Nuclear Reaction Rates in EBR-II Irradiated Stainless Steel

Production rates (atoms/gram megawatt day) of ⁵⁸Co, ⁵⁴Mn, ⁵⁵Fe, ⁶³Ni, and ⁶⁰Co in the Experimental Breeder Reactor-II (EBR-II) irradiated stainless steel are reported. These rates can be used as precise flux and fluence monitors in fast reactors when appropriate spectrum-averaged cross sections are applied. Seven spectrum-averaged cross sections for the core and four spectrum-averaged cross sections at eight radial positions in EBR-II are also reported. The ratio of ⁵⁴Mn/⁵⁵Fe atoms produced from ⁵⁴Fe represents a sensitive spectral hardness indicator for fast-reactor spectra. This study also indicates that in EBR-II the flux per megawatt measured at high power is the same as that measured at low power by other authors. Results show that a diffusion theory calculation provides a reasonably accurate representation of the flux in the core of EBR-II but overestimates the flux in the blanket region.