radyasyon güvenliği 1

8/12/2019 radyasyon güvenliği 1

http://slidepdf.com/reader/full/radyasyon-guevenligi-1 1/51

“Radiation Safety in PublicHealthcare”

**Radiation ProtectionRadiation Protection

Seminar 2013Seminar 2013

Muhamad Samudi Yasir

Pusat Pengajian Fizik Gunaan

FST, UKM

[email protected]



*Introduction

*Types and Characteristic of Radiation Sources

*Radiation Hazard

*Facility Planning

*Classification of Work Areas

*Work Procedures for Unsealed Sources

*Procedure in Working with Sealed Sources*Safety Equipment

*Transportation

*Treatment and Disposal of Waste

*Monitoring



**Why Do People FearWhy Do People FearIonising Radiation?Ionising Radiation?

*Unknown threat*Can not be seen, felt ……

*Conflicting information in mass media*Contradictory data from different “scientists” *Long term consequences of radiation exposure*Lack of education among general public, physicians

and other professionals*Social understanding of any situation involving the

term “radiation” is negative.



Radiation in Research

Education IndustryMedicine Agriculture

Introduction

Introduction



Types of Radiation Sources

The first step in managing radiation hazards is to identify the typesand characteristics of the radiation source

Types and Characteristics of Radiation

Sources


Sources

Nuclear

Reactor

Sealed

Radioactive

Sources

Irradiating

Apparatus

Unsealed

Radioactive

Sources



*There are numerous types of irradiating apparatus usedin research. Examples:X-rays

XRD

XRF

XPSSESM machines

Linear accelerator etc

*Unlike radionuclide, these radiation sources will onlyemit radiation when high voltage is applied to it or

when it is switched ON. Safety engineering features arebuilt into their design.


Sources


Sources



*Radionuclides may be categorized into:

Sealed radionuclides

oSealed radionuclide or sealed source is radiation source consistingof any radioactive material, nuclear material or prescribed substancefirmly incorporated in solid and effectively inactive material, or sealed

in an inactive container of sufficient strength to prevent, under normalconditions of use, any dispersion of its contents.

oSealed sources when intact posed an external radiation hazards.

Unsealed radionuclidesoThese are exposed radionuclides usually in solid, liquid and gaseousforms.

oUnsealed radionuclides posed internal and external radiationhazards.


Sources


Sources



Characteristics of Radiation

Quality (e.g.

types of

radiation the

sources emit,

i.e. alpha,

beta, gamma,neutron and

heavy charged

particles).

Radiation of

different quality

exerts differentLinear Energy

Transfer (LET). LET

is defined as the

amount of energy

transferred to the

media per unit

distance ittraverses in the

media (keV m-1).

Radiation quantity

• source activity

(Bq)

• activity

concentration (Bqml-1 or Bq g-1)

• dose it produces

(Sv, Gy)


Sources


Sources



3 categories of radionuclide are used in research

Radionuclideswith long half-

lives Radionuclides

with medium

half-lives Radionuclides

with short half-

lives

Types and Characteristics of

Radiation Sources

Types and Characteristics of

Radiation Sources



Types of Radiation Hazard

Radiation HazardRadiation Hazard

ExternalRadiation

Exposure

InternalRadiation

Exposure

Contamination



Contamination

o Contamination involves deposition of radionuclide on the

outer surface of the body (e.g. skin), or on wall and floorsurfaces of building.

o Contamination involves unsealed radionuclides ororiginally sealed radionuclides that leaks due to acompromise seal.

o Radionuclide contamination is both an internal radiationhazard when it is ingested, inhaled or penetrated the skinand into the body, and an external radiation hazard if theradiation is highly penetrating.

Radiation HazardRadiation Hazard



**PropertiesProperties of of somesome radionuclidesradionuclides

Properties H-3 C-14 S-35 P-32 I-125 I-131

T1/2 12.3 yr 5730 yr 87.4 dy 14.3 dy 60 dy 8.04 dy

Mode of

decay

Beta Beta Beta Beta Gamma Beta &

gamma

Detector LS Beta -counter

Beta -counter

Beta -counter

Gammaprobe

Beta orgamma

probe

Biological

half-life

12 dy 12 dy 44 dy 14 dy 42 dy 8 dy

Critical organ Whole

body

Whole

body

Whole body /

testis

Bone Thyroid Thyroid

Gamma dose

rate at 1 m

(uGy/h/GBq)- - - - 34 51



**Units ofUnits of

MeasurementMeasurement

Source strength:CiBqkVp,mAs…

Exposure:RX

Absorbed dose:rads, Gy

&Dose equivalent:

rem, Sv

Radiation source Radiation beam Absorbing Medium



*Selection of locations and arrangements of workareas, radioactive waste storeroom, and office

Facility planning may involve selection of locations andarrangements of work areas (including laboratories),

radioactive waste storeroom and office. Suchselections depend on:

oTypes of radiation used;

oPhysical properties of radionuclides;

oQuantity of radionuclides to be kept;

oMethods of using radionuclides; and

oMethods of disposing the radionuclides.

Facility PlanningFacility Planning



*Construction consideration

Facility construction is dependent on types of radiation, physicaland chemical properties of radionuclide, quantity of radionuclides

to be used, stored and disposed.

Consideration must take into account the stage of construction(e.g. whether it is on the plan or during modification).

It is relatively cheaper to make any modification of facility at theplanning stage compared to when the building or facility is fullycompleted.




*Work place design

Work place design depends on:

oTypes of radiation;oRadionuclide quantity;

oSealed and unsealed conditions;

oMethods of use; and

oStorage and disposal of radioactive waste.

Work place is designed to provide for protection andsafety in compliance with the applied standards.




*Work place design

Design must meet engineering, performance and functionalspecifications.

Design must meet quality norms commensurate with theprotection and safety significance of components and systems.

Design must incorporate the need for classification of workingareas, storerooms to store radiation source and waste.

If radioactive dust or gas is to be used than a proper ventilatedroom must be considered.




*Work place design

A control barrier must be erected at the entrance of acontrolled room used to handle unsealed sources.

Radiation monitoring equipments (e.g. hand and footmonitor, survey meters etc.), and personal protectiveequipment are placed at the entrance/exit to theworking area.

Specially built shielded room must be erected forirradiating apparatus and sealed sources.




*Work place design

Shielded rooms for irradiating apparatus and sealed sources havesome general requirements. These include:

oRoom is designed and built according to the standards required for itspurpose;

oRoom must be classified and demarcated appropriately; and

o All necessary control measures and procedures in accordance to its

classification must be enforced.

Besides safety, the overall work place design must provide forcomfort of work and security of the facility.




*Work place design

Work place design includes storage area. Storage area should atleast:ohave adequate shielding for the types of radiation;

oallow easy access to stored materials;

obe ventilated;

obe under locked security (e.g. bomb pit for storing radiation sourcesused in NDT);

ohave appropriate label with warning signage; and

o include dedicated delay tanks for temporary storage of liquid waste.

Work place design is not limited to the planning stage. Modificationand alteration of work place could come when new work activity isintroduced to the facility. Consequently, workplace design comesafter construction of the facility.




Radiation Work Areas

Clean AreaSupervised

Areas

Controlled

Area

Classification of Work AreaClassification of Work Area



*Clean area

Area where the expected maximum dose for that areadoes not exceed the dose limit for a member of the

public.

*Supervised area

Work area for which the occupational exposureconditions are kept under review even though specificprotective measures and safety provisions are notnormally needed.

Classification of Work

Areas


Areas



*Controlled area

Work area where specific protection measures and safetyprovisions are or could be required for controlling normal

exposures or preventing the spread of contamination duringnormal working condition, and preventing or limiting the extent ofpotential exposures.

Area where the expected maximum Permissible Dose Limit isgreater than 3/10 (6 mSv y-1).

This area is subject to special rules for the purposes of protectionagainst ionizing radiation and to which access is controlled.


Areas


Areas



* All safe work procedures must be tested before use andreviewed periodically to ensure their relevancy andappropriateness for the intended purposes.

* All safe work procedures need to be explained to users.While most procedures require briefing and explanationsome require prior training, while others need to befurther complemented with supervision.

* All safe work procedures must be developed followingradiation risk assessment.

Work Procedures for

Unsealed Sources

Work Procedures for

Unsealed Sources



*Handling techniques

The objectives of handling techniques in works related to radiationsource are to reduce exposure and to prevent contamination.

Handling techniques involve:

oThe use of shielded room for work with very high radioactivity;

oThe use of remote control apparatus (e.g. tongs) to handle sources;

oProcedure to transfer liquid sample (e.g. should never pipette with themouth);

oThe use of suitable waste bin for different radionuclides, and physicalproperties of waste (e.g. liquid, solid or gaseous waste); and

oThe use of correct personal protective equipment when handlingunsealed radionuclides. E.g. the use of rubber gloves and laboratorycoats while handling unsealed sources.

Work Procedures for

Unsealed Sources

Work Procedures for

Unsealed Sources



*Separation of activity and dilution of concentration

The safest way to work with radiation source is to use the optimum

amount or quantity. Radionuclides are not cheap and a posedradiation risk when used in excess.

Lower activity means lower doses. If spillage and contaminationoccur, then the cleaning up process will only involve low activityand concentration.

It is important to follow the recommendations of supplier on theneed to separate and dilute the radionuclides.

Work Procedures for

Unsealed Sources

Work Procedures for

Unsealed Sources



Radioactive gases

Radioactive gases can cause internal radiation exposure. Theuse of proper ventilation system with continuous monitoring ofdischarge must be installed in facility using radioactive gases.

Vertical laminar flow may be considered for use in handlingradioactive gases but care must be taken to prevent airturbulence in the hood.

All exhaust system related to possible discharge ofradionuclide outside the working must be strictly monitored andcontrolled. No release of radioactive materials for disposal,recycling or reuse is allowed without prior written approval ofthe appropriate authority.

Work Procedures for

Unsealed Sources

Work Procedures for

Unsealed Sources



Handling low activity sources

This is normally related to handling environmental materialscontaining low activity naturally occurring radioactive sources.

Although the source activity is low, care must always be taken toensure unnecessary exposure to the radiation.

Care must also be taken to ensure that the level of activity remainsbelow the permissible level approved by the authority.

Area monitoring of work area and storage room must be carried outcontinuously.

The concept of ALARA must always be used during handling of low activitysources to ensure the lowest achievable dose exposure.

Work Procedures for

Unsealed Sources

Work Procedures for

Unsealed Sources



*Time, shielding and distance

Time, shielding and distance are three principles of methods of control thatcan be incorporated into engineering as well as management controls ofradiation hazard.

Longer exposure times means higher dose of exposure and vice versa.

Thickness, density as well as types of materials (Z number) determine theeffectiveness of shield against a particular radiation quality. Generally thickermaterial increases the attenuation of radiation intensity. High Z materials (e.g.Pb) are effective in attenuating electromagnetic radiation (e.g. gamma and x-

rays). Low Z materials (e.g. H) are effective in attenuating neutron sources.

Inverse square law is used to reduce dose through distance.

Procedure in Working

with Sealed Sources


with Sealed Sources



Leak test

A radiation leak is divided into two:

oDesign leak or allowed leakage by the manufacturer on aparticular apparatus; and

oDefect of sealed sources, apparatus or machine.

Leak test is a physical test conducted on sealed

sources to ensure the integrity of the source capsule.Leak test is also done on irradiation machine (e.g. X-ray machine).


with Sealed Sources


with Sealed Sources



*Leak test

Level of radiation leakage is determined based on the deviation ofmeasured dose from the dose of design leak.

Purpose of leak test is to confirm the classification of sealedsources and performance of irradiation machine is maintained atall times during its use.

Leaks due to defect of sealed sources, apparatus or machine mustbe assessed periodically (interval is prescribed by the authority) orwhenever damage of the source (if radiation source, it is thecapsule or seal) is suspected, or when there is a presence ofcontamination (allowable leaked activity = 185 Bq).


with Sealed Sources


with Sealed Sources



Methods used in leak test

Test methods used in detecting and measuring leaksfrom sealed sources may be divided into two:

*Radioactive methodso Example of radioactive methods include:

* Wipe (smear) test

* Cellulose tape test

* Scrub test

* Soaked-I test

* Soaked-II test

Procedure in Working with

Sealed Sources


Sealed Sources




Test methods used in detecting and measuring leaksfrom sealed sources may be divided into two:

*Non-radioactive methodso Examples of non-radioactive methods include:

* Vacuum bubble test

* Hot liquid bubble

* Gas pressurization bubble test

* Helium test

* Helium pressurization test

* Water pressurization test


Sealed Sources


Sealed Sources




Counting equipment is used in leaktests.

Counting equipment used in leak testsare similar to that used to detect thetypes of radionuclide, radiation as wellas to measure the activity of the leaksource.

Liquid scintillation counters may be usedfor beta emitters while gamma countersmay be used to measure gammaemitters.


with Sealed Sources


with Sealed Sources



Storage equipment

Storage equipment include portable radioactive waste containerfor temporary storage of waste emitting different types of radiationemitters. (e.g. lead pot).

Transport equipment

Transport equipment may be divided into on-site and off-siteequipment.

On-site transport equipment is usually designed for transportinglow activity sources.

Sources are carried in transport container with secondaryshielding by trained personnel.

Safety EquipmentSafety Equipment



*Laboratory equipment

Containers are used to temporarily store radioactive materials.Containers to store gamma emitters must be lead lined.Containers may be made of disposable materials (e.g. plasticbags) that may be disposed after used.

Disposable tools include disposable pipettes, and dishes.Disposable tools are used with unsealed sources.

Remote arm (or tongs) may be used to handle radiation sources ata distance.

Shields are another example of laboratory equipment. Shield maybe portable or permanently fixed. Example of portable shields forbeta particles is Perspex.




Personal Protective Equipment (PPE)

PPE are used to reduce the likelihood of exposure and/orcontamination, and their radiological impact should exposure orcontamination do occur. Examples of PPE include overalls,aprons, rubber gloves, footwear, safety goggles and visors, and

even respirators and breathing apparatus.

PPE such as lead apron and lead glasses are used to reduceexposure to penetrating ionizing radiation (e.g. x-ray and gamma-ray).

PPE should always be the last choice of radiation risk control afterall other risk control measures have been considered andpreferably implemented. Preference should be given toengineering control followed by administrative control in controllingradiological risk.




TLDTLD



The lead gown



*Movement of radioactivematerial within and off-siteof the premise shall becarried out according to

Radiation Protection(Transport) Regulations1989.

*Get an approval from

AELB 14 days beforetransportation.

TransportationTransportation

d i l f

d i l f



*Research facility produces radioactive wastesthrough the use of unsealed sources. Thesewastes could be the element itself or the

radionuclides tagged to a non-radioactivecompound.

*Problem of disposing the radioactive waste is

now complicated by the presence of chemicalcompounds, which by itself could be toxic to theecosystem.

Treatment and Disposal of

Waste


Waste

T d Di l f

T d Di l f



*Radioactive wastes mix with other toxic chemical compounds mustbe treated before disposal. Treated radioactive wastes may bedisposed either through delay and decay, dilute and disperse orconcentrate and contain.

Long-lived radionuclides or radionuclides with long half-life (e.g. U-238and Th-232) require them to be kept in a proper container and stored in asafe place.

Radionuclides with short half-life (e.g. P-32) may require that it betemporarily stored to facilitate the radionuclides to decay to its stable formbefore being treated in a non-radioactive procedure or discharged into theenvironment.

Radionuclide may be diluted and dispersed if they are naturally found inthe environment and is at a concentration similar to that in theenvironment (e.g. H-3 and C-14).


Waste


Waste





*Treatment process for radioactive waste doesnot differ from other non-radioactive waste exceptfor the needs to provide for shielding againstionizing radiation.

*General procedure of waste managementinvolves:classification of the waste

pre-treatment

treatmentconditioning

storage

disposal


Waste


Waste

T t t d Di l

T t t d Di l



*Classification of waste

Is done based on its half-live and activity. IAEA proposed thatradioactive waste be classified according to:

oExempted waste (EW): its disposal results in an exposure of less than0.01 mSv to the public;

oLow and intermediate level waste with short half-lives (LILW-SL);

oLow and intermediate level waste with long half-lives (LILW-LL): A 30years half-life is used to differentiate between short and long half-lives;and

oHigh level waste (HLW).

Waste may also classified according to the physical properties of thewaste, i.e. solid, liquid or gaseous wastes. Except for researchreactor facility, most research facility does not produce high-levelwaste.

Treatment and Disposal

of Waste


of Waste

T t t d Di l

T t t d Di l



*Pretreatment At this stage the waste is categorized and separated according to

its physical state or stabilizing it with specific materials.Pretreatment helps to reduce the volume of the waste.

*TreatmentThe main purpose of treatment is to reduce the waste volume. At

this stage the principles of delay and decay, and concentrate andcontain is applied where practicable. Treatment may also increasethe volume (e.g. in dilute and disperse).

*Conditioning At this stage, binding matrix is added to liquid or solid waste to

become homogenous solid monolith with low leach ability.


of Waste


of Waste

T t t d Di l

T t t d Di l



*Storage

With some costs research facility may send their waste to ANM forstorage. Otherwise some research facility stores their own waste.Delay tank should be used for temporary storage of short half-lives

radionuclides before disposal into the environment or treated asnon-radioactive waste.

*Disposal

Upon treatment radioactive waste will eventually be disposed offinto appropriate repository. MINT does provide repository fororganization that are unable to dispose of their waste. Wastesfrom sealed sources are disposed according to the proceduresapproved by the appropriate authority.


of Waste


of Waste



*Monitoring starts before operation,continues during operation and afteroperation ceases. Such monitoring practiceis pertinent for facility that uses unsealedradionuclide sources.

*Radiation monitoring is carried out usingspecialized equipment that includes:

Dosimeters (pocket dosimeters, film and TLDbadge) are used to measure accumulateddose received by radiation workers over thepreset time; and

Geiger Mueller survey meters may be usedto monitor external radiation includingdetecting and measuring surfacecontamination.

MonitoringMonitoring

Alpha

Beta and Gamma



**Masih adaMasih ada

kemusykilan?kemusykilan?

radyasyon güvenliği 1

Documents

Transcript of radyasyon güvenliği 1