Given today’s nuclear industry business climate, it has become very popular and financially advantageous for Utility companies to consider increasing unit capacities. An integral part of the studies conducted by many towards this end, involve the generation of a set of turbine cycle heat balances with predicted performance parameters for the uprated condition. Once these tentative operating values are established, it becomes necessary to evaluate the suitability of the existing components within each system to ensure they are capable of continued safe and reliable operation. The ultimate cost for the uprate, including the cost for any major required modifications or significant replacements is weighed against increased revenue generated from the uprate over time.
Exelon’s Peach Bottom Atomic Power Station (PBAPS) is currently planning for an Extended Power Uprate (EPU) for both units. To ensure the existing Feedwater Heaters (FWH) could maintain the operating and transient response margins at the EPU condition, an engineering study was conducted. Powerfect Inc. in conjunction with SPX Heat Transfer Inc. were contracted to provide engineering services to analyze the design, thermal performance, reliability and operating conditions at projected EPU conditions.
The goal of the study was to identify the most susceptible areas within the heaters for problems and potential failures when operating at the higher duty of the EPU condition for the remaining life of the Unit. Various calculation methods were employed to evaluate critical parameters and quantify the effect of the EPU operating condition on each individual FWH. The results were based on each heater’s current condition and comparison of calculated values of several parameters against industry standards (i.e. HEI, TEMA, EPRI) in order to determine the acceptability for continued operation of the Station’s existing 30 FWHs. Recommendations for additional monitoring, heater modification, or heater replacement were provided based on the margin by which each heater approached or exceeded the established limits. This paper shall describe the approach taken to evaluate the above parameters for each FWH at the estimated EPU conditions.