Oxidizer

In a rocket engine, fuel and a source of oxygen, called an oxidizer, are mixed and exploded in a combustion chamber. The combustion produces hot exhaust which is passed through a nozzle to accelerate the flow and produce thrust.

In a liquid rocket, the propellants, the fuel and the oxidizer, are stored separately as liquids and are pumped into the combustion chamber of the nozzle where burning occurs.

Chemical propulsion uses a fuel and an oxidizer, converting energy stored in the chemical bonds of the propellants, to produce a short, powerful thrust.

Chemical propulsion uses a fuel and an oxidizer, converting energy stored in the chemical bonds of the propellants, to produce a short, powerful thrust, or what we see as fire.

Both chemicals are solid oxidizers in granular form and have a chlorine odor. […] Plant 12 also stored super sacks of bromochloro-5,5-dimethylimidazolidine-2,4-dione (BCDMH), which is a granular solid oxidizer with a halogen odor that, in addition to chlorine gas and hydrogen chloride, can also release bromine gas and hydrogen bromide upon decomposition.

BioLab officials told the investigators they had established a permanent fire watch two or three months prior to the incident after strong odors from oxidizers in two storage buildings were detected, according to the CSB report. BioLab also told CSB two employees were on duty for fire watch on September 29.