ANALYSIS OF AHWR DOWNCOMER PIPING SUPPORTED ON ELASTO-PLASTIC DAMPERS AND SUBJECTED TO NORMAL AND EARTHQUAKE LOADS

摘要

Three layouts have been considered for AHWR downcomer for codal qualification in order to ensure its structural integrity under normal and occasional, loads. In addition to codal qualification a good piping layout should have less number of bends and weld joints in order to reduce the in-service inspection cost. Less number of bends will reduce the pressure drop in natural circulation and lesser number of weld joints will reduce the total time of in-service inspection that finally reduces the radiation dose to the workers. Conventional seismic design approach of piping with snubbers leads to high cost, maintenance and possible locking causing undue higher thermal stress during normal operation. New seismic supports in the form of Elasto-Plastic Damper (EPD) are the best suited for nuclear piping because of their simple design, low cost, passive nature and ease in installation. In this report the characteristics of EPD obtained from theory, finite element analysis and tests have been presented and comparison has also been made among the three. Analysis method and code qualification of AHWR downcomer piping considering the loadings due to norrnal operating and occasional loads such as earthquake have been discussed in detail. This report also explains the concept of single support and multi-support response spectrum analysis methods. The results obtained by using both types of supports i.e. conventional and EPD supports have been compared and use of EPD supports in AHWR downcomer pipe is recommended.