TNR

The temperature of no return (TNR) is the temperature at which, for a defined available cooling rate, thermal equilibrium cannot be reached and a runaway reaction becomes inevitable. Any temperature above TNR results in runaway reactions.

Reference: adapted from Townsend, D. I. (1981). Accelerating rate calorimetry. In I. Chem. E. Symposium Series (No. 68, p. 3).