Design Study on a Demonstration Core for a Practical LMFBR in Monju

Maeda, Seiichiro; Togashi, Nobuhito*; Higuchi, Masashi*; Takano, Mitsuhiro*; Abe, Tomoyuki

JNC TN8400 2003-028, 135 Pages, 2003/12

JNC-TN8400-2003-028.pdf:85.68MB

The Monju advanced core concept to demonstrate a practical LMFBR core with 150GWd/t (average discharged burnup) was embodied in this design study. A high performance fuel with annular pellets of a large diameter filled in ODS (oxide dispersion strengthen ferritic steel) claddings was applied in the advanced core. This enables improvement of an internal conversion ratio in combination with increase of effective fuel volume fraction, achievement of high burnup up to 150GWd/t and a long operation period beyond 1 year in Monju. The core in which the practical high burnup lessens a burden for a fuel cycle system including fuel fabrication and reprocessing can be demonstrated. In the first step, constraints in the existing plant and requirements to demonstrate the practical LMFBR were clarified. The core and fuel specifications were surveyed with parameters of a number of fuel pins in an assembly and so on. Two types of cores with 127-pin-bundle and 91-pin-bundle were selected as candidates. In the second step, performances of these core options were specified in this design study. It was shown that major parameters in neutronic design, hydraulic design and fuel design would meet criteria. The application of the high performance fuel significantly contributes the enhancement of economical efficiency of Monju itself. The net operation cost will be greatly reduced by increase of the annual electricity generated caused by a boost of the plant operating rates and by saving of the annual discharged fuel assemblies up to 1/2 or 1/3. The deliberate margin for thermal limits ensures the irradiation field to develop new type fuels and core materials and to demonstrate a low decontaminated fuel with miner actinides as a candidate of advanced fuel cycle. The results in this study may become a technically credible guideline to make the future management plan of Monju.