Design and Analysis of Components of 700mwe PHWR Nuclear Steam Generator

Abstract

Steam generators are basically large size shell and tube type heat exchangers, used in steam generation for various applications such as power generation. In nuclear power plant, every pressurised heavy water reactor (PHWR) is connected with four nuclear steam generators. High pressure and high temperature steam generated by steam generator is used to run steam turbine. Steam turbine turns electric generator to produce electricity. Due to high pressure and temperature of working fluid and nuclear application, design of steam generator is done in very conservative way to ensure uninterrupted operation of nuclear equipment for specified life. Design of the steam generator is done considering various service conditions and test conditions safely. To ensure safe design of process nozzles of steam generator local load stress due to external pipe load are calculated. Data sheet is created for aid in converting load combination to have different load cases. Modelling of all process nozzles has been carried out in PV-Elite software. Local load analysis has been carried out in PV-Elite software in WRC (Welding Research Council) 107 and WRC 297. The work consists of design of support attachment of steam generator as per governed by ASME boiler and pressure vessel code, Sec III, Div. 1. An automated data sheet is created as per the procedure described in ASME. The Solid model is prepared using solid modelling software while the meshing and analysis for linearized stress is done using ANSYS. Local load analysis of process nozzles and design and analysis of support lug assembly has been carried out. Local stresses in all process nozzles are ensured to be less than allowable limits of WRC 107 and 297. Support lug dimensions and maximum deflections are calculated and found to be with in the allowable limits.