Half-life
5730 Years
Emitter
Beta
Beta Energy
156 keV
Travel distance
- Air: 24 cm or 10 inches
- Water/Tissue: 0.28mm or 0.012 inches ( ~1% of 14C betas transmitted through dead skin layer, i.e. 0.007 cm depth)
- Plastic: 0.25mm or 0.25 inches
Annual Intake Limit
- Inhalation: 2000 µCi
- Ingestion: 2000 µCi
Detection
- Portable Survey Meters:
- Geiger-Mueller [~10% efficiency];
- Beta Scintillator [~5% efficiency]
- Wipe Test: Liquid Scintillation Counting is the best readily available method for counting 14C wipe tests
Shielding
None required – mCi quantities not an external radiation hazard
Dosimeter Monitoring
- Urine bioassay is the only readily available method to assess intake [for tritium, no intake = no dose].
- After any accident/incident in which an intake is suspected please provide urine sample for analysis.
Precautions
- Avoid skin contamination [absorption], ingestion, inhalation, & injection [all routes of intake].
- Many 14C compounds readily penetrate gloves and skin; handle such compounds remotely and wear double gloves, changing the outer pair at least every 20 minutes.
Recommendations
- Wipe test of work areas and equipment surfaces and count them in a Liquid Scintillation Counter.
- Monitor surfaces routinely and keep records of the results. A GM probe may detect 14C if the probe is used within a ½ inch of the surface and the proper probe is used.
- Dispose the waste as per USC radiation waste policies. Do not mix the waste with any other isotope.
Radiological Data
- Radiotoxicity:
- 0.023 mrem/uCi of 14CO2 inhaled;
- 2.09 mrem/uCi organic compounds inhaled/ingested
- Critical Organ:
- Fat tissue [most labeled compounds]; bone [some labeled carbonates]
- Exposure Routes:
- Ingestion, inhalation, puncture, wound, skin contamination absorption
- Radiological Hazard:
- External Exposure – None from weak 14C beta
- Internal Exposure & Contamination – Primary concern