Analyses were performed by Kalsi Engineering, Inc. (KEI) on the main steam isolation valves (MSIV) and main steam check valves (MSCV) at 4 pressurized water reactors to evaluate their capability to perform design basis functions at Extended Power Uprate (EPU) conditions. Disc closing velocities and actuator pressures (for MSIV) were calculated by using RELAP™. These inputs included valve specific flow and torque coefficients obtained by detailed Computational Fluid Dynamics (CFD) analyses to accurately predict hydrodynamic torque imposed on the disc throughout the stroke. Stresses, strains and displacements in all of the critical MSCV and MSIV components were determined by performing appropriate 2-D and 3-D elasto-plastic, transient dynamic finite element analysis (FEA). Fatigue life of the components under spurious closure was determined in accordance with applicable ASME Section III Code. The evaluation also included the propensity for excessive wear of the MSCV due to disc flutter, vibration and erosion.

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