A nuclear power reactor produces 3GW of thermal power from thefission of 235U for a period of 10 weeks and then it is shut down.Note: All numerical answers are expected with 3 significantfigures. (a) Assuming 78% of the 200MeV released per fission eventis converted to heat, estimate the number of 235U nuclei fissionedover the 10 week period. (b) 6 % of the 235U fission events produceas a fission fragment some radioactive nuclide X (e.g. 137Cs),which has a half-life of 38 years. Consider the amount of X nucleiproduced during the 10 week operation of the reactor in Part A andcalculate the activity of X left in the used fuel 38 years afterthe reactor is stopped. (c) Following Part B, estimate the power(in kW) produced by these decays of X 38 years after the reactorshutdown if each decay of X releases 1.6 MeV .
