Table of Contents

Gas-cooled fast reactor (GFR)

What's so interesting about them?

Gas-cooled fast reactors (GFRs) use the fast neutron spectrum and helium for cooling at high temperatures, serving purposes like power generation and hydrogen production. Overcoming challenges in fuel performance is a key focus. GFRs employ a multi-step process for electricity generation, utilising helium in various circuits.

Fuel

Fuel

These reactors are fast reactors meaning that they can use common fuels such as Uranium and others such as Thorium, which when it absorbs fast neutrons decays into Uranium-233.

Moderator

Moderator

As SFRs are fast reactors they don't require neutron moderation.

Coolant

Coolant

GFRs use a variety of gases however the most common are Helium at super critical temperatures, Carbon Dioxide and steam.

Typical technical data:

Neutron Spectrum Outlet Temperature (Degrees Celsius) Fuel Cycle Net Electrical Energy Generation seen in Development (MW)
Fast
850
Closed
1,200

What is happening with them today?

The concept dates back to the 1970s, with General Atomics leading design efforts. Despite no GFRs being built, a 75 MWth experimental GFR, Allegro, is in development by Euratom.

An alternative GFR design by General Atomics uses lower-temperature helium and supercritical CO2 for power generation, addressing challenges associated with extremely high temperatures. Collaborations with partners introduce innovative reactor designs like the Energy Multiplier Module (EM2) and the 50 MWe Fast Modular Reactor (FMR).

Research priorities focus on improving fuels, materials, and thermal hydraulics to advance GFR development, contributing to more efficient and sustainable nuclear energy technologies.

Matt Moore

World Nuclear Association – Generation IV Nuclear Reactors
The Generation IV International Forum – Gas-Cooled Fast Reactor (GFR)
The Generation IV International Forum – Technology Systems