Application of the 226Ra–230Th–234U and 227Ac–231Pa–235U radiochronometers to uranium certified reference materials

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

“…R is the 230 Th/ 234 U atom ratio measured in the sample. Because the active period of operation of the mine/mill for nuclear purposes is aer World War I, 2,5,16,23 the reliable model age t in units of a −1 of UOCs must be less than 100 a.…”

“…The model age or model production date of uranium materials is an important signature that has been used to constrain the production history and possible origins of the material, 23 and also establish genetic links among different samples of interest in a nuclear forensic investigation. In order to understand the At present, 19 few reference materials for age dating are certied and available to the scientic community for use in the validation of Th-U age dating methods.…”

“…In order to understand the At present, 19 few reference materials for age dating are certied and available to the scientic community for use in the validation of Th-U age dating methods. 19,23,30 The ID-MS method was rstly applied to obtain the concentrations of 238 U and 230 Th of CRM124, GBW04234 and GBW04238 from the primary solutions, as graphed in Fig. 5.…”

“…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.…”