Preparation and calibration of a ²³¹Pa reference material

Area of Science:

• Nuclear Chemistry
• Radiochemistry
• Metrology

Background:

• Accurate ²³¹Pa and ²³³Pa measurements are crucial for nuclear forensics and safeguards.
• ²³¹Pa-²³⁵U dating requires precise calibration of ²³³Pa tracers.
• Existing calibration methods for ²³³Pa tracers can be complex and introduce uncertainty.

Purpose of the Study:

• To characterize a new ²³¹Pa reference material for accurate protactinium quantification.
• To establish metrological traceability for ²³¹Pa measurements.
• To simplify and improve the accuracy of ²³³Pa tracer calibration for ²³¹Pa-²³⁵U model age determinations.

Main Methods:

• Isotope dilution mass spectrometry (IDMS) was used for the primary characterization of a purified ²³¹Pa solution.
• A ²³³Pa isotopic spike was employed for the ²³¹Pa quantification.
• The ²³³Pa spike was calibrated using a reverse-spike method involving ²³³U ingrowth and subsequent IDMS measurement against a certified uranium standard.

Main Results:

• A well-characterized ²³¹Pa reference material was successfully produced.
• The calibration method for the ²³³Pa spike using ²³³U ingrowth was validated.
• The new reference material provides a simplified and traceable calibration pathway for ²³³Pa tracers.

Conclusions:

• The developed ²³¹Pa reference material enhances the reliability of ²³¹Pa-²³⁵U model age measurements.
• This advancement supports improved accuracy in nuclear forensics and nuclear safeguards applications.
• The metrological traceability established will benefit the broader scientific community involved in actinide measurements.