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
Retrospective. INES was introduced in 1990, so this rating is an attribution made
afterwards rather than an assessment a regulator issued at the time.
|
| 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 |
| Chalk River NRX | 5 | 1952-12-12 |
| Windscale Pile 1 fire | 5 | 1957-10-10 |
| Three Mile Island Unit 2 | 5 | 1979-03-28 |
| SL-1 | 4 | 1961-01-03 |
| Lucens | 4 | 1969-01-21 |
| Saint-Laurent A1 fuel melt | 4 | 1969-10-17 |
| Bohunice A1 refuelling accident | 4 | 1977-02-22 |
| Tokaimura criticality accident | 4 | 1999-09-30 |
| Browns Ferry cable fire | 3 | 1975-03-22 |
| Greifswald cable fire | 3 | 1975-12-07 |
| Vandellòs I turbine fire | 3 | 1989-10-19 |
| Tomsk-7 reprocessing explosion | 3 | 1993-04-06 |
| Davis-Besse vessel head corrosion | 3 | 2002-03-06 |
| Paks fuel cleaning accident | 3 | 2003-04-10 |
| Fukushima Daini | 3 | 2011-03-11 |
Sources
- IAEA INES documentation · retrieved 2026-09-07
How these sources are used, including the corrections applied on top of them and what is deliberately left blank · download the underlying data