What condition is referred to as thermal runaway?

Thermal runaway is a phenomenon that occurs when heat generation within a material or system exceeds the heat that can be lost to the environment. This imbalance leads to a continuous increase in temperature, which can ultimately result in uncontrolled reactions, degradation of materials, or even combustion. This concept is particularly relevant in situations involving batteries, chemical reactions, or other processes where exothermic reactions may occur.

In the context of fire investigation, understanding thermal runaway is crucial because it can predict the behavior of materials under certain conditions. If investigators identify a situation where heat is accumulating without a mechanism for dissipation, they can recognize the potential for fire or explosion and take appropriate action or record it in their analysis.

The other options describe different aspects of fire dynamics but do not capture the specific principle of thermal runaway. For instance, failure of fire extinguishing agents relates to fire suppression capabilities rather than the thermal properties of materials. Uncontrolled fire spread refers to the dynamics of fire movement, while a lack of flammable properties pertains to materials that cannot sustain combustion, none of which directly define the condition of thermal runaway.