Jon Petter Omtvedt, Zeljka Raskovic-Lovre, Frøydis Schulz, Olga N. Salina, and Deniz Avsar
Department of Chemistry
Zoom on-line course, January 2021
UiO Three-day Course on
Radiation Protection
-Theory, Practicalities & Hands-on
Session is recorded!
Slide 2 UiO Radiation Protection Course, 2021
Schedule – Day 5
09:00-10:00 Summary of yesterday and discussion about video
10:15-12:00 How to work in the lab
12:15-13:00 Extra time
The Only Radiation Units You Need to Know
Slide 3 UiO Radiation Protection Course, 2021
Useful Book on Radiation & Health
● "Radiation and Health" by Thormod Henriksen et al. (UiO) (2015)
● Can be bought as an ordinary book, but is also freely available from the Department of
Physics web-page:
● https://www.mn.uio.no/fysikk/english/services/know ledge/radiation-and-health/
● An earlier edition (2005) is available in Norwegian:
● https://www.mn.uio.no/fysikk/tjenester/kunnskap/st raling/
Slide 4 UiO Radiation Protection Course, 2021
Recap: Radiation Quantities and Units
Radioactivity Qty: Activity
Unit: Bequerel (Bq)
1 Bq = 1 dis per sec 1 Ci = 3.7∙1010 Bq
Radiation Risk
Qty: Dose Equivalent Unit: Sievert (Sv)
Quality factor
1 Sv = 1 Gy for β, γ, and X-ray 1 Sv = 0.05 Gy for α
Radiation Absorbed Dose Qty: Dose
Unit: Gray (Gy) 1 Gy= 1 J / kg
A few slides more on:
- Dose, dose limits, and dosimetry
Slide 5 UiO Radiation Protection Course, 2021
Tissue Weighting Factor
The proportion of the risk of
stochastic effects resulting from irradiation of an organ or tissue to the total risk of stochastic effects when the whole body is irradiated uniformly.
Tissue or Organ
wT (2007 recomm.) Bone
marrow
0.12 Benmarg
Colon 0.12 Tarm
Lung 0.12 Lungene
Stomach 0.12 Mage
Liver 0.04 Lever
Thyroid 0.04 Skjoldbrusk-
kjertellen
Skin 0.01 Hud
Brain 0.01 Hjernen
Slide 6 UiO Radiation Protection Course, 2021
Effective Dose (ED)
● Takes into account that some tissues and organs in the human body are more sensitive to radiation than others
● Multiply the Biological Dose Equivalent (H
T) to each organ/tissue by the tissue weighting factor (w
T) for that organ/tissue and add them all together
𝐸𝐷 =
𝑇
𝐻
𝑇× 𝑤
𝑇● ED is comparable to the dose received if the whole body is
irradiated by an external (γ) source.
Slide 7 UiO Radiation Protection Course, 2021
Dose Coefficients
● ICRP Publication 119 (ISBN 978-1-4557-5430-4) provides conversion factors («Dose Coefficients») between Dose in Sv and corresponding amount of radioactive material (in Bq).
● Table A1: Effective Dose Coefficients for ingested and inhaled particulates for workers
● Example: 8x10-10 Sv/Bq for inhalation of 1 µm particles
● Table B1: EffectiveDose Coefficients for inhalation of soluble or reactive gases for workers
● Example: 4.1x10-11 Sv/Bq for organically bound tritium
Slide 8 UiO Radiation Protection Course, 2021
Effective Dose Coefficient
● A measure of the hazard of nuclear material is provided by the toxicity and in particular its radiotoxicity arising from its radioactive “quality” rather than the chemical toxicity.
● The radiotoxicity of a nuclide is determined by its effective dose coefficient e(T), which accounts for radiation and tissue weighting factors, metabolic and biokinetic
information.
● The quantity T is the integration time in years following intake. For adults, the integration time is 50 years, such that the radiotoxicity (in Sievert, Sv) or committed effective dose resulting from intake of a particular nuclide is the product of the effective dose
coefficient (units Sv/Bq) and the activity (in Bq) of that nuclide i.e.
Committed effective dose = Activity · e(50).
● The two main pathways for intake of a radionuclide are through ingestion and inhalation.
Accordingly one can differentiate between the ingestion dose coefficient eing(50) and the inhalation does coefficient einh(50) for inhalation.
Slide 9 UiO Radiation Protection Course, 2021
Examples
Nuclide Inhalation 1 μm (Sv/Bq)
Inhalation 5 μm (Sv/Bq)
Ingestion (Sv/Bq)
3H 4.2∙10-11
14C 5.4∙10-10
32P 8.0∙10-10 1.1∙10-9 2.4∙10-9
137Cs 1.0∙10-11 1.8∙10-11 2.5∙10-11
Slide 10 UiO Radiation Protection Course, 2021
Jon Petter Omtvedt Department of Chemistry Blindern Campus, January 2021
Radiation Protection Course:
- Fundamental Radiation Protection Principles
Slide 11 UiO Radiation Protection Course, 2021
ALARA Techniques
● You reduce radiation doses by:
● Decreasing Time
● Increasing Distance
● Using Shielding
● Implementing good Control Methods
• Administrative
• Engineering
ALARA = As Low As Reasonably Achievable
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Lab Work Examples
https://www.menti.com/vbso3fat44
Write the errors you find
to the Mentimeter!
Slide 16 UiO Radiation Protection Course, 2021
Radiation vs. Contamination
● Radiation is particles or waves of energy emitted from unstable
atoms.
● Radioactive contamination is radioactive material usually in any location you do not want it.
● Radioactive contamination emits radiation.
● Contact with Contamination can contaminate you with the
material.
Slide 17 UiO Radiation Protection Course, 2021
Exposure Risk – External and Internal
● The best protection is to reduce the radiation dose as much as possible!
● ALARA - As Low As Reasonable Achievable.
● We distinguish between two main types of exposure:
External Exposure Internal Exposure
Least
dangerous α particles γ radiation Inbetween β particles β particles
Most
dangerous γ radiation α particles
Slide 18 UiO Radiation Protection Course, 2021
Internal Exposure - through the skin
● Can easily be avoided.
● Usually happens due to spill on unprotected skin or when handling contaminated equipment.
● On-time gloves provides good protection in most cases.
● They must be inert to chemicals used.
● Immediately change gloves if spilled on.
● Check gloves with monitor frequently.
● Good work practise is important - avoid spills and splashing.
● Use spill trays with absorbing paper.
● Check frequently for contamination.
● Cover open solutions.
● Dedicated lab coats should be used, preferentially they should not leave the lab.
Slide 19 UiO Radiation Protection Course, 2021
Rad. dose from β-contamination
Slide 20 UiO Radiation Protection Course, 2021
Internal exposure through ingestion
● Usually happens by transfer of contamination you have got on your hand to your mouth when eating, drinking, or smoking.
● In order to reduce this risk it is absolutely forbidden to:
● Eat,
● Drink,
● Smoke,
● Chew chewing gum,
● Put on make-up.
● Food and drink should not be stored in the lab!
● Before you leave the rad. lab/area you should:
● throw away gloves,
● wash hands,
● take of lab coat.
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Internal exposure through inhalation
● Air borne contamination is the most likely way that radioactivity will enter the body.
● A contamination in the air will quickly contaminate every
surface in the laboratory and may even propagate outside of the laboratory.
● The likelihood of airborne contamination is reduced by using fume hoods and glove boxes.
● All work with volatile compounds, aerosols or dust/small particles must be performed in a fume hood or glove box.
● Consider what will happen in case of a power failure.
● The fume hoods and work surfaces must be smooth and without pores.
● Keep hoods tidy and clean.
Slide 22 UiO Radiation Protection Course, 2021
External Exposure
● Can be reduced by considering
▸Time
▸Distance
▸Shielding
Slide 23 UiO Radiation Protection Course, 2021
External Exposure - Time
● The radiation dose is directly proportional to the time in the radiation field.
● The simplest method to reduce dose is to reduce exposure time.
● For example, you can
● Plan how to perform the experiment
● Practise - perform the experiment without radioactivity
● Label areas with strong radiation fields
Slide 24 UiO Radiation Protection Course, 2021
External Exposure - Distance
● The γ-ray intensity from a point source is inverse proportional to the square of the distance
● Use tongs or other suitable tools when handling strong sources
● Please note that for alpha and beta sources the reduction is quicker due to interaction with air.
I I a
b
=
a b
22Where I
aand I
bis the intensity at distance a and
b, respectively.
Slide 25 UiO Radiation Protection Course, 2021
Radiation field from β sources
Example: 37 MBq (1 mCi)
32P
Slide 26 UiO Radiation Protection Course, 2021
BASIC CONCEPT is to:
Place materials between the
source and person to absorb some or all of the radiation
Shielding for α, β and γ
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Extern β-exposure - shielding
Slide 28 UiO Radiation Protection Course, 2021
Plexiglas cupboard
Slide 29 UiO Radiation Protection Course, 2021
Pippette Sheild
Slide 30 UiO Radiation Protection Course, 2021
External γ-radiation - Shielding
● γ-radiation intensity will be reduced by any kind of absorber, but can never be reduced to zero.
● Absorbers of high-Z material are more effective.
● Lead (Pb) is most common.
● Beware that the shielding will scatter and reflect the radiation field!
● Necessary thickness of shielding can be found by
considering the necessary number of "Half-Value- Layers"
HVL.
● Beware that HVL is a function of the energy of the γ radiation.
Slide 31 UiO Radiation Protection Course, 2021
External γ-Exposure - Shielding
0,01 0,1 1 10
0,01 0,1 1 10
HVL (mm)
Energy (MeV)
A A
p
=
n02
n = number of HVL,
A0 = intensity w.o. screen, Ap = intensity w. screen.
Slide 32 UiO Radiation Protection Course, 2021
End of Rad. Protection Principles!
Slide 33 UiO Radiation Protection Course, 2021
Jon Petter Omtvedt Department of Chemistry
Blindern Campus, 2021
Radiation Protection Course:
- Handling Accidents
Disposing of Radioactive Waste
Slide 34 UiO Radiation Protection Course, 2021
Accidents Will Happen
Titanic proved that there is no such thing as an
unsinkable ship..
→ Perform risk analysis!
→ Follow procedures!
→ Be prepared!
→ Do not hurry!
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Risikomatrise
Slide 36 UiO Radiation Protection Course, 2021
Alternative Risk-Analysis Form
http://www.arbeidstilsynet.no/binfil/download2.php?tid=79062
Slide 37 UiO Radiation Protection Course, 2021
If an accident happen..
● Accidents can be grouped according to seriousness:
→Spill on a bench top or hood dedicated for radioactive work (less serious).
→Spill on the floor or work area not dedicated for radioactive work (somewhat more serious).
→A person has become contaminated by radioactive material (very serious).
● The amount of radioactive material is of course
also important in classifing the seriousness of the
accident.
Slide 38 UiO Radiation Protection Course, 2021
Emergency Response – Radiation Safety
● In the event of a radiation accident involving an injured person, the first action should be life saving.
● SWIMS
● Stop work and think
● Warn others in the area
● Isolate the spill or radiation area
● Monitor the area
● Secure the area
Slide 39 UiO Radiation Protection Course, 2021
Reporting an Accident
● §19 in the radiation law describes how accidents and "events" are to be reported. This includes:
● Events where personnel got contamintated or could have become contaminated.
● Loss or theft of radiation sources.
● Accidental release of radioactivty to the environment.
● Events where the general public might receive doses above 0.25 mSv/yr.
● Serious contamination of area or equipment.
● Discovery of a radioactive source without owner.
Slide 40 UiO Radiation Protection Course, 2021
Reporting an Accident (II)
● Minor accidents should not be reported to the NRPA.
● However, they should be reported to your Radiation Protection Coordinator (RPC)!
● Your RPC will deceide if the accidents need to be reported further "up".
Slide 41 UiO Radiation Protection Course, 2021
Reporting an Accident (III)
● The following is not a minor accidents and needs to be reported to NRPA:
● A skin contamination which cannot be removed even after several attempts of washing.
● If you have a skin injury.
● If you get an internal contamination.
● Severe contamination of a work area or equipment.
● Fire or water leakage accident in a place with open radioactive sources.
● If you are in doubt, always ask for advice!
Slide 42 UiO Radiation Protection Course, 2021
Useful Instruction Videos
How to clean up a radioactive spill
http://www.youtube.com/watch?v=s4ggHTQWBXo
How to do a swipe
http://www.youtube.com/watch?v=sH77YrueOa0
Fra Environmental Health and Safety Iowa State University:
How to clean up a liquid spill
http://www.youtube.com/watch?v=cJG4rsgIBjM&feature
=c4-overview&list=UU-RZMc3wt09Cb0vHo6bf35Q
How to correctly remove gloves
http://www.youtube.com/watch?v=KTNemIYPNqA&list
=UU-RZMc3wt09Cb0vHo6bf35Q
Slide 43 UiO Radiation Protection Course, 2021
Disposal of Radioactive Waste
?
Slide 46 UiO Radiation Protection Course, 2021
Radioactive Polution Act
● Annex I a) defines activity limits for what should be considered radioactive waste (and therefore threated as such).
● Annex I b) defines total activity and specific activity limits for waste which must be delivered as special radioactive waste.
● Annex II defines total activity and specific activity release limits for which a permit is required.
Slide 47 UiO Radiation Protection Course, 2021
Waste Limits
Radioactive waste
Annex I a) (Bq/g)
Special waste handling* Annex I b)
Permit is required Annex II
(Bq) (Bq/g) (Bq) (Bq/g)
3H 100 109 106 108 105
14C 10 107 104 106 103
*Sum for all waste during a complete year
Slide 48 UiO Radiation Protection Course, 2021
Waste Log
Slide 49 UiO Radiation Protection Course, 2021
Avfallsdeponi i Norge
● Alt norskt, radioaktivt avfall (langlivet) behandles på Kjeller, av Institutt for Energiteknikk (IFE) og lagres i
fjellhaller i Himdalen.
● Et unntak er scale fra oljeindustrien, dette lagres i eget lager på Stangeneset i Gulen kommune.
● Formålet med avfallsbehandlingen er å overføre avfallet til en slik fysisk form at den kan langtidslagres på en sikker og trygg måte.
● Volumet reduseres så mye som mulig.
● Avfallet innkapsles i betong-eller blyskjermede stålbeholdere.
● Flytende avfall overføres til fast form ved tilsats av sement.
Slide 50 UiO Radiation Protection Course, 2021
Labeling and Signs
Requirements:
- The word “Radioactivity”
(Radioaktivitet, in Norwegian).
- The international symbol for radiation.
- The Nuclei’s name and amount.
- Date.
- Chemical environment (e.g. solvent).
It is recommended to also add the name or initials of the
“owner”.
Radioaktivitet
Radioaktivitet
Nuklide: ...
Mengde: ...
Dato: ...
Sign: ...
Slide 51 UiO Radiation Protection Course, 2021
Classification
If it is possible to encounter radiation doses above:
→1 mSv/year, the work space should be classified as a Supervised area (50 mSv/year to the hands).
→6 mSv/year, the work space should be classified as a controlled area (150 mSv/year to the hands).
Slide 52 UiO Radiation Protection Course, 2021
ADVARSEL
CAUTION
OVERVÅKET OMRÅDE
FOR STRÅLEVERN
OPPLÆRING I
STRÅLEVERN PÅKREVD BESØKENDE MÅ FØLGES
SUPERVISED AREA FOR RADIATION PROTECTION
RADIATION SAFETY TRAINING REQUIRED VISITORS MUST BE ESCORTED
C-LAB
RADIOAKTIVE KILDER BRUKES I DETTE OMRÅDET
RADIOACTIVE SOURCES ARE USED IN THIS AREA
Slide 53 UiO Radiation Protection Course, 2021
KONTROLLERT OMRÅDE
FOR STRÅLEVERN
OPPLÆRING I
STRÅLEVERN PÅKREVD BESØKENDE MÅ FØLGES
CONTROLLED AREA FOR RADIATION PROTECTION
RADIATION SAFETY TRAINING REQUIRED VISITORS MUST BE ESCORTED
B-LAB
RADIOAKTIVE KILDER BRUKES I DETTE OMRÅDET
RADIOACTIVE SOURCES ARE USED IN THIS AREA
ADVARSEL
CAUTION
Slide 54 UiO Radiation Protection Course, 2021
Labeling of rooms
Supervised area
B-lab
(Controlled area)
Rad.
waste storage
C-lab
Slide 55 UiO Radiation Protection Course, 2021
Sign for a Single Lab
Supervised area
C-lab
Slide 56 UiO Radiation Protection Course, 2021
Labels inside the laboratory
Used for labeling of cupbords, drawers,
safes, etc. where radioactive material
is stored.
Labels a workspace where work with radioactive material is performed. I.e. a hood or work bench.
Labels a dedicated accumulation area
for radioactive waste.
Slide 57 UiO Radiation Protection Course, 2021
Radiation Field Labels
Used to mark an area where the radiation field is above the general field (background level) in the room.
As a working principle, you should try to keep the radiation field below 7,5 μSv/h. Areas with higher fields must be labeled.
Slide 58 UiO Radiation Protection Course, 2021