HT2004: Reactor PhysicsReactor Kinetics1 REACTOR KINETICS. What is reactor kinetics? Reactor reaction on reactivity changes (whatever are the reasons of changes) Generally not possible

HT2004: Reactor PhysicsReactor Kinetics2 Principles of a Nuclear Reactor n/fission N1N1 N2N2 Leakage Fast fission Resonance abs. Non-fuel abs. Leakage Non-fissile abs. Fission Slowing down Energy E 2 MeV 1 eV 200 MeV/fission ν ≈ 2.5

HT2004: Reactor PhysicsReactor Kinetics3 Graphite-moderated: l p = Water-moderated: l p = Fast reactors: l p = 10 -7

HT2004: Reactor PhysicsReactor Kinetics4 Homogeneous infinite reactor

HT2004: Reactor PhysicsReactor Kinetics5 GroupHalf-life T 1/2 (s) Mean life  mi (s) Decay constant i  (s -1 ) Fraction of total fission neutrons,  i

HT2004: Reactor PhysicsReactor Kinetics6 Kinetic Equations

HT2004: Reactor PhysicsReactor Kinetics7 Solution of Kinetic Equations

HT2004: Reactor PhysicsReactor Kinetics8 Time ρ0ρ0 ρ 0 > 0 ρ 0 < 0 n(t)/n(0) C(t)/C(0) Delayed neutrons ignored

HT2004: Reactor PhysicsReactor Kinetics9 Inhour Equation Unit “inverse hour” = inhour 1 inhour = amount of reactivity needed to make the reactor period equal to one hour 1 pcm (per cent mille) = of Δk/k 1$ is equal to ρ = β

HT2004: Reactor PhysicsReactor Kinetics10

HT2004: Reactor PhysicsReactor Kinetics11 Special Cases

HT2004: Reactor PhysicsReactor Kinetics12

HT2004: Reactor PhysicsReactor Kinetics13

HT2004: Reactor PhysicsReactor Kinetics14 n(t)/n(0) ρ 0 = –0.5% ρ 0 = –5% ρ 0 = –10%

HT2004: Reactor PhysicsReactor Kinetics15 The END

HT2004: Reactor PhysicsReactor Kinetics16

HT2004: Reactor PhysicsReactor Kinetics17

HT2004: Reactor PhysicsReactor Kinetics18