US prototype supports microreactor development

Tuesday, 8 February 2022

Microreactors are very small, factory fabricated, transportable reactors which could provide power and heat for decentralised generation in civilian, industrial and defence energy sectors.

The DOE last year announced its plans to build MARVEL - a sodium-potassium cooled microreactor that will generate 100 kW of power - to help researchers and end-users understand how microreactors can integrate with other technologies. DOE plans connected the reactor to the world's first nuclear microgrid at INL by 2024.

Simulation software is a key component for predicting reactor performance, but on its own is not sufficient to confirm that the reactor will perform as expected.

"We use modelling tools to help regulators have confidence in the reactor design, but we can't model all aspects of the flow and heat dynamics," said Yasir Arafat, MARVEL technical and project lead.

"A demonstration is necessary for us to be certain that the final reactor will perform to a high degree of reliability and confidence level."

The prototype - known as the primary coolant apparatus test (PCAT) - will be used to confirm simulation results, allowing the MARVEL team then to use modelling and simulation tools to verify and support the reactor's safety case.

The PCAT was built by INL machinists in just nine months. Comprising several stainless-steel components, including four Stirling engines that will generate electricity through primary and intermediate coolant pumps, and weighing in excess of 2000 pounds (over 900 kg), it is one of the largest components ever built at the laboratory's Materials and Fuels Complex fabrication shop and has been built to the same standards as a deployed reactor vessel.

MARVEL will be used to test microreactor applications, develop regulatory approval processes, evaluate systems for remote monitoring, and develop autonomous control technologies. It will also be used to explore and test the capabilities of such microreactors capabilities for a wide variety of electrical applications and non-electrical applications such as water purification and low-grade heat production for district heating.

The MARVEL project is funded through the DOE Microreactor Program.