1. What is reactor kinetics?
Reactor reaction on reactivity changes (whatever are the reasons of changes)
Generally not possible
HT2005: Reactor Physics
T11: Reactor Kinetics

2. Principles of a Nuclear Reactor
Leakage N2
2 MeV N1
Fast fission
Energy
n n/fission
Slowing down
Resonance abs.
ν ≈ 2.5
Non-fissile abs.
Non-fuel abs.
1 eV
Fission
200 MeV/fission
Leakage
HT2005: Reactor Physics
T:Reactor Kinetics

3. Homogeneous infinite reactor
HT2005: Reactor Physics
T:Reactor Kinetics

4. Fraction of total fission neutrons, bi
Group
Half-life
T1/2(s)
Mean life
tmi (s)
Decay constant
li (s-1)
Fraction of total fission neutrons, bi 1
55.7
80.2
.0124 2
22.7
32.7
.0305 3
6.2
8.9
.111 4
2.3
3.3
.301 5
.61
.88
1.14 6
.23
.33
3.01
HT2005: Reactor Physics
T:Reactor Kinetics

5. Kinetic Equations
HT2005: Reactor Physics
T:Reactor Kinetics

6. Solution of Kinetic Equations
HT2005: Reactor Physics
T:Reactor Kinetics

7. Delayed neutrons ignored n(t)/n(0)
ρ0 > 0
C(t)/C(0)
ρ0 < 0 ρ0
Time
HT2005: Reactor Physics
T:Reactor Kinetics

8. 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
HT2005: Reactor Physics
T:Reactor Kinetics

9. HT2005: Reactor Physics
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10. Special Cases
HT2005: Reactor Physics
T:Reactor Kinetics

11. HT2005: Reactor Physics
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12. HT2005: Reactor Physics
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13. ρ0 = –0.5% ρ0 = –5% ρ0 = –10% n(t)/n(0) HT2005: Reactor Physics
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14. The END
HT2005: Reactor Physics
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15. HT2005: Reactor Physics
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16. HT2005: Reactor Physics
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17. HT2005: Reactor Physics
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18. Graphite-moderated: lp = 10-3 Water-moderated: lp = 10-4
Fast reactors: lp = 10-7
HT2005: Reactor Physics
T:Reactor Kinetics