Question

A large cubic thermal reactor, moderated and reflected by an infinite reflector of water, is fueled with
235U at a concentration of (10)^-4 g/cm3.
(a) Calculate the critical dimensions of the core.
(b) Compute the critical dimensions if the reactor is bare.
Assume that the system is at room temperature.

Answer 1

ANS)

On "Twofold Criticality" Ishiguro et a!.

1 case to have been the first to watch and characterize "twofold criticality," which they show in a uniform-control reflected reactor. Regarding this announcement, I might want to report a comparable wonder happening in overwhelming water reactors. 2 the nearby bumup dispersion pursues the bend in Fig. 1 (Ref.

3). The relating neutron transition conveyance is then given by the equation [cf>(x)/cf>(O)J2='Y+(l-'Y)cos2Kx,

(1) where 'Y is a consistent given by the character of the reliance of the clasping I< on the bumup s (here taken as a quadratic). From the limit and congruity conditions on the corereflector interface h, pursues the criticality condition: Consider a substantial water-directed and - reflected section reactor energized with consistently conveyed characteristic uranium and ask how the nearby bumup of the fuel ought to be dispersed so the normal bumup will be maximal-one finds that 'Y =-[tanl