Calibration of the National Institute of Standards and Technology tritiated-water standards

Comparison of tritiated-water standards by liquid scintillation for calibration of a new Standard Reference Material®

“…The most recent of these were standardized by length-compensated internal gas proportional counting [2][3][4]. 3 The procedure for the preparation of tritiated-water standards and the internal proportional gas counting method used at NIST has been described by Unterweger et al [7] and Unterweger and Lucas [8].…”

“…The procedure used to perform such large-volume gravimetric dilutions has been described in detail previously by Collé, et al [17] for the preparation of a different radioactivity SRM. For this dilution, the mass from ampoule M3 was obtained from both dispensed and contained mass differences with a Mettler AT20 electronic microbalance (Mettler-Toledo, Columbus, Ohio) and a larger-capacity (3 kg) mechanical balance with optical scale (Voland Jupiter 3000) 8 , respectively. The total mass was obtained from the mass difference between the empty dispensing bottle and the filled bottle with the large capacity balance.…”

Water resources during drought conditions and postfire water quality in the upper Rio Hondo Basin, Lincoln County, New Mexico, 2010-13

“…The radioisotopes of hydrogen (tritium [ 3 H]) and carbon-14 ( 14 C) are used to determine approximate groundwater age, groundwater flow paths, and aquifer mixing. Tritium is a short-lived isotope of hydrogen that has a halflife of 12.33 years (Unterweger and Lucas, 2000), making it useful for the dating of young water (recharged since about 1950). Tritium is produced naturally from the bombardment of nitrogen by cosmic radiation in the upper atmosphere (Clark and Fritz, 1997), where it becomes incorporated into water molecules that fall to the land surface as precipitation.…”

Standardization of Tritium Water by TDCR Method

“…The specify activity of 4 samples determined by the TDCR method was well consistent with each other and the mean value was 342.8±2.4 kBq/g which agrees with the certified value within the En criterion. But it seems that each measured value is a bit less than the certified value, which implies that there might exist a system deviation between the TDCR method and internal gas proportional counting (IGPC) [10] used to standardize NIST tritium water in 2000.…”