well logging • Cat 4 1>A/D≥0.01 • LD brachytherapy (except eye plagues and permanent implants), industrial gages (low activity), bone densitometers, static eliminators • Cat 5 0.01>A/D and A> exempt • XRF devices, electron capture, PET check sources, LD brachytherapy eye plagues and permanent implants

14. Example of DSRS Categorization Common SRS used in industry – Cs-137 D = 0.1 TBq Cat 1 source (food irradiator) – 1.1 E5 TBq A/D = 1.1 E6 (> 1000) Cat 2 (brachytherapy) – .11 TBq A/D = 1.1, but recommended Cat 2 Cat 3 (gage) – 0.19TBq >> A/D = 1.9 Cat 4 (fixed gage) – 0.0022 TBq >> A/D=0.022 Cat 5 (check source) – 7400 Bq >> A/D=7E-5

15. Categorization of DSRS’s • Operational considerations • BSS and GSR-1 requirements to ensure safety and security “commensurate” to the practice and likelihood of exposures. • Short half-life sources and unsealed sources • Tc-99m and I-131 – Carefully choose “A” for A/D • Aggregation – sources in close proximity per RB • Sum isotopic activities, divide by isotope D , add A/D’s • Cat III sources may end up with a Cat II quantity • Other factors may dictate final category. • Additional labeling of high activity sources • National registry of at least Cat I or II sources • Cat III sources can also be registered

16. Categorization of DSRS’s • Operational considerations • Additional inspection protocols • Constant monitoring/restricted access • Coordination with local law enforcement • Trustworthy individuals only allowed unrestricted access • Hardened source devices

17. Compare and ContrastCharacterization vs. Categorization • Similarities • Activity is critical to both • Protection of public is paramount • Physical properties dictate handling • Differences • Physical and chemical properties • License – safety requirements • High activity sources – additional security

18. Summary • Characterization and Categorization are not the same creature • Characterization specifies the physical, chemical and radiological properties of the source. • Categorization specifies the degree of safety and security needed to protect people from deterministic effects. • With multiple sources within a facility (for storage or conditioning), aggregation will be required. • Additional license conditions are required for Cat 1/2 sources. • Inspections review additional license conditions.

19. Thank you!