Development of a standard data base for FBR core nuclear design(VII); Advances in JUPITER experiment analysis

Sugino, Kazuteru; Yokoyama, Kenji   ; Ishikawa, Makoto; Sato, Wakaei*; Numata, Kazuyuki*; Iwai, Takehiko*

The present report compiles the advances in experiment analyses of JUPITER, which was joint research programs between U.S.DOE and PNC of Japan, using the Zero Power Physics Reactor (ZPPR) large fast critical facility at ANL-Idaho in 1978 to l988. The advances here are use of the latest nuclear data library and the application of analytical methods which treat mechanisms in more detail or use fewer modeling approximations. As a result of using the latest nuclear data library, C/E values of nearly all characteristics approached unity, and the discrepancies between cores were reduced. Thus it is shown that the latest data library is effective for an analysis of nuclear characteristics. Further, an advance in analytical methods brought C/E value close to unity, and it clarifies the causes of differences between the calculational and experimental values. The current evaluation for each nuclear palameter shows following: (1)Criticality. The C/E values are from 0.993 to 0.997, a systematic underestimate. This underestimation is much smaller than the error caused by the uncertainty in nuclear data, which is the dominant error for this characteristic. In terms of analytical method, there are significant differences in calculation results between present and Monte-Carlo based methods, so more investigation will be required in future. (2)Doppler reactivity. The C/E values are from 0.8 to 0.9, a systematic underestimate. The analytical method, which is stood for by the use of ultra fine energy structure analysis, is so detailed that there is little room for improvement in that term. Therefore, some evaluation of the self-shielding factors and comparison with other Doppler reactivity experiments will be required. (3)Reaction rate distribution. It is judged that the present analytical method has an adequate accuracy for the core regions of homogeneous and axially heterogeneous cores, because the C/E values varied from unity by less than 2% for Pu-239 fission, U-235 fission ...