The US Argonne National Laboratory (ANL) said on 10 May that it had added new capabilities to support testing of liquid metal fast reactors. The Thermal Hydraulic Experimental Test Article (THETA) will provide high-resolution and high-quality data that can be used to develop computer codes to support the licensing of liquid-metal fast reactor designs. THETA is currently running its first test with Oklo company, which seeks to better understand the behaviour of its fast reactor designs.
THETA is a 450-liter pool-type sodium vessel installed inside ANL’s Mechanisms Engineering Test Loop (METL) facility. THETA consists of a primary system, submerged in a liquid sodium pool, and a secondary system, located outside of the pool, that contains all the major components of a sodium-cooled fast reactor. It is equipped with fibre-optic temperature sensors that provide thousands of temperature measurement points across a specific flow field. The instrumentation allows tests to be performed in real-time with immediate feedback.
THETA “provides validation data for sodium nuclear reactor system codes as well as a test bed for liquid sodium components and sensors”, said Matthew Weathered, Principal METL Experimental Operations Engineer.
Oklo is the first developer to utilise THETA thanks to a voucher through the US Department of Energy’s Gateway for Accelerated Innovation in Nuclear (GAIN) initiative. The GAIN Voucher aims to address the gap in high-quality experimental data related to fluid flow behaviour and validation activities for liquid-metal reactors.
"THETA represents a unique opportunity where experimental and computational researchers can collaborate closely on requirements and design of experiments with a strong focus on the industry needs for advanced reactor licensing,” said Lander Ibarra, Principal Nuclear Engineer at ANL.
The test performed by the Argonne and Oklo team will simulate various conditions, including unprotected loss of flow in a liquid-metal fast reactor. The data will provide validation for systems-level and high-fidelity analysis tools related to flow rate and natural circulation. “Oklo, through the GAIN voucher, can submit direct feedback on the validation data and mitigate the risk reactor developers encounter when working with legacy measurements," Ibarra said.
This is expected to enhance the experimental and validation database for liquid-metal fast reactors as well as set a standard validation process for system-level codes. The reduced uncertainties associated with fluid flow behaviour will improve economic competitiveness of US advanced reactor designs and support licensing activities. Testing is expected to be complete by the end of 2022.