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 Practice and risk at Nuclear Installations

References

IAEAInternational Atomic Energy Agency

DISCUSSION

What to do when…

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: L.Sagi@iaea.org | T: (+43-1) 2600-22508 | F: (+43-1) 2600 29653 | Fol low us on www.iaea.org