SPG-MSR – Research facility of a reliable and Sustainable Power Generating cycle components for Nuclear Molten Salt Reactors

Molten salt reactors (MSRs) are among the most promising Generation IV designs thanks to their inherent safety features, high thermal efficiency, and potential for load-following operation. The high temperatures achieved in the reactor core make it possible to integrate these reactors with advanced power cycles such as Brayton cycles. Heat exchangers play a critical role in this process and represent an important area of research. Furthermore, integrating thermal storage with MSRs could enable the plant to perform load-following operations without varying the reactor power. This is of particular interest in the context of increasing renewable energy penetration. This project will assess the feasibility of new experimental research infrastructure to advance the technology readiness level (TRL) of key integration components up to TRL 4 – 5.

Background

As efforts to build a fully decarbonized energy system continue, nuclear power is increasingly emerging as a cornerstone of clean electricity generation. In 2024, 40% of electricity was generated from nuclear power (8%) and renewables (32%). By the end of the year, 75 GW of nuclear power was under construction, and an acceleration in annual capacity addition have been foreseen in all International Energy Agency (IEA) future energy scenarios. In this context, Generation IV reactors, such as MSRs, have the potential to offer significant advantages over traditional designs in terms of sustainability, economics, reliability, safety and proliferation resistance. Their high operating temperatures (above 600 °C) make MSRs well-suited to integration with advanced power conversion cycles and thermal energy storage. However, further research is required into power conversion systems and heat transfer interfaces that can operate under extremely high temperatures, with non-conventional fluids and in corrosive salt environments, as well as under high-pressure differentials in both stationary and dynamic operating conditions.

Aim and Objectives

The advancement of MSR power cycle technology is currently hampered by a critical infrastructure gap. This project aims to evaluate the feasibility of creating a new experimental research infrastructure that can test the operation of critical power cycle components for MSR nuclear applications. The test loop will be able to operate molten salt mixtures at temperatures above 600 °C and working fluids such as supercritical carbon dioxide (sCO₂) at pressures of up to 20–30 MPa, with real-time monitoring of the thermal-hydraulic performance and long-duration testing of material compatibility and corrosion. To achieve these objectives, the project will:

Conduct a detailed analysis of the technical requirements for a high-temperature molten salt test loop operating at 600–850 °C. This will include selecting materials, designing safety systems and instrumentation, and integrating gas working fluid loops at pressures of up to 30 MPa.
Perform preliminary design studies for at least two scalable heat exchanger concepts for molten salt-CO₂/Ar applications.
Assess the technical challenges and instrumentation requirements for validating integrated control strategies between nuclear heat sources and thermal energy storage.
Develop conceptual designs and cost estimates for the core components of the research infrastructure.
Map existing complementary research infrastructure in Sweden and internationally to identify partnership opportunities and knowledge gaps.