b'Figure 1. Control rod worths as a function of fuel burnup.The standard Silver-Indium-Cadmiumworths as a function of fuel burnup (AIC) control rod (24-rodlets) wasare shown in Figure 1 based on replaced by selected improvedbranch calculation of rod-out/control rods utilizing materials withrod-in, i.e., the control rod material higher temperature capabilities andremained at its initial composition. comparable or better absorptionThese results suggest that the number properties.The reference AIC rod plusof control rods needed to satisfy its steel cladding was replaced withcontrol/shutdown requirements can solid rods of hafnium (Hf), iridiumbe reduced, but may have a negative (Ir) and rhenium (Re).In addition, aimpact on ejected and stuck-rod gadolinium-oxide (Gd2O3) absorberworths/impacts.A possible approach with a Zircaloy cladding (samefor retrofit would be to reduce the dimensions as the AIC rod) wasnumber of fingers in the standard evaluated.The control rod worths atcontrol rod design from 24 to a beginning-of-life (BOL) from TRITONnumber that can match the worth of were compared to results from MCNPAIC rods.with good agreement.Control rod 2019|AFC ACCOMPLISHMENTS 151'