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Radiation Safety
Radiation – is ENERGY IN TRANSITENERGY IN TRANSIT in the form of high speed particles and electromagnetic waves.
NOTENOTE W t l t ti dW t l t ti d
Introduction
NOTENOTE: We encounter electromagnetic waves every day. : We encounter electromagnetic waves every day. They make up our visible light, radio and television They make up our visible light, radio and television waves, ultra violet (UV), and microwaves with a spectrum waves, ultra violet (UV), and microwaves with a spectrum of energies. These examples of electromagnetic waves do of energies. These examples of electromagnetic waves do not cause ionizations of atoms because they do not carry not cause ionizations of atoms because they do not carry enough energy to separate molecules or remove enough energy to separate molecules or remove electrons from atoms.electrons from atoms.
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Bedok Safety Group Seminar on Industrial Health - 21 October 2010
Radiation Safety - by Kelvin Low
Page 2
Ionizing radiation – is radiation WITHWITH enough energy so that during an interaction with an atom, it can remove tightly bound electrons from their orbits, causing the atom to become
Introduction
charged or ionized. Example is X-RAY
Non-ionizing radiation – is radiation WITHOUTWITHOUT enough energy to remove tightly bound electrons from their orbits around atoms. Example is LASER
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Electromagnetic Spectrum
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Bedok Safety Group Seminar on Industrial Health - 21 October 2010
Radiation Safety - by Kelvin Low
Page 3
IONIZING NON-IONIZINGDAMAGES chemical bonds Lower energy, CAN’T
DAMAGE bonds
Health Effects
Alpha, Beta, Gamma, X-Ray Microwave, Infrared, Visible, Ultraviolet, Laser
CUMULATIVE effects THRESHOLD effects
damage from low levels damage occurs only
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damage from low levels of exposure that can add-up over time
damage occurs only above a “threshold” levelno cumulative effects below “threshold”
Types of Ionizing RadiationAlpha, Beta and Gamma rays from the decay of radioactive substances matter
Ionizing Radiation
X-ray produced electronically by X-ray machines. X-ray machine emits radiation only when the machine is energised.
Alpha
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Alpha decay is a radioactive process in which a particle with two neutrons and two protons is ejected from the nucleus of a radioactive atom.
Bedok Safety Group Seminar on Industrial Health - 21 October 2010
Radiation Safety - by Kelvin Low
Page 4
BetaA beta is a high speed particle, identical to an electron, that is
Ionizing Radiation
emitted from the nucleus of an atom.
GammaGamma rays are electromagnetic
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waves or photons emitted from the nucleus (center) of an atom.
X – RayX Rays are electromagnetic waves or photons not emitted from the nucleus, but normally emitted by energy changes in l t X d ti OCCURSOCCURS h l t f
Ionizing Radiation
electrons. X-ray production OCCURSOCCURS whenever electrons of high energy STRIKESTRIKE a heavy metal target, like tungsten or copper.
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Bedok Safety Group Seminar on Industrial Health - 21 October 2010
Radiation Safety - by Kelvin Low
Page 5
Penetrating Distances
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Sievert (Sv), rem (rroentgen-eequivalent mman) Old unit is rem where 1 Sv = 100 remSievert (Sv) is a unit of RADIATION DOSERADIATION DOSE due to ionizing
Ionizing Radiation Dose
Sievert (Sv) is a unit of RADIATION DOSERADIATION DOSE due to ionizing radiationExpress doses received by human beingsDose depends on ACTIVITYACTIVITY of radioactive source, distance, shielding and exposure time.
Sievert is named after Rolf M Sievert aSievert is named after Rolf M Sievert a
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Sievert is named after Rolf M. Sievert, a Sievert is named after Rolf M. Sievert, a Swedish Physicist who was one of the Swedish Physicist who was one of the pioneers in protection against ionizing pioneers in protection against ionizing radiationradiation
Bedok Safety Group Seminar on Industrial Health - 21 October 2010
Radiation Safety - by Kelvin Low
Page 6
Ionizing radiation can cause two main biological effects, namely
Somatic effects (acute & chronic) in which the damage
Effects Due To Ionizing Radiation
Somatic effects (acute & chronic) in which the damage appears in the IRRADIATED PERSON HIMSELFIRRADIATED PERSON HIMSELF, and
Genetic effects which arise only in the OFFSPRING OFFSPRING of the irradiated persons as a result of radiation damage to germ cells in the reproductive organs.
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Dose (Sv) Effect1,000 Spastic seizures; death in minutes.
Acute Effects of Irradiation at Different Doses
100 Damage to central nervous system; death in hours.
10 Circulating changes; death in days.
1 Radiation sickness (nausea, vomiting, fatigue; following a short latent period epilation, loss of appetite, fever, diahorrea, rapid emaciation, and
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possible death); decrease in life expectancy and disease resistance; sterility, erythema – reddening of the skin.
0.1 No obvious injury.
Bedok Safety Group Seminar on Industrial Health - 21 October 2010
Radiation Safety - by Kelvin Low
Page 7
Sv Casualties Deaths
Statistics for Chernobyl Accident
< 1 105 0
1 – 4 53 1
4 – 6 23 7
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6 - 16 22 21
Effect Mean Latent Period Evidence For Effect
Leukemia 8 - 10 yearsAtomic bomb casualties,M di l X t t t
Some Chronic Effects of Radiation
yMedical X-ray treatment
Bone cancer 15 years Radium luminous dial painters
Thyroid cancer 15 - 30 yearsAtomic bomb casualties,Medical treatment
Lung cancer 10 - 20 years Mine workers
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Life shortening -- Experiments with mice
Cataract 5 - 10 years Atomic bomb casualties
Bedok Safety Group Seminar on Industrial Health - 21 October 2010
Radiation Safety - by Kelvin Low
Page 8
(a) The dose from any medical or dental exposure as a patient, from the exposure to natural background radiation or from other exposures received by the radiation worker as a member of the public shall not be taken into account.
Application Dose Limit per year (mSv)
Eff ti d ( h l b d ) 201
Second Schedule - Part I Dose Limits For Radiation Workers
(b) Where only a part or parts of the body are irradiated by external radiation, the effective dose received from external radiation shall be determined by calculating the sum WTHTover all organs and tissues irradiated, where ----
Effective dose (whole body)Equivalent dose in
201
the lens of the eyethe skin2
the hands and feet
150
500
500
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g ,(i) HT is the equivalent dose received by any particular tissue or organ T; and(ii) WT is the weighting factor for that tissue or organ
1. The limit on effective dose (whole body) is 20 mSv per year, averaged over defined periods of 5 years and with the further provision that the effective dose shall not exceed 50 mSv in any single year.
2. The limit of 500 mSv for skin is averaged over areas of no more than 1 cm2 regardless of the area exposed
Application Dose Limit per year (mSv)
Effective dose (whole body)Equivalent dose in
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the lens of the eye 15
Second Schedule – Part II Dose Limits For Individual Members Of The Public
the lens of the eyethe skin2
1550
1. In special circumstances, a higher value of effective dose for the whole body is allowed in a single year provided that the average over 5 years does not exceed 1 mSv per year. The limit shall apply to the sum of the relevant doses from the external exposure in the specified period and the committed effective dose
2. The limit of 50 mSv for skin is averaged over areas of no more than 1 cm2 regardless of the area exposed
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Bedok Safety Group Seminar on Industrial Health - 21 October 2010
Radiation Safety - by Kelvin Low
Page 9
Whole body effective dose limit for radiation worker should not be more than 20 mSv a year for whole body exposure and 1 mSv a year for public members
Control of Ionizing Radiation ExposureControl of Ionizing Radiation Exposure
All unjustifiable doses should be avoidedHigh dose accumulation is to be avoided for women of reproductive capacity
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ShieldingShieldingTimeTime
Reduction of Exposure to Ionizing RadiationReduction of Exposure to Ionizing Radiation
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DistanceDistance
Bedok Safety Group Seminar on Industrial Health - 21 October 2010
Radiation Safety - by Kelvin Low
Page 10
Distance - keeping a RESPECTFULRESPECTFUL distance from a radiation source is often the most effective way of REDUCINGREDUCING dose (moving from 1 m to 10 m from strong
di ti d di ti d i d b 100
Reduction of Exposure to Ionizing Radiation
radioactive source reduce radiation dose received by 100 times).
Shielding – INCREASEINCREASE the amount of shielding will DECREASEDECREASE the amount of exposure.
Time - radiation dose is directly proportional to exposure time Keep exposure time to as SHORTSHORT as possible
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time. Keep exposure time to as SHORTSHORT as possible.
Engineering ControlsX-ray machine adequately shielded so that radiation level anywhere outside the enclosure when the X-ray
Control Measures
y ymachine is energized is within legal limit.
Effective safety interlocks shall be provided so that when the X-ray machine has to be switched off before any enclosure door can be opened and cannot be switched on so long as the door is opened.
Ad t i t i th i i it h ll b
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Adequate warning to everyone in the vicinity shall be given by appropriate light or audible signals or both while X-ray machine is energized.
Bedok Safety Group Seminar on Industrial Health - 21 October 2010
Radiation Safety - by Kelvin Low
Page 11
Example of Safe Work ProceduresElectrical Safety
Control Measures
Lockout/Tagout (LOTO)
Reproductive Health Hazard
Radiation Safety
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LicensesApply for required licenses L3 (machine) L5
Operating a X-ray machine
Safe Work Procedures
Apply for required licenses, L3 (machine), L5 (Supervision of R1 holder) and/or R1 (Radiation Worker) from National Environment Agency (NEA)Applicant must be at least 18 years old
Medical Examination
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Before beginning radiation work. Must be certified fit for radiation work by registered medical doctor. If there is directive from NEA.
Bedok Safety Group Seminar on Industrial Health - 21 October 2010
Radiation Safety - by Kelvin Low
Page 12
Site MonitoringA monitoring survey is required after installation of a new X-ray machine,
Safe Work Procedures
move a X-ray machine or modify a X-ray machine
Geiger counterScintillation counter
Training
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TrainingAll radiation worker must be adequately trained on operation of X-ray machine and know the hazards associated with the work.
Warning Label
Safe Work Procedures
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Bedok Safety Group Seminar on Industrial Health - 21 October 2010
Radiation Safety - by Kelvin Low
Page 13
Safety GuidesFollow the recommended safety guidelines from the equipment manufacturer
Safe Work Procedures
q pReport any abnormal situation to immediate supervisor, Radiation Safety Officer and/or Safety Department
Test interlocks at the frequency required for your particular type of X-ray machine
Document and understand alignment procedures for the
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X-ray machine you own or use
Pregnant radiation worker shall declare pregnancy to their immediate supervisor and managers so that arrangement can be made to exempt them from working X-ray machine during the pregnancy.
Personal DosimetersThermoluminescent Dosimeter (TLD) is used to measure the estimated radiation dose absorbed thru
Safe Work Procedures
skin and body.
TLD consists of TLD card and holder, also known as TLD badge.
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Bedok Safety Group Seminar on Industrial Health - 21 October 2010
Radiation Safety - by Kelvin Low
Page 14
Personal DosimetersTLD card provide early warning
TLD d i i d bi thl
Safe Work Procedures
TLD card is issued bi-monthly
TLD card is tested individually, data is retained forever (by NEA)
After the TLD cards are processed, a dose report is generated
M i S
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Measures exposure in mSv
Identifies radiation energy, type, and direction
TLD Badge – Do’s and Don’ts
DO Put in TLD card properly in TLD holder with name appearing on window
Safe Work Procedures
name appearing on windowWearer name should be against the wearer when TLD badge is wornWear TLD at chest level when working around X-ray machineKeep TLD at workplace
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DON’T Place TLD on X-ray machineDeliberately expose TLD to radiationWear TLD during medical testsExpose TLD to heat
Bedok Safety Group Seminar on Industrial Health - 21 October 2010
Radiation Safety - by Kelvin Low
Page 15
Establish System for Reporting When
Acquire a X-ray machine
Safe Work Procedures
Dispose a X-ray machine
Suspect an abnormal condition
Move a X-ray machine
Modify a X-ray machine
Return a X ray machine to service
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Return a X-ray machine to service
Radiation Protection ActRadiation Protection (Ionizing Radiation)
Licenses required for manufacture possess use and
Statutory RequirementStatutory Requirement
Licenses required for manufacture, possess, use and import, and sale of radioactive and irradiation apparatusRadiation workers must not be younger than 18 yrs old, required to register, go for medical examination, instructed to do radiation work and wear personal dosimeter
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dosimeter.Not allowed to receive excess of annual dose limit in 2nd Schedule
Bedok Safety Group Seminar on Industrial Health - 21 October 2010
Radiation Safety - by Kelvin Low
Page 16
Radiation Protection (Ionizing Radiation) RegulationsMedical examination include full blood examination & certified fit by approved registered doctor before
Statutory RequirementStatutory Requirement
y pp gengaged in radiation workRadiation worker has been adequately trainedTransfer record in approved form for employees who had left the companyRadioactive materials, irradiating apparatus and radiation areas must be appropriately labeled
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radiation areas must be appropriately labeledSafe storage and accounting of radiation sourcesDesign aspects such as shielding, interlocks, warning devices, layout, instrumentation, ventilation must meet applicable requirements
Radiation Protection (Ionizing Radiation) RegulationsPenalty for individual not exceeding $2000Appropriate procedures in dealing with radiation
Statutory RequirementStatutory Requirement
Appropriate procedures in dealing with radiation accidentsCalibration of area monitors and dosimetersL3 - license to keep or possess an irradiating apparatus (company)L5 - license to use irradiating apparatus (individual)
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5 ce se to use ad at g appa atus ( d dua )R1 - license to register as a radiation worker (individual using ionizing irradiating apparatus under supervision of licensee L5)
Bedok Safety Group Seminar on Industrial Health - 21 October 2010
Radiation Safety - by Kelvin Low
Page 17
Types of Non-Ionizing RadiationElectromagnetic radiation & fields with wavelengths greater than 100 nm & acoustic radiation & fields with
Non-Ionizing Radiation
frequencies above 16 KHz,Microwave RadiationInfrared RadiationVisible Radiation Ultraviolet RadiationUlt d
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UltrasoundLaser
LASER is an acronym for LLight
AAmplification by
Laser
LASER light differs from ordinary light in three ways,
SStimulated
EEmission of
RRadiation
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Monochromatic (single wavelength)
Coherent (in-phase)
Directional
Bedok Safety Group Seminar on Industrial Health - 21 October 2010
Radiation Safety - by Kelvin Low
Page 18
Laser can pose more of a hazard than ordinary light because they can focus a lot of energy onto a small area
Laser
LASERS ARE “POINT” SOURCES OF LIGHTLASERS ARE “POINT” SOURCES OF LIGHT
LASER(POINT SOURCE)
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INCANDESCENT LIGHT BULB(EXTENDED SOURCE)
Lasing media (gas, liquid, solid, semiconductor)Excitation mechanism (power supply, flash lamp, laser)Feedback mechanism (mirror grating)
Laser DesignLaser Design
Lasing medium
Feedback mechanism (mirror, grating)Output coupler (partially reflecting mirror)
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Feedback
mechanism
Output
Coupler
Excitation mechanism
Bedok Safety Group Seminar on Industrial Health - 21 October 2010
Radiation Safety - by Kelvin Low
Page 19
Lasers are generally classified according to the materials used
Gas (CO Argon)
Types of LaserTypes of Laser
Gas (CO2, Argon)
Solid (Nd:YAG, Ti:Sa)
Semiconductor (Gallium-Arsenide)
Dye
Mode of Operation – Continuous Wave; P l d W Q it h d
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Pulsed Wave; Q-switched
Wavelength – UV; Visible to Near IR; Mid to Far IR
Beam HazardsEye
Ski
Non Beam HazardsChemical
El t i l
Laser HazardsLaser Hazards
Skin Electrical
Explosion
Fire
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Bedok Safety Group Seminar on Industrial Health - 21 October 2010
Radiation Safety - by Kelvin Low
Page 20
Eye HazardsRisk for retinal injury is dependent on wavelength and/or total power entering the eye
Laser HazardsLaser Hazards
For wavelengths that focus on the retina, the optical gain of the eye is about 100,000 times! If the irradiance entering the eye is 1mW/cm2, then the irradiance at the retina will be 100 W/cm2
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Skin HazardSkin injury from laser energy is primarily THERMAL
( t f UV) Hi hl d d t
Laser HazardsLaser Hazards
(except for UV). Highly dependent on:
Beam Irradiance
Exposure Duration
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Bedok Safety Group Seminar on Industrial Health - 21 October 2010
Radiation Safety - by Kelvin Low
Page 21
Non-beam HazardsChemical Hazards - from dyes; from solvents used to clean optics
Laser HazardsLaser Hazards
solvents used to clean optics
Electrical Hazards – from high voltage power supplies
Explosion Hazards – from high pressure arc lamps, from compressed gases
Fire Hazards – from electrical circuit
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Fire Hazards from electrical circuit, ignition of gases, flammable solvents BOOM
Class Description1 Lasers that are inherently safe & incapable of producing
dangerous levels of emissions
Laser Classification
2 Do not normally present a hazard because of normal human bright-light aversion response. May present potential eye hazard if viewed directly for long time,
3a Would not injure the eye if viewed for only momentary periods with the unaided eye, Eye damage possible if viewed with collection optics
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3b Hazardous under direct viewing or a reflected beam is viewed.
4 Hazardous under all viewing conditions, may produce significant skin hazards as well as fire hazards.
Bedok Safety Group Seminar on Industrial Health - 21 October 2010
Radiation Safety - by Kelvin Low
Page 22
Protective housing that prevents human access during operation to laser
Enclosed beam path
Engineering Controls
Enclosed beam path
Safety Interlocks
Remote control firing
Key –actuated master control
Beam stops and attenuators
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Example of Safe Work ProceduresElectrical Safety
L k t/T t (LOTO)
Control Measures
Lockout/Tagout (LOTO)
Radiation Safety
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Bedok Safety Group Seminar on Industrial Health - 21 October 2010
Radiation Safety - by Kelvin Low
Page 23
LicensesApply for required licenses, N2 (machine) and/or N3 (laser worker) from National Environment Agency
Safe Work ProceduresSafe Work Procedures
Applicant must be at least 18 years old
Medical ExaminationBefore beginning laser work. Must be certified fit for laser work by registered medical doctor.
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TrainingAll radiation worker must be adequately trained on operation of X-ray machine and know the hazards associated with the work.
Protective EyewearAppropriate for all wavelengths in use
Safe Work ProceduresSafe Work Procedures
Sufficient attenuation (Optical Density) at wavelengths in use
Good visible light transmission
Good field of viewing
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Comfortable to wear
Bedok Safety Group Seminar on Industrial Health - 21 October 2010
Radiation Safety - by Kelvin Low
Page 24
Warning Label
Safe Work ProceduresSafe Work Procedures
LASER RADIATIONDO NOT STARE INTO BEAM OR VIEW
DIRECTLY WITH OPTICAL INSTRUMENTS
TYPE OF LASERPOWER & WAVELENGTH
CLASS 3A LASER PRODUCT
LASER RADIATIONDO NOT STARE INTO BEAM OR VIEW
TYPE OF LASERPOWER & WAVELENGTH
CLASS 2 LASER PRODUCT
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Class 3a Laser ProductClass 2 Laser Product
Warning Label
Safe Work ProceduresSafe Work Procedures
LASER RADIATIONAVOID EXPOSURE TO BEAM
TYPE OF LASERPOWER & WAVELENGTH
CLASS 3b LASER PRODUCT
LASER RADIATIONAVOID EYE OR SKIN EXPOSURE TO DIRECT OR SCATTERED RADIATION
TYPE OF LASERPOWER & WAVELENGTH
CLASS 4 LASER PRODUCT
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Class 3b Laser Product Class 4 Laser Product
Bedok Safety Group Seminar on Industrial Health - 21 October 2010
Radiation Safety - by Kelvin Low
Page 25
Do not attempt to operate systems with enclosures openDo not defeat or tamper with safety interlocks
Safety Guides
Safe Work ProceduresSafe Work Procedures
Do not defeat or tamper with safety interlocksDo not operate machine if enclosures are damagedFollow the recommended laser safety guidelines of the equipment manufacturer as in the user/service manual
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For Repair WorkControl access to the equipment during service e.g. Laser curtains, barriers, closing entranceways
Safe Work ProceduresSafe Work Procedures
Post NOTICE sign at entranceway into controlled areaAfter maintenance or servicing,
Remove NOTICE signRemove unnecessary objects from the vicinity of the laser
NOTICE
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the laserChecked to confirm all safety interlocks are operating effectively
LASER REPAIR IN PROGRESS
Laser Safety Eyewear Required
Bedok Safety Group Seminar on Industrial Health - 21 October 2010
Radiation Safety - by Kelvin Low
Page 26
Laser should be discharged in a non-reflective & fire resistant backgroundArea should be cleared of personnel for a reasonable
Safe Work ProceduresSafe Work Procedures
Area should be cleared of personnel for a reasonable distance on all sides of laser beamLooking into the primary laser beam, specular reflections of the beam, including those from lens surface, should be avoided at all timesAvoid aiming laser into eye to prevent looking along the axis of the beam which increases the hazard from
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axis of the beam which increases the hazard from reflections
Laser work should be carried out in areas of high general illuminations to keep pupils constricted thus limiting the energy which might inadvertently enter the eyes
Safe Work ProceduresSafe Work Procedures
Personnel should be instructed on potential eye hazards & the importance of limiting unnecessary exposureSafety eyewear designed to filter off specific frequencies & to provide protection should be worn at all times.Binoculars or aiming telescopes should not be used to view direct laser beam or reflected beam from mirrors
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unless the beam intensities are greatly below safety levels.
Bedok Safety Group Seminar on Industrial Health - 21 October 2010
Radiation Safety - by Kelvin Low
Page 27
Radiation Protection ActThe Radiation Protection (Non-Ionizing Radiation) Regulations
A l t th f ll i i i i t
Statutory RequirementStatutory Requirement
Apply to the following non-ionizing apparatus: a) ultraviolet sunlamps (for irradiating living human
body) ; b) microwave ovens ; c) medical and industrial ultrasound apparatus; d) magnetic resonance imaging (MRI) apparatus; e) entertainment lasers; and
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e) entertainment lasers; and f) high power lasers
N2 - license to keep or possess for use of class 3b & 4 lasers & ultrasoundN3 - license to use class 3b & 4 lasers
The Radiation Protection (Non-Ionizing Radiation) Regulations
Detail requirements in dealing with NIR
Statutory RequirementStatutory Requirement
Detail requirements in dealing with NIR
Requirements on shielding, interlocks, warning devices
Appropriately labeled to give adequate warning
Worker must be at least 18 yrs old to perform laser radiation work, adequately trained & holds a license
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radiation work, adequately trained & holds a license for class 3b or 4 lasers
Bedok Safety Group Seminar on Industrial Health - 21 October 2010
Radiation Safety - by Kelvin Low
Page 28
Thank You
Bedok Safety Group Seminar on Industrial Health - 21 October 2010
Radiation Safety - by Kelvin Low