A reactor operates at a thermal flux for long enough that its poisoning has reached…
PHYSICS · Multi-part · Fermi University Physics · Nuclear Physics · Fission, fusion and nuclear energy · Fission, fusion and nuclear energy
The Nucleus Resolved, Ch The reactor as a field equation: diffusion, criticality, feedback and burn-up
Problem
A reactor operates at a thermal flux ϕ=2.0×1013cm−2s−1 for long enough that its 135Xe poisoning has reached equilibrium. The equilibrium xenon reactivity is ρXeeq=−ρmaxϕ+ϕ0ϕ, where ρmax=2730pcm is the saturation worth reached at very high flux and ϕ0=λXe/σXe=7.9×1012cm−2s−1. After shutdown the xenon concentration continues to rise for a time, peaking, at this flux, at about 1.54 times its equilibrium worth roughly 7.4h later.
((a)) Find the equilibrium xenon worth at this flux.
((b)) Find the peak xenon worth after shutdown.
((c)) The control system can supply at most 2500pcm of excess reactivity to override poisoning. Decide whether the reactor can be restarted at the moment of the xenon peak.