Demonstration of Elastic Recoil Detection as a Technique for Quantifying 6Li Burnup in Tritium Breeder Materials.

Lithium-6 enriched lithium aluminate, LiAlO2, is utilized as the tritium breeding material in Tritium Producing Burnable Absorber Rods (TPBARs). TPBARs are now the primary approach for maintaining the United States’ tritium supply. When positioned inside a fission reactor, 6Li absorbs neutrons and transmutes into ³H+4He. Hydrogen and helium accumulation will eventually result in significant material degradation and mechanical failure. Individual light isotope concentrations would provide beneficial information for predicting accumulation levels required for material degradation to occur, and useful information for comparing with neutronics calculations of 6Li burnup in tritium breeding materials but are difficult to quantify experimentally. This paper reports demonstrated success in using the ion beam analysis technique Elastic Recoil Detection (ERD) to measure the 6Li fraction in LiAlO² pellets. This technique utilized a 42 MeV Si7+ ion beam to recoil the light isotopes into a detector telescope that separated each isotope by simultaneously measuring the energy and stopping power of these recoils. This technique was used to accurately measure the enriched 6Li/Li-total of 0.25 ± 0.02, compared to the known value of 0.239. The isotopes ¹H, ²H, and 4He were also measured. [ABSTRACT FROM AUTHOR]