IAEAInternational Atomic Energy Agency

Management of disused sealed radioactive sources

Day 9 – Lecture 7

IAEA 2

• 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 questionThe level of radioactivity

• To consider the implications for predisposal management

• To consider some disposal options

Objective

IAEA 3

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

IAEA 4

Introduction

• Disused sealed radiation sourceA 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

IAEA 5

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)

IAEA 6

• Radioactive sources can present a hazard in various ways:

External exposureIngestion InhalationDermal absorption

• The type and magnitude of the hazard depends on the radionuclide and the level of activity

Hazards

IAEA 7

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.

IAEA 8

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:

IAEA 9

Activity ranges of radiation sources

Miscellaneous waste containing DSRS

IAEA 10

Sr-90 radioactive sourcerecovered in the Rep. of GeorgiaSources used in mobile caesium

irradiators in the former Soviet Union

Miscellaneous waste containing DSRS

IAEA 11

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

IAEA 12

Category Typical uses Activity Ratio A/D

1 Radio-thermal generators; Irradiators; Teletherapy; Gamma knife

A/D>1000

2 Gamma radiographyBrachytherapy(HDR/MDR)

1000>A/D>10

3 High activity industrial gaugesWell 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; ECD0.01>A/D>Exempt/D

Inc r

e asi

ng R

isk

A = source activity; D = radionuclide-specific “dangerous” activity

Dangeroussources

Categorization of Radioactive Sources used in Common Practices

IAEA 13

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

IAEA 14

Best Options for Disused Sources?

• Return to supplier• Long term storage (50 y, 100 y, ???)• Disposal

IAEA 15

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.  

IAEA 16

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.

IAEA 17

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.

IAEA 18

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.

IAEA 19

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.

IAEA 20

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.

IAEA 21

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.

IAEA 22

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.

IAEA 23

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.

IAEA 24

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.

IAEA 25

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.

IAEA 26

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

IAEA 27

Conditioning and Packaging of Disused Sources

IAEA 28

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

IAEA 29

Storage of Disused Sources

IAEA 30

Storage of Disused Sources

IAEA 31

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.

IAEA 32

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

IAEA 33

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

IAEA 34

Disposal of Disused Sources

IAEA 35

Disposal of Disused Sources

IAEA 36

Disposal of Disused Sources

IAEA 37

References