Manipal Entrance Test 2015 Physics Paper

Total energy produced by the reactor in time t = 10yr.
E=1000×106×10 ×3.15×107J =3.15×107J
∵ Efficiency =

output energy

input energy

Input energy caused by fission =

output energy

Efficiency

=

3.15×1017

( 10 100 )

=3.15×1018J
Energy produced by one fission of 235U = 200 MeV
=200×1.6×10−13J =3.2×10−11J
Therefore, number of fissions required =

total energy

energy per fission

=

3.15×1018

3.2×10−11

=9.8×1028
Hence, mass of uranium required is given by
m=

N

Na

×235=

9.8×1028

6.02×1026

=38.2×103‌kg