Browns Ferry cable fire
A worker checking for air leaks with a lit candle set fire to the cable trays, burning out the controls for both operating units and leaving the plant without most of its safety systems for seven hours.
| Date | 1975-03-22 |
|---|---|
| INES rating | 3 Serious incident
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 | Browns Ferry nuclear power plant 1 |
| Reactor type | Boiling water reactor (BWR) |
| Country | United States |
| Deaths at the time | 0 |
|---|---|
| Acute radiation deaths | not established |
No deaths, no injuries and no radiological release.
A candle used to test for air leaks ignited cable insulation
What happened
The candle flame was drawn into a cable penetration and ignited polyurethane foam sealant. The fire spread along cable trays carrying control and power wiring for Units 1 and 2, disabling emergency core cooling on Unit 1. Operators kept the core covered using systems the designers had never intended for the purpose.
Consequences
Nothing was released and nobody was hurt. Both units were out of service for over a year.
What changed afterwards
The single most consequential fire in nuclear history and the origin of nuclear fire protection regulation. It produced the American fire rules that still govern the industry, and made physical separation of redundant safety trains a design requirement rather than good practice. The vulnerability was not the reactor; it was that redundant cables ran in the same tray.
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 |
| 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
- US Nuclear Regulatory Commission, The Browns Ferry Nuclear Plant Fire of 1975 · 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