Method of Evaluating SMR Decay Heat Removal in a Floating Nuclear Power Plant During Vessel Flooding Scenarios

Abstract The paper presents a novel methodology for evaluating SMR decay heat removal solutions that will be deployed in Floating Nuclear Power Plants (FNPPs), specifically during vessel flooding scenarios, by leveraging data produced by both flooding and decay heat removal simulations in tandem. For Offshore Maritime Assets such as FNPPs or Nuclear-Powered Ships to become a viable solution, the design of both the Small Modular Reactor (SMR) and the ship/barge must be closely integrated and tailored to the marine conditions in which they will operate. After a reactor shutdown, residual heat generated from the decay of fission products must be dissipated to avoid excursions beyond the operating limits of SSCs. The operational conditions of Offshore Maritime Assets, offer both opportunities and challenges for decay heat removal, especially under emergency conditions such as vessel flooding resulting to loss of power, which are investigated using a combined methodology. The first step in the proposed approach is the development of a conceptual architecture for both the ship and the decay heat removal system. Using these architectures, a series of sinking simulations are conducted across a range of representative scenarios. The simulation results are then leveraged to inform dynamic decay heat removal modelling, starting from the moment of hull breach and factor ing in the loss of power and other elements associated with varying flooding conditions, as they occur. This methodology of combining simulation data can be used to inform the concept design of FNPPs or Nuclear Powered Ships and reactor cooling systems. This methodology allows for evaluating the impact of parameters such as the time from a hull breach until a static heel angle of 30 degrees is reached (as well as trim), the design of the cooling system, and its capacity to enable natural circulation for passive heat removal. This integrated methodology offers a framework for improving the design of future systems as early as the concept design stage. Passive decay heat removal systems that rely on natural circulation will be influenced by factors such as the angle of heel and the orientation of the heat source relative to the ultimate heat sink. Gaining insight into how this relationship evolves during the dynamic pro cess of flooding provides a novel contribution to FNPP development, enabling more effective design and operational strategies for ensuring safety in challenging marine environments.