A Nuclear reactor is operating with a fuel having a net absorption cross section of 4.75 barns. Heavy water is used as a moderator with the composition being 200 molecules of D2O for every fuel molecule. Boron is used as part of the control mechanism. Capture cross sections of D2O and boron are 0.001 and 760 barns respectively. If a thermal utilization factor of 0.8 is the objective, the required number of boron atoms for every 1000 atoms of the fuel is closest to:

A nuclear reactor is operating with a fuel having a net absorption cross section of 4.75 barns. Heavy water is used as a moderator with the composition being 200 molecules of D20 for every fuel molecule. Boron is used as part the control mechanism. Capture cross sections of D20 and boron are 0.001 and 760 barns, respectively. If a thermal utilization factor of 0.8 is the objective, the required number of boron atoms for every 1000 atoms of the fuel is closest to a) 1.3 b) 0.7x 10-4 Oc) 3.7 d) 1.5 x 10-2