Saint-Laurent A2 fuel melt
The most serious accident at a French power reactor: a blocked channel melted fuel inside a gas-cooled unit, with no release outside the site.
| Date | 1980-03-13 |
|---|---|
| INES rating | 4 Accident with local consequences |
| Facility | power reactor |
| Unit | Saint-Laurent nuclear power plant A-2 |
| Reactor type | Gas-cooled reactor (GCR) |
| Country | France |
| Deaths at the time | 0 |
|---|---|
| Acute radiation deaths | not established |
No deaths or injuries, and no release beyond the site.
Corrosion products blocked cooling to a fuel channel in the gas-cooled reactor, melting fuel in that channel.
What happened
Saint-Laurent A2 was a graphite-moderated, CO₂-cooled reactor of the French UNGG line. Debris from corroding structures blocked the coolant path to one fuel channel, and the fuel in it melted.
A similar event had already occurred at the neighbouring A1 unit in 1969, also rated INES 4.
Consequences
Contamination was confined to the reactor. The unit was off line for over two years.
France abandoned the UNGG line entirely in favour of licensed Westinghouse pressurised water designs — the decision that produced the standardised French fleet, and with it the highest nuclear share of electricity of any country.
What changed afterwards
The accidents are part of why France's fleet is so uniform. Standardising on one PWR family made the operating experience of every unit relevant to every other, which is a safety argument as much as an economic one.
Other accidents
| Accident | INES | Date |
|---|---|---|
| Chernobyl | 7 | 1986-04-26 |
| Fukushima Daiichi | 7 | 2011-03-11 |
| Kyshtym (Mayak) | 6 | 1957-09-29 |
| Windscale Pile 1 fire | 5 | 1957-10-10 |
| Three Mile Island Unit 2 | 5 | 1979-03-28 |
| SL-1 | 4 | 1961-01-03 |
| Tokaimura criticality accident | 4 | 1999-09-30 |
| Vandellòs I turbine fire | 3 | 1989-10-19 |
| Davis-Besse vessel head corrosion | 3 | 2002-03-06 |
Sources
- IAEA INES documentation · retrieved 2026-09-07