Radioactive Materials

What are Radioactive Materials?

Radioactive materials (RAM) are materials that have been artificially enhanced or combined with radioisotopes. Radioisotopes are unstable atoms that undergo spontaneous nuclear decay, releasing energy in the process. This energy may be released as ionizing radiation in the form of alpha particles, beta particles, gamma rays, or neutrons. Ionizing radiation produces ion pairs in matter exposed to it. In inanimate matter this does not pose a hazard. However, ionizing radiation may cause damage to living tissue. Many radioisotopes occur naturally in our environment, while many others are produced in nuclear reactors or particle accelerators.

Use and possession of radioactive materials is regulated by the Texas Department of State Health Services under the rules listed in Title 25 of the Texas Administrative Code, part 289 (25TAC289).  UT policies for safe use of radioactive materials are based on those rules.

The Medical Use and Clinical Research Involving Radiation webpage contains information on human use of radioactive materials.

There are two basic categories of radioactive materials used at UT:

Unsealed (Open Form) Radioactive Materials

Unsealed (open form) radioactive materials are radioactive materials that can be aliquoted or separated into smaller quantities; used in chemical or physical processes; and will mix with other reagents or other non-radioactive materials.  Open Form use has specific monitoring requirements, because the materials can be released accidentally and contaminate lab surfaces, equipment, and radiation workers.  Most labs that use open form radioactive materials conduct biological and chemistry research. Working with unsealed, open form radioactive materials requires the PI to submit an Application to use Radioactive Materials (DOC) to the RSO for approval by the Radiation Safety Committee.  Some authorizations require ongoing personal Radiation Dosimetry be worn to track radiation dose to workers. Unsealed radioactive materials generate Radioactive Waste, which must be disposed in accordance with state regulations.

Sealed Sources of Radioactive Material

Sealed Sources are designed to remain intact throughout their useful life.  They are encapsulated to prevent any radioactive material from escaping—either in stainless steel or hard plastic sealed casings.  They may require model and serial numbers to track their purchase, inventory, and disposal.  Sealed sources must be leak tested and inventoried every six months.  Sealed sources are often used by physics and engineering labs.  The RSO approves the purchase and use of most sealed sources.  However, some sealed sources may require the PI to submit an Application to use Radioactive Materials (DOC) to the RSO for approval by the Radiation Safety Committee, and may also require that ongoing personal Radiation Dosimetry be assigned to track radiation dose to workers.  All sealed source disposal is coordinated with the RSO.

Radiation Policies and Support

The Radiation Safety Policies and Support page contains information on administrative processes and program implementation details, such as ordering and receiving radioactive materials, radiation detection instruments, lab monitoring, and other information.


Anyone who wishes to use radioactive materials or perform contamination surveys in a radioactive materials lab must first complete the appropriate Radiation Safety Training.

The Radiological Health Manual (PDF) contains information specific to radiation safety and radioactive materials.  This includes basic information about units of radioactivity, exposure, and dose; radioactive decay; annual dose limits; personal monitoring (dosimetry); and lab survey requirements.  There are also radiological data sheets on the most common radioisotopes used on campus in an appendix at the end of the manual.