Measurement of U Doppler Effect using various samples in FCA XVII-1

Ando, Masaki  ; Okajima, Shigeaki  ; Oigawa, Hiroyuki 

U Doppler effect measurements were carried out using 6 uranium samples with various composition or diameter varying self-shielding factors of U. Calculation accuracy of the standard analysis method for fast reactor cores at FCA was investigated.The Doppler effect were measured by the sample-heated and reactivity worth measurement method up to 800 degree in the FCA XVII-1 assembly, which simulated Na-cooled MOX fueled FBR. In the analysis, the Doppler effect was calculated using the effective cross sections obtained by the PEACO-X code. The calculated values based on the diffusion theory agreed well with the experiment for the U-metal and UO samples. The calculation underestimated the experiment from 10% to 30% for the UO samples containing BeO. This underestimation was improved by the use of the transport calculation. The calculation, however, underestimated about 20% for the sample whose background cross section is greater than 300 barns.