Neutron activation analysis of lithium in graphite

Trace impurities of lithium in graphite is one of the sources of tritium in high-temperature reactors. To determine contents of less than 1 ng/g a procedure based on the (n,α)-reaction of 6Li was developed. The samples are irradiated in a reactor and then ignited in a Wickbold apparatus. Thereby the tritium produced by the (n,α)-reaction is completely converted in HTO, which can be easily purified by distillation and, if necessary, by a scavenger precipitation step. Several types of graphite have been investigated and the lowest content measured was 0.2 ng/g. (author)