Temporal Characterization of Tritium Smear Activities

Area of Science:

• Radiological control and environmental monitoring.
• Nuclear safety and contamination assessment.

Background:

• Tritium contamination surveys are crucial for preventing inadvertent releases.
• Standard smear media can exhibit variable collection efficiencies and time-dependent activity measurements.
• Accurate tritium monitoring is essential for regulatory compliance in nuclear facilities.

Purpose of the Study:

• To evaluate the tritium collection efficiency of different smear media.
• To assess the time dependence of measured tritium activity on various smear types.
• To develop improved operational limits for tritium contamination surveys.

Main Methods:

• Comparison of water-wetted cotton swabs, water-wetted paper smears, and ethanol-wetted Styrofoam wipes (NUC-Wipes™).
• Systematic sectioning and surveying of a tritium-contaminated stainless steel vessel.
• Determination of total activity via repeated decontamination and study of time-dependent measurements.

Main Results:

• Cotton swabs demonstrated significantly reduced tritium collection efficiency.
• Both paper smears and cotton swabs exhibited significant time dependence in measured tritium activity.
• Styrofoam wipes (NUC-Wipes™) showed more consistent results compared to cotton and paper.

Conclusions:

• Standard smear media like cotton swabs and paper smears require careful consideration due to variable efficiency and time-dependent effects.
• Updated, more restrictive operational limits based on fitted curves for time dependence and average efficiency are necessary.
• Implementing these revised limits ensures regulatory compliance while allowing for rapid tritium smear measurements.