In a pressurized water reactor (PWR) the nuclear fuel elements are kept in the reactor until 500 GW day per ton of uranium 235 is transferred from the elements to the water.

(a) If upon fission, uranium 235 makes available 1 MW day/g, what fraction of uranium 235 has fissioned when the elements are withdrawn?

(b) If the thermal power rating of the reactor is 3 GW, one-half of the power comes from uranium 235 (the other half is due to plutonium), and the reactor is opened once a year, how mu uranium has fissioned when the elements are withdrawn?

(c) If coal that makes energy available at about 30 MJ/kg is used, how mu coal is consumed to replace the uranium in part (b)?