Tritium

Half-life

12.3 Years

Emitter

Beta

Beta Energy

18.6 keV

Travel distance

  • Air: 0.24 inches or 0.61 cm
  • Solids/Tissue: Insignificant (No 3H betas pass through dead layer of skin)

Annual Intake Limit

  • Inhalation: 80,000 µCi
  • Ingestion: 80,000 µCi

Detection

  •  Liquid Scintillation Counting is the only readily available method for detecting 3H
  • NOTE: portable survey meters will not detect laboratory quantities of 3H

Shielding

None required –  not an external radiation hazard

Dosimeter Monitoring

  • Urine bioassay is the only readily available method to assess intake [for tritium, no intake = no dose].
  • Confirmatory bioassay whenever your annual 3H use exceeds 8 mCi

Precautions

  • Avoid 4 routes of entry: absorption, ingestion, inhalation and injection
  • Many tritium compounds readily penetrate gloves and skin; handle such compounds remotely and wear double gloves, changing the outer pair at least every 20-30 minutes
  • ALIs can vary considerably, e.g. DNA procedures such as tritiated thymidine are regarded as more toxic than tritiated water partly because the activity is concentrated in cell nuclei
  • There is a high probability of undetected spread of contamination due to the inability of direct-reading instruments to detect tritium and the slight permeability of most material to [tritiated] water & hydrogen [tritium]. Use extreme care in handling and storage [e.g. sealed double or multiple containment] to avoid contamination, especially with high specific activity compounds.

Recommendations

  • Wipe test of work areas and equipment surfaces and count them in a Liquid Scintillation Counter.
  • Dispose the waste as per USC radiation waste policies. Do not mix the waste with any other isotope.

Radiological Data

  • Radiotoxicity: Least radiotoxic of all nuclides;
  • Committed effective dose equivalent (CEDE), ingestion or inhalation:
    • Tritiated water: 0.064 mrem/uCi of 3H intake
    • Organic compounds: 0.16 mrem/uCi of 3H intake
  • Critical Organ:
    • Body water or tissue
  • Exposure Routes:
    • Ingestion, inhalation, puncture (injection), wound, skin contamination absorption
  • Radiological Hazard:
    • External Exposure – None from weak 3H beta
    • Internal Exposure & Contamination – Primary concern