Nuclear power II

8.4.7 Describe how neutron capture by a nucleus of uranium-238 results in the production of a nucleus of plutonium-239.

A uranium-238 can capture a neutron which leads to the formation of uranium-239. The uranium-239 would then decay into a neptunium-239 through B-decay. The neptunium-239 would then decay into a plutonium-239 through B-decay again.

Tim Kirk

8.4.8 Describe the importance of plutonium-239 as a nuclear fuel.

Plutonium-239 is an important nuclear fuel as it is one of the few isotopes that is capable of maintaining fission reaction.

Plutonium-239 also utilizes different reactors like a fast breeder reactor.

Tim Kirk

8.4.9 Safety issues and risks associated with the production of nuclear power.

1) If the nuclear fission process gets out of control, it would bring about an explosion and a thermal meltdown of the core. This would then cause fatalities to arise in the surrounding region.

Tim Kirk

The Chernobyl accident was by far the worst nuclear disaster up till now. It caused deaths and made the area inhabitable due to the radiation.

2) Production of nuclear power produces radioactive nuclear waste as a byproduct. This nuclear waste can be radioactive for a long time, and be a radioactive threat to its surrounding during that time.

3) To actually obtain the uranium fuel, miners would have to mine underground, which is a dangerous process. In fact, the ore is so radioactive that miners need special precautions when mining uranium.

4) There needs to be special measures in transporting the uranium from the mine to a nuclear power station so that there would be no harm done to the environment.

5) There is always the possibility of nuclear weapons being produced as a by-product of nuclear power.

Tim Kirk

8.4.10 Outline the problems associated with producing nuclear power using nuclear fusion.

As of now, there is no method of sustaining and enclosing the plasma at the necessary temperature and density which is required for nuclear fusion.

Tim Kirk

"Currently, researchers are working on using deuterium and tritium (a D-T reaction), two hydrogen isotopes with extra neutrons, to nuclear fusion." This method requires the lowest temperature to take place, but even then, we would need a temperature of a 100 million degrees in order for the process to work.

external image NuclearFusion.jpg

The temperature of a 100 million degrees would also create other problems, since it is not possible for materials to withstand such a high temperature. The solution to this would be to use magnetic fields.

8.4.11 Solve problems on the production of nuclear power.

Fission of a uranium-235 nucleus produces approximately 200MeV of energy. The overall efficiency of a nuclear reactor is 23% and its output power is 220 MW.

a) Calculate the number of fissions required per second.

200 MeV = 3.2 x 10^-11 J per reaction

220 MW/0.23 = 956.5 MW input

956.5 x 10^6 W/ 3.2 x 10^-11 J / reaction = 2.98 x 10^19 or 3 x 10^19 reactions / second

b) Calculate the mass in kilograms of uranium-235 consumed per second.

235 U mass = 235 u

235u x 1.661 x 10^-27 = 3.9 x 10^-25 kg

3 x 10^19 (3.9 x 10^-25 kg) = 1.2 x 10^-5 kg