TU Electric’s Experiences with the Development and NRC Approval of a Reload Safety Analysis Methodology

Abstract

TU Electric has developed and obtained U.S. Nuclear Regulatory Commission (NRC) approval of the methodologies required to support core reload safety analyses. The Electric Power Research Institute-sponsored computer codes RETRAN-02 and VIPRE-01 are used in the non-loss-of-coolant-accident thermal-hydraulic analyses. These methods were employed to support the loading of the core of the Comanche Peak Steam Electric Station, Unit 1 (CPSES-1), Cycle 5.An overview of the reload safety analysis development effort is provided, with the focus on the qualification of the system transient analysis methodologies. Interactions with the NRC are described. Included is a discussion of the types of questions asked by the NRC and the corresponding TU Electric responses. Comparisons of calculated results to actual plant data which demonstrate the validity of the CPSES plant model, are provided. The importance of performing “good” benchmark comparisons is addressed as it relates to the demonstration of technical competence in the use and interpretation of RETRAN.The effectiveness of the approach used by TU Electric to obtain NRC approval of the reload safety analysis methodology is examined in retrospect. Finally, an assessment is made of the benefits, tangible and intangible, derived from having an in-house reload safety analysis capability.