In geotechnical engineering, a nuclear densometer or soil density gauge is a field instrument used to determine the density of a compacted material. The device uses the interaction of gamma radiation with matter to measure density, either through direct transmission or the “backscatter” method.

What is a radioactive densitometer?

A device for measuring the density of fluids in a completed well, using a radioactive source of gamma rays and a detector. … The results then reflect the density of the fluids passing through the tool.

How do you do a soil compaction test?

1. Obtain layered soil sample (via our VTK Soil Sampler if equipped)
2. Determine the weight of the Proctor mold with the base and the collar extension.
3. Assemble the compaction tool.
4. Place soil in the mold in 3 layers.
5. Compact the soil with 25 well-distributed blows of the hammer.

What are some advantages of nuclear gauges?

• Portability. One person can easily transport a typical nuclear density gauge.
• Quick results. Most nuclear gauges allow both one and four minute readings. …
• Virtually non-destructive. Used in the backscatter mode, the nuclear density gauge is entirely non-destructive.

Are nuclear density gauges safe?

Nuclear gauges use radioactive sources to identify the thickness, density or make up of a wide variety of material or surfaces. These gauges, which are safe to use when the proper safety measures are followed, help people build safe buildings, roads, and make reliable products.

What's the safest level of radiation?

Adult: 5,000 Millirems. The current federal occupational limit of exposure per year for an adult (the limit for a worker using radiation) is “as low as reasonably achievable; however, not to exceed 5,000 millirems” above the 300+ millirems of natural sources of radiation and any medical radiation.

How does a Densiometer work?

A Spherical Crown Densiometer works similar to a periscope. The spherical shaped mirror reflects the sky above you to help determine the amount of tree canopy. A cross shaped grid with 24 quarter inch squares helps plot the overhead reflection. In order for a Densiometer to be used properly, it must be level.

How does a Troxler gauge work?

The gauge works by counting the radiation that is received over a given period of time, usually one minute. When you push the button to take a test the gauge counts the radiation for one minute and calculates the density based on the depth of measurement.

What property of nuclear radiation is most harmful?

It depends on whether your exposure to radiation is internal or external. Alpha particles are the most harmful internal hazard as compared with gamma rays and beta particles. Radioactive materials that emit alpha and beta particles are most harmful when swallowed, inhaled, absorbed, or injected.

Can you use a nuclear density gauge in the rain?

Do not use the gauge in the rain. If it gets wet dry it immediately. If needed, open the keypad and allow air to flow through.

Article first time published on

How much radiation does a nuclear gauge emit?

For comparison, studies indicate that for every test (shot) that a gauge operator performs, they are exposed to approximately 1.2 µSv. From this number, we can calculate our annual exposure amount and compare it to regulatory numbers that indicate a threshold where increased cancer risks are to be expected.

What are some examples of nuclear measurement gauges?

Example: Gamma, beta and neutron radiation sources can all be used in nuclear gauges, depending on the application. Neutron radiation is very penetrating and is scattered by materials with a high hydrogen content, e.g. water. It is frequently used for measuring the moisture content in soil and asphalt.

How long is a nuclear gauge certification good for?

It can be taken to renew your Hazmat certification (every 3 years) or for individuals who may need to transport nuclear gauges, but not operate them. This course satisfies US DOT training requirements of 49 CFR 172, subpart H (Hazmat) for individuals shipping or transporting hazardous materials.

What does it mean to have 95% compaction?

95% compaction means that the soil on the construction site has been compacted to 95% of the maximum density achieved in the lab. It means that when you conduct compaction test(in the laboratory) on a small soil sample of a particular site. You get some value of maximum dry unit weight at certain moisture content.

Why is compaction test important?

Standard Proctor test or Proctor compaction test establishes the variation of the unit weight of soil and degree of compaction with the moisture content. It also helps us find out the optimum moisture content for the highest practical density.

How compaction is done?

Compaction is accomplished by use of heavy equipment. In sands and gravels, the equipment usually vibrates, to cause re-orientation of the soil particles into a denser configuration. In silts and clays, a sheepsfoot roller is frequently used, to create small zones of intense shearing, which drives air out of the soil.

What is a Troxler test?

The Troxler Model 3440 Roadreader™ nuclear moisture/density gauge offers two test modes for measuring the density of soil, aggregate, concrete and asphalt materials. The direct transmission mode allows the source to be lowered below the surface in order to test a larger area of material and improve gauge precision.

When transporting a gauge you can safely secure block and brace it?

When transporting a gauge you can safely secure, block and brace it in the front seat. The time it takes for a radioactive material to decay to ½ its activity/strength is known as a half-death.

How do densitometers work?

Within a densitometer the light passes through the optical system bundled from a stabilized light source on the printed surface. The amount light absorbed depends on the ink density and pigmenting of the ink. The non-absorbed light penetrates the translucent (transparent) ink layer and is weakened.

How many squares are in a Densiometer?

Both types of densiometers have curved reflecting surfaces with a grid of 24 squares. Standard proce- dures (Lemmon 1956) call for counting the number of 4 equally spaced imaginary dots/square (96 total dots) covered by forest canopy.

What is the most radioactive place on earth?

2 Fukushima, Japan Is The Most Radioactive Place On Earth Fukushima is the most radioactive place on Earth. A tsunami led to reactors melting at the Fukushima nuclear power plant. Even though it’s been nine years, it doesn’t mean the disaster is behind us.

What household items give off radiation?

• Radon Seeping Into The Basement. …
• Granite Countertops Could Emit Low Levels of Radiation. …
• Check for Radioactive Elements in Ceramics. …
• Drinking Glasses That Contain Uranium. …
• Glow in the Dark Clocks or Watches With Radium in the Paint. …
• Old Box Shaped Television May Emit X-Ray Radiation.

Can you feel radiation?

You may need anesthesia to block the awareness of pain while the radioactive sources are placed in the body. Most people feel little to no discomfort during this treatment. But some may experience weakness or nausea from the anesthesia. You will need to take precautions to protect others from radiation exposure.

What nuclear decay does aluminum stop?

Beta particles travel faster than alpha particles and carry less charge, so they interact less readily with the material through which they pass. They can be stopped by a few millimetres of aluminium. Gamma rays are highly penetrative.

What can alpha penetrate?

Alpha radiation is absorbed by the thickness of the skin or by a few centimetres of air. … It can pass through the skin, but it is absorbed by a few centimetres of body tissue or a few millimetres of aluminium. Gamma radiation is the most penetrating of the three radiations. It can easily penetrate body tissue.

Can radiation be destroyed?

Radiation can come from as far away as outer space and from as near as the ground that you are standing on. Because it is naturally all around us, we cannot eliminate radiation from our environment. We can, however, reduce our health risks by controlling our exposure to it. Some unstable atoms emit alpha particles (α).

How do you perform a nuclear gauge leak test?

All radioactive licenses issued by regulatory agencies have a requirement for you to perform a leak or wipe test on your gauges. This test typically takes less than 5 minutes per gauge and it usually involves wiping a small piece of filter paper across areas near the locations of the sources in the gauge.

How much does a nuclear gauge weigh?

Gauge Size (including handles)12” – 23.5”x9”x14.5” (59cm x 22.9cm x 36cm) 8” – 19.5” height (49.5cm)(75cm x 35cm x 42cm)Shipping Weight83lbs (37.6kg)Weight31lbs (14.1kg)Operating Temperature32º to 122º F (0º to 50º C)

What is the first action that should be taken after the discovery of a damaged nuclear gauge?

Immediately inform the radiation safety officer. If the damage is minor or superficial, and the source is in the safe, shielded position, a Type A transport container (such as the gauge transport case) can be used to transport the device.

How do you measure soil density?

The wet weight of the recovered excavated soil is divided by the test hole volume to determine the wet density. Dry density is calculated by dividing the weight of the wet soil by its water content in percent.

What is ASTM D6938?

ASTM D6938 This test method describes the procedures for measuring in-place density and moisture of soil and soil-aggregate by use of nuclear equipment. The density of the material may be measured by direct transmission, backscatter, or backscatter/air-gap ratio methods.