Development of an Advanced Freeze Valve System for Molten Salt Reactor

Abstract

Molten Salt Reactors (MSR) offer distinct advantages, including low system pressure, small-sized core, and minimal nuclear proliferation risk. Yet, MSRs are facing challenges such as high system temperature and the corrosiveness of the coolant material. These harsh conditions render conventional mechanical valves inadequate for MSR flow control. To overcome this problem, Oak Ridge National Laboratory (ORNL) has designed a specialized freeze valve system to address coolant transport within their MSRE (Molten-Salt Reactor Experiment) projects and proven in operation for over 20,000 hours. Despite its success, issues like slow response time for opening and closing, limited experiences for small diameter pipes only, and leakage detected at the end of the project due to improper field reform calls for further enhancements. Leveraging the lessons learned from the MSRE project, our current initiative is to explore the development of an advanced freeze valve system suitable for a new 100 MWth-class MSR. This system is envisioned to support carbon-free marine power systems, including ship propulsion and offshore floating power plants. This work is preparatory; we are going to present study of the MSRE freeze valve in deep, basic concepts and the preliminary proof of concept efforts to mitigate previous limitations, aiming to deliver a prototype that excels in response time, leak prevention, flow rate, and ultimately aiming to enhance MSR safety and efficiency.