Alfa class
Fuel enrichment
90% U-235
HEU
Alfa class is a nuclear-powered submarine operated by Soviet Navy, powered by BM-40A / OK-550 of about 155 MWt. Retired.
Lead-bismuth cooled, titanium hulled, and the fastest submarines ever built. The coolant froze solid if the reactor was allowed to cool, so the boats had to be kept hot continuously in port. An unsuccessful design, and the only serious attempt at a liquid-metal-cooled naval reactor.
Propulsion
| Reactor | BM-40A / OK-550 |
|---|---|
| Reactors per vessel | 1 |
| Thermal output | 155MWt |
| Fuel enrichment | 90% U-235HEU |
| Refuelling | not disclosed |
Vessel
| Category | submarine |
|---|---|
| Role | SSN |
| Operator | Soviet Navy |
| Country | Russia |
| Vessels in class | not stated |
| In service from | 1971 |
| Status | Retired |
Other submarines
| Class | Enrichment | Status |
|---|---|---|
| AUKUS submarines | HEU | Planned |
| Arihant class | HEU | Operating |
| Astute class | HEU | Operating |
| Borei class | HALEU | Operating |
| Dreadnought class | HEU | Under construction |
| Ohio class | HEU | Operating |
| Suffren class (Barracuda) | LEU | Operating |
| Type 093 and 094 (Shang and Jin) | LEU | Operating |
| USS Nautilus | HEU | Retired |
| Virginia class | HEU | Operating |
| Yasen class | HALEU | Operating |
Sources
- World Nuclear Association, Nuclear-Powered Ships · retrieved 2026-09-07