[en] Mock-up experiments of the prototype fast breeder reactor MONJU proceeding with FCA. The assembly VI-2 is the second physics mock-up. It consists of a test region simulating the MONJU inner-core composition, a U-235 fueled driver and a uranium metal blanket, the assembly VI-1 is the MONJU outer-core mock-up. The experimental results are presented: critical mass, plutonium higher isotopes effect, sample reactivity worths, reaction rates, fuel bunching effect, axial blanket effect, and pin-plate comparison by using pin-fuel assemblies. (author)