Understanding Radiation, Radioactivity, and Ionizing Radiation

Understanding Radiation, Radioactivity, and Ionizing Radiation


All too often all that people know about radiation is its connection to the atom bomb and its massive destructive powers.  The terms Radiation and Radioactivity or Radioactive are used interchangeably, while not always technically correct, and most have never even heard of Ionizing Radiation.  In this article we will peer into this invisible part of our universe to better understand what they are, their relationship to one another, and how they are different.

What is Radiation?

Let’s begin by first understanding what Radiation is.  Radiation is the emission or transmission of energy in the form of waves or particles through space or through materials.  The two energy forms, waves and particles, are important to understand so let’s explore each of these beginning with energy in the form of waves.

The word radiation arises from the phenomenon of waves radiating meaning traveling in all directions, from a source.  One visible example of waves being radiated is when you drop an object onto a body of still water that produces waves emitted from the center and traveling outwards.  Another great example is our sun, which radiates its energy outward in all directions. 

When we think of the sun, we think of it radiating visible light, but in fact it also radiates infrared and ultraviolet light as well.  The infrared, visible, and ultraviolet energies are all part of what is called the Electromagnetic Spectrum. 

The Electromagnetic spectrum as represented on the accompanying chart is a range of energies measured by their frequency (in terms of Hertz or cycles per second), their wave lengths, and their photon energies.


Electromagnetic Spectrum

This chart shows the electromagnetic spectrum of waves and begins at the left side of the chart with low energy, long waves known to us as radio waves. Radio waves can be anywhere from one kilometer to 1,000 kilometers and more in length. As the energy increases, the wave frequency also increases with the wavelength becoming shorter and shorter until you arrive at the far-right side of the spectrum where the wave length is only a small fraction of the diameter of an atom and where the frequency and energy strength are both very high.

While we may not readily recognize these wavelengths, we do easily recognize the devices that operate at these different energy levels such as radios, microwave ovens, and infrared lamps. Going up in energy there is the very narrow visible energy band we humans are able to see with our eyes. After visible light, the energies progress on to ultraviolet, through x-rays, and ending with gamma-rays.

Man has been able to use the different frequencies to operate separate AM & FM radio broadcasting channels for our listening pleasure, navigation systems like LORAN, GPS, and beacons, communications for HAM radio, cell phones, walk i-talkies, secure military communications, emergency broadcasting, Morse code, Telecom and much much more.

What is Ionizing Radiation?

A primary concern is at what energy level across this entire spectrum do we begin to experience negative effects that cause damage to our bodies?  More specifically, at what energy point do we see cell damage occurring in the tissues that make up our body?  While this question continues to be vigorously debated today as in the case of cell phones, one clearer distinction is the energy level required that cause changes to the electrical charges within atoms.

Atoms as we know all have a delicate balance of protons, neutrons and electrons.   Any radiation energy with sufficient power to knock off electrons results in an imbalanced charged atom known as an ion.  Scientists have measured the radiation with enough power to knock off electrons at about 10 electron volts and higher and have classified them as ionizing radiation.  Any radiations with insufficient power to knock off electrons are classified as non-ionizing radiation.

The ionizing region begins in the midst of the ultraviolet range of energies and then proceeds through the increasingly higher x-ray and gamma regions.  That is why we see cautionary measures being exercised anytime we’re exposed to these type of ionizing radiations.  Studies have shown that Ion Atoms with missing electrons results in an electrical imbalance that cause chemistry changes to occur to the molecules and also our DNA that make up our tissues and can lead to harmful outcomes. 

Damage to cells vary by energy and the amount of exposure they receive.  Ultra-violet energy is relatively low and does not have much penetration capability so damage is limited.  X-rays and Gamma-rays on the other hand are both very powerful as they are more energetic and have deep penetrating power. 

When exposed to low or intermittent levels of ionizing radiation our bodies are able to handle it and repair themselves.  But when the exposures are too severe, our bodies cannot keep up with the rate of damage and we begin to experience radiation sickness, burns, and death in the most extreme cases.


What is Radioactivity?

This now leads us to the last term Radioactivity.  Radioactivity is when alpha, beta, and neutron particles from inside an atom’s interior are spontaneously being emitted or ejected either because they are:

  • Electrically unstable
  • Being bombarded by man made accelerators
  • Interacting with other radioactive materials as in the case of producing fission.

There exists a variety of radioactive elements that occur naturally here on earth like uranium, thorium, potassium, radium, and radon.  Added to this are man made radioactive elements like plutonium, americium, californium, and einsteinium to name a few.

All of these radioactive elements emit particles as they strive to neutralize their energy in a process we call decay.  Some elements will emit particles for fractions of a second before neutralizing and becoming non-radioactive; others can take up to millions of years.

While the particles types and energies will differ they are classified as ionizing type of radiation along with their higher energy electromagnetic wave counterparts.  The chart seen here gives us a good overview of radiation as a whole with distinction between particles and electromagnetic waves and between non-ionizing and ionizing classifications.

Radiation Chart


In conclusion radiation is energy being emitted or transmitted through space or materials like the tissue in our bodies.  We are most concerned with ionizing type of radiation where the radiation energy has sufficient power to knock off electrons that can cause harmful effects to our bodies if we receive excessive exposures.

Electromagnetic waves in the form of x-rays and gamma-rays are ionizing radiation.  So too are radioactive elements emitting alpha, beta, gamma and neutrons particles.

Knowing what these terms mean helps us to better understand the invisible realm all about us.

What are the Area Radiation Survey and Radiation Survey Meter Requirements for Fixed Gauges?

What are the Area Radiation Survey and Radiation Survey Meter Requirements for Fixed Gauges?

Why are Area Radiation Surveys Required?

All licensees are required to have radiation area surveys conducted anywhere there is a radiation device or the potential for receiving a dose greater than what is allowed.  The regulation citing is found in 10 CFR 20.1501.

Area radiation surveys serve three primary safety functions which are to:

  1. Create a basis for assessing public dose estimates
  2. Verify area dose rates do not allow individuals to receive more than 2 mRem (0.02 mSv/hr) of accumulated dose in any one hour
  3. Verify there is no contamination present

When are Area Radiation Surveys Required?

Area radiation surveys are required whenever non-routine operations are performed.  Non-routine operations include the following list of activities:

  • Installation of a Gauge
  • Initial Survey
  • Relocation
  • Removal from Service
  • Dismantling
  • Alignment
  • Replacement
  • Disposal of Sealed Source
  • Non-Routine Maintenance & Repair Activities Related to the Radiological Safety of the Gauge
  • Gauge Failure Investigation
  • Surrounding Area Changes
  • Gauge Storage Area
  • Shipping Radioactive Material/Gauges
  • Emergencies

Who is Authorized to Perform Area Surveys?

Any time an area survey is required as identified in the list above, it must be performed by a trained person who works for a company that is specifically authorized by the NRC or Agreement State.  Gauge operators; however, are encouraged to have one or more survey meters on hand where trained users can also conduct unofficial surveys or spot checks to verify radiation fields are all normal and that no anomalies exist.

Survey Records Maintenance & Storage Requirements

Licensees are required to maintain records of official survey results and store them for 3 years after the record is made (10 CFR 20.1501). If the survey results are used in the assessment of individual dose equivalents in lieu of personnel dosimetry, the licensee must maintain and store the records until termination of the license (10 CFR 2103).

Requirements for Possessing a Radiation Survey Meter

There are no regulations that require you to have a radiation meter in your possession; however, you must have access to one.  In the event of an emergency, you must have a plan in place to get one quickly. 

Given the relatively low cost of owning a radiation meter, most companies own one or more.  Having two radiation meters better ensures you’ll always have one on hand while the other is out for calibration or repairs.

A radiation meter should be one of the key tools in the Radiation Safety Officer’s toolbox.    As radiation is undetectable by human senses, it is the only way to really know if you ever have a problem or not in your plant.

Which Type of Radiation Survey Meter Should We Use?

Radiation detection instrumentation

Regulations do not specify what type of radiation meter is to be used.  There are a variety of radiation survey meters and types available on the market.  Too many assume radiation meters and detectors are all identical so acquiring one at the most affordable price is all that matters.  This is absolutely not the case; there’s a whole lot more to radiation meters than price alone.  Radiation meters range from expensive to cheap, complicated to simple, hard to read to easy, and rugged to fragile.

Each radiation meter type has different detection characteristics and sensitivities largely due to the type of detector employed.  So matching the mission or application in which it is to be used to the correct detector type is very important.   One very key criteria for measuring dose is ensuring your detector has sufficient sensitivity to measure background levels.  More often than not, the least expensive radiation detectors are also the least sensitive. 

When selecting a radiation meter/detector be sure to look at the detector count rate at background levels that are normally between 5 to 15 micro Roentgens per hour (uR/hr).  A highly sensitive NaI type detector, as referenced below, typically has a sensitivity of 175 cpm/uR/hr so at 10 uR/hr, the count rate is 1750 cpm which provides pretty good statistics.  By contrast, a GM pancake type detector only produces 3.3 cpm/uR/hr with a total of 33 cpm in a 10 uR/hr field.  This is not only 53 times less sensitive, it is also does not give a statistically good result and cannot easily see small changes in background levels.

Radiation Safety Officers have two primary missions relative to radiation detection:

  • Verify that the dose rates in an area are not elevated so any surrounding personnel will not pick up unnecessary dose
  • Verify that objects or personnel are not contaminated with radioactivity

Some radiation detectors do both functions, but not equally well.  Ideally, you would have a separate radiation meter/detector for each function.

Here are the most common types of radiation detectors, their intended purpose, and their pro’s and cons.

Ludlum Model 9-3 Ion Chamber
Ludlum Model 9DP

Ion Chambers

Pro’s: Absolutely the very best detector system for measuring dose rates and dose. This type of detector produces the most pure and accurate dose rate measurement for gamma and x-ray energies.  It’s also the very best instrument of choice when calculating dose assessments. 

Con’s:  Is not the most sensitive or responsive at low background radiation levels even though it will still be reasonably accurate.  You just need to be a little more patient in taking readings at lower levels.  The other drawbacks are they are more expensive, larger in size, and need to be treated more carefully.    They also do not measure contamination.

Micro-R Meter

Micro-R Meters

Pro’s: Highly sensitive and can detect very small changes in background in the micro-R range. The industry standard is a 1” x 1” NaI (Sodium Iodide) detector.  If the instrument units can be switched to counts per second (CPS) it can also be used to detect contamination.

Con’s:  These detectors respond differently to different energies.  They are typically calibrated to Cs-137 (660 keV energy level).  Any deviation to the energy being measured needs to be considered, especially if assessing one’s true dose.

Ludlum Model 3 with GM Pancake Detector
Ranger Radiation Survey Meter

GM Meters

Fundamentally, there are three basic types of Geiger-Mueller (GM) counter detectors, so it’s important to know which detector type is being used in the radiation meter you have or are considering to purchase.

  1. Energy Corrected GM
    1. Pro’s: These detectors have a surrounding matrix of metals to soften detection to high energies while still maintaining the right balance of low energies to produce a fairly linear energy curve response.  When measuring dose rates and dose, this is the preferred type of GM detector.  You must be sure that the dose rate range of the detector meets your detection range.  Beware of those who claim the detection range goes from zero to a very high range as they deliver very low sensitivity at low ranges where you normally are trying to measure.  Higher dose rate detectors are purposefully designed to detect elevated levels while sacrificing lower range sensitivity. 
    2. Con’s: Cost a little more.  Is not the right type of detector for measuring contamination.
  2. Non-Energy Correct GM
    1. Pro’s: least expensive GM type of detector
    2. Con’s: Not energy corrected, do not recommend using these for industrial applications unless you’re only using these as a gross indicator of relative levels to spot problems and then use a better detector to perform actual dose rate and dose measurements
  3. GM Pancake
    1. Pro’s: Great detector for seeking contamination and displaying activity in cpm.  Most instruments employing these types of detectors will also present dose rate and dose measurements making them both versatile and affordable. 
    2. Con’s: These detectors are very inefficient when measuring dose rate and dose.  They are also not energy corrected and can produce different readings depending on the orientation of the detector to the source.  This type of detector also has a known over-response to certain lower energies upwards of 300%.  It’s common practice to point the backside of the detector (instead of the face) towards the object being measured when taking a dose rate measurement.  This can be challenging when the detector is not separate from the instrument.

After selecting the correct detector, the meter functionality and ease of use features come into play.  Most older style radiation meters employed analog meters and scale switches.  The analog scales are typically what trip most users as they can be complicated.  Some meters have multiple scales and the instrument operator has to know which one to look at to get an accurate reading.  Analog scales come in varieties of linear and logarithmic form, so users need to understand how to interpret the one they are using correctly.  With analog type meters, users have to constantly and correctly view the right meter scale, look at the value, and then multiply the value by the selected range switch value in their mind to determine the final measurement value.  This takes training and can often lead to a misinterpreted reading. 

More modern electronics now afford direct digital readouts with automatic range-switching so users have no doubt what the measurement value truly is.  One advantage of an analog meter scale though is the sense of upward or downward movement and trending which is readily visible whereas one has to interpret this on a digital readout that only displays a numerical number that is constantly being updated.  Some digital meters include both a reading and an analog display to give you the best of both worlds.

Verify Your Radiation Meter Meets Operational Environmental Conditions

It’s not enough that a radiation meter meets the type of measurement and proper detection range.  Another key factor is verifying the radiation meter operating environmental specifications meets your true operational conditions.  Temperature, moisture, and EMF/RFI interferences can cause unwanted anomalies that may skew your measurement readings.

If you are operating in excessively low or high temperatures, your meter may have electronic or detector limitations.  Depending on the detector type, they may need to be turned on and warmed up for a few minutes before becoming operational.  In other cases, temperature shock, going from normal to extremely cold or high temperatures can cause anomalies or in some cases detector damage.  LCD’s and batteries often have greater temperature limitations than do the detectors, so be sure that your instrument will function properly in the environment in which you will be operating the instrument. 

If there is ever a question, ask the manufacturer to see if they have a report for your instrument where it was tested to ANSI N42.17.  The report will provide you with any specific performance degradation or issues, if there are any, for the conditions you will be operating under.  These reports are not intended to state the instrument meets all conditions, but to accurately report their behavior.  It is up to the user to determine whether the reported behavior is acceptable under your operational conditions.

Cold Weather

Properly Calibrated Radiation Meters

Radiation meters and detectors are to be calibrated as a minimum annually or as indicated by the manufacturer, if it is shorter than once per year.  In no case shall it be more than one year. 

Each time a meter is used, the user should be trained to verify that the meter is still in calibration before use.  If not, the user should notify the proper manager or RSO.  Instruments out of calibration should not be used.

It’s important to recognize that these are scientific type of measurement systems and can be prone to electronics drift or detector sensitivity losses.  Their calibration can also be adversely impacted if the instrument is accidentally dropped, bumped, or if their batteries are running low. 

Radiation meters and detectors should be calibrated at a laboratory using radiation sources with traceability to NIST and have a Quality Management System conforming to ISO 17025.  This ensures not only a proper measurement but will also better protect you in the event of a lawsuit if a dose assessment comes into play.  In such cases, you don’t want to be caught using an improperly calibrated or out of cal instrument.   

Calibration cycles times at laboratories typically take from 5 to 10 days.  With shipping, the meters could be out another week or two in travel so plan ahead to accommodate what may take a complete month.  Here again it’s always good to have a backup or second meter available.


Radiation Meter Calibration Records

Calibration records for the radiation meters must be retained for 3 years (10 CFR 20.2103(a).

Document Records

Elements of a Good Area Survey

Area radiation survey

A good survey report should include the following elements:

  • Area or gauge description. Gauge descriptions should include make, model, serial number, isotope and activity.
  • Survey meter information including make, model, serial number, calibration date and next calibration due date
  • A diagram of the area, points where a measurement were taken and their respective values
  • Notes describing conditions or any abnormalities
  • An occupational dose calculation based upon the highest reading
  • Identification and signature of surveyor including which organization they belong to
  • Date of the survey

Importance of Area Radiation Surveys

Radiation surveys are the only way operators can be certain they are compliant with regulations and more importantly ensuring the radiation levels are safe.  The RSO has direct responsibility to ensure all radiation levels remain safe at all times independent of who conducts the survey.   

A good RSO will ensure surveys are conducted anytime a non-routine operation is performed and review each survey to make sure they are accurate, complete.  It’s equally important to see if any problem areas exist and to remedy the situation immediately.  Finally,  it is wise to conduct periodic checks of radiation levels using your own radiation survey meter to verify everything is still within the expected levels. 

Radiation is a stealthy force and when used properly yields tremendous benefits.  When unchecked and released, it becomes a tremendous problem and endangers lives.  Don’t ever let your guard down; take area surveys seriously and not just as another check mark on your regulatory action list.

What’s the Difference Between Routine and Non-Routine Maintenence for Fixed Nuclear Gauges?

What’s the Difference Between Routine and Non-Routine Maintenence for Fixed Nuclear Gauges?


Today’s Radiation Safety Officer (RSO) face increasing pressure to lower operating costs in order to remain profitable and competitive in their respective industries.  Maintenance is typically a major budget item that comes under scrutiny and careful inspection to see where cost cuts can be found.  Many companies find increasing or enhancing their internal maintenance capabilities and becoming less dependent on outside contractors can lead to cost savings they are striving for.  When dealing with nuclear gauges; however, there are very strict regulatory limits that may directly conflict with a company’s cost-cutting directives.  Knowing the regulatory maintenance constraints, and complying with regulatory maintenance criteria is an important function of the RSO.

Nuclear Gauge Maintenance Categories

Due to the high strength radioactive sources employed in these nuclear gauges and potential risk of harmful exposure, the NRC regulations specifically address nuclear gauge maintenance activities.  Regulations separate maintenance into two categories; routine, and non-routine.  Typically, routine maintenance activities are allowed to be performed in-house, whereas, non-routine are most often performed by specially trained outside specialists. 

The license granted to each company for use of nuclear gauges very specifically and clearly addresses which of these two types of activities are allowed.  What is not always clearly identified in either the license or the regulations are which category each maintenance activity is categorized.  Additional ambiguity also exists due to use of different terms used by manufacturers and their distributors.

This article reviews the regulations and more specifically categorizes all maintenance activities associated with nuclear gauges. 

Regulatory References

Routine Maintenence

Routine maintenance includes general cleaning and operational checks as described by the gauge manufacturer or distributor as allowed by the operator. 

Maintenance technicians must:

  1. Be trained in accordance with the gauge manufacturer or distributor instructions
  2. Follow good radiation safety practices in accordance with ALARA
  3. Ensure the gauge functions as designed and source integrity is not compromised

Allowed Activities

  • Cleaning the Gauge Housing
  • Leak Testing: With a little training, the RSO or an Authorized User will be able to take a smear of each gauge and then send the sample off to a certified testing laboratory to confirm the absence of radioactive contamination.  To perform the leak test analysis in-house, your organization must have the right kind of equipment, a well-controlled program, and be specifically licensed by the NRC or an Agreement State.
  • Shutter Operational Checks
  • External Lubrication of Shutter Mechanism
  • Calibration
  • Electronic Repairs
  • Follow-up Radiation Surveys: Radiation surveys after the initial survey are only required if any physical changes surrounding the gauge are made that does not directly involve the gauge itself.  Any time a gauge is modified, removed, or relocated, a non-routine initial survey is required.
  • Gauge Mounting: (is only allowed if the specific gauge SSD permits it, see Gauge Mounting vs. Gauge Installation section below)

Non-Routine Maintenence

Non-routine activities include any maintenance or repair where a risk exists for being exposed to the radiation’s primary beam that could result in an over exposure.  Specific authorization by the NRC or an Agreement State is required to perform non-routine maintenance and repair of gauges.  Licensed personnel are required to have specialized training and follow appropriate procedures consistent with the manufacturer’s or distributor’s instructions and recommendations.  They must also employ proper radiation safety practices in accordance with ALARA, and be equipped with a radiation survey meter, a shielded container for the source, and personal dosimetry wherever required.  Licenses for non-routine maintenance activities on nuclear gauges are usually not granted to gauge operators.


  • Gauge Installation: (see Gauge Mounting vs. Gauge Installation section below)
  • Initial Survey
  • Maintenance and repair of radiological safety components which include:
    • The source
    • Source holder
    • Source drive mechanism
    • Shutter
    • Shutter control
    • Shielding
  • Relocating Gauges
  • Removal of a gauge from service
  • Beam Alignment
  • Source Reloading
  • Disposal of Sealed Sources
  • Dismantling
  • Decommissioning
  • Any activity where a potential for any portion of the body can come into contact with the primary radiation beam
  • Any activity that would result in excessive dose or a dose exceeding NRC limits
Gauge Maintenence Activities

Gauge Mounting vs. Gauge Installation

Mounting a gauge is permitted as a routine maintenance activity only if the gauges’ SSD registration explicitly permits it.  Mounting is defined by the NRC as unpacking, uncrating the gauge and fastening or hanging it into position before using.  Mounting does not include electrical connection, activation, or operation of the gauge. 

Installation of a gauge is a non-routine maintenance activity and is defined as mounting, electrical connection, activation, and first use of the device.


The RSO must be able to clearly understand which maintenance activity falls under the routine and non-routine categories and see to it that each are carried out in accordance with regulations.

The primary difference between routine and non-routine maintenance activities are the risk factors involving:

  1. An over exposure to radiation
  2. Any operation that could potentially alter the gauges performance from its original design specifications

If the maintenance activity poses any of these risks, they fall under the non-routine category where an outside contractor with a specifically trained and licensed technician is required to perform them. 

The strict safety design parameters of these nuclear gauges and the ruling for which they are maintained has resulted in a very noteworthy industry safety record.  Keeping your workers safe and your nuclear gauge maintenance program regulatory compliant is an important role the Radiation Safety Officer is entrusted with.  Don’t let cost cutting measures pressure you into crossing the line between routine and non-routine maintenance activities.  Be smart, be safe, be compliant, and keep the excellent industry record rolling forward.


Radioactive Consumer Products

Radioactive Consumer Products

Radioactive Consumer Products Around Us

Most people are unaware of the fact that there are several radioactive consumer products in existence.  Radioactive materials ability to radiate its rays flawlessly over many years without an external power source has attracted manufactures to utilize them.  Other times they are utilized for their illumination properties.  In many cases the materials best suited to their purpose just so happened to also be naturally radioactive. 

Naturally radioactive materials have very low activity levels and present no threat to us or society.  They represent the most common type of radioactive consumer products still in existence.  Most others have fallen out of favor and have been replaced with substitute materials and means. While naturally radioactive materials pose no threat, they can present problems when grouped together in larger volumes reaching the size of a shipping container or a semi-truck.  The collective volume produces enough activity to trigger alarms whenever they are scanned by radiation detectors at shipping yards or border crossings. 

Here’s a list of the more common radioactive consumer products from the present, recent past, and even cray stuff from the long past.


Radioactive Clockface

Clocks & Watches

Some luminous watches and clocks contain a small quantity of hydrogen-3 (tritium) or promethium-147. Older watches and clocks (made before 1970) may contain radium-226 paint on dials and numbers to make them visible in the dark.

Smoke Detector

Smoke Detectors

This application probably wins the prize for the least expected radioactive consumer product.  Most smoke detectors used in our homes utilize americium-241, a radioactive element.

The radioactive material is positioned between two electrically charged plates, which ionizes the air and causes current to flow between the plates. When smoke enters the chamber, it disrupts the flow of ions, thus reducing the flow of current and activating the alarm. 

Unless tampered with, smoke detectors pose little to no health risk; a smoke detector’s ability to save lives far outweighs the health risks from the radioactive materials.  Visit RadTown to learn more.

Thorium Welding Rod

Thorium Welding Rods

Thoriated welding rods are really electrodes used in tungsten inert gas (TIG) welding.  This type of welding is typically used where high-quality welding is required like in the aircraft and petrochemical industries.  Thorium is added to the tungsten because it increases the current carrying capacity of the electrode and it reduces contamination of the weld. In addition, it is easier to start the arc and the latter is more stable. 

By weight, the rods are usually 1 or 2% thorium oxide although higher concentrations up to 4% have been used.  The rods are color coded to indicate the thoria content: yellow indicates 1 %, and red indicates 2 %. The color usually appears as a band at one end of the rod. While they range from 0.25 to 6.35 mm in diameter and 7.6 to 61 cm long, a “typical” rod would be about 2.4 mm in diameter, 15 cm long, and contain 0.23 grams of thorium. Estimates over the last two decades put the annual production at 1 to 5 million electrodes.

Radioactive Gas Mantle

Gas Lantern Mantles

Older, and some imported, gas lantern mantles generate light by heating thorium (primarily thorium-232). Unless gas lantern mantels are used as the primary light source, radiation exposure from thorium lantern mantles is not considered to have significant health impacts.  Because they were so readily available in the past, they were also frequently used to verify or demonstrate radiation meters!

CRT Monitor

CRT Computer Monitors

Older televisions and computer monitors that contain cathode ray tubes (CRTs) may emit x-rays. X-ray emissions from CRT monitors are not recognized as a significant health risk.

Radioactive Fertilizer


Commercial fertilizers are designed to provide varying levels of potassium, phosphorous, and nitrogen to support plant growth. Such fertilizers can be measurably radioactive for two reasons: potassium is naturally radioactive, and the phosphorous can be derived from phosphate ore that contains elevated levels of uranium.

Water Softner

Water Softner

A variety of materials can be used as the water softener salt, e.g., sodium chloride (NaCl) or potassium chloride (KCl). In the example shown here, the water softener salt is over 99% potassium chloride.

All potassium contains potassium-40, a naturally occurring beta gamma emitter, and in large enough quantities it is easily detected with a simple survey meter. This bag, for example, could not get through a monitor at a nuclear power plant without setting off an alarm.

Radioactive Ceramics


Ceramic materials such as tiles and pottery may contain elevated levels of naturally-occurring uranium, thorium, and/or potassium. In many cases, the activity is concentrated in the glaze. Unless there is a large quantity of the material, the amount of radioactivity in these products is unlikely to be greater than natural background levels. However, some older dishware (e.g., pre-1972 Fiesta®ware) can have radioactivity exceeding background levels; to minimize health risks, you may not want to use these pieces for eating or drinking.

Radioactive Glassware


Glassware, especially antique glassware with a yellow or greenish color, can contain easily detectable quantities of uranium. Such uranium-containing glass is often referred to as canary or vaseline glass. In part, collectors like uranium glass for the attractive glow that is produced when the glass is exposed to a black light. Even ordinary glass can contain high-enough levels of potassium-40 or thorium-232 to be detectable with a survey instrument. However, the radiation received when using glassware – even canary or vaseline glass – is unlikely to exceed background radiation levels.

Thorium Camera Lens

Camera Lenses

Older camera lenses from the 1950s-1970s incorporated thorium into the glass, allowing for a high refractive index while maintaining a low dispersion. The health risk from using older camera lenses is low; the radiation received when using a thoriated lens camera is approximately equal to natural background.

Radioactive Exit Signs

Exit Signs

Some EXIT signs contain the radioactive gas called tritium, allowing them to glow in the dark without electricity or batteries. The tritium used in EXIT signs gives off low-level beta radiation, causing a light-emitting compound to glow. Tritium EXIT signs do not pose a direct health hazard, as the beta radiation can be stopped by a sheet of paper or clothing. Tritium EXIT signs must not be disposed of in normal trash.  Learn more about tritium exit signs.

Brazil Nuts

Brazil Nuts

It has been known since the 1930s that Brazil nuts contain relatively large concentrations of barium (approximately 0.1 – 0.3% by weight).  That Brazil nuts also contain high levels of radium was first reported in the 1950s.

Brazil nuts are the seeds of Bertholletia excelsa, a large tree that is grown in various parts of world, not just Brazil.  The nuts, in groups of 12 to 25 much like the sections of an orange, form the globular (4-6” diameter) fruit of the tree.  It is not true, as is sometimes thought, that the high concentration of radium in Brazil nuts is due to elevated levels of the uranium and/or thorium series in the soil in which the tree grows. The accumulation of the radium (and barium) is due to the very extensive root system of the tree. For what its worth, measurements by Penna-Franca et al indicated that higher radium concentrations are found in the leaves and cork of the tree than in the nut.

Crookes Spintharscope

Crookes Spintharscope

The spinthariscope was invented in 1903 by William Crookes. These two photos show an example of the first commercially-available version of the spinthariscope. This particular spinthariscope came from Robert Millikan’s Laboratory at Cal Tech and dates from the 1920s or earlier.

After dark-adapting the eyes, the viewer looks through the lens of the spinthariscope and observes a screen of zinc sulfide where tiny flashes of light appear, an image Crookes described as a “turbulent luminous sea.” Each flash of light is produced by an alpha particle emitted from a tiny sample of radium on the tip of a pointer positioned just above the screen. The spinthariscope can be considered the first radiation counter, i.e., it is capable of recording individual events.

Crazy Radioactive Consumer Products & Services from Long Ago

Shortly after Wilhelm Roentgen discovered X-rays and Marie Curie’s discovery of radium, the world immediately recognized the powerful value in the field of medicine.  Not to be left behind, enterprising individuals introduced their own elixirs to remedy ailments of almost any kind.  It did not take too long, in most cases, to realize they did more harm than good.    With our current knowledge of radioactivity and the risks to health, we view these early adoptions with shock and horror; but back then, they simply had no idea.

Below are some of the more interesting innovations of the time.



A Thomas Radium C. R. (aka Thomas Radium Ore) jar promised good health to those who drank waters stored in them. 

A short note in the February 1921 issue of Popular Science Monthly written by him stated”

“Pottery is now manufactured which has in it a small percentage of radioactive material. This is mixed with the clay and baked in the kiln. Water left in the pottery of this nature for a short time will become radioactive by induction, and a health-giving drink is made. Such water may also be employed in the watering of plants with good results, since the presence of a radioactive compound near the roots of a plant is very helpful to its growth.”

Thomas placed the following advertisement in the November 5, 1921 issue of the El Paso Herald:

RADIUM ORE. that will keep you supplied with soft Radio Active Water for generations is the greatest remedy and cure ever discovered for each and every disease.

Degens Eye Glasses

Degnen's Radioactive Eye Applicator

Quoting the manufacturer’s literature: “the Radio-Active lenses will be found helpful in imperfect refraction, MYOPIA or Nearsight, HYPERMETROPIA or Farsight, PRESBYOPIA or Oldsight, HETROPHOBIA or difficulty in focussing.”

“Headaches, caused by eyestrain and other eye disorders, can be quickly relieved by the use of the lenses.”

“The best results are obtained by wearing the lenses for a period of from five to ten minutes twice a day, keeping the eyes closed during treatment.”

A brochure describing Degnen’s Radio-Active Eye Applicator includes testimonial letters that date from 1921 and 1922.

Exposure Rates:   10 – 15 uR/hr above background at one foot

Energized Golf Ball

Energized Golf Ball

The ENERGIZED Golf Ball, highest quality ball made in the USA, is treated with gamma rays from radioactive Cobalt 60 in our laboratories in Oak Ridge to give it greater distance and a tougher cover.  It has a steel center and carries an exclusive guarantee that compression will be a constant 95+.  Also the ENERGIZED Golf Ball conforms to USGA Rules.  Exclusively unique, this new golf ball creates interest, excitement, fun.

Frisky Whiskey

Frisky Whiskey

This one is not exactly a radiation consumer product, but fun and interesting at the same.  According to the label on the front of the bottle, it was produced by the fictitious Oak Ridge Distilling Company, aged by radiation and tested with a Geiger Counter. In reality, it is an empty plastic container with a battery powered motor inside that causes the bottle to shake violently when it is picked up. That’s what the label is referring to when it states “you will note its 150 proof strength from the moment you pour.” Since it comes empty, it is up to you to fill it with your favorite beverage.

The earliest reference for the “Frisky Whiskey” is a brief mention in the December 13, 1965 issue of the Odessa American. It was said to add laughs galore to a Christmas party – exploding cigars were also recommended. The following year, it was advertised as a great Father’s Day present (Cincinnati Enquirer, June 12, 1966):

“Frisky Whiskey bottle looks so innocent . . .watch the unsuspecting dad pick it up . . as he starts to pour, the bottle starts vibrating to shake his hand uncontrollably.”

Shoe Fitting Fluorscope

Shoe Fitting Fluoroscope

One of the most unexpected radioactive consumer products is the shoe fitting fluoroscope.  This was a common fixture in shoe stores during the 1930s, 1940s and 1950s. A typical unit, like the Adrian machine shown here, consisted of a vertical wooden cabinet with an opening near the bottom into which the feet were placed. When you looked through one of the three viewing ports on the top of the cabinet (e.g., one for the child being fitted, one for the child’s parent, and the third for the shoe salesman or saleswoman), you would see a fluorescent image of the bones of the feet and the outline of the shoes.

According to Duffin and Hayter, Dr. Jacob Lowe created his first fluoroscopic device for x-raying feet during World War I. By eliminating the need for his patients to remove their boots, the device sped up the processing of the large number of injured military personnel who were seeking his help. After the war, he modified the device for shoe-fitting and showed it for the first time at a shoe retailer’s convention in Boston in 1920.

If you wish to dispose of any of the radioactive items presented here or from industrial products, call Radiation Solutions at 208-206-3203.

Remembering the Harmful Effects of Ionizing Radiation

Remembering the Harmful Effects of Ionizing Radiation

Harmful Effects from Ionizing Radiation Known Since the Beginning

Scientists have known for a very long time now that exposure to ionizing radiation can have harmful effects in humans.  Awareness first manifested itself by radiation burns on the early experimenters who paid dearly for their work.  Fortunately, modern radioactive devices employ many well engineered safety measures to prevent this from ever happening when used properly.  Radiation induced injuries are relatively rare anymore which is a very good thing.  But it can also result in a lack of full appreciation for what damage can occur if ignored.  This article serves as a reminder of how harmful and painful radiation burns can be if we don’t take all safety precautions and procedures seriously.

The early pioneers investigating radioactivity in the late 1800’s and early 1900’s were not aware of the harmful effects until radiation burns began manifesting themselves.  Radiation burns were first noted in 1896, within just one month after Roentgen’s announcement of the discovery of what he called x-rays.  Within a year or two it became widely known that those working with x-ray devices had to take some precautions.

Early experimenters with natural radioactive sources were not immune from harmful effects and also received burns.  Most notable was Henri Becquerel who burned himself by carrying a sample of radium in his pocket.  The famous Marie Currie and her husband Pierre also received radiation burns on their skin from their work with radium and are believed to have also developed leukemia.  While Pierre was tragically killed relatively early and was largely spared long term suffering, Marie’s lifetime exposure resulted in a great deal of pain that she had to endure, especially to her hands.

By 1905 it was also known that excessive exposure to radiation could cause cancer.  Repeated large doses to the hands of workers frequently caused fatal skin cancer.  Many of the early medical radiologists either died of skin cancer or had to have their fingers or hands amputated. 

Immediate and Long-Term Effects of Ionizing Radiation

Very large doses of radiation can cause harmful health effects within just hours or weeks.  Such effects are called prompt effects because they appear relatively soon after the exposure.  The prompt effects result in radiation burns to the skin as well as radiation sickness, which can be fatal.

Other effects that manifest themselves years later are called delayed effects.  Cancer and genetic effects in offspring are examples of delayed effects

Radiation Burns

A radiation burn is not a temperature induced injury as the name would suggest; however, the cell damage appears in identical fashion; hence the name.  The severity of the cellular damage by ionizing radiation increases with dosage.  Lower one-time doses enable the body to heal itself over time.  As the dose levels increase, additional medical attention will be required to assist in recovery.  Eventually you reach a dose level where the damage becomes so great death becomes inevitable.  The chart below presents the prompt effects of one-time doses at increasing dose levels.

Effects to One-Shot Doses

600 rem

Radiation cell damage is equivalent to a first-degree heat burn or mild sunburn.  Within a few hours reddening occurs and often disappears over the next few days as the body does its healing work (assuming no further exposures occur). 

1000 rem

Results in serious tissue damage like a second-degree heat burn.  The initial inflammation is followed by swelling and tenderness.  Blisters will form within 1-3 weeks and break open leaving raw, painful wounds susceptible to infection.  Hands exposed to these dose levels become stiff and finger motion is often painful.  After several months the visible damage may heal but there will be some permanent damage to the surrounding tissue and make it more susceptible to injury in the future.

2000-3000 rem

An injury resembling a scalding or chemical burn is caused.  Medical treatment is immediately needed.  The injury may not heal without surgical removal of the exposed tissue.  Damage to blood vessels also occurs.  Future medical problems can be expected as this area will be more susceptible to pain, lower resistance to injury and reopening of the wound.

> 3000 rem

When more than 3000 rems are received at one time the tissue is completely killed and must be surgically removed. 

Prolonged Dose Effects

A radiation dose between 5000 to 10,000 rems received gradually over a period of several weeks will result in a chronic irritation, inflammation, dryness, and itching of the skin.  Once this condition has developed, it seldom heals completely.  Open sores may erupt and the regenerative and recuperative powers of the body are greatly reduced.  Malignant skin cancer occurs in a large percentage of these cases.

Severe Radiation Burn Cases

Back Pocket Carry

In 1979 a man found a 28-curie iridium radiography source that had accidently been left at the jobsite by a radiographer.  Not being a radiation worker or understanding what the material was he picked it up and put it in his back pocket for about 45 minutes. 

About an hour after the exposure he became nauseated, at 6 hours he noticed a burning feeling and a reddening of his right buttock.  The burning and reddening got worse and after 2 days went to a doctor.  The doctor not knowing what he was dealing with assumed the skin irritation was most likely caused by an insect bite.  But the burn got worse and worse until it became a large open sore.  After 17 days, the man was hospitalized and it took another three days of persistent questioning by doctors before they realized that he had a radiation burn.  By this time the man had an open wound about 4 inches in diameter and 1 inch deep.  Figure 1 shows the wound 31 days after the incident. 

It was later calculated that the radiation dose to the man’s right buttock exceeded 20,000 rems.  At a tissue depth of about 3 inches the dose still exceeded 1000 rems. 

To treat the burn, doctors surgically removed the dead tissue and a thick piece of skin from his thigh was sewn to close the wound, see Figure 2.  Six months later, the skin flap edge was not healing so at 10 months a second skin flap was sewn on.  At 19 months, the wound was still not healed, see figure 3 & 4, and further constructive surgery would be needed.  Two years after the accident, the man still walks with a limp and experiences pain where he was burned.

Figure 1
Figure 2
Figure 3
Figure 4

Front Pocket Carry

A similar incident occurred to a man in Argentina who placed a highly radioactive source in his front packet.  The front pocket location placed the source too close to his arteries that carried blood to his legs.  The arteries disintegrated because of the radiation damage and both legs had to be amputated.

Fatality Cases

Construction Watchman

The previous two cases were about those who survived, but there are also very sad fatalities that have been recorded.  In March of 1962 a construction watchman in Mexico was given a 5-curie Co-60 source for safekeeping by his employer.  Not understanding what he had, he took it home for safe-keeping where he, his wife, mother-in-law, son, and daughter were all exposed over a period of several months.  The employer retrieved the source in late July.  The damage was done, and one-by-one, members of his family began dying beginning in April and ending in Oct of that year.  Only the watchman survived because he was away so much of the time working.   

Scrap Yard in India

An incident in India more recently occurred whereby a university abandoned irradiator was taken to a metal scrap yard by individuals who had no idea what the device was.  The scrap yard placed the irradiator next to their worker bunk house.  A few days later several men became sick and at least one died. 


Fortunately, severe cases like those presented herein are rare.  Never-the-less, accidents and moments of forgetfulness do still occur.  Maintaining diligence is something Radiation Safety Officers and all those who work with or around radiation sources and devices cannot afford to ignore. 

The stealth properties of radiation make us vulnerable and so we each need to practice and follow procedures very carefully to avoid incidents of any kind.  It’s too easy to take safety for granted or to ignore when it comes to radiation exposure.  It’s much easier to think and act safely when climbing a ladder high above the ground.  It’s quite another mindset that is needed when you cannot see, smell, hear, taste or feel the impending danger.   Its stealthy nature all too often lure us into a false sense of security or a relaxed state of mind that typically exists at the beginning of any radiation incident.

While the incidents shown here are severe in nature, less severe exposures can still impact the quality of our lives, and we need to remember that too.  Sometimes we need a good dose of reality of what has already happened to others to fully appreciate the dangerous nature of the materials that are all about us in the industrial world.  Remembering the very real-life tragedies of others along with training and repeat training will hopefully keep your radiation safety program on guard at all times and in all places. 

Radiation safety should never be an after-thought, or just another item added to an already long list of duties.  It needs to be taken very, very seriously.  Let the tragic lessons of others be ever present on your mind as you strive to protect your fellow workers, friends and family.  Ionizing radiation is an excellent servant to mankind when contained and properly used and highly destructive and lethal when not carefully watched over and used properly.