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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

Radiation Safety and Operations

The University of Montana-Missoula

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

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

Today s mixed message

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

Nrc enforcement policy

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…”

What are we not talking about at least not much

What are we not talking about? At least not much

Non-Ionizing Radiation

Non ionizing radiation from high to low frequency

Non-Ionizing Radiation from High to Low Frequency

Radiation and radioactive material are a natural part of our lives

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.



Unstable atoms decay

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”

How unstable is it

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,

Half life calculation

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

Half Life Calculation

Some isotopes their half lives

Some Isotopes & Their Half Lives

The amount of radioactivity is not necessarily related to size

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

Radiation safety and operations

Structure of the Atom








(Electron Clouds)

Radiation safety and operations











 has a discrete energy that can be measured and related to the parent

4He Nucleus

Ejected from Nucleus

Most of the energy

associated with 

Radiation safety and operations

 Decay














Three products share energy – therefore beta has a continuous range of energies

Either too many neutrons or too many protons

Take away + charge and change a proton into a neutron

Take away - charge and change a neutron into a proton

Radiation safety and operations

 Decay




Gamma Photon









  • Emission of a photon from the nucleus

  • Often occurs after  or  when nucleus is in an excited state

  • Given off with discrete energies

  • Can measure photon energy and possibly identify parent

Radiation safety and operations

Shielding for ,  and 


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

Ionizing radiation at the cellular level

Ionizing Radiation at the Cellular Level

  • Causes breaks in one or both DNA strands or;

  • Causes Free Radical formation

Cellular effects

Cellular Effects

Cellular effects1

Cellular Effects

Cell death

Cell repair

Cell change

Is this change good or bad?

Dividing cells are the most radiosensitive

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)

At high doses we know radiation causes harm

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.

Us terms

US 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

More us terms

More US 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

New terms sort of

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

Units of radioactivity

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

Effects of acute exposures

Effects of ACUTE Exposures


Annual dose limits

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

Typical doses

Typical Doses

Radiation is a type of energy contamination is material

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

Rad use at um

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

  • No Nukes in Designated Areas

Ordering radionuclides

Ordering Radionuclides

Rad orders may be emailed, ordered via the web or faxed to EHRM and must include an index code

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

What if i don t pay for my nukes

What if I Don’t Pay for my Nukes

Free shipments must be approved

Inter-Laboratory Transfers must

Be approved

Incoming shipments

Incoming Shipments


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

  • Run a Blank with each time

  • 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



  • 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.

Contamination surveys

Contamination Surveys

Record the Results

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

Spill response

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



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.

The workstation should not present an exposure hazard to other individuals

The Workstation Should NOT Present an Exposure Hazard to Other Individuals

Radiation protection

Radiation Protection

  • Decrease Time

  • Increase Distance

  • Increase Shielding

Reduce waste volume

Reduce Waste Volume

  • Exercise care in handling—avoid spills

  • Use counter covers with overlays or cutouts

  • Keep primary rinse volumes to the minimum necessary

Something extra

Something Extra

  • Irradiating Food

  • Radon

  • Dirty Bombs

What should you remember

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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