45 Radioactive Materials Safety Manual Environmental Health and Safety 3H TRITIUM Half - Life Physical Biological Effective 12.3 years 12 days 12 days Radiation Emitted Type Energy (max) Range (max) Beta 18.6 keV Air: 6 mm Tissue: 6 µm External Hazard None Internal Hazard Effective Committed Dose Ingestion Inhalation Equivalent per Unit Intake: 6.4 x 10-2 mrem/µCi (1.73 x 10-11 Sv/Bq) 6.4 x 10-2 mrem/µCi (1.73 x 10-11 Sv/Bq) Annual Limit on Intake: (ALI)* 80 mCi Water 80 mCi Water *ALIs expressed are from Appendix B, Table 1 – Iowa Administrative Code 641.40 (136C). Special Considerations • 3H emits the lowest energy beta particle of any commonly use radionuclide. • 3H contamination cannot be detected directly by any type of portable survey meter. • Certain 3H compounds, such as tritiated water, readily penetrate gloves and skin in relatively short periods of time. • 3H is often found in freezer frost/ice. Radiation Safety Practices • Dosimetry – None • Bioassay – Required when quantities of 25 mCi (925 MBq) or more are used • Shielding – None • Surveys – Wipes, analyzed in an LSC • General – Because 3H contamination is particularly difficult to detect, extra care should be taken in observing contamination control practices. • Two pairs of gloves should be worn, and the outer pair changed frequently, when working with tritiated water. • Tritiated water should be used in a fume hood.