A bare spherical light-water-moderated core of radius has and migration area
PHYSICS · Multi-part · Fermi University Physics · Nuclear Physics · Fission, fusion and nuclear energy · Fission, fusion and nuclear energy
Energy from Physics, Ch The critical reactor: neutron diffusion, buckling and the size of a core
Problem
A bare spherical light-water-moderated core of radius R=80cm has k∞=1.10 and migration area M2=65cm2. A trainee operator, told the core has just gone critical, says: "Critical means the reaction is about to run away; the flux will keep climbing until someone shuts it down."
((a)) Compute the geometric buckling Bg2=(π/R)2 of this sphere and the material buckling Bm2=(k∞−1)/M2 of this lattice.
((b)) Using the result of (a), say whether the trainee's description of what "critical" means is correct, and explain in one or two sentences what actually happens to the flux at Bg2=Bm2.