What defines a thermal runaway condition?

A thermal runaway condition occurs when the heat generated by a chemical reaction exceeds the heat that can be lost to the environment. In this scenario, the system reaches a point where the increasing temperature accelerates the reaction, producing even more heat. This cycle can continue uncontrollably, potentially leading to explosive reactions or severe fires.

In the context of fire investigation, understanding thermal runaway is crucial for assessing fire hazards, particularly with substances that can undergo exothermic reactions. It emphasizes the importance of managing heat in chemical processes to prevent dangerous situations. Recognizing that the heat generated surpasses what can escape is a key factor in identifying potential risks in both industrial and laboratory environments where volatile substances are present.

The other options do not accurately capture the essence of thermal runaway. Rapid cooling of materials does not relate to the accumulation of heat and can actually help prevent runaway conditions. Heat loss equating to heat generation describes a balanced system, which is not the scenario in a thermal runaway. Complete combustion pertains more to the energy release during a reaction rather than the conditions leading to uncontrolled reactions.