Transcript Radiation Protection in Nuclear Medicine

IAEA Training Material on Radiation Protection in Nuclear Medicine
Part 10
Radioactive Waste
Objective
To be aware of the general principles of the handling
and the safety of radioactive waste. To be able to
identify, store and dispose of the different types of
waste generated in a nuclear medicine department
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Contents
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Introduction
Basic requirements & legal framework
Waste collection, segregation and storage
Waste treatment and disposal
Examples of waste management in nuclear
medicine. Local rules.
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IAEA Training Material on Radiation Protection in Nuclear Medicine
Part 10
Radioactive Waste
Module 10.1 Introduction
Radioactive Waste in
Nuclear Medicine
The use of unsealed sources in diagnosis and therapy will
generate radioactive waste of different kinds during preparation,
patient examination and care
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Radioactive Waste in
Nuclear Medicine
Sealed sources used for calibration and quality control of
equipment, Point sources and anatomical markers, will end up
as radioactive waste.
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Radioactive Waste in
Nuclear Medicine
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Solid waste.
Cover papers, gloves, empty vials and syringes.
Radionuclide generators. Items used by hospitalized patients
after radionuclide therapy. Sealed sources used for calibration
of instruments. Animal carcasses and other biological waste.
Liquid waste.
Residues of radionuclides. Patient excreta. Liquid scintillation solutions.
Gaseous waste.
Exhausted gas from patients in nuclear medicine
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IAEA Training Material on Radiation Protection in Nuclear Medicine
Part 10
Radioactive Waste
Module 10.2 Basic Requirements
and Legal Framework
Fundamental Principles
1. Radioactive waste shall be managed in such a way as to
secure an acceptable level of protection for human health.
2. Radioactive waste shall be managed in such a way as to
provide an acceptable level of protection of the environment.
3. Radioactive waste shall be managed within an appropriate
national legal framework including clear allocation of
responsibilities and provision for independent regulatory
functions.
4. Generation of radioactive waste shall be kept to minimum
practicable.
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Waste Management Definitions
Exempted
waste
Interim
storage
Pre-treatment
Treatment
Conditioning
Radioactive
material for
reuse/recycle
Transportation
Disposal
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Waste Management Framework
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Nuclear Medicine
Organization and responsibilities
Waste inventory
Waste management plan
Waste minimization
Safety assessments
Facilities
Transports
Staff training
Documentation and records
Quality assurance
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Quality Assurance
•Local rules
Normal working conditions
Accidents
•Waste identification and traceability
Record system
•Process control
Safe handling of radioactive sources
Facilities
Monitoring
Quality of containers
Arrangements for storage
Documentation
•Audits
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IAEA Training Material on Radiation Protection in Nuclear Medicine
Part 10
Radioactive Waste
Module 10.3 Waste Collection,
Segregation and Storage
Radioactive Waste
BSS: Interim Edition
3.131. Registrants and licensees, in cooperation with suppliers,
as appropriate:
(a) Shall ensure that any radioactive waste generated is kept to the
minimum practicable in terms of both activity and volume;
(b) Shall ensure that radioactive waste is managed in accordance
with the requirements of these Standards and the requirements of
other applicable IAEA standards, and in accordance with the
relevant authorization;
(c) Shall ensure that there is separate processing of radioactive
waste of different types, where warranted by differences in factors
such as radionuclide content, half-life, activity concentration,
volume, and physical and chemical properties, taking into account
the available options for waste storage and disposal, without
precluding the mixing of waste for purposes of protection and
safety;
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Radioactive Waste contd…
(d) Shall ensure that activities for the predisposal management of and
for the disposal of radioactive waste are conducted in accordance with
the requirements of applicable IAEA standards37, and in accordance
with the authorization;
(e) Shall maintain an inventory of all radioactive waste that is
generated, stored, transferred or disposed of;
(f) Shall develop and implement a strategy for radioactive waste
management and shall include appropriate evidence that protection
and safety is optimized.
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Waste Minimization
A good planning of the nuclear medicine activity including selection of
radionuclides and good working procedures will result in a reduced
volume of radioactive waste.
Selection of radionuclides should take into account half-life, type of
radiation, activity etc.
Working procedures should take into account the number of operations
and material involved in the preparation, the risk of contamination etc.
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Examples of Waste from
Nuclear Medicine
•Biological waste which may undergo decomposition.
•Infectious waste requiring sterilization prior to disposal.
•Broken glass-ware, syringes etc, requiring collection in
separate containers to prevent personnel being injured.
•Radionuclide generators
•Bed linen and clothing from hospital wards.
•Liquid scintillation solutions
•Patient excreta ?
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Segregation of Waste from
Nuclear Medicine
Some examples of the different types of waste generated in a
hospital
•Liquid waste containing short-lived radionuclides capable of being
stored for decay (radiopharmaceuticals).
•Solid waste containing short-lived radionuclides capable of being
stored for decay (contaminated items).
•Liquid waste which after proper treatment and conditioning can be
handled in the public waste treatment system (long-lived
radiopharmaceuticals).
•Solid waste which after proper treatment and conditioning can be
handled in the public waste treatment system (biological samples,
anatomical markers).
•Sealed sources. (sources for calibration and QC)
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Segregation/Waste Containers
Containers to allow segregation of different
types of radioactive waste should be
available in areas where the waste is
generated. The containers must be suitable
for purpose (volume, shielding, leak proof,
etc.)
•Glassware with radionuclides (short half-life)
•Syringes and needles
•Gloves and paper
•Glassware with radionuclides (medium halflife)
•..
•..
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Storage of Radioactive Waste
A room for interim storage of radioactive waste should be
available. The room should be locked, properly marked and
ventilated.
Each type of waste should be kept in separate containers
properly labeled to supply information about the
radionuclide, activity concentration etc. Flammable goods
should be kept apart.
Records should be kept where the origin of the waste can
identified.
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Storage of Radioactive Waste
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Storage of Radioactive Waste
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Storage of Radioactive Waste
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IAEA Training Material on Radiation Protection in Nuclear Medicine
Part 10
Radioactive Waste
Module 10.4 Waste Treatment
and Disposal
Radioactive Waste
Registrants and licensees shall ensure that radioactive
substances from authorized practices and sources not
be discharged to the environment unless:
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either clearance has been granted for the radioactive
substance or the discharge is within the discharge limits
authorized by the Regulatory Authority.
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Treatment of Solid Waste
(general principles)
The objective of the treatment process is to reduce the
volume of solid waste, reduce or eliminate potential
hazards associated with the waste and to produce waste
packages suitable for destruction, storage or transportation
to and disposal at a licensed repository.
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Conditioning of Solid Waste
Waste packages
Public system
National plant
Solid waste should be conditioned in order to produce a
waste form suitable for storage and transportation governed
by the properties of the waste, the transport regulations
and the specific waste disposal acceptance requirements
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Disposal of Solid Waste
Example of national regulations of disposal of waste from
hospitals:
Disposal via the public waste treatment system
•Maximum 10 ALImin /month and maximum 1 ALImin
per package.
•The dose rate at the surface of each package should be
<5 uGy/h.
•The package should not contain any single sealed source
with activity >50 kBq.
•Each package should be properly labeled with a warning
sign containing information on radionuclide and activity. The
origin of the waste should also be given on the package.
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Liquid Waste
Effluent Discharges
Liquid Waste
Treatment
Solid Waste
Effluents
•Liquid waste can be transformed to solid waste by some
treatment process such as evaporation.
•Liquid waste can be discharged to the environment if either
clearance has been granted for the radioactive substance
or the discharge is within the limits authorized by the
Regulatory Authority.
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Effluent Discharges:
Example of Rules
<10 ALImin per month and <1
ALImin or not more
than 100 MBq at each
occasion.
Flush with plenty of water.
Use a special sink for the
discharge.
A label should be posted
informing personnel that
disposal of liquid waste is
allowed at this point.
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National Discharge Limits
Example
R a d io n u clid e
S e-7 5
S r-8 9
T c-9 9 m
In -1 1 1
I-1 2 5
I-1 3 1
T l-2 0 1
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D isch a rg e
(M B q ea ch tim e)
20
5
100
100
1
1
100
Part 10. Radioactive waste
D isch a rg e
(M B q /m o n th )
200
50
30000
2000
10
10
6000
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IAEA Training Material on Radiation Protection in Nuclear Medicine
Part 10
Radioactive Waste
Module 10.5 Examples and
Local Rules
Short-Lived Radionuclides
Radionuclides such as Tc-99m, I-123, Tl-201, I-131
Sm-153, Sr-89 etc. should, after segregation, be stored
for decay during a period of time established locally by
the RPO, taking into account all applicable national
regulations.
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Patient Excreta
Diagnostic Patients:
Generally no need for collection of excreta.
Ordinary toilets can be used.
Therapy Patients:
Different policies in different countries:
• Use separate toilets equipped with delay tanks or
an active treatment system, or
• Allow the excreta to be released directly into
the sewer system.
The Regulatory Authority should define the principles taking
the environmental impact into consideration
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Liquid Dischages
I-131
Estimation of the generic clearance value for aquatic
release of I-131 is quite complicated. Is all material
retained in the sewage sludge at sewage treatment
works or is all the activity discharged to a water body?
Who will get the highest exposure? Which dilution of
the radionuclide concentration will be found etc?
Calculations must be made by qualified persons taking
into account the guidance given by IAEA (TECDOC 1000)
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Mo-Tc Generators
Store for decay
Check for contamination
Dismount the generator
Return to producer
Exempted waste?
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Mo-Tc Generator
(store for decay & dismounting)
Assume a generator with 20 GBq Mo-99 at reference time.
The half-life of Mo-99 is 2.75 d and the exemption activity is
1 MBq (BSS). The time for interim storage should then
be 40 d.
The dose rate at 1 m from the unshielded column will then be
0.04 μSv/h. Hence, the external exposure will be very small when
dismounting the generator.
The dismounted column is exempted waste and the sign of
its previous radioactivity should be removed. The column can
now be discharged together with similar waste from the
hospital.
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Dismounting Mo-Tc Generator
3. Check for radiation
1. Check for radiation
2. Remove the plastic cover
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4. Remove the column
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Dismounting Mo-Tc Generator
5. Remove the lead shield
7. Check if the column
can be classified as exemted
waste
6. Separate the different materials
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Sealed Sources for QC of Equipment
• Co-57 flood sources, anatomical markers etc used in
diagnostic nuclear medicine
• Co-57, Cs-137 etc calibration sources for activity meters.
• Ge-68 calibration sources(phantom/rods) for PET scanners
Should be transferred to a national plant for final disposal
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Liquid Scintillation Solutions
Small activities of H-3 or C-14 in organic solvents.
Glass or plastic vials of 5-10 ml volume.
Controlled Incineration in a plant!
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Biological Waste
Incineration
Pre-treatment (deep
freezing, quicklime, chemical
methods)
Store for decay
Transfer to
depository
Exempted waste
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Local Rules
Department of Diagnostic Nuclear Medicine
Radiation Protection Manual
RADIOACTIVE WASTE
Gloves, cover paper etc
Syringes, needles
Vials containing Tc99m
Tl-201, In-111, Ga-67
Technetium generator
Flood sources, markers
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Summary
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The requirements of the BSS and other IAEA publication
formulates the general rules regarding waste management.
An efficient national infrastructure and policy is required.
National regulations regarding disposal of waste should be
available and form the basis of local rules in the hospital.
A well planned use of radionuclides is fundamental in a waste
management system.
A system for segregation of the waste should be available in the
department. This includes proper containers.
A room for storage of waste should be available.
A quality assurance programme in nuclear medicine should
include management of radioactive waste.
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Questions?
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Discussion
How should a room for interim storage be classified?
Controlled area? Supervised area?
Where should the room be localized and how should
it be designed?
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Discussion
A physicist is measuring the radionuclide purity
of a technetium generator. The measurements
reveal small amounts of Pu-239. Will this affect
the disposal of the generator?
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Discussion
Discuss the possibilities of incineration of radioactive
waste. What basic requirements should be fulfilled by
the plant?
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Where to Get More
Information
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Other Sessions:
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Part 4 Safety of Sources. Design of Facilities
Part 9. Quality Assurance
Part 5 Occupational Protection
Further Readings:
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IAEA, International Basic Safety Standards for Protection Against Ionizing Radiation and for
the Safety of Radiation Sources Safety Series No.115, Interim Edition (2011)
IAEA, The Principles of Radioactive Waste Management, Safety Series No. 111-F, (1995)
IAEA, A Safety Guide on Predisposal management of radioactive waste from medicine,
industry and research, Safety Standard Series No 111-G-2.2 (1997)
IAEA/WHO Manual on Radiation Protection in Hospitals and General Practice, Volume 4,
Nuclear Medicine. Manuscript.
Handling and disposal of radioactive materials in hospitals, ICRP Publication No. 25. Oxford,
Pergamon Press, 1977 (Annals of the ICRP No. 2)
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Pre-Treatment
Any or all the operations prior to waste treatment
such as:
•collection
•segregation
•chemical adjustment
•decontamination
Collection and segregation of waste are important factors
to consider in a system of waste management in nuclear
medicine
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Exempted Waste
Storage for decay may release the waste from
nuclear regulatory control. Clearance levels
should be given by the national Regulatory
Authority.
All signs of its radioactive origin should be
removed and the waste can be treated as any
similar waste in the hospital taking into account
the possible biological and chemical hazards.
This is the most common way to handle radioactive
waste in nuclear medicine.
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Disposal
The emplacement of waste in an approved specified facility (for
example, near surface or geological repository) without the
intention of retrieval ("confine and contain”). Disposal may also
include the approved direct discharge of effluents (for example,
liquid and gaseous wastes) into the environment with
subsequent dispersion ("dilute and disperse”).
Both methods are used in disposal of waste in nuclear
medicine
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Treatment
Operations intended to benefit safety and/or
economy by changing the characteristics of the
waste. Three basic treatment objectives are:
•volume reduction
•removal of radionuclides from the waste
•change of composition.
After treatment, the waste may or may not be
immobilized to achieve an appropriate waste form.
Generally not used ín Nuclear Medicine
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Conditioning
Those operations that produce a waste package suitable for
handling, transportation, 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.
Should be applied to long lived sealed sources used for
calibration and QC of nuclear medicine equipment.
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Interim Storage
Storage of waste at different stages of the waste
management process, before the final disposal.
A room for interim storage of waste should be available
in a nuclear medicine facility. It is mainly used for
storage for decay to exemption levels. This is the main
method of final disposal of waste generated in nuclear
medicine.
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Waste Transportation
Transportation of waste at different stages of the waste
management process, before the final disposal. The
international regulations established by IAEA shall be
followed.
Note that radioactive waste should be handled similar
to any radioactive source.
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Local Rules 1
Department of Diagnostic Nuclear Medicine
Radiation Protection Manual
RADIOACTIVE WASTE
Gloves, cover paper etc
• Shall continuously be collected in the plastic bags placed in the rooms
for preparation and injection of radiopharmaceuticals
• When the bag is filled, seal it and move it to room 2:13.
• Write the expected date of disposal (today's date+14 days)
• Before disposal, check the external dose rate on the surface. If the dose
rate does not exceed the background,.the bag can be disposed of as
ordinary waste.
• If the dose rate exceeds the background, write the new date of disposal
on the bag and store it for another 14 days.
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Local Rules 2
Department of Diagnostic Nuclear Medicine
Radiation Protection Manual
RADIOACTIVE WASTE
Used syringes and needles etc
• Shall continuously be collected in the shielded container in the rooms
for preparation and injection of radiopharmaceuticals
• When the container is filled, seal it and move it to the fume hood in room
2:13.
• Write he expected date of disposal (today's date+4 weeks) on the
container and place it behind the lead shield.
• Before disposal, check the external dose rate on the surface. If the dose
rate does not exceed the background,.the container can be disposed of
according to the ordinary rules for dangerous items
• If the dose rate exceeds the background, write the new date of disposal
on the container and store it for another 4 weeks,
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Local Rules 3
Department of Diagnostic Nuclear Medicine
Radiation Protection Manual
RADIOACTIVE WASTE
Vials containing residues of Tc-99m
• Shall continuously be collected in the shielded container in the room for
preparation of radiopharmaceuticals
• When the container is filled, seal it and move it to the fume hood in room
2:13.
• Write the expected day of disposal (today's date+4 weeks) on the
container and place it behind the lead shield.
• Before disposal, check the external dose rate on the surface. If the dose
rate does not exceed the background,.the container can be disposed of
according to the ordinary rules for glassware
• If the dose rate exceeds the background, write the new date of disposal
on the container and store it for another 4 weeks,
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Local Rules 4
Department of Diagnostic Nuclear Medicine
Radiation Protection Manual
RADIOACTIVE WASTE
Vials containing residues of Tl-201, In-111 and Ga-67
• Measure the residual activity
• Put the vial in the original lead shield and move it to room 2:13
• If the activity is below 100 MBq, open the vial and pour the content in the
sewage system. Use the sink in room 2:13. Flush with plenty of water.
Rinse the vial and dispose it as ordinary glass ware. Use protective
gloves and clothing during the work.
• Check for contamination of the sink. Clean it if contamination is detected
• If the residual activity is >100 MBq, calculate the time of storage using
the tables posted in the room. Write the date of disposal on the vial and
put in the fume hood.
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Local Rules 5
Department of Diagnostic Nuclear Medicine
Radiation Protection Manual
RADIOACTIVE WASTE
Technetium generator
• Put the used generator back into the transport container
• Move the container to the room for interim storage of waste (no 01:24
located in the basement). The key to the room is kept by the Chief
Technician
• Fill in the record (generator no and today's date)
• The used generators will be picked up every 8th week by the producer.
Check the containers for contamination before they are removed. Fill in
the date of removal in the record.
• Notify the RPO (NN phone xxxxxx if contamination is detected)
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Local Rules 6
Department of Diagnostic Nuclear Medicine
Radiation Protection Manual
RADIOACTIVE WASTE
Sealed sources
Flood sources, anatomical markers, check sources
• Move the used source to the room for interim storage of waste (no 01:24
located in the basement). The key to the room is kept by the Chief
Technician
• Fill in the record (source id no and today's date)
• The final disposal of the source is handled by the RPO (NN, phone
xxxxxx)
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