Fig. 4-4 Isotopic composition in 241Am sample before and after irradiation Many nuclides, nonexistent before irradiation, are produced by various nuclear reactions. It is possible to validate nuclear data by investigating changes of each nuclide during irradiation.

Fig. 4-5 Comparisons of experimental and calculated values change of nuclides during irradiation for typical samples The results for primary nuclides and secondary nuclides produced by irradiation are presented. In the calculations, three nuclear libraries, ENDF/B-VI.8, JEFF-3.0 and JENDL-3.3, were used. Comparison results show large differences between experimental and calculated values for the secondary nuclides produced. The calculated values depend on nuclear libraries. These results especially demonstrate the need to improve the capture cross section of MAs.

JAERI has been developing technologies for partitioning and transmutation of long-lived nuclides in high-level radioactive waste. For a dedicated transmutation system, JAERI has conducted research and development on an accelerator-driven system (ADS). In the ADS design, the major fuel materials are minor actinide (MA) nitrides. Therefore, reliable MA nuclear data are required to achieve a sound design for the dedicated system. In this study, the radiochemical analysis results of the actinide samples irradiated at the Dounreay Prototype Fast Reactor (PFR) in the 1980s were used to validate the reliability of nuclear data. Chemical analysis was performed for 21 different isotopic samples (from Th to Cm). The chemical analysis results (Fig. 4-4) provide valuable data from systematic irradiation in the fast neutron spectrum. This validation of nuclear data was performed by comparisons of the chemical analysis results and calculation results. The burnup calculations performed with three evaluated nuclear data files, ENDF/B-VI.8, JEFF-3.0 and JENDL-3.3, were compared with the experimental data (Fig. 4-5). The results have good agreement for the main actinides, such as 235U and 239Pu. However, relatively large disagreements are present for the MAs. From these results, the future direction for improvement for MA nuclear data can be determined.

Reference K. Tsujimoto et al., Integral Validation of Minor Actinide Nuclear Data by Using Samples Irradiated at Dounreay Prototype Fast Reactor, AIP Conference Proceedings, #705, 523 (2005).

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