Cardinal Surveys Radiation Safety Page

Cardinal Surveys Company

Radiation Safety Information

Radiation Placard

ALARA - 3 Key Factors
What if I find something?
Radioactive Isotopes Used At Cardinal Surveys
Detection Of Radiation
Radiation Doses To Be Considered
Classification Of Radiation Doses
Other Applications For Radioactive Isotopes


Before we get too far into this section, I would like to point out that we do not handle any high activity sources. All the radioactive materials we use in the field are measured in millicuries (mCi). Most of the information contained in this section is more pertinent to nuclear facilities that handle sources measured in Curies (Ci). However, regardless of material strength, the same principles of radiation safety and exposure still apply.

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ALARA - 3 Key Factors

Chesty Demonstrates Three Key Points

If you leave this web site with only one idea, this is the one to get! As Low As Resonably Achievable exposure to radioactive sources both man made and natural. ALARA is very simple. There are only 3 things to remember:

time near source

TIME - The less time you spend near a source, the less radiation you will receive.

shielding from source

SHIELDING - The more shielding you have, the less radiation you will receive.

distance from source

DISTANCE - The farther you get from a source, the less radiation you will receive.
See the Inverse Square Law

What if I find something?

Radiation Placard

The symbol on the right is the internationally recognized symbol for radioactive material. If you ever see this symbol on any object, leave the area immediately! You can not see, smell, feel, taste, or hear radiation. Radiation Detection can only be accomplished with instruments designed for that purpose. You have no way of knowing how strong the source is or even if there is a source. Remember ALARA:


Do - Get Away From The Potential Source
This one simple act takes care of 2 ALARA concepts. You minimized the time you were near the potential source and you lowered your exposure with distance. You had no shielding.

Do - Keep other people away
If possible, leave someone in the distant, vicinity to keep other people away while you go call for help. Remember, distance is your friend!

Do - Call the local authorities
Call your local fire department, police, or sheriff. Most fire departments have specially trained Hazmat Teams to deal with these types of situations. You should still call them even if you know they are not equipped for such a situation. They will know somebody who is!

To the authorities in rural areas, don't forget your neighbors. Many industries use radioactive materials and have trained personnel that know how to handle, transport, and store them safely. Oilfield logging, industrial X-ray, non-destructive testing, mining, hospitals, and many more organizations can help you.

Do - What the authorities tell you
You may not understand why you are asked to do something. Don't question them. Your cooperation will expedite the process.


Don't - Panic
Keep a calm head and leave the vicinity. Get away in a responsible fashion. You won't have accomplished anything if you're killed in a car wreck while going to get help!

Don't - Pick up the container!
You will only increase your exposure and possibly contaminate your body if there is any loose material.

Don't hang around, period.
There is no justifiable reason for you to be near the potential source.

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Radioactive Isotopes Used At Cardinal Surveys
Isotope Atomic Symbol Half-Life Special Concerns Photopeaks Mev
Iodine 131I 8.04 days Thyroid Seeker 9.99 (X-ray), 0.08, 0.2843, 0.3645, 0.638, 0.724
Iridium192IR 74.2 days None 0.067 (X-ray), 0.140 (Compton), 0.210 (Compton), 0.315, 0.470, 0.605, 0.79, 0.90 (sholder)
Scandium46SC 83.8 days High Beta/Energy0.887, 1.119, (0.89 plus 1.1 sum peak)
Antimony124SB 60.2 days High Beta 0.603, 0.645 (hidden shoulder), 0.722 (shoulder peak), 1.30 - 1.37, 1.69, 2.09, (1.69 plus 0.603 sum peak)
Gold198AU 2.696 days High Beta 0.412
Bromine82BR 35.34 hours High Energy 0.55, 0.61, 0.7, 0.77, 1.04, 1.33, 1.48, 1.90, 2.14

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Detection of Radiation:

Standard Survey Meters

General purpose, portable, battery operated survey and counting meters. These units use the Geiger-Mueller tube which is sensitive to gamma and medium energy beta radiation. Most of these instruments have three to four full scale ranges. They shall be calibrated every six months.

Micro R Meters

General purpose, portable, battery operated survey and counting meters. These units use a scintillation detector which is much more sensitive to lower levels of radiation. They shall be calibrated every six months.

Pocket Dosimeters

Direct reading Picker Dosimeter reads instantaneously the total accumulated dosage. The Dosimeter is designed for detection and measurement of X and gamma radiation only. Pocket dosimeters should be worn by the person handling radioactive materials if the radiation dose exceeds 20 mR/hr at one meter.

Film Badge Service

Light-weight plastic holder contains a slide-in film packet that is evaluated monthly. The use of ultrasensitive films and exclusive evaluation techniques make it possible to provide accurate evaluation of very low doses. X, gamma and beta radiation can be detected by this means.

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Radiation Doses to be Considered in Normal Safety Precautions:

  1. Acute Effects of Whole-Body Penetrating Ionizing Radiation on Human Beings

    Dose in LessThan One Week

    0-150 Rems
    No acute effects other than blood changes. May be a serious long-time hazard.

    150-250 Rems
    Nausea and vomiting within 24 hours. Minimal incapacitation after 2 days.

    250-350 Rems
    Nausea and vomiting in under 4 hours. Some mortality will occur in 2 to 4 weeks. Symptom free period 48 hours to 2 weeks.

    350-600 Rems
    Nausea and vomiting likely before 2 hours. Mortality probable in 2 to 4 weeks. Incapacitation prolonged.

    Greater than 600 Rems
    Nausea and vomiting almost immediately. Mortality in 1 to 2 weeks.

  2. Tolerance Dosages

    Whole Body
    5 Rems / Year to the Whole Body; head and trunk; active blood forming organs; lenses of eyes; or gonads.

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Mild dose:
A small dose of radiation which produces no detectable clinical effects on the body. 25-50 rems.

Moderate Dose:
Acute exposure with doses ranging from 50 to 200 rem. Injury may vary from slight to serious. Recovery from moderate doses of radiation is likely unless complication related to poor health, injuries or infections set in.

Median Lethal Dose (MLD):
When acute exposure results in a dosage from 200 to 600 rem there is a possibility of up to 50% mortality. Injury and disability are certain at higher exposure.

Acute Effect:
Those effects of radiation which appear within approximately one month, which includes the immediate (0 - 48 hours) and the delayed (1 - 5 weeks) effect.

Chronic Effects:
Long term effects of radiation which result in persistent changes (radiation dermatitis) and vascular or atrophic changes (appearing after one year-tumor indication, cataract formation).

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Other Applications For Radioactive Isotopes

Industrial labs are constantly seeking new techniques to improve the control and evaluation functions of specific applications. New and sophisticated methods have been developed to lower production costs, improve products, and provide solutions to problems heretofore unapproachable. The nuclear tool has saved millions of dollars in the nondestructive testing field alone. A few of the applications are listed below with brief explanation.

Gamma Irradiation
Treating food stuffs in such a manner that deterioration and spoilage is reduced considerably.

Mixer evaluation
To determine the relative mixing capability of certain mixing machines, short lived isotopes are introduced so results can be obtained and the isotope will have decayed away by the time the products reach the consumer.

Interface marking
Some petroleum pipelines may carry many different products. Radioactive tracers are used at the interface of different products. Now an operator is signaled by a detector when a new material is entering the system and a change over can be made with very little loss of the preceding batch.

Level gaging
Suppose a company wants to monitor the level of cooking molasses in a large tank. Sight tubes and windows are not suitable, the material is too viscous to drain, and internal floats gum up and stick, therefore, the best method to this solution is external monitoring.

A typical gaging system would consist of a detector and a Co-60 or Cs-137 source traveling in a track system on opposite sides of the tank. The detector signal depends on whether gamma rays from the source pass through the molasses or the air. As the source and detector rise from the bottom of the tank, at the same rate, an increase in counting rate would indicate the liquid level.

Wear measurement
A motor manufacturer wished to know the wear rate of his piston rings. A crude method would be to disassemble the motor and do definite measurements on the ring. By utilizing the iron in the piston ring, the ring is made radioactive by induction into a reactor. Fe-59 isotopes are produced. The ring is inserted on the piston and the cause minute particles of radioactive iron to wear off into the lubricating oil. Due to the extreme high sensitivity, one part in 10 million can be detected, the total amount of wear can be determined as a proportion to the increase in activity.

To replace the x-ray machines, a costly oversized and fixed instrument used in nondestructive testing, persons concerned about field application of NDT developed gamma radiography. A nuclear source 1/4" x 14" containing 100 curies of activity could be introduced into areas which x-ray machines were never able to radiograph. When mounted on a flexible cable, portable system with it's own power supply built right in. Now examination of piping mazes can be accomplished, where integrity of weld areas is an absolute must.

Oil Well Logging
In the petroleum industry, core sampling, a very tedious and time consuming method was used to determine the strata of possible oil bearing areas. When nuclear sources were introduced, the crude method was immediately disregarded. A neutron source is introduced into a well casing, from the source are emitted fast neutrons. The principle here is to determine the hydrogen content of the strata. If hydrogen is present and the neutrons enter this hydrogenous area, they are slowed down considerably and scattered back to the well casing. The neutrons become slow neutrons by virtue of their energy. The ratio of fast to slow neutrons is a good indication of the quantitative value of hydrogen present. This method is sufficiently sensitive enough to distinguish between water and oil.

Spacecraft Fuel Gauge
One very unique application of radioisotopes is the application of a fuel gauge on the Apollo and Saturn Spacecrafts. A standard fuel gauge normally operates by measuring the height of a confined liquid. This type of gauge falls in the weightlessness of space as the liquid fuel breaks up into globules and floats around the tank. With nuclear gauging system a row of detectors and gamma sources placed on opposite sides of the tank, a measurement can be made of the remaining fuel in the tank and is not dependent upon how it is distributed.

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ALARA - 3 Key Factors
What if I find something?
Radioactive Isotopes Used At Cardinal Surveys
Detection Of Radiation
Radiation Doses To Be Considered
Classification Of Radiation Doses
Other Applications For Radioactive Isotopes
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