Removing Linear Accelerators with Depleted Uranium (DU) Counterweights

Varian low/single photon energy linear accelerators manufactured in the 1970’s through the early 1990’s often contain depleted uranium shielding (also referred to as counterweights). Depleted uranium is a radioactive material that must be handled appropriately during the removal and disposal of this equipment. NRC regulations and most states’ regulatory agencies require such material to be disposed of properly.

Below is a list of machines that require special handling for removal and disposal.

• Varian Clinac 4 linear accelerators (manufactured from 1972 to 1990)
• Varian Clinac 4/80 linear accelerators
• Varian Clinac 4/100 linear accelerators
• Varian Clinac 6X linear accelerators (manufactured from 1975 to 1978)
• Varian Clinac 6/100 linear accelerators (manufactured from 1979 to 1989)
• Some Varian 600C’s have depleted uranium (DU) shielding

Varian Clinac 6/100 Linear Accelerator

Depleted uranium plates are not to be confused with Cobalt-60 sources found in many other radiotherapy systems, Gamma Knife systems, Gyro Knife systems, and others. DU plates are generally easier to handle and less expensive to dispose than Cobalt-60 systems.

While the amount of depleted uranium counterweights can vary per machine, the typical amount of DU found in Varian Clinac 6/100’s are as follows:

• Primary collimator – 96 lbs.
• Secondary collimator – 300 lbs.
• Faceplate shield  – 17 lbs.
• Gun shield disks (3) – 40 lbs. x 3

Total 533 lbs.

Depleted Uranium (DU Counterweights)

Disposal of this hazardous material by low waste radioactive material disposal specialists can range in price, and is often quoted on a per pound basis.  The linear accelerator is disassembled and the DU plates are carefully placed in a marked container properly labeled. When the radioactive materials are picked up, the facility will receive a certificate of disposal. Transportation of such hazardous material also requires a special license, and often the materials must be shipped to a disposal facility in a different state.

Depleted uranium counterweights are one of many factors that make removing older linear accelerator systems so complex. When faced with this situation, it is important to work with a reputable linac specialist. For over 25 years, ROS has been safely and professionally removing and disposing linear accelerators and other heavy, hard-to-remove medical equipment.  If you are in need of radiation therapy equipment disposal services, or any other radiation oncology equipment removal services, please reach out to one of our qualified team members to see how ROS can help you today.