Question

At typical nuclear power plants, refueling occurs every 23 months. Assuming that a plant has operated continuously since the last refueling and

produces 1.9 GW of electrical power at an efficiency of 28%, how much less massive are the fuel rods at the end of the 23 months than at the start?

(Assume 30-day months.)

kg

Answer 1

The useful energy produced,

E = power * time =

which gives us

  

Since E corresponds to only 28% of the total energy produced, TE,we can see that
(28/100) * TE = E => TE = E/0.28  

thus

which gives us

This TE was produced by the loss in mass, m; whihc we can nowcompute using TE = m*c²=>
m = TE/c²

thus

which gives us

this much less massive will be the fuel rods