Measurement of TPR distribution in natural Li2TiO3/Be assembly with DT neutrons

In the previous blanket neutronics experiments conducted at the FNS facility of Japan Atomic Energy Agency, the following disagreements between experiments and analyses have been pointed out: (1) in the experiment with a 6Li-enriched Li2TiO3 layer and a beryllium layer, the calculation was found to overestimate the tritium production rate (TPR) by approximately 10% when a neutron source reflector composed of SS316 was attached. (2) In the experiment with natural Li2O pebbles sandwiched by beryllium layers, TPR near the rear beryllium layer was overestimated by up to 10%. In order to identify the cause of the above problems clearly, a new blanket neutronics experiment with DT neutrons using natural Li2TiO3 layer and beryllium layers was conducted at FNS. TPR distributions inside the natural Li2TiO3 layer in assemblies with and without the source reflector were measured with Li2CO3 pellets. The measured TPR agreed well with the calculations within 6% in both assemblies. The influence of the reflector and beryllium on TPR prediction accuracy was not seen in the present experiment.