Updated uranium reference material 231Pa/235U consensus model ages for nuclear forensics

Radiochronometry provides the model age of nuclear materials, which is useful for understanding the production history of materials found outside of regulatory control. Certified reference materials (CRMs) are important for radiochronometry to increase confidence in measurement quality; however, the absence of ²³¹Pa/²³⁵U CRMs necessitates that nuclear forensic laboratories measure the ²³¹Pa/²³⁵U model ages of preexisting uranium reference materials. Here, new consensus ²³¹Pa/²³⁵U model ages are reported from three nuclear forensic laboratories for three reference materials using current analytical methods. These updated consensus values can be used for quality control of ²³¹Pa/²³⁵U model age measurements.