Nuclear reactor reactivity is a nonlinear term in the point-kinetics model.[^1] Nuclear Reactivity is measured in dollars and cents. [^2] The simplified reactivity model is[^6]
$$\rho(t)+\alpha_F(T_F(t)-T_{F,0})+\alpha_M(T_M(t)-T_{M,0})-\beta_{mix}(t)$$
Where \(\rho\) is the reactivity, \(T_F\) is the fuel temperature, \(T_M\) is the moderator temperature, \(\beta_{mix}\) is the effective delayed neutron fraction, \(\alpha_F\) is the fuel temperature feedback coefficient, and \(\alpha_m\) is the moderator temperature feedback coefficient.[^2] Reactivity is the fractional change in the multiplication factor of the system.[^2] Another form of these equations are[^3]
$$\Delta\rho(t)=\beta\Delta\rho_{ext}+\alpha_F\Delta T_F+\alpha_C\Big(\frac{\Delta T_{\theta 1}+\Delta T_{\theta 2}}{2}\Big)$$[^3]
Where \(\Delta\rho\) is the change in reactivity, \(\Delta\rho_{ext}\) is the reactivity change due to control rods, \(\Delta T_F\) is the fuel temperature deviation, \(\alpha_F\) is the fuel coefficient of reactivity, \(\alpha_C\) is the coolant coefficient of reactivity, and \(\Delta T_\theta\) is the temperature deviation in coolant nodes 1 and 2.[^3]
[[Neutron Poison]] – neutron poisons affect the reactivity
[[Point Kinetics Reactivity]]
[[Sodium-Cooled Fast Reactors]] – can bloom which changes the reactivity
[[TRIGA Mk 2 Reactivity]] – reactivity model
[[Fuel Temperature Coefficient]] – shows how the reactivity changes with fuel temperature
Submarine Reactors]] – have a higher initial reactivity
[[Ramp Reactivity Insertions]]
[[Coolant Average Temperature Mode]] – output of controller is a change in reactivity
- NumericalSolutionPoint2020[^1]
- nuclearengineeringlecturesNE560LectureIntro2020[^2]
- chenComprehensiveRealTimeHardwareIntheLoop2020[^3]