Temperature coefficient of reactivity (${\alpha }_T=\partial \rho /\partial T$)

The change of reactor reactivity with a specified material temperature, with the other variables held as stated. Several component coefficients need not have the same sign.

The change of reactor reactivity with thermal power along a specified family of states. In a quasistatic process, the chain rule weights each temperature coefficient of reactivity by that component's temperature response to power.