Chemistry Questions

Question

1. To be an effective energy source, a nuclear reaction must sustain itself. What characteristic of the proceeding reactions allows them to continue without input from an external source?

 

2. When one ^235₉₂U atom undergoes fission, approximately 3.244 x 10^-11 J of energy are released. Assuming that all of the energy released by each fission event can be converted to electricity, how many ²³⁵₉₂U atoms must be split each second to generate the power of a nuclear reactor with an output of 556 MW? (W stands for watt. 1 W = 1 J/s where J stands for Joule.)

 

3. Nuclear reactors average 35% efficiency in converting fission energy to electricity. Realistically, how many ²³⁵₉₂U atoms must be split each second to generate the 556 MW that will come from the reactor?

Answer 1

1. The nuclear energy is not 100% renewable. Even the fusion reaction occurring at the surface of the sun will not continue forever, although there is a cyclic process going on ,and to some extent is self sustainable. Breeder reactor is one way of generating self supporting fuel within the reactor but even that process cannot last forever without external supply .So practically it seems to be impossible to device any such process but we can have reactions continuing for long time without external supply.

2. If N is the required number of split per sec
Then N x 3.244 x10 ^-11 = 556 x 10⁶ as 1 MW = 10⁶ W = 10⁶ J/s
N = (556 x 106)/(3.244x10 ^-11 )=1.713 x 10 ¹⁹ per sec

3. As the efficiency is 35 %
The new value of N will be (100/30) x 1.173 x 10 ¹⁹ = 3.91x 10 ²⁰ per sec