Parametric Study of the Effect of Control Rods for PWR Burnup Credit

摘要

The Interim Staff Guidance on burnup credit for pressurized water reactor (PWR) spent nuclear fuel (SNF), issued by the United States Nuclear Regulatory Commission's Spent Fuel Project Office, recommends the use of analyses that provide an 'adequate representation of the physics' and notes particular concern with the 'need to consider the more reactive actinide compositions of fuels burned with fixed absorbers or with control rods fully or partly inserted.' In the absence of readily available information on the extent of control rod (CR) usage in U.S. PWRs and the subsequent reactivity effect of CR exposure on discharged SNF, NRC staff has indicated a need for greater understanding in these areas. In response, this report presents a parametric study of the effect of CR exposure on the reactivity of discharged SNF for various CR designs, including Axial Power Shaping Rods, fuel enrichments, and exposure conditions (i.e., burnup and axial insertion).