To take into account the reactivity loss in spent fuels, an experimental program was set up in 1993 at CEA-Cadarache, France, oscillating separated fission products (FPs) in the MINERVE reactor. Reactivity worth measurements of small samples allow the extraction of information about nuclear data of the studied isotopes. A fully validated calculation scheme has been implemented to interpret pile-oscillation measurements. Therefore, calculation over experiment ratios can be accurately transposed to trends in the integral capture cross section of the FPs. With the European JEFF3.1.1 library, results show a discrepancy below 3% for several nuclides: 155Gd, 149, 152Sm, 143Nd, and 95Mo, but improvements may be needed for some others: 133Cs, 103Rh, 99Ru, and 153Eu. Based on the Integral Data Assimilation technique, we propose new thermal cross-section values, (348 ± 14) b and (42 478 ± 1793) b, for two of the most absorbing nuclides, 143Nd and 149Sm, respectively.