Radioactive Sealed Sources

Any radioactive material that is encased in a capsule designed to prevent leakage or escape of the radioactive material is defined as a sealed source. It is imperative that all radioactive sources sealed or encapsulated are properly accounted for and are periodically checked for leakage.

Registration of Sources: All sources of radioactive material sealed or encapsulated, regardless of the activity must be registered with EHS. This requirement applies to sources such as low activity check sources or sources which are incorporated into machines or devices. Be aware that all Liquid Scintillation Counters contain sealed sources.

Leak Testing of Sealed Sources: All sealed sources containing 100 µCi or more of Beta or Gamma emitting radionuclides or 10 µCi or more of alpha emitting material in any form other than gas will be tested for leakage and contamination by EHS every six months. Exceptions are as follows:

  • sources containing exclusively hydrogen-3
  • sources containing radionuclides with a half-life of less than 30 days
  • Iridium-192 seeds in nylon ribbons
  • sealed sources that are no longer in use (i.e., in storage)
Inventory Control: A physical inventory of all sealed sources must be conducted at least annually by the individual authorized to possess the source or a designee. The inventory consists of the model, serial number if any, location (room, building) of the source, and initials of the individual conducting the inventory. EHS conducts a physical inventory of sealed sources every three months.