Tritium breeding mock-up experiments containing lithium titanate ceramic pebbles and lead irradiated with DT neutrons

Abstract Experiments were conducted with breeding blanket mock-up consisting of two layers of breeder material lithium titanate pebbles and three layers of pure lead as neutron multiplier. The radial dimensions of breeder, neutron multiplier and structural material layers are similar to the current design of the Indian Lead–Lithium cooled Ceramic Breeder (LLCB) blanket. The mock-up assembly was irradiated with 14 MeV neutrons from DT neutron generator. The local tritium production rates (TPR) from 6 Li and 7 Li in breeder layers were measured with the help of two different compositions of Li isotopes (60.69% 6 Li and 7.54% 6 Li) in Li 2 CO 3 . Tritium production in the multiplication layers were also measured with above mentioned two types of pellets to compare the experimental tritium production with calculations. TPR from 6 Li at one location in the breeder layer was also measured by direct online measurement of tritons from 6 Li(n, t) 4 He reaction using silicon surface barrier detector and 6 Li to triton converter. Additional verification of neutron spectra ( E n  > 0.35 MeV) in the mock-up zones were obtained by measuring 115 In(n, n′) 115m In reaction rate and comparing it with calculated values in all five layers of mock-up. All the measured nuclear responses were compared with transport calculations using code MCNP with FENDL2.1 and FENDL3.0 cross-section libraries. The average C/E ratio for tritium production in enriched Li 2 CO 3 pellets was 1.11 in first breeder zone and 1.09 in second breeder zone with uncertainty 8.3% at 1 σ level. The experimental details and results are discussed in this paper.