Reactor physics activities relevant to FBR and ATR programs in PNC, Japan, October, 1980 - August, 1981

The experimental fast reactor, Joyo, has been operated at the 75 MWt normal operation cycle without any serious problem since the beginning of 1980. The test results of the core characteristics obtained so far were generally satisfactory in comparison with the prediction. The application for licensing the construction of the prototype fast breeder reactor, Monju, was filed to the regulatory body on December 10, 1980. The design study of the demonstration fast breeder reactor is in progress, and the first phase of a program has been completed. Concerning the heavy water moderated, boiling light water cooled reactor, Fugen, the repair is now going on because of stress corrosion cracking, and the normal operation will begin to generate electricity in October, 1981. The evaluation of the neutron nuclear data of 243-Cm was carried out in the neutron energy region from 10-5 eV to 20 MeV, and the results were compiled in the ENDF/B format and stored in JENDL-2. The assessment of the sets of nuclear reactor constants concerning fast reactors, the development of core analytical method, the mockup experiments of Monju, and the research on shielding have been made. Since 1978, a series of studies have been made on the optimization of the neutronic, thermohydraulic and safety characteristics of heterogeneous LMFBR cores. The studies of reactor physics parameters have been continued by using uranium and plutonium fuels in the DCA (deuterium critical assembly). (Kato, T.)