Reactor type 7 of 10
Lead-cooled fast reactor
by Joe Miller
Lead-cooled fast reactors use melted lead (or lead-bismuth) as the coolant. Lead does not burn or react with water, boils at about 1,750°C and shields radiation itself, so steam generators can sit right in the reactor pool.
Plain-English explainer by Joe Miller, a nuclear engineer. Not investment advice. Figures are the latest public numbers we could find and change fast; sources are at the bottom of each page.
What it looks like
How the coolant circulates
- Pumps move lead up through the core (about 480 to 540°C out).
- Hot lead flows directly through steam generators inside the pool.
- Water in the steam generator tubes becomes steam for the turbine.
- Cooled lead sinks back to the pumps.
The main components
| Component | What it does |
|---|---|
| Reactor pool | A tank of molten lead at near-atmospheric pressure holding everything. |
| Core | Nitride or oxide fuel in a fast-neutron spectrum. |
| Main pumps | Move the very heavy lead slowly; many designs rely partly on natural circulation. |
| Steam generators in the pool | No intermediate loop is needed because lead does not react with water. |
| Heaters | Lead freezes at 327°C, so the system is kept hot even when shut down. |
Key details
| Item | Detail |
|---|---|
| Coolant | Molten lead or lead-bismuth |
| Moderator | None (fast spectrum) |
| Fuel | Nitride or oxide, enriched |
| Pressure | Near atmospheric |
| Temperature | About 480 to 540°C |
| Efficiency | About 40 to 43% |
| Refueling | Long cycles; some designs sealed for years |
How it is maintained
- Corrosion and erosion control: lead attacks steel, so oxygen in the lead is carefully controlled.
- Keeping lead liquid during outages with heaters.
- Very heavy structures: the lead weighs thousands of tons, so seismic design and supports matter.
- Steam generator tube inspection since tubes sit in the lead.
Where it runs
Russia's BREST-OD-300 under construction at Seversk; Soviet Alfa-class submarines used lead-bismuth reactors; Westinghouse and Newcleo are developing lead-cooled designs.
Who's writing this? I'm Joe Miller, a nuclear engineer since 1974 and an ASME Fellow. I've run safety analyses for PWRs and BWRs, directed nuclear engineering at a working BWR, and reviewed new reactor designs for the NRC. This site explains every kind of reactor in plain English. My background and papers.