Thermo-structural analysis of a dump nozzle for conducting hot liquid sodium

Abstract

Liquid sodium is found to be an essential element in nuclear reactors for transferring enormous amount of heat between source and sink. Conducting hot liquid sodium through metal pipes is witnessed to be challenging owing to the huge thermomechanical stress involved during the process. The present research work aims at designing a dump nozzle for the safe transfer of hot liquid sodium (at 923 K) to a storage tank through SS316LN pipe. Numerically simulated results showed the development of huge thermal stress at the weld junction formed between pipes and storage tank, which is primarily due to the sudden increase in temperature. The newly proposed dump nozzle with reducer/baffle (connecting pipe with storage tank) is witnessed in reducing the sudden increase in temperature and henceforth, minimized the stress intensity of the weldment by 70 %. The fatigue-creep interaction diagrams are plotted for the weld and the reducer; the results showed that the induced stress values for the parts are well below the safety envelops for the given boundary conditions of liquid sodium flow velocity and temperature. The proposed dump nozzle design is hence validated for the safe handling of transferring liquid sodium to storage tank.