Two people died at a caramel coloring plant in Louisville, and most of the coverage summed it up in a line: a reactor exploded. That is true, and it is also the least useful thing you can say about it. So here is the longer version, because the longer version is the only one that helps you.
What Happened
On November 12, 2024, Reactor 6 at the Givaudan Sense Colour plant ruptured. It was a 2,500 gallon batch reactor, and it was making caramel color. Two workers were killed and three more were hurt badly enough to need a hospital. By the time the damage was tallied, across the plant and the homes around it, it came to about 40 million dollars.
The shell of the reactor, roughly 2,000 pounds of steel, landed around 245 feet away in a residential neighborhood. Debris went out as far as 400 feet. The county put a one mile shelter in place order around the site. None of this stayed behind the fence.
When the CSB published its final report in May 2026, the cause came back to a runaway decomposition reaction. What ran away was the sugar.
The Easy Story
You could close this one out fast if you wanted to. Benign ingredient, freak event, nobody could have seen it coming. That version is comfortable, and it is also wrong, and the report is pretty direct about why.
What Actually Set It Up
The CSB found that Givaudan did not recognize the sugar could run away, and did not really understand the reactive hazards sitting inside its own process. That is the finding I keep coming back to. The people who owned the process did not know the hazard was there.
The testing afterward made it look worse. When investigators ran reactivity tests, both the caramel color mixture and the sugar by itself could run away within the reactor's normal range for temperature and pressure. Not in some far off upset you would never reach in practice. Inside the window the unit ran in every day.
And the relief system, the thing that is supposed to save you when everything else has gone wrong, was built for a different problem. Pressure reached 237 psig before the vessel let go, against a maximum allowable working pressure of 75. The CSB estimated the relief would have needed to be something like four times larger to pass what the decomposition actually produced. So this was not a sizing job that came up a little short. It was guarding against an event that was never going to be the one that happened.
The Gap
This matters to you even if you have never made a pound of caramel color. Reactive chemistry does not give you a warning. The material was food grade. It was sugar. And because it looked harmless, it never got reactivity testing, never got a worst case relief sizing, never got the attention anybody automatically gives a chemical they are afraid of.
Most plants have a version of this somewhere. Some material, some step, some holding temperature nobody thinks twice about because it has run for years without trouble. Givaudan's reactor had run for years too.
I want to be careful with the word operator here, because it does not really apply. No operator action and no amount of operator caution changes the outcome once the reaction is possible in the normal window and the relief cannot keep up. Whatever went wrong was decided long before anyone was standing at a panel that morning. That is the kind of cause this newsletter goes after.
Monday Morning Checklist
Take your list of materials marked low hazard or non reactive and pull a few. For each, find out whether anyone has actually tested it for reactivity at your real operating and upset conditions, or whether that label is just an assumption everyone inherited.
For any vessel where a runaway is even plausible, ask what scenario the relief was sized for, and whether a decomposition or runaway case was ever in that math.
Look at where your process safety effort actually goes. If it follows the chemicals that sound dangerous instead of the ones that are, you have the same blind spot Givaudan had.
You do not need a reactor for any of this. You need one material everybody quit thinking about.
Before Human Error is a teardown of industrial incidents for EHS and operations leaders. Every issue is built from public investigation findings. If this was useful, forward it to one person who would get something out of it.
Source: U.S. Chemical Safety and Hazard Investigation Board, final investigation report on the Givaudan Sense Colour explosion, released May 27, 2026.