Development of rapid methodologies for uranium age dating

Separation of protactinium from uranium-niobium alloys for 231Pa–235U radiochronometry in nuclear forensic investigations

“…Like those at other laboratories, the standard operating procedures for sample digestion and radiochronometry at AWE were independently developed, tested, and optimized on uranium materials of high purity [ 25 ]. For such routine materials, samples are readily digested in nitric acid (HNO 3 ) and then redissolved in concentrated hydrochloric acid (HCl) to create a primary sample solution.…”

“…The combined use of a vacuum-assisted flow chamber and this stacked column technique, which eliminates time-consuming evaporative dry down steps, makes the execution of this purification scheme relatively rapid. Purified sample aliquots of U, Pa, and Th can be ready for mass spectrometric analysis within several hours [ 25 ]. Additionally, the elimination of dry down stages reduces Pa loss due to hydrolysis [ 23 ], maximizing Pa chemical recovery.…”

“…

Fig. 4 Comparison of AWE’s (a) standard operating procedure for Pa separations on pure U metals [ 25 ] and (b ) the modified procedure for depleted U–Nb alloys. The columns are Rockbourne R1010 medium columns and are stacked on top of a vacuum-assisted flow chamber.

…”

Precise and accurate isotopic analysis of uranium and thorium in uranium ore concentrates using ICP-MS and their age dating for nuclear forensic analysis

“…During the process of mining and milling of uranium ores, 5,20 the U-series equilibrium is broken and the uranium concentration of UOC traded on the commercial market should be over 65 wt%, 21 resulting in higher 230 Th abundance in UOC than in the ore at the clock to "zero", which means the beginning of the production process. In uranium materials, [22][23][24][25] the 230 Th-234 U chronometer is the most widely utilized chronometer due to the relatively high abundance of ingrown 230 Th. However, 5,20 the calculated age or "model" age of UOC was usually older than the real age because of the incomplete separation of thorium from uranium.…”

“…In most of the papers dedicated to age dating, [23][24][25] 230 Th/ 234 U ratios have been achieved by laboratories that performed 230 Th and 234 U concentration measurements by isotope dilution mass spectrometry (ID-MS). This method is accurate and precise, 22 reaching an uncertainty of about 0.4 a.…”