Appendix A Characteristics of Commonly Used Radionuclides Tritium (H-3)

DOE-HDBK-1106-97

APPENDIX A

CHARACTERISTICS OF COMMONLY USED RADIONUCLIDES

TRITIUM (H-3)

Tritium is a low-energy beta emitter and cannot be monitored directly with a thin-window G-M

probe. Monitoring is normally performed by taking a swipe of the area and counting the swipe in

a liquid scintillation counter.

1. Maximum energy: 0.018 MeV (average energy is 0.006 MeV or about 1/3 the

maximum energy).

2. Maximum range in air: 1/4 inch (6 mm).

3. Maximum range in water: 6 x 10-3 mm.

4. International Atomic Energy Agency (IAEA) toxicity classification: Low.

5. Physical half-life (T1/2): 12.35 years.

6. Effective half-life (Teff): 10 days (the time it takes for of the material to be eliminated

from the body by both biological processes and radioactive decay).

7. Critical organ: Whole body (the part of the body where the most limiting dose is

delivered).

8. Personnel monitoring: Bioassay - urinanalysis, NOT detected with a dosimeter

(thermoluminescent dosimeter or film).

9. Annual Limit of Intake (ALI):

Tritiated water: 80 mCi (3 x 109 Bq) by inhalation or ingestion.

10. Shielding: None (the low-energy beta is not very penetrating).