PRINCIPLES OF RADIATION PROTECTION 1

Why do we need radiation protection? z Radiation is a hazard z Radiation is senseless (no odor, invisible & cannot be felt) z However : Radiation is useful if used wisely 2

OBJECTIVES  To protect human and environment from unnecessary exposure to radiation, without affect the net benefit from using the radiation and radioactive material. zTo prevent the occurrence of deterministic effects and limit the probability of stochastic effects to level deemed acceptable zWays to protect and minimize exposure to radiation 3

Content zIntroduction zSystem of Dose Limitation zProtection from Radiation Hazard zClassification of Areas zProtection against External Hazard zProtection against Internal Hazard 4

How does radiation harm us? zRadiation can change/destroy cells in human body/change its functions 5

System of Dose Limitation ICRP 26 zJUSTIFICATION of a practice zOPTIMIZATION of Radiation Protection zDOSE LIMIT for individuals 6

JUSTIFICATION of practice zA practice is justified only when there is za net positive benefit zRadiation technique is more superior/better zNo other technique available (e.g. well logging) zIn short: Compare alternative methods/techniques which do not involve the use of ionizing radiation if possible 7

OPTIMIZATION of Radiation Protection zALARA -As Low As Reasonably Achievable, social & economic factors taken into account z To achieve ALARA for occupational exposure e.g. a) QC & maintenance program is to reduce the number of rejected diagnostic films and in turn, to reduce the dose presently incurred by nursing staff, radiographer and patients. 8

DOSE LIMIT for individuals  Shall not exceed the limits stipulated as recommended by ATOMIC ENERGY LICENSING (BASIC SAFETY RADIATION PROTECTION) REGULATIONS 2010 zIntended to prevent deterministic effects and to limit the occurrence of stochastic effects to an acceptable limit 9

10 Dose limit is used to apply controls on each individual’s accumulation of dose and is not a line of demarcation (borders) between “safe” and “dangerous”, Dose limit is apply for occupational exposure only, excluding dose received from natural radiation and medical exposure Dose limits are similar for men and women except pregnant women. DOSE LIMIT for individuals

Annual Dose Limit (ADL)  External exposure + Internal Exposure  Few categories:- I.Worker II.Public III.Planned special circumstances IV.Pregnant Worker V.Research Student 11

TYPES OF EXPOSURE TO RADIATION zExternal Exposure: Exposure arises from sources outside the body zInternal Exposure: Exposure from sources inside the body due to inhalation, ingestion and absorption through skin I-131 Internal  X-rays External 12

Annual Dose Limit (ADL) Annual Limit of Intake (ALI) Resulting from the intake of radionuclide (Bq) via internal exposure Derived Air Concentration (DAC) DAC(Bq/m 3 ) = ALI (inhalation)(Bq) / volume of air (m 3 ) inhaled per year The values for ALIs and DACs for various radionuclides are given in ICRP Internal Exposure

DOSE LIMIT FOR RADIATION WORKERS & PUBLIC ______________________________________________________________________ ApplicationRadiationPublic Pregnant Student/ Workers Apprentice ______________________________________________________________________ Effective dose20 mSv/y 1mSv/y 1mSv/y 6mSv/y (2,000 mrem/y) (100mrem/y) Annual Equivalent Dose Eye lens150(15,000)15(1,500)- 50 Skin500(50,000)50(5,000)- 150 Hand & feet500(50,000) _______________________________________________________________ Notes: 1) 100 rad ~ 100 R = 1 Gy = 1Sv 14

15 Dose limit in special circumstances (1)Apply to the appropriate authority(AELB) for a temporary change in the dose limit requirement for specified workers. Licensee shall comply with any procedures, information as specified by the AELB).  extension of the averaging effective dose to not more than 10 consecutive years, and the effective dose shall not exceed 20 mSv per year averaged and not exceed 50 mSv in any one calendar year,  Plan exposure shall be reviewed when the dose accumulated by any worker reaches 100 mSv;  a change in the limit on average effective dose per year to a value not exceeding 50 mSv for a period of not more than five consecutive years, subject to a limit of 50 mSv in any one calendar year. -(Suatu perubahan dalam had bagi purata dos berkesan bagi setiap tahun hingga suatu nilai yang tidak melebihi 50 mSv bagi suatu tempoh yang tidak melebihi lima tahun berturut-turut, tertakluk kepada suatu had 50 mSv dalam mana-mana satu tahun kalendar).

PROTECTION FROM RADIATION HAZARD 1) Remove the hazard 2) Guard the hazard 3) Guard the workers 16

(1) Remove/Minimize the hazard zKeep amount of RAM to minimum possible zChoose RAM that pose least possible hazard zChoose safe and most practicable procedures zDispose RAM waste safely and restrict movement to as minimum as possible 17

(2)Guard the Hazard (2) Guard the Hazard zReduce radiation level outside the controlled area, well within permissible level zUse hot cells, lead bricks and shielded transport containers where appropriate zPrevent hazardous release of RM to the environment zUse fume cupboards, glove boxes and sealed containers 18

(3) GUARD THE WORKERS zChoose correct materials, instruments & facilities zprovide rules, regulations, procedures, Emergency procedures, contamination monitoring for area, site etc zUse appropriate PPE 19

CLASSIFICATION OF AREAS Objectives: zsegregate working areas according to the expected hazard involved zbased on exposure level expected in normal working condition zNeed regular survey to confirm area concerned/unchanged zClassified areas should be marked appropriately X CA SA ClA 20

3 TYPES OF AREA CLASSIFICATION Demarcation of Area surroundings the source: Uncontrolled Area : z< 1/10 of dose limit z< 2mSv (0.2rem)/year (1.0  Sv/h); zcan work 40 hours/week and 50 weeks/year without exceeding 2mSv/year (No action required) Supervised Area: z> 1/10 but <3/10 of dose limit z< 6 mSv/year (3.0  Sv/h) zpersonnel working need supervision and personnel monitoring Controlled Area: z>3/10 of dose limit z> 3.0  Sv/h zpersonnel require regular Medical Checking and routine personal monitoring zspecial precautions include access limit, protective equipment and monitoring devices 21

(1.1) PROTECTION AGAINST EXTERNAL HAZARD  , X-rays and neutron are main concern of the external radiation - highly penetrative z  - to penetrate 0.07mm skin requires energy greater than 70 keV to reach the underlying tissues - E can go up to 2 MeV z  - to penetrate 0.07mm skin requires energy greater than 7.5 MeV to reach the underlying tissues - most  only with E 5.0 MeV 22

(1.2) PROTECTION AGAINST EXTERNAL HAZARD a) Minimize Radiation output: Use X-ray machine with minimum output or radionuclide with minimum activity. e.g. For  source, radiation dose rate at 1 m D(1m) = 0.55 CE rad/h 23

(1.3) PROTECTION AGAINST EXTERNAL HAZARD b) Distance: Dose rate is inversely proportional to square of distance from source D 1 (d 1 ) 2 = D 2 (d 2 ) 2 d1d1 d2d2 D1D1 D2D2 24

(1.3) PROTECTION AGAINST EXTERNAL HAZARD b) Distance: The dose rate at 2 m from a gamma source is 400 mSv/hr, at what distance will it give a dose of 25 mSv/hr? Answer: 8 metres 25

(1.4] PROTECTION AGAINST EXTERNAL HAZARD c) Time: Limiting time spent in the vicinity of the source to minimum necessary Dose = Dose rate x time 26

(1.4] PROTECTION AGAINST EXTERNAL HAZARD c) Time: A worker spend 40 hours per week and 50 weeks per year and the annual dose limit is 50 mSv, what is the maximum dose rate allowed? Answer: 25  Sv/hour 27

(1.5) PROTECTION AGAINST EXTERNAL HAZARD d) Shielding: Using appropriate shielding between the source & workers in order to minimize radiation dose received. Utilize TVL/HVL (cm) concept. E.g. To shield  from Co-60: Concrete, TVL =22.86cm, HVL= 6.85cm; Lead, TVL =4.11cm, HVL = 1.24cm; Uranium, TVL = 2.29, HVL = 0.69 HVL 44 22 11 28

(1.6) PROTECTION AGAINST EXTERNAL HAZARD 29 Shielding effectiveness depend on - Atomic number - Density - Thickness - Radiation Energy

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(2.1) PROTECTION AGAINST INTERNAL HAZARD Mode of entry of RAM material (unsealed sources) are through: InhalationIngestion Absorption through skin/cut/injury/openings 31

(2.2) PROTECTION AGAINST INTERNAL HAZARD zAll are hazardous -  being the most toxic. zEnsure minimum quantity of RAM used zConduct all operation in enclosure (fume hood/cupboard, hot cells) zEnsure good house keeping habit zConfined RAM spillage zConduct periodic survey of areas to detect contamination zPractice first for new operation with dummy zHand and foot must be monitored before exit the area zConduct periodic survey of areas to detect contamination 32

Worn by radiation workers to reduce the risk of radiation exposure from internal radiation exposure and radioactive contamination. Radiation Personal Protective Equipment (PPE) The last line of defense in controlling risk from ionizing radiation. Since the radiation hazards still exist, PPE should only be used to complement other means of radiation hazard control already in place. 3.1Protection Against Radiation Hazards

... continue Examples of personal radiation protection equipments/ clothing include: Laboratory coat Overall or boiler suit Rubber gloves Overshoes Rubber boots Self Contained Breathing apparatus 3.2Protection Against Radiation Hazards

Safety Equipment And Facilities At The Place Of Work Safety facilities include building design incorporating safety features to handle radiation and radioactivity. Examples of such equipment and facilities are: These equipments are not worn by workers but are used by them to reduce exposure and contamination. Remote-handling tongs Lead brick Liquid transfer system Radioactive containers Ventilated facility 3.3Protection Against Radiation Hazards

Safety Procedures and Surveillance Safety procedures employed in work related to handling unsealed sources must stress the importance of preventing inhalation, ingestion and penetration of radionuclides through the skin, and contamination of personnel and working areas in normal routine procedure and emergency situations. Handling of unsealed sources increases the risk of internal radiation exposure and contamination. 3.4Protection Against Radiation Hazards

Having a safe working procedure does not guarantee its compliance. Surveillance of compliance and monitoring of radiation levels must be carried out periodically. Both visual surveillance and those using radiation monitoring and detectors must be used.... continue 3.5Protection Against Radiation Hazards Safety Procedures and Surveillance

Thank you 38