nuclear energy

Nuclear energy:
Nuclear energy means the energy generated from the activity of the nucleus. In general, two nuclear activities are found in the world. They are nuclear fission and nuclear fusion. Currently, all the nuclear energy we use in daily life are from nuclear fission. In the nature, there are some elements with high atomic weight such as Uranium (U). The nucleus is therefore not stable and they can break down into smaller nuclei and neutron to stablize itself. During the fission process, some mass is missing. According to the relativity, E=MC2. the missing mass has been converted to energy. We can utilize this energy for pushing the dynamo and produce electricity.



Nuclear fusion is a cleaner process in which the hydrogen is fused together to generate the helium. In the process, some mass is also missing and converted to energy. This nuclear fusion is in fact happening every in the Sun in which the heat and light is generated by nuclear fusion. This process is much cleaner. However, this process need a very high temperature to start. Practically, we cannot control such high temperature to start the fusion. In 60's, the hydrogen bomb is using this principle. It starts the atomic bomb to creat the high temperature and it can then initiate the fusion process of the hydrogen in the bomb.
核動力是利用可控核反應來獲取能量，從而得到動力，熱量和電能。因為核輻射問題和現在人類還只能控制核裂變，所以核能暫時未能得到大規模的利用。利用核反應來獲取能量的原理是：當裂變材料（例如鈾-235）在受人為控制的條件下發生核裂變時，核能就會以熱的形式被釋放出來，這些熱量會被用來驅動蒸汽機。蒸汽機可以直接提供動力，也可以連接發電機來產生電能。世界各國軍隊中的某些潛艇及航空母艦都以核能為動力（主要是美國），同時，核能每年提供人類獲得的所有能量中的7%，或人類獲得的所有電能中的15.7%。
環境影響

- The advantages and disadvantages of using nuclear energy.

空氣污染
無放射性的水蒸氣是核電站在運行時釋放出來的主要排泄物。[53]核裂變會產生一些氣體，比如說碘-131和氙-133。這些氣體主要會被封在燃料棒中，但是在假定的事故中，會有少量氣體被釋放到冷卻劑中。化學物品控制系統會將放射性氣體隔離，這些氣體需要被存放很長時間（半衰期的幾倍），直到它們變的安全。碘-131和氙-133的半衰期分別為8.0天和5.2天，因此它們需要被儲藏好幾個月的時間。
核能發電不直接產生二氧化硫，氮氧化物，汞或其它與化石燃料的燃燒有關的污染物。（僅在美國，每年就有許多人因為燃燒化石燃料產生的污染物而死去[54]）。它也不直接產生二氧化碳，這使一些環境保護者通過支持對核能的依靠來減少溫室氣體的排泄（溫室氣體造成了全球暖化）。

2009-02-20 23:08:53 補充：
No.3

Actually, nuclear energy is used to generate electricity in Hong Kong for a few years already.Although the percentage is very low but it is a good proof for say that nuclear energy can be used in Hong Kong.

2009-02-20 23:10:03 補充：
Advantage:

The nuclear energy generates electricity to be unlike the pollution material that the fossil fuel generates electricity to exhaust the huge quantity so in the atmosphere, so nuclear energy's generating electricity will not cause the air pollution.

2009-02-20 23:10:15 補充：
The nuclear energy generates electricity the carbon dioxide that will not produce to aggravate the Earth green house effect.

The uranium fuel of the nuclear energy power station usage, in addition to generating electricity, have no other uses.