NCERT Class XII Chapter <br>Nuclei <br> Questions With Solutions

NCERT Class XII Chapter
Nuclei
Questions With Solutions

Question : 18

Total: 31

A 1000 MW fission reactor consumes half of its fuel in 5.00 y. How much

235

‌

U did it contain initially? Assume that the reactor operates 80% of the time and that all the energy generated arises from the fission of

235

‌

U and that this nuclide is consumed by the fission process.

Solution:

In the fission of one nucleus of

235

‌

U , energy generated is 200 MeV.
Energy generated in fission of 1 kg of

235

‌

U
= 200 ×

6.023×1023

235

× 1000 N = 5.106 × 1026 MeV
= 5.106 × 1026 × 1.6 × 10–13 J = 8.17 × 1013 J
Time for which reactor operates =

100

× 5 yr 4 yr.
Total energy generated in 5 year = 1000 × 106 × 60 × 60 × 24 × 365 × 4 J
∴ Amount of

235

‌

U consumed in 5 years
=

1000×106×60×60×24×365×4

8.17×1013

Kg = 1544 kg
∴ Initial amount of

235

‌

U = 2 × 1544 kg = 3088 kg

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