Standardisation of low-activity actinide solutions by alpha-particle counting at a defined solid angle

Area of Science:

• Nuclear Metrology
• Radiochemistry
• Isotope Analysis

Background:

• Accurate quantification of radionuclides is crucial for various applications, including nuclear safeguards and environmental monitoring.
• Standardization of radioactive tracers ensures traceability to the International System of Units (SI).
• Challenges in standardization include low activity levels and interference from daughter nuclides.

Purpose of the Study:

• To standardize 232U, 236Pu, and 229Th tracers.
• To assign SI-traceable property values for these radionuclides.
• To address challenges in low-activity measurements and daughter nuclide interference.

Main Methods:

• Alpha-particle counting at a defined solid angle.
• Application of standardized measurement techniques within an IAEA co-ordinated research project.
• Careful consideration of potential sources of error, including background radiation and detector efficiency.

Main Results:

• Activity concentrations were determined for 232U, 236Pu, and 229Th.
• The determined activity concentrations were (734+/-4) Bq g(-1) for 232U, (142.0+/-0.9) Bq g(-1) for 236Pu, and (528.2+/-2.6) Bq g(-1) for 229Th.
• Results are reported at a reference date of 1 January 2003.

Conclusions:

• Successful standardization of 232U, 236Pu, and 229Th tracers was achieved.
• The methods employed provided SI-traceable activity concentration values.
• The study highlights the importance of addressing low-activity and daughter nuclide interference in radionuclide metrology.