Study on the super-critical $CO_2$ cycle as the power conversion system for the marine pressurized water reactor

Abstract

Recently, nuclear-powered ships have attracted attention due to strengthening of international regulations on greenhouse gas emissions while ships are becoming larger and faster. In order for a nuclear system to be used in marine propulsion, it is important to achieve small in size and should be able to respond to rapid load demand changes. In this thesis, a super-critical carbon dioxide (S-$CO_2$) cycle is proposed as a power conversion system for pressurized water reactors (PWR) for marine propulsion. The conceptual design of the S-$CO_2$ power conversion system is first performed under the reference reactor conditions, including cycle design and component design. To conduct system analysis, MARS-KS code, one of the nuclear thermal-hydraulic safety analysis codes developed by Korea Atomic Energy Research Institute (KAERI), is improved to accurately simulate the S-$CO_2$ power conversion system combined with PWR. The PID controller based automatic control strategy is designed to respond to rapid load changes. To investigate applicability of the proposed system to nuclear propulsion system, transient analyses is performed under actual load change requirements of the nuclear merchant ships.