介绍核能~急

简介 核能发电，是利用核分裂产生巨大的能量，制造高温高压的蒸气或气体，驱动发电机组发电。 核能所用的燃料，乃是可分裂或融合的放射性物质，例如铀235、钸239、铀233等。例如1克铀235分裂所产生的能相当于燃烧3000吨上等的煤所产生的热量 目前核能发电量仅占全球能源和电力供应百分之七和十七。 核能优点 1. 减少依赖化石燃料 2.生产巨大能量 3.祇需小量原料 4.铀矿蕴藏量足够长期使用 5.运作成本较低（约为火力发电三分之一） 6.生产电力时不会造成空气污染 缺点 * 产生高低阶放射性废料，或者是使用过之核燃料，虽体积不大，但具有放射线，故必须慎重处理，且需面对相当大的政治困扰。 * 核能发电厂热效率较低，比一般化石燃料电厂排放更多废热，故热污染较严重。 * 核能电厂投资成本太大，电力公司的财务风险较高。 * 核能电厂较不适宜做尖峰、离峰之随载运转。 * 兴建核电厂较易引发政治歧见纷争。 * 核电厂的反应器内有大量的放射性物质，如果在事故中释放到外界环境，会对生态及民众造成伤害。 English Nuclear energy This article concerns the energy stored in the nuclei of atoms; for the use of nuclear fission as a power source

see Nuclear power. Nuclear Energy is energy that is directly released from the atomic nucleus. The conversion of nuclear mass to energy is consistent with the mass-energy equivalence formula ΔE = Δm.c?

in which ΔE = energy release

Δm = mass defect

and c = the speed of light in a vacuum (a physical constant). Nuclear energy is released by three exoenergetic (or exothermic) processes: Radioactive decay

where a neutron or proton in the radioactive nucleus decays spontaneously by emitting either particles

electromagic radiation (gamma rays)

neutrinos (or all of them) Fusion

o atomic nuclei fuse together to form a heavier nucleus Fission

the breaking of an heavy nucleus into o (more rarely three) lighter nuclei Nuclear energy was first discovered by French physicist Henri Becquerel in 1896

when he found that photographic plates stored in the dark near uranium were blackened like X-ray plates

which had been just recently discovered at the time 1895.[1] Nuclear chemistry can be used as a form of alchemy to turn lead into gold or change any atom to any other atom (albeit through many steps).[2] Radionuclide (radioisotope) production often involves irradiation of another isotope (or more precisely a nuclide)

with alpha particles

beta particles

or gamma rays. Iron has the highest binding energy per nucleon of any atom. If an atom of lower average binding energy is changed into an atom of higher average binding energy

energy is given off. The chart shows that fusion of hydrogen

the bination to form heavier atoms

releases energy

as does fission of uranium

the breaking up of a larger nucleus into *** aller parts. Stability varies beeen isotopes: the isotope U-235 is much less stable than the more mon U-238. Fromen. *** /wiki/Nuclear_energy

参考: .knowledge.yahoo/question/?qid=7007080300467

参考：.wrs.yahoo/_ylt=A8tU32z1.J5HIqQAua..ygt./SIG=12tlvgd86/EXP=1201687157/**%3Awisdomstore.us/images/Nuclear%2520Mushroom%2520Cloud%25205 核能是通过转化其质量从原子核释放的能量，符合阿尔伯特·爱因斯坦的方程E=mc?，其中E=能量，m=质量，c=光速常量。核能通过三种核反应之一释放： 核裂变，打开原子核的结合力。 核裂变，又称核分裂是指由重的原子，主要是指铀或钸，分裂成较轻的原子的一种核反应形式。 原子弹以及裂变核电站的能量来源都是核裂变。 其中铀裂变在核电厂最常见，加热后铀原子放出2到4个中子，中子再去撞击其它原子，从而形成「链式反应」而自发裂变。撞击时除放出中子还会放出热，再加快撞击，但如果温度太高，反应炉会熔掉，因此通常会放控制棒（硼制成）去吸中子以降低分裂速度 核聚变，原子的粒子熔合在一起。 核聚变，又称核融合。是指由质量小的原子，主要是指氘或氚，在一定条件下（如超高温和高压），发生原子核互相聚合作用，生成新的质量更重的原子核，并伴随着巨大的能量释放的一种核反应形式。原子核中蕴藏巨大的能量，原子核的变化（从一种原子核变化为另外一种原子核）往往伴随着能量的释放。如果是由重的原子核变化为轻的原子核，叫核裂变，如原子弹爆炸；如果是由轻的原子核变化为重的原子核，叫核聚变，如太阳发光发热的能量来源。 相比核裂变，核聚变几乎不会带来放射性污染等环境问题，而且其原料可直接取自海水中的氘，来源几乎取之不尽，是理想的能源方式。 目前人类已经可以实现不受控制的核聚变，如氢弹的爆炸。但是要想能量可被人类有效利用，必须能够合理的控制核聚变的速度和规模，实现持续、平稳的能量输出。科学家正努力研究如何控制核聚变，但是现在看来还有很长的路要走。 在2005年，部份科学家相信已经成功做出小型的核聚变1，并且得到初步验证2。首个实验核聚变发电站将选址法国3。 目前主要的几种可控核聚变方式： 超声波核聚变 雷射约束（惯性约束）核聚变 磁约束核聚变（托卡马克） 核衰变，自然的慢得多的裂变形式。 核衰变是放射性核素自发地释放射线和能量，最终转化为其他稳定核素的过程。放射性核素在进行核衰变的时候，根据核素的性质可能放射出α射线、 β射线、γ射线以及俘获电子等。 由于一个原子的衰变是自然地发生，即不能预知何时会发生，因此会以机会率来表示。每颗原子衰变的机率大致相同，做实验的时候，会使用千千万万的原子。当原子开始发生衰变，其数量会越来越少，衰变的速度也会因而减慢。例如一种原子的半衰期为一小时，一小时后其未衰变的原子会剩下原来的二分一，两小时后会是四分一，三小时后会是八分一。 原子的衰变会产生出另一种元素，并会放出阿尔法、贝塔粒子或中微子，在发生衰变后，该原子也会释出伽马射线。根据爱因斯坦的质能守恒公式E = mc2，衰变是其中一个把质量转为能量的方式。通常衰变所产生的产物多也是带放射性，因此会有一连串的衰变过程，直至该原子衰变至一稳定的同位素。 发生核衰变的放射性核素有的是在自然界中出现的天然放射性同位素，如碳14，但其衰变只会经过一次β衰变转为氮14原子，并不会一连串地发生。也有很多是经过粒子对撞等方法人工制造的核素。 A nuclear weapon is a type of explosive weapon that derives its destructive force from nuclear reactions of fusion or fission. As a result

even a nuclear weapon with a *** all yield is significantly more powerful than the largest conventional explosives

and a single weapon is capable of destroying an entire city. In the history of warfare

o nuclear weapons have been detonated — both by the United States

during the closing days of World War II. The first was detonated on the morning of 6 August 1945

when the United States dropped a uranium gun-type device code-named "Little Boy" on the Japanese city of Hiroshima. The second was detonated three days later when the United States dropped a plutonium implosion-type device code-named "Fat Man" on the city of Nagasaki. These bombings resulted in the immediate deaths of around 120

000 people from injuries sustained from the explosion and acute radiation sickness

and even more deaths over time from long-term effects of radiation. The use of these weapons was and remains controversial. (See Atomic bombings of Hiroshima and Nagasaki for a full discussion.) Since the Hiroshima and Nagasaki bombings

nuclear weapons have been detonated on over o thousand occasions for testing purposes and demonstration purposes. The only countries known to have detonated such weapons are (chronologically) the United States

the Soviet Union

the United Kingdom

France

the People's Republic of China

India

Pakistan

and North Korea.

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