Radiation safety and operations
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Radiation Safety and Operations. The University of Montana-Missoula. How most of us feel about radiation until we understand the principles of safe use:. Today’s Mixed Message.

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Radiation Safety and Operations

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Radiation Safety and Operations

The University of Montana-Missoula

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How most of us feel about radiation until we understand the principles of safe use:

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Today’s Mixed Message

The amount and type of radionuclides used at the University of Montana do not pose undue risk HOWEVER

The Nuclear Regulatory Commission does NOT have a sense of humor

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NRC Enforcement Policy

…”Prompt and vigorous enforcement action will be taken when dealing with licensees and their employees who do not achieve the necessary meticulous attention to detail and the high standard of compliance which the NRC expects…”

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What are we not talking about? At least not much

Non-Ionizing Radiation

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Non-Ionizing Radiation from High to Low Frequency

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Radiation and Radioactive Material are a Natural Part of Our Lives

  • We are constantly exposed to low levels of radiation from outer space, earth, and the healing arts.

  • Low levels of naturally occurring radioactive material are in our environment, the food we eat, and in many consumer products.

  • Some consumer products also contain small amounts of man-made radioactive material.



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Unstable Atoms Decay

  • The number of “decays” that occur per unit time in the radioactive material tell us how radioactive it is.

    • Units include Curies (Ci), decays per minute (dpm), and Becquerels (decays per second).

  • When an unstable atom decays, it transforms into another atom and releases it’s excess energy in the form of radiation. Radiation can be

    • Electromagnetic radiation (like X or gamma rays), and

    • Particles (like alpha, beta, or neutron radiation)

  • Sometimes the new atom is also unstable, creating a “decay chain”

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How Unstable Is It?

  • The “Half-Life” describes how quickly Radioactive Material decays away with time.It is the time required for half of the unstable atoms to decay.

  • Some Examples Example:

    • Some natural isotopes (like uranium and thorium) have half-lives that are billions of years,

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Most medical isotopes (like Technicium-99m) last only a few days

Half Life Calculation

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Some Isotopes & Their Half Lives

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The Amount of Radioactivity is NOT Necessarily Related to Size

  • Specific activity is the amount of radioactivity found in a gram of material.

  • Radioactive material with long half-lives have low specific activity.

    1 gram of Cobalt-60has the sameactivity as1800 tons of natural Uranium

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Four Primary Types of Ionizing Radiation:Alpha Particles

Alpha Particles: 2 neutrons and 2 protons

They travel short distances, have large mass

Only a hazard when inhaled

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Four Primary Types of Ionizing Radiation:Beta Particles

Beta Particles: Electrons or positrons having small mass and variable energy. Electrons form when a neutron transforms into a proton and an electron or:

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Four Primary Types of Ionizing Radiation:Gamma Rays

Gamma Rays (or photons): Result when the nucleus releases

Energy, usually after an alpha, beta or positron transition

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Four Primary Types of Ionizing Radiation:X-Rays

X-Rays: Occur whenever an inner shell orbital electron is removed

and rearrangement of the atomic electrons results with the release of

the elements characteristic X-Ray energy

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Four Primary Types of Ionizing Radiation:Neutrons

Neutrons: Have the same mass as protons but are uncharged

They behave like bowling balls

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Four Primary Types of Ionizing Radiation

  • Alpha particles

  • Beta particles

  • Gamma rays (or photons)

  • X-Rays (or photons)

  • Neutrons

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Shielding for ,  and 


Place materials between the source and person to absorb some or all of the radiation

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Direct Ionization Caused By:

  • Protons

  • Alpha Particles

  • Beta Particles

  • Positron Particles

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Indirect Ionization Caused By:

  • Neutrons

  • Gamma Rays

  • X-Rays

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DNA and Radiation

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Ionizing Radiation at the Cellular Level

  • Causes breaks in one or both DNA strands or;

  • Causes Free Radical formation

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Cellular Effects

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Cellular Effects

Cell death

Cell repair

Cell change

Is this change good or bad?

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Our Bodies Are Resilient

  • DNA damage is most important and can lead to cell malfunction or death.

  • Our body has ~ 60 trillion cells

    • Each cell takes “a hit” about every 10 seconds, resulting in tens of millions of DNA breaks per cell each year.

    • BACKGROUND RADIATION causes only a very small fraction of these breaks (~ 5 DNA breaks per cell each year).

  • Our bodies have a highly efficient DNA repair mechanisms

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Dividing Cells are the Most Radiosensitive

  • Rapidly dividing cells are more susceptible to radiation damage.

  • Examples of radiosensitive cells are;

    • Blood forming Cells

    • The intestinal lining

    • Hair follicles

    • A fetus

This is why the fetus has a exposure limit (over gestation period) of 500 mrem (or 1/10th of the annual adult limit)

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At HIGH Doses, We KNOW Radiation Causes Harm

  • High Dose effects seen in:

    • Radium dial painters

    • Early radiologists

    • Atomic bomb survivors

    • Populations near Chernobyl

    • Medical treatments

    • Criticality Accidents

  • In addition to radiation sickness, increased cancer rates were also evident from high level exposures.

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Effects of ACUTE Exposures


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Old Terms

  • Roentgen-Based on the quantity of electrical charges produced in air by X or Gamma photons 1R=2 billion pr

  • RAD-Radiation Absorbed Dose is the work energy resulting from the absorption of one ROENTGEN or 6.24 E5 Mev

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More Old Terms

  • REM-Roentgen Equivalent Mammal is equal to the absorbed does in RADS multiplied by a quality factor

  • Quality Factors

  • Beta = 1

  • Gamma & X ray photons = 1

  • Alpha = 10

  • Neutrons = 20

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New Terms sort of

International Units have replaced the RAD and REM

GRAY (Gy) = 100 RAD

SIEVERT (Sv) = 100 REM

Same Quality Factors apply to the Sv

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Units of Radioactivity

  • Curie (Ci) = 2.22 E12 dpm or 3.7E10 dps

  • Becquerel (Bq) = 1 dps

  • Maximum Dose/year = 5 REM or 50 mSv

  • Maximum Dose/year for Declared Pregnant Woman & Minors= 0.5 REM or 5 mSv

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Adult ($18 yrs)

Minor (< 18 yrs)

Whole body*

5000 mrem/yr

500 mrem/yr

Lens of eye

15000 mrem/yr

1500 mrem/yr


50000 mrem/yr

5000 mrem/yr


50000 mrem/yr

5000 mrem/yr


50000 mrem/yr

5000 mrem/yr

Annual Dose Limits

External/Internal Exposure Limits for Occupationally Exposed Individuals

  • *Effective dose equivalent

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Typical Doses

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Radiation is a type of energy; Contamination is material

  • Exposure to Radiation will not contaminate you or make you radioactive

  • Contamination is Radioactive Material spilled someplace you don’t want it.

  • Radioactive contamination emits radiation

  • Contact with Contamination can contaminate you with the material

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RAD use at UM

  • Prior to first use of radionuclides, the Authorized User must provide written and interactive training.

  • Read the Radiation Safety Manual

  • Specific, clear and detailed instruction on safe handling

  • Documentation

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Ordering Radionuclides

Rad orders may be emailed or faxed to EHOS and must include an index code

EHOS will place order and enter charges in Banner for you—This allows us to check inventory totals prior to ordering

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What if I Don’t Pay for my Nukes

Free shipments must be approved

Inter-Laboratory Transfers must

Be approved

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Incoming Shipments


  • Use the appropriate survey meter to confirm the TYPE and AMOUNT of detectable radiation is proper

  • Wipe test outer package and run wipes in LSC

  • Check each inner increment of packaging

  • Record the Results on your inventory sheet in the Rad Manual

  • Notify the RSO if any contamination is found

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  • All Radioactive Materials must be secured or under direct supervision at all times

  • There MUST be someone in the room at all times OR the door must be locked.

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Contamination Surveys

Record the Results

Wipe tests must be done monthly if you have inventory on hand

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Spill Response

  • On Skin—flush completely

  • On Clothing—remove

  • If Injury—administer first aid

  • Radioactive Gas Release—vacate area, shut off fans, post warning

  • Monitor all persons and define the area of contamination

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As Low As Reasonably Achievable—means making every reasonable effort to maintain exposures to radiation as far below the dose limits as is practicable consistent with the purpose for which the licensed activity is undertaken, taking into account the state of technology, the economics of improvements in relation to the state of technology, the economics of improvements in relation to benefits to the public health and safety, and other societal and socioeconomic considerations, and in relation to utilization of nuclear energy and licensed materials in the public interest.

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Radiation Protection

  • Decrease Time

  • Increase Distance

  • Increase Shielding

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Reduce Waste Volume

  • Exercise care in handling—avoid spills

  • Use counter covers with overlays or cutouts

  • Keep primary rinse volumes to the minimum necessary

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Waste Handling

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Waste Handling

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Waste Handling

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Waste Handling

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Something Extra

  • Irradiating Food

  • Radon

  • Dirty Bombs

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What should you remember?

  • The NRC has no sense of humor

  • The amount and type of radionuclides used

  • at UM are very unlikely to cause you harm

  • You must abide by all the rules

  • If you have questions make sure they get answered ASAP

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