Management of disused sealed radioactive sources Day 9 – Lecture 7

Objective 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 The overall objective of the lecture is to provide some high-level insights into the hazards associated with sealed sources ; to discuss the various methods that exist for judging the likely magnitude of these hazards, primarily based on the identity of the radionuclide in question and its activity; and then to consider the implications for storage and disposal

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 We shall begin this lecture by looking at the kinds of sources that, typically, cause difficulties to the authorities through getting lost or forgotten We then go on to speak about the rationale for characterizing disused sealed sources Then we cover the IAEA code of conduct and finally we consider methods of disposal

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

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)

Hazards 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 Radioactive sources can present a hazard in various ways most usually by External exposure Ingestion Inhalation and by Dermal absorption The type and magnitude of the hazard depends on the radionuclide and the level of activity But for sealed sources in situations other than disposal, the main form of exposure is external radiation

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. Radioactive sources found in every country and in many place within the country

Reasons for loss of source control Experience shows that: 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. Emphasize the political and economic collapse problem

Activity ranges of radiation sources Miscellaneous waste containing DSRS

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

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

Categorization of Radioactive Sources used in Common Practices Category Typical uses Activity Ratio A/D 1 Radio-thermal generators; Irradiators; Teletherapy; Gamma knife A/D>1000 2 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>0.01 5 Brachytherapy (eye pl. & perm implants); XRF; ECD 0.01>A/D>Exempt/D Increasing Risk Dangerous sources A = Activity and D is that value of radionuclide specific activity which if not under control could cause severe deterministic effects for a range of scenarios that include both external exposure from an unshielded source and internal exposure following dispersal of the source material. A = source activity; D = radionuclide-specific “dangerous” activity

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

Best Options for Disused Sources? Return to supplier Long term storage (50 y, 100 y, ???) Disposal Borehole - BOSS

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.   While disused sealed sources are usually a small fraction of the volume of radioactive waste generated by a particular operator, they may dominate the activity content of the waste arisings. It should be noted that, although the radiation output of teletherapy sources and other large sources may have fallen below useful levels, the potential for injury from such sources remains substantial. It should be noted in particular that 137Cs teletherapy sources normally contain caesium compounds in dispersible form and represent a severe hazard should their primary containment be breached.

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. While disused sealed sources are usually a small fraction of the volume of radioactive waste generated by a particular operator, they may dominate the activity content of the waste arisings. It should be noted that, although the radiation output of teletherapy sources and other large sources may have fallen below useful levels, the potential for injury from such sources remains substantial. It should be noted in particular that 137Cs teletherapy sources normally contain caesium compounds in dispersible form and represent a severe hazard should their primary containment be breached. 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.

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. The most sustainable option for managing disused sealed sources is to recycle them for further use. If this is not possible, the preferred management option for disused sealed sources and always for spent sources is the return of the source to its supplier. This option is not always available for many old sources; however, as the original supplier may not be known or may no longer exist. This is particularly important for high activity sources from which regulatory control cannot be removed until after many years of decay storage or for sources containing long lived radionuclides. Recycling and reuse can involve the following activities: (a) Reuse of sealed sources by the owner or a new owner with appropriate legal provisions; (b) Recycling of sealed sources by the manufacturer; (c) Decontamination and/or reuse of material such as equipment and protective clothing; (d) Recycling and reuse of material that fulfils the conditions for the removal of control from material as defined by the regulatory body.

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. While spent or disused sealed sources may be a small fraction in terms of the volume of the radioactive waste generated by a particular operator, they may dominate in terms of the activity content of the radioactive waste generated. It is essential to note that, although the radiation output of teletherapy sources and other large disused sources of radiation may have fallen below useful levels for their initial purposes, the potential for radiation induced injury from such sources remains substantial. It should be noted that 137Cs teletherapy sources may contain caesium compounds in a dispersible form and that these can represent a very significant hazard if their primary containment is breached.

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.

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. For spent and disused sealed sources with short half-lives, not exceeding around 100 d, and of high activity (e.g. 192Ir sources as used in medical applications and in gamma radiography), secure storage for decay may be the preferred option. All spent and disused sealed sources should be conditioned unless the half-life of the radionuclides they contain is short enough to permit their removal from regulatory control in a period of around two to three years). 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.

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. In instances where the operator does not have either the facilities or the expertise for the conditioning of spent and disused sealed sources by encapsulation 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.

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. The management of disused sealed sources can involve potentially serious hazards. Sealed sources should not be subjected to compaction, shredding or incineration. As a general principle, the overriding need for safety means that sealed sources should not be removed from their primary containers, nor should the container be physically modified. Peripheral components of large irradiation equipment (those not directly associated with the source) should be removed, monitored and disposed of appropriately. A safety assessment and environmental impact assessment should be carried out before any operations are undertaken. 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

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. The management of disused sealed sources can involve potentially serious hazards. Sealed sources should not be subjected to compaction, shredding or incineration. As a general principle, the overriding need for safety means that sealed sources should not be removed from their primary containers, nor should the container be physically modified. Peripheral components of large irradiation equipment (those not directly associated with the source) should be removed, monitored and disposed of appropriately. A safety assessment and environmental impact assessment should be carried out before any operations are undertaken. 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.

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. There have been many cases of sealed sources being acquired for specific purposes (such as industrial process control) and of subsequently being lost because the operating organization ceases operation and control over the sources is lost. Many portable radiography devices contain valuable heavy metals and become attractive for scrap purposes. These are some of the reasons for spent and/or disused sealed sources being lost from regulatory control. States should establish and implement appropriate strategies for these ‘orphan’ sources. In all cases the strategy should ensure that whenever an orphan source has been identified, appropriate recovery measures are taken. These measures should include the identification of the responsible organizations and funding within the State to recover, handle, condition, store and, if necessary, dispose of the source.

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. Loss and misuse of radioactive material (such as sealed sources) can give rise to accidents resulting in the radiation exposure of workers and members of the public and the contamination of working premises and land. This can lead to the unplanned and accidental generation of radioactive waste. Both users and operators should take measures to ensure that technical and organizational means are in place, including the necessary contingency arrangements, for the processing and storage of any such accidentally generated radioactive waste.

Conditioning and packaging of disused sources 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

Conditioning and Packaging of Disused Sources

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

Storage of Disused Sources

Storage of Disused Sources

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.

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

Disposal of Disused Sources 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

Disposal of Disused Sources

Disposal of Disused Sources

References This lecture is based on the four references listed here plus conference and other reports on the BOSS borehole disposal system