Tomsk-7 reprocessing explosion
A tank at the Siberian Chemical Combine exploded during reprocessing, contaminating about 120 square kilometres. It was the most significant Russian nuclear accident after Chernobyl.
| Date | 1993-04-06 |
|---|---|
| INES rating | 3 Serious incident |
| Facility | reprocessing |
| Country | Russia |
| Evacuated | No evacuation ordered |
| Deaths at the time | 0 |
|---|---|
| Acute radiation deaths | not established |
No deaths and no overexposure of personnel, which is why the IAEA rated it 3 rather than higher despite the size of the contaminated area.
A runaway chemical reaction in a tank of uranium and plutonium in nitric acid
What happened
Nitric acid was added to a tank containing uranium, plutonium and organic solvent residues without adequate mixing. Pressure rose until the tank ruptured, destroying part of the building and throwing radioactive material into the air.
Consequences
A contaminated plume extended over roughly 120 square kilometres of mostly forested land. No worker received an overexposure and nobody was evacuated permanently.
What changed afterwards
One of very few reprocessing accidents on the public record, at a plant that still operates as Russia's only conversion site and one of its four enrichment plants. The IAEA published a full account, which is unusual for a closed city.
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 |
| Davis-Besse vessel head corrosion | 3 | 2002-03-06 |
| Paks fuel cleaning accident | 3 | 2003-04-10 |
| Fukushima Daini | 3 | 2011-03-11 |
Sources
- International Atomic Energy Agency, The Radiological Accident in the Reprocessing Plant at Tomsk · 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