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IAEAInternational Atomic Energy Agency
Radiation Protection Issues in Nuclear Installations
(NPP & RR)
Laszlo SagiRadiation Safety and Monitoring Section
Division of Radiation, Transport and Waste Safety
Department of Nuclear Safety and Security
IAEA Practice and risk at Nuclear Installations
Objectives
• Health risks for staff while visiting nuclear facilities− Nuclear power plants (NPPs)− Research reactors (RRs)
• Procedures to enter, stay in and exit controlled areas
IAEA Practice and risk at Nuclear Installations
Outline
• Sources of radiation
• Measures to reduce risk− External radiation exposure− Internal radiation exposure
• Controlled areas− Definition− Boundaries− Entrance and exit− Instrumentation
IAEA Practice and risk at Nuclear Installations
Nuclear Installations
• Research reactors− “Neutron factories” for training, research, materials testing or isotope
production for medicine and industry− Currently around 240 facilities in 56 countries
− Power: 100 kWth to 100 MWth in continuous operation
− Inventory of fission products (10 MWth unit): 1018 Bq
• Nuclear power plants− For energy production
− Power: 100 MWth to 2000 MWth
− Inventory of fission products (1000 MWth unit): 1020 Bq
IAEA Practice and risk at Nuclear Installations
Sources of Radiation
• Fuel in reactor core, spent fuel and core components• Activation, fission and corrosion products• Activated equipment, systems and piping• Solid and liquid radioactive waste• Gaseous radioactive material• Experimental facilities generating activated or other radioactive material • Tools and facilities for storage and handling of radioactive material• Irradiated material• Start-up neutron sources• Neutron detectors (fission chambers, self-powered neutron detectors)• Components of purification (filters and ion exchange columns)
IAEA Practice and risk at Nuclear Installations
External Radiation Exposure
10 100 10000.0
0.2
0.4
0.6
0.8
1.0 All applications Hospital Testing Isotope Nuclear power
Sp
ec
tra
l dis
trib
uti
on
(No
rma
lise
d t
o m
ax
=1
)
Photon energy (keV)
Averages
IAEA Practice and risk at Nuclear Installations
Measures to Reduce Risk
• Basic principles to reduce radiation exposure and risk
− Minimise the time of radiation exposure− Increase the distance from the source− Use appropriate material to provide shielding
Time (t) → Distance (d) → Shielding (s)
IAEA Practice and risk at Nuclear Installations
Internal Radiation Exposure
• No risk for intake of radionuclides by inhalation or ingestion during normal operation
Risk for immersion
IAEA Practice and risk at Nuclear Installations
Measures to Reduce Risk
• Basic measures to reduce internal radiation exposure
− Do not smoke− Do not eat or drink− Do not apply cosmetics
− Use personal protective equipment (gloves, overcoats, respirators, …)
− Fit test before use
IAEA Practice and risk at Nuclear Installations
Supervised and Controlled Areas
• Radiation areas are designated as to the maximum permissible effective dose rates
0.5 µSv/h 3 µSv/h 10 µSv/h
1 mSv/yr 6 mSv/yr 20 mSv/yr
Freearea
Supervisedarea
Controlledarea
PUBLIC OCCUPATIONALLY EXPOSED WORKERS
IAEA Practice and risk at Nuclear Installations
Protective Measures
• In controlled areas, specific protective measures or safety provisions are or could be required for
− Preventing incorporation and
the spread of contamination
during normal working conditions
− Preventing or limiting the extent of potential exposures
IAEA Practice and risk at Nuclear Installations
Administrative Procedures
• Read and follow the local rules and procedures that are appropriate for controlled areas
IAEA Practice and risk at Nuclear Installations
Boundaries of Controlled Areas
• Extent of controlled areas should be clearly defined
• Where practicable, the boundaries coincide with fixed barriers such as walls and doors of a room
Registrants and licensees shall delineate controlled areas by physical means or, where this is not reasonably practicable, by some other suitable means
IAEA Practice and risk at Nuclear Installations
Entrance to Controlled Areas
• Registrants and licensees shall provide, as appropriate, at entrances to controlled areas
− Protective clothing and equipment
− Individual and workplace monitoring equipment
− Suitable storage for personal clothing
IAEA Practice and risk at Nuclear Installations
Signs and Symbols
Warning symbol and instructions at access points to :
• prohibit unauthorized access• To use suitable PPE
Symbols recommended by International Organization for
Standardization (ISO)
IAEA Practice and risk at Nuclear Installations
Instrumentation in Controlled Areas
• Fixed and portable radiation monitors• Alarm system (acoustic and visual)
IAEA Practice and risk at Nuclear Installations
Exit from Controlled Areas
• Monitoring equipment regardingcontamination of skin, clothing andobjects to be removed from area
• Washing or showering facilities
• Suitable storage for contaminatedprotective clothing and equipment
IAEA Practice and risk at Nuclear Installations
Personnel Contamination Monitoring
Monitoring : systematically and carefully • stand straight on clean pad,
feet spread slightly, armsextended, palms up andfingers straight out
• Monitor both hands and arms,then repeat with hands andarms turned over
• Monitor carefully forehead,nose, mouth, neckline, torso,knees and ankles; repeaton back of body
• Monitor soles of feet
IAEA Practice and risk at Nuclear Installations
Barrier Procedures for Footwear
• Disciplined shoe change procedure is essentialto contain contamination in designated area
- Remove one overshoe before immediatelyswinging the shoeless foot over the barrier
- Other foot may then be lifted to remove thesecond overshoe and again swinging the legover the barrier without the shoeless foottouching the dirty area floor
- Dirty overshoes may not leave the dirty area
IAEA Practice and risk at Nuclear Installations
Conclusions
• Most facilities have their own radiological protection programmes, which are largely based on IAEA safety standards
• However, some facilities do not
IAEA
Where to keep the personal dosimeter (TLD) during checking ?
• Hold luggage ?
1-2 mSv
or
• Hand luggage ?• 10- 20 µSv
Quantities, exposures and Services 23
IAEA Practice and risk at Nuclear Installations
Can we take the TLD to the medical inspection (e.g. X-ray check) ?
• Please No ! • The exposure 7- 8 mSv
IAEA
What to do when your EPD beeps?
• Know what the alarm levels are (dose rate and dose).
• Walk away from the high dose rate area. (Increasing the distance reduces the dose rates at the occupied location).
• Make dose rate measurements (if you have a dose rate meter - Do not use your EPD!!!)
• Plan through the work, using time, distance and shielding.
• If applicable - share the work with a colleague
Quantities, exposures and Services 25
IAEA
Am I protected from external radiation by external barriers?
Cotton Gloves, Overalls, Boots, Shoe Covers, Vinyl Gloves
• Prevents contamination of skin• Helps minimize spread of
contamination
• Does not provide protection against external exposure
Quantities, exposures and Services 26
IAEA Practice and risk at Nuclear Installations
Thank you for your kind attention!
Mr Laszlo Sagi | Operational Radiation Monitoring Service Group Leader | Section of Radiation Safety and Monitoring | Division of Radiation, Transport and Waste Safety | Department of Nuclear Safety and Security | International Atomic Energy Agency | Vienna International Centre, PO Box 100, 1400 Vienna, Austria | Emai l: [email protected] | T: (+43-1) 2600-22508 | F: (+43-1) 2600 29653 | Fol low us on www.iaea.org