Answer to Question #8929 Submitted to "Ask the Experts"
Category: Radiation Basics — Radiation Shielding
The following question was answered by an expert in the appropriate field:
I've been told that some linear accelerators contain depleted uranium in their shielding materials, but that modern linacs do not. We have Varian 2100 series linacs with 6-18 MV energies. What models or types of accelerators contain depleted uranium?
Depleted uranium (DU) is a byproduct of the nuclear fuel enrichment process. It is abundant and inexpensive. The chemical and physical properties of DU make it ideal for several applications. It is 67% denser than lead, has a high melting point (2070° F, 1132° C), and has a tensile strength comparable with that of most steels. Since it is cheaper than tungsten and denser than lead, it is an ideal compact shielding material for applications where space is a premium. DU metal and DU-metal alloys are commonly used as shielding and collimator material in industrial radiographic imaging and gauging devices and in medical diagnostic and therapeutic devices that contain radiation sources or medical linear accelerators.
However, as I mentioned above, there are more expensive alternatives to DU and in the light of costs and regulatory issues regarding disposal of "radioactive" material, hospitals or industries that use such devices may opt for buying devices that do not contain DU.
To determine what types and models of accelerators contain DU, I suggest you ask the manufacturer of these accelerators directly.
Kamran Vaziri, PhD