Nuclear Fission Reactors

Actually, the answers can be found easily on the web. I jst give you the main points. For detailed information, you should search the web yourself.

1. How do nuclear fission reactor generate energy?
It is done by splitting uranium-235 atoms by slow moving nuetrons. The process, known as nuclear fission, produces energy and additional neutrons for sustaining the fission reaction.

2. What safety process are there?
Fission reaction is carried out in fuel rods which contain uranium fuel pellets. The fuel rod cladding prvents the leakage of fission products into the cooling water. In addition, there is a closed reactor core housed inside a containment building that prevents the leakage of fission products to the environment.

3. What are the different types of nuclear fission reactor?
The common commercial reactor types include:
boiling water reactor, gas cooled/advanced gas colled reactor, pressurized water reactor, liquid-metal-fast breeder reactor.

See the web-page below:
http://hyperphysics.phy-astr.gsu.edu/hbase/nucene/reactor.html#c1

4. What caused the chenobyl accident?
The main cause is that the Chernobyle nuclear reactor used graphite as moderator, in contrast to the use of water as moderator in pressurized water reactor, such as the one in operation at Daya Bay.

During a reactor power boosting on 26 April 1986, the reactor was overheated and the high temperature ignited the graphite moderator, thus causing a severe fire. Because of the lacking of a containment in the Chernobyle reactor, the fire eventually burnt away the reactor, leading to a release of fission products into the environment.