Presentation is loading. Please wait.

Presentation is loading. Please wait.

IAEA International Atomic Energy Agency Management of disused sealed radioactive sources Day 9 – Lecture 7.

Similar presentations


Presentation on theme: "IAEA International Atomic Energy Agency Management of disused sealed radioactive sources Day 9 – Lecture 7."— Presentation transcript:

1 IAEA International Atomic Energy Agency Management of disused sealed radioactive sources Day 9 – Lecture 7

2 IAEA To provide some high-level insights into the hazards associated with sealed sources To discuss various methods of judging the likely magnitude of these hazards based on The identity of the radionuclide in question The level of radioactivity To consider the implications for predisposal management To consider some disposal options Objective 2

3 IAEA Content Identification of Problem Sources Characterization of disused Sources Safe management of disused sealed sources Conditioning and Packaging of Disused Sources Storage of disused sources Disposal Considerations 3

4 IAEA Introduction Disused sealed radiation source A source permanently sealed in a capsule, or closely bonded and in a solid form, emitting ionizing radiation and that is no longer in use or intended to be used In use since 1901; until 1940 limited to radium used in medicine thus resulting in widespread storage of radium needles Today, widely used in medicine, industry, agricultural, research and consumer products Physically small, but contain high concentrations of radionuclides Require heavily shielded containers for safe use, transport and storage Give rise to serious safety problems if not managed properly 4

5 IAEA Introduction Poor management practices resulted in disused sources being stored in unsatisfactory conditions or no longer under regulatory control. Deliberate and malicious acts involving disused sources Chechens placed a Cs-137 container in Moscow park (1995) Lithuanians arrested with Cs-137 in their possession (Vilnius, 2002) Accidents involving abandoned, lost or stolen gamma- radiation sources Cobalt-60 in Juarez, Mexico, 1983 Cesium-137 in Goiania, Brazil, 1987 Others include accidents Morocco (eight people died) Shanxi Province in China (54 injured, 4 died) 5

6 IAEA Radioactive sources can present a hazard in various ways: External exposure Ingestion Inhalation Dermal absorption The type and magnitude of the hazard depends on the radionuclide and the level of activity Hazards 6

7 IAEA Why do we need better management? SRS found in virtually all countries – approximately two million devices containing sources in the US. A small percentage are not properly controlled. Approximately 375 sources or devices are lost or stolen in the US each year. 7

8 IAEA Reasons for loss of source control Mobile sources are lost or stolen while in transit. Sources are abandoned, either deliberately or through lack of awareness. Sources are stolen, either for the scrap value of the source or its container Political instability and economic hardship. Experience shows that: 8

9 IAEA Activity ranges of radiation sources Miscellaneous waste containing DSRS 9

10 IAEA Sr-90 radioactive source recovered in the Rep. of Georgia Sources used in mobile caesium irradiators in the former Soviet Union Miscellaneous waste containing DSRS 10

11 IAEA Categorization of disused sources IAEA TECDOC 1344 (Categorization of radioactive sources) To provide a simple, logical system for ranking radioactive sources Their potential to cause harm to human health Group practices in which sources are used into discrete categories To provide a fundamental and internationally harmonized basis for risk- informed decision making Used as an input to activities relating to the safety and security of radioactive sources Develop or refine (inter)national safety standards Develop or refine national regulatory infrastructures to meet the State’s requirements Optimize decisions about priorities for regulation within resource constraints Optimize security measures for radioactive sources, including potential malicious use Emergency planning and response Develop national strategies for improving control over radioactive sources Each category contains a mixture of radionuclides, half-lives 11

12 IAEA CategoryTypical usesActivity Ratio A/D 1 Radio-thermal generators; Irradiators; Teletherapy; Gamma knife A/D> Gamma radiography Brachytherapy (HDR/MDR) 1000>A/D>10 3 High activity industrial gauges Well logging 10>A/D>1 4 Brachytherapy (LDR except eye plaques & perm implants) Low activity gauges; Static eliminators; Bone densitometers 1>A/D> Brachytherapy (eye pl. & perm implants); XRF; ECD 0.01>A/D>Exempt/D Increasing Risk A = source activity; D = radionuclide-specific “dangerous” activity Dangerous sources Categorization of Radioactive Sources used in Common Practices 12

13 IAEA Categorization of disused sources IAEA-TECDOC-1368 (Safety considerations in the disposal of disused sealed radioactive sources in borehole facilities) Categorize sources according to radioactive half-life More suitable to define long-term management strategies for disused sealed radioactive sources Make distinction between three categories Category 1: Half-life < 100 days Category 2: 100 days < Half-life = 30 years Category 3: Half-life > 30 years Expected required containment period under natural radioactive decay Maximum expected activity for each radionuclide in each category Radioactive half-life 13

14 IAEA Best Options for Disused Sources? Return to supplier Long term storage (50 y, 100 y, ???) Disposal 14

15 IAEA Safe management of disused sealed sources (I) Sealed sources are considered to be disused when: the practice is decided not to be continue, they have decayed to the extent that they are no longer useful for their original purpose, because the appliance in which they are housed has become outdated, or because routine tests have indicated that the source is leaking. Spent or disused sealed sources are not considered waste in certain States but the safe management of such sources is achieved by compliance with the requirements for radioactive waste. 15

16 IAEA Safe management of disused sealed sources (II) The most important consideration in the management of sealed sources, once they are no longer useful, is the maintenance of continuity of control. The operator and the regulatory body should make provision to maintain and periodically review the status of control of such devices and material. 16

17 IAEA Safe management of disused sealed sources (III) Wherever possible, when purchasing sealed sources, contractual arrangements should allow the return of sources to the manufacturer or predetermined waste manager following use. Recycling and reuse can involve the following activities: Reuse of sealed sources by the owner or a new owner; Recycling of sealed sources by the manufacturer; Decontamination and/or reuse of material; Recycling and reuse of material that fulfils the conditions for the removal of regulatory control. 17

18 IAEA Safe management of disused sealed sources (IV) Once the disused sealed source is declared radioactive waste, its safe management should comply with the safety requirements for the management of radioactive waste Safety related details of the history of disused sealed sources, considered as waste, should be included in the inventory. 18

19 IAEA Safe management of disused sealed sources (V) The following aspects should be considered in respect of the safe management of spent and disused sealed sources: (a) The further authorized use of the disused source by some other authorized organization; (b) Return of the source to the supplier; (c) Temporary storage in its original shielding (for example for radionuclides with half-lives of less than 100 days); (d) Conditioning (for example overpacking); (e) Long term storage (such as in a dedicated storage facility); (f) Disposal. 19

20 IAEA Safe management of disused sealed sources (VI) For spent and disused sealed sources with short half- lives, secure storage for decay may be the preferred option. All spent and disused sealed sources should be conditioned Long lived sources are generally conditioned by means of encapsulation into welded steel capsules to facilitate future management. Conditioning methods should be approved by the regulatory body. 20

21 IAEA Safe management of disused sealed sources (VII) Where the operator does not have the expertise for the conditioning of spent and disused sealed sources or adequate storage facilities, arrangements should be made to transfer the sources to another licensed organization with proper and adequate facilities. Centralized facilities should be established for the safe long term storage of spent and disused sealed sources containing 226Ra, 241Am and other long lived radionuclides. 21

22 IAEA Safe management of disused sealed sources (VIII) Sealed sources should not be subjected to compaction, shredding or incineration; Sealed sources should not be removed from their primary containers, Peripheral components of large irradiation equipment should be removed, monitored and disposed of appropriately; A safety assessment and environmental impact assessment should be carried out before any operations are undertaken. 22

23 IAEA Safe management of disused sealed sources (IX) For sources (such as spent radium sources) with a potential for leakage, particular radiological precautions should also be taken during the handling and storage. Special attention should be paid to monitoring for surface and airborne contamination. These sources should be stored in a dedicated area with appropriate ventilation and equipment. 23

24 IAEA Orphan sources States should establish and implement appropriate strategies for these ‘orphan’ sources. Strategy should ensure that whenever an orphan source has been identified, appropriate recovery measures are taken. The State should: Identify responsible organizations and funding within the State to recover, handle, condition, store and, if necessary, dispose of the source. 24

25 IAEA Accidental generation of radioactive waste Loss and misuse of sealed sources can give rise to accidents and the contamination of working premises and land. This can lead to the unplanned and accidental generation of radioactive waste. Technical and organizational means should be in place, including the necessary contingency arrangements, for the processing and storage of any such accidentally generated radioactive waste. 25

26 IAEA Conditioning and packaging of disused sources Conditioning Those operations that produce a waste package suitable for handling, transport, storage and/or disposal Conditioning may include the conversion of the waste to a solid waste form, enclosure of the waste in containers and, if necessary, providing an overpack Packaging Preparation of radioactive waste for safe handling, transport, storage and/or disposal by means of enclosing it in a suitable container Include disused source handling facility in management strategy Source characteristics and national or regional strategy will determine conditioning strategy Conditioning performed for storage must take possible disposal option into consideration 26

27 IAEA Conditioning and Packaging of Disused Sources 27

28 IAEA Storage of Disused Sources Issues to consider Storage conditions are not always satisfactory Most sources remain in storage pending availability of a suitable disposal option Adequate final management option for sources containing short-lived radionuclides Centralized storage facility for a country/region Various options can be used as storage facilities –Shipping container –Corrugated iron shed –Below surface (basements) –Boreholes Record keeping and radiation protection principles essential 28

29 IAEA Storage of Disused Sources 29

30 IAEA Storage of Disused Sources 30

31 IAEA Terrorist threat New paradigm must be built into your safety case for operating and disused sources. How long will we be concerned about this threat? – Forever!! Concerns many players in the national system of protection. Ultimate responsibility with the Operator. Safety and security systems must evolve. 31

32 IAEA Disposal of Disused Sources Issues to consider Waste acceptance criteria –Many sources exceed criteria for near-surface disposal facilities –Constitute high, localized conc. (hot spots) –Unacceptable risk during human intrusion conditions –Reasonable assurance of compliance with safety requirements not always adequately demonstrated –Assumed institutional control not always the answer 32

33 IAEA Higher levels of isolation required –Geological disposal a possibility, but usually not available –Lack of long-term waste management infrastructure –Borehole disposal of disused sealed radioactive sources IAEA Safety Guide SSG-1 –Safety considerations in the disposal of disused sealed radioactive sources in borehole facilities Disposal of Disused Sources 33

34 IAEA Disposal of Disused Sources 34

35 IAEA Disposal of Disused Sources 35

36 IAEA Disposal of Disused Sources 36

37 IAEA References 37


Download ppt "IAEA International Atomic Energy Agency Management of disused sealed radioactive sources Day 9 – Lecture 7."

Similar presentations


Ads by Google