Soil Gauge Radiation Safety Training

Soil Moisture Gauges

Many industries use measuring gauges that incorporate a radioactive source. These nuclear gauges provide an inexpensive, yet highly reliable and accurate method of measuring the moisture, density, or composition of materials. The hydro-probe, sometimes called a moisture gauge, measures moisture in soil. The neutrons from a neutron source such as Americium 241/Beryllium (Am-Be), are moderated (slowed down/thermalized) by water molecules and reflected into the detector. The detector in the gauge is only capable of detecting moderated neutrons. Hydrogen which is a part of the water molecule is a very effective neutron moderator and the number of moderated neutrons is proportional to the presence of hydrogen (moisture).

Soil Gauge Probe Source Location

 

 

Internal Probe Source Located Under Additional Shielding

 

Never remove the shielding!

Shielding

Increasing the amount of shielding decreases your exposure. Proper thickness and appropriate materials are critical to shield you from a radiation hazard.

* Use appropriate shielding. Neutrons are shielded by hydrogen rich materials, such as high density polyethylene.
*High activity sources in storage must be shielded appropriately when in storage.
* Sources should be stored away from normally occupied areas.
* If you are uncertain about whether a source should be shielded or is sufficiently shielded, contact the Radiation Safety Office for information at 509-335-1763 or e-mail radsafe@ad.wsu.edu

Source Security

WSU’s broadscope License Condition 25. C. requires that each portable nuclear gauge has a lock designed to prevent unauthorized or accidental removal of the sealed source(s) from a shielded position.

The gauge and its container must be locked when in transport, storage, or when not under the direct control of an authorized user.

Gauges must be secure both during transport and storage!

Gauge handle must be Locked During Storage and Transport

Soil Gauge Security

Soil Gauges are readily portable. It is important to pay extra attention to ensuring that gauges with radioactive sources are secured.

WAC 246-221-150 requires that: Each portable gauge licensee shall use a minimum of two independent physical controls that form tangible barriers to secure portable gauges from unauthorized removal, whenever portable gauges are not under the control and constant surveillance of the licensee.

Soil Gauge Storage Security

Gauges must be locked in a secured container and a secured storage area when not in use.

* Any room in which a gauge containing radioactive sources is being used or stored must be locked when unattended. Radioactive materials signs are required on the storage cabinet only. They are not required on the door to the room. Other postings required on the cabinet are the emergency contact list and the DOH RHF-3 form.

Transportation

U.S. Government Department of Transportation (DOT) regulations control the transportation of radioactive materials on public roads. All gauges are furnished with Type A shipping and storage containers. They are labeled with Yellow II labels which means that the radiation field outside of the container is less than 50 mR/hr on any surface and less than 1.0 mR/hr at one meter from any surface. Under these conditions, no placarding of the vehicle is required. These devices must only be transported in their approved labeled shipping containers.

Soil Gauge Transport Security

When transporting a gauge, the Three Levels of security shall be used at all times!

The outer two levels of security will be established so that each independently prevents the transport box with gauge from being removed from the transport vehicle and keep the lid of the transport box from opening.

DOH and WSDOT requires 3 levels of security.

1) Gauge case locked.
2) Gauge case chained to the vehicle with locks on either side of the vehicle (2 chains, 2 locks).
3) Do not simply loop the chains through the gauge handles. Wrap chains across gauge case so that lid can not be opened by simply cutting the lock on the case.

                                       

During transport you must

Block and lock the instrument carrying case in the bed of the vehicle and ensure the gauge is stored and locked within the carrying case. The Gauge handle must be locked to ensure the source stays shielded.

Gauge and case must not be visible when gauge is not in use (cover with a tarp or burlap sack).

Before leaving make sure “Transportation Information” Sheet or “Shipping Paper” is visible within the front of vehicle.
Place orange ERG book in front of vehicle

                                                             

Security Performance Audits

WSU’s Broadscope License Condition 25. D. also requires an annual “Performance Audit” of each gauge user to assure all security measures are in use and correctly applied.

RSO will contact you to perform this audit annually.

 

Additional Transport Requirements

The Department of Health also requires that a device be returned to the licensed storage location each day unless the job is farther than 50 miles from that licensed storage location. This is regardless of the distance from the job location to the operator’s home.

Soil Gauge Transport Box Must Have These Labels

Soil Gauge Transport Box Must Have These Labels

One (1) USA DOT 7A label placed on the front side of the transport box

 

Two (2) Yellow-II labels, one on the front side and one on the back side of the transport box.

One (1) DANGER DO NOT LOAD IN PASSENGER AIRCRAFT on top of the transport box.

 

 

Emergency Procedures

Damage to Sealed Radioactive Source Holder.

* Evacuate the immediate vicinity around the source holder.
* Place a barrier at a safe distance from the source holder.
* Identify the area as a radiation hazard.
* Contact your authorized user and the Radiation Safety Office: 509-335-1763 M-F 8-5 or
*Facilities Operation: 509-335-9000 after 5PM and weekends or if unable to reach any of the above call 911.

Sealed Source Leak Test

The purpose of the leak test is to ensure that the source inside the gauge is not leaking radioactive material. Under the terms of the Washington State University’s Radioactive Materials Licenses, a leak test must performed of the sealed sources inside gauges to ensure the integrity of the source encapsulation. Such leak tests are required at three or six-month intervals or annually depending on the nature of the source.
In addition, a semi-annual inventory of these sources is required.
If you suspect that a sealed or plated source has been damaged, notify the RSO and do not use the source until Radiation Safety staff have leak tested the source.

 

Gauge Repairs

If you have a gauge that needs repair or calibration from an outside vendor, please coordinate this with the Radiation Safety Office. We can make sure that your gauge is packaged properly and is shipped in accordance with Department of Transportation’s Dangerous Goods regulations.

Test Time!

  • Follow this link to the test. https://myresearch.wsu.edu
  • Use your WSU user name and password to sign in.
  • Click on the training tab.
  • Then click on the available training tab
  • Find the radiation safety training Soil Gauges course, in the OR section, click on it and take the test.