New-Build HELOKA-US Platform for Balance of Power of DEMO Power Plant

HELOKA-US (HELOKA-Upgrade Storage) is a new-build experimental facility designed to provide a test platform for investigating the behaviour of complex heat transfer loops under conditions representative of the DEMO Helium-Cooled Pebble Bed (HCPB) concept.

In this setup, an indirect coupling design is used, where a molten salt loop serves as an intermediate heat transfer system. Its purpose is to act as a thermal buffer between the pulsating power output of the DEMO fusion reactor and the requirements of continuous power generation.

The R&D program focuses on:

• Experimental validation of key components, such as a helium-to-molten salt heat exchanger, and

• Qualification of thermohydraulic (T/H) simulation tools under realistic DEMO operating scenarios.

A two-tank molten salt loop using HITEC-Composition (a mixture of KNO₃ 53 wt.%, NaNO₂ 40 wt.%, NaNO₃ 7 wt.% ) is implemented, designed for a thermal power of 260 kW.

• In Phase 1, the system is powered by an electrical heater.

• In Phase 2, the heat source will be helium gas provided by the existing HELOKA infrastructure.

• The heat sink of the system is a pressurized water loop.

This facility will provide crucial experimental data and system insights that support the development of molten salt-based thermal storage for both fusion energy systems and high-temperature industrial applications.