Radiation Protection

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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!

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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

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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/

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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

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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

w_T (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

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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.

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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

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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 e_ing(50) and the inhalation does coefficient e_inh(50) for inhalation.

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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

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Jon Petter Omtvedt Department of Chemistry Blindern Campus, January 2021

Radiation Protection Course:

- Fundamental Radiation Protection Principles

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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

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https://www.menti.com/vbso3fat44

Write the errors you find

to the Mentimeter!

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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.

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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

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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.

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Rad. dose from β-contamination

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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.

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External Exposure

● Can be reduced by considering

▸Time

▸Distance

▸Shielding

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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

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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

²₂

Where I

_a

and I

_b

is the intensity at distance a and

b, respectively.

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Radiation field from β sources

Example: 37 MBq (1 mCi)

³²

P

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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

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Plexiglas cupboard

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Pippette Sheild

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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.

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External γ-Exposure - Shielding

0,01 0,1 1 10

HVL (mm)

Energy (MeV)

A A

p

=

n⁰

2

n = number of HVL,

A₀ = intensity w.o. screen, A_p = intensity w. screen.

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End of Rad. Protection Principles!

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Jon Petter Omtvedt Department of Chemistry

Blindern Campus, 2021

Radiation Protection Course:

- Handling Accidents

Disposing of Radioactive Waste

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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

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Alternative Risk-Analysis Form

http://www.arbeidstilsynet.no/binfil/download2.php?tid=79062

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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.

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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

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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.

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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".

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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!

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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

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Disposal of Radioactive Waste

?

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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.

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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

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Waste Log

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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.

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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

Nuklide: ...

Mengde: ...

Dato: ...

Sign: ...

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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).

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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

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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

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Labeling of rooms

Supervised area

B-lab

(Controlled area)

Rad.

waste storage

C-lab

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Sign for a Single Lab

Supervised area

C-lab

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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.

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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.

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