⁹⁰Sr determination in water samples using Čerenkov radiation

Area of Science:

• Environmental Science
• Radiochemistry
• Analytical Chemistry

Background:

• Accurate determination of radioactive isotopes like strontium-90 (⁹⁰Sr) in environmental samples is critical for radiological protection.
• Čerenkov radiation coupled with liquid scintillation counting offers a sensitive method for detecting low-activity beta emitters.
• Challenges in Čerenkov counting include color quenching in environmental water samples.

Purpose of the Study:

• To optimize a procedure for determining ⁹⁰Sr in environmental water samples using Čerenkov radiation and a low-level liquid scintillation counter (Quantulus 1220).
• To evaluate the effect of different vial types on the counting process.
• To apply and validate the sample channel ratio (SCR) method for correcting color quenching.

Main Methods:

• Utilized Čerenkov radiation detection with a Quantulus 1220 liquid scintillation counter.
• Compared the performance of low diffusion polyethylene, high performance glass, and low potassium borosilicate glass vials (20 ml volume).
• Employed the sample channel ratio (SCR) method to correct for color quenching in water samples.

Main Results:

• Achieved counting efficiencies of 45.86(9)%.
• Attained a minimum detectable activity (MDA) of 0.32 Bq L^-1 using a 20 ml polyethylene vial over a 300-minute measurement.
• Successfully applied the SCR method to mitigate color quenching effects.

Conclusions:

• The optimized procedure provides a sensitive and reliable method for ⁹⁰Sr determination in environmental waters.
• Polyethylene vials demonstrated suitability for ⁹⁰Sr analysis via Čerenkov counting.
• The study's methodology was validated through participation in an international proficiency test (IAEA-TEL-2015-03).