Paks fuel cleaning accident
Thirty fuel assemblies were severely damaged in a chemical cleaning tank in the spent fuel pond at Paks. Nothing went wrong with the reactor at all.
| Date | 2003-04-10 |
|---|---|
| INES rating | 3 Serious incident |
| Facility | power reactor |
| Unit | Paks nuclear power plant 2 |
| Reactor type | Pressurised water reactor (PWR) |
| Country | Hungary |
| Deaths at the time | 0 |
|---|---|
| Acute radiation deaths | not established |
No deaths or injuries. The damage was to fuel, in a tank, outside the reactor.
Inadequate cooling in a contractor-supplied cleaning tank
What happened
Assemblies were being cleaned of crud in a tank supplied by an outside contractor. The tank's cooling was insufficient for the heat the assemblies were still producing. Thirty assemblies overheated, and when the tank was opened the cladding failed and fission products were released into the pond.
Consequences
Off-site release was negligible. Recovering the damaged fuel took years and specialised equipment. Unit 2 was out of service for over a year.
What changed afterwards
The clearest example on this site of decay heat causing an accident with the reactor shut down and the fuel outside it, and of a contracted operation falling outside the safety analysis that covered the plant. Hungary's regulator rated it 3, the highest rating any event has received in the country.
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 |
| Saint-Laurent A2 fuel melt | 4 | 1980-03-13 |
| 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 |
| Fukushima Daini | 3 | 2011-03-11 |
Sources
- International Atomic Energy Agency INIS, Lessons learned from the INES-3 event at Paks NPP · 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