Progress in the blanket neutronics experiments at JAERI/FNS

The neutronics study in support of the DEMO blanket concept has been performed using the DT neutrons at the FNS facility in JAERI on blanket mockups and a bulk beryllium assembly. From the results obtained in the blanket mockups, it has been clarified that the C/Es of the integrated tritium production are 1.01–1.04 and 1.11–1.13 in the experiments without and with the neutron reflector, respectively. The tritium production can be very accurately predicted in the experiment without the reflector. In the mockups with the 12.6 and 25.2 mm thick tungsten armors, the integrated tritium productions are reduced by 3 and 6% relative to the case without the armor, respectively. Based on analysis of the integral experiment on the beryllium assembly, it is possible to conclude that the calculation uncertainty of the reaction rates in beryllium provides an acceptable agreement with the experimental data related to tritium breeding. Tritium techniques used for TPR measurements have been tested in the international benchmark experiment. There is a very good agreement within the estimated uncertainties between results obtained at JAERI and at TUD, though the results obtained at ENEA show an underestimation (about 15–20%) in comparison with FNS and TUD results.