Round-robin analysis of highly depleted lithium for Generation IV nuclear reactor applications

•Round robin analysis of commercially available Li hydroxide depleted in 6Li.•Multiple mass spectrometry techniques, including ICP-MS and TIMS.•Reference point for analyses of depleted Li used in nuclear reactors. Lithium reference materials containing unnaturally high abundances of 7Li are not currently available, which poses quality control problems for highly depleted lithium materials (i.e., depleted in 6Li) required for Generation IV nuclear reactors. This study presents an interlaboratory comparison of a lithium carbonate (NIST SRM924a) containing nominally natural isotopic abundances (∼92.4 % Li-7) and a highly depleted lithium hydroxide material (∼99.95 % Li-7). The natural lithium isotope abundances of NIST SRM924a are confirmed, and the 6Li/7Li ratio of the lithium hydroxide ranged from 0.000399 to 0.000436 with an average of 0.000428 ± 0.000023 (2SD, n = 9). Going forward this material can be used as quality control for analytical work involving highly depleted lithium.