抄録
This report summarizes the present status on the safety evaluation codes for fast reactors, and indicates the regions where more studies are called for to increase the reliability of these analyses.
Anomalies occurring in reactor operation are analyzed under the headings of (1) reactor stability, (2) credible accidents, and (3) hypothetical accidents. Under the first heading, a discussion is given on a model and codes to evaluate reactor stability including the bowing effect of fuel subassemblies, which might introduce a positive temperature coefficient. Under the second heading, a typical computational model and codes for credible accident analysis such as EXCURS and FORE II are described, and an account is given of efforts to develop codes that can deal more precisely with the space dependent effect. Under the third heading, a description is given of a method of analyzing an accident in which a fast reactor core melts and collapses. The usefulness of the modified Bethe-Tait analysis is discussed in this connection.
Codes to treat phenomena that follow a nuclear burst (such as sodium fire and fission product release) are briefly presented. Finally. a discussion is given on problems calling for further development to improve safety analyses.
