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

2. 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

3. HT2004: Reactor PhysicsReactor Kinetics3 Graphite-moderated: l p = 10 -3 Water-moderated: l p = 10 -4 Fast reactors: l p = 10 -7

4. HT2004: Reactor PhysicsReactor Kinetics4 Homogeneous infinite reactor

5. 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 155.780.2.0124.000215 222.732.7.0305.001424 36.28.9.111.001274 42.33.3.301.002568 5.61.881.14.000748 6.23.333.01.000273

6. HT2004: Reactor PhysicsReactor Kinetics6 Kinetic Equations

7. HT2004: Reactor PhysicsReactor Kinetics7 Solution of Kinetic Equations

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

9. 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) = 10 -5 of Δk/k 1$ is equal to ρ = β

10. HT2004: Reactor PhysicsReactor Kinetics10

11. HT2004: Reactor PhysicsReactor Kinetics11 Special Cases

12. HT2004: Reactor PhysicsReactor Kinetics12

13. HT2004: Reactor PhysicsReactor Kinetics13

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

15. HT2004: Reactor PhysicsReactor Kinetics15 The END

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