The accident
On Saturday April 26, 1986, at 1:23:58 a.m. local time, the unit 4 reactor of
the Chernobyl power plant—known as Chernobyl-4—suffered a catastrophic
steam explosion that resulted in a fire, a series of additional explosions,
and a nuclear meltdown.
[edit]
意外
在1986年4月26日的星期天早上當地時間1點25分58秒，車諾比發電廠的第四號反應爐，也
就是為人所知的車諾比四號，發生了災難性的蒸氣爆炸，造成了不可收拾的大火及
一連串的爆炸，也導致了爐心溶毀。
Causes
There are two conflicting official theories about the cause of the accident.
The first was published in August 1986 and effectively placed the blame
solely on the power plant operators. The second theory, proposed by Valeri
Legasov and published in 1991, attributed the accident to flaws in the RBMK
reactor design, specifically the control rods. Both commissions were heavily
lobbied by different groups, including the reactor's designers, Chernobyl
power plant personnel, and the government. Some independent experts now
believe that neither theory is completely correct.
Another important factor contributing to the accident was that the operators
were not informed about problems with the reactor. According to one of them,
Anatoliy Dyatlov, the designers knew that the reactor was dangerous in some
conditions but intentionally concealed this information. Contributing to this
was that the plant's management was largely composed of non-RBMK-qualified
personnel: the director, V.P. Bryukhanov, had experience and training in a
coal-fired power plant. His chief engineer, Nikolai Fomin, also came from a
conventional power plant. Anatoliy Dyatlov himself, deputy chief engineer of
Reactors 3 and 4, only had "some experience with small nuclear reactors",
namely smaller versions of the VVER nuclear reactors that were designed for
the Soviet Navy's nuclear submarines.
起因
官方對於這次事件的起因提出了兩個互相矛盾的理論。第一個理論在1986年8月被提出並
把所有的矛頭指向發電廠的操作員。第二個則是由Valeri Legasov在1991年所提出，此次
報告把這次意外歸因於RBMK(石墨沸水管反應器)核子反應爐的設計瑕疵上，特別是在控制
棒的設計上。提出這兩個理論的調查委員會都受到來自於反應爐設計者、車諾比發電廠員
工以及政府部門在內的多方施壓及遊說。而一些獨立而不受干預的研究相信這兩個理論皆
非完全正確。
另一個促使意外發生的重要因素則是操作員並未被告知反應爐潛在性的問題。依據其中一
名員工Anatoliy Dyatlov的說法，反應爐的設計者知道反應爐在某種情況下可能造成危險
，但他不但沒有將這個問題揭露出來，反而刻意的隱瞞事實。此外，由於發電廠的管理人
員大部分都沒有操作過RBMK核子反應爐的經驗也是造成悲劇的因素之一，如發電廠的廠長
V.P. Bryukhanov只有過燃煤發電廠的歷練，首席工程師Nikolai Fomin來自一個傳統動力
發電廠，而第三號及第四號反應爐的副工程師Anatoliy Dyatlov自己則只有過操作一些小
型核反應爐的經驗，如前蘇聯海軍的核子動力潛艇所使用的的小型VVER(或是WWER,輕水式
反應器)反應爐。
In particular,
細節
* The reactor had a dangerously large positive void coefficient. The RBMK
reactor design used liquid as its coolant. Coolant gives the operators some
control over the speed of the reactions, controlling the reactors energy
output. If the coolant has bubbles in it (voids), from steam, these voids
increase the amount of energy the reactor produces (i.e. no liquid to absorb
neutrons). Without intervention, the reactor produces more energy, creating
more voids, becoming harder to control. That the RBMK reactor design was
dangerous at low power levels was counter-intuitive and unknown to the crew.
*反應爐有著一個危險的正空泡係數。RBMK(石墨沸水管反應器)反應爐使用"液體(輕水)"
來當作冷卻劑.而冷卻劑可以用來幫助操作員控制反應器的反應速率及控制反應器的能量
輸出功率。假如冷卻劑在反應器內形成蒸氣氣泡，會使得反應爐內的核反應加劇(也就是
說沒有"液體"可以來吸收中子了)。少了這些液體的干預，反應爐產生了更多的能量，變
成了惡性循環，使得越來越多的液體變成蒸氣，最終使得反應變得難以控制。RBMK反應爐
在低功率運轉時會造成危險，但工作人員並不明白這點且這個概念(即低功率運轉會造成
危險)也和他們原本所預期的相反。
* A more significant flaw of the reactor was in the design of the control
rods. In a nuclear reactor, control rods are inserted into the reactor to
slow down the reaction. 1[;32mHowever, in the RBMK reactor design, the control rod
end tips were made of graphite, the extenders (the end areas of the control
rods above the end tips, measuring 1 m in length) were hollow and filled with
water, while the balance of the control rod—the truly functional area,
absorbing the neutrons and thereby halting the reaction—were made of boron
carbide. For the initial few moments when control rods of this design are
inserted into the reactor, coolant was displaced by the graphite ends of the
rods. The coolant (water), a neutron absorber, was therefore replaced by
graphite, a neutron moderator – that is, a material that enables the nuclear
reaction rather than slow the reaction down. For the first few seconds of
control rod activation the rods increased the reactor's speed, rather than
the desired effect of decreasing the reaction. This behavior is rather
counter-intuitive and was not known to the reactor operators.
*反應爐在控制棒的設計上更是有明顯的瑕疵。在核子反應爐中，控制棒是被插反應爐當
中以用來減低反應的速率。然而，在RBMK(石墨沸水管反應器)反應爐的設計中，控制棒的
末端是由石墨所製成，延長的區域(指在控制棒末端上方1公尺的範圍)是由碳化硼所構成
而其內部為中空且充滿著水，這部份用來平衡控制棒且做為吸收中子進而停止連鎖反應。
在這種控制棒(RBMK型)被插入反應爐後，做為中子吸收劑的冷卻劑(水)在極短時間內就
被在控制棒末端做為中子緩和劑的石墨所取代。也就是說，石墨不能減慢核反應的速率而
是增加核反應的速率(譯者註:緩和劑可以減低中子能量使之變為慢中子進而引發下一個鈾
-235原子核之分裂)。 而反應爐操作者並不明白這點且這種概念也和他原本的預期相反，
所以在最初的幾秒內，控制棒加速了核反應，而不是如期望般的減慢反應。
中間有一小段不大會翻(while...那裡)不大會翻且覺得這段前後意思有點矛盾?
前面說這型的控制棒可以吸收中子然後停止反應，可是後文中又說RBMK
用的控制棒無法減緩反應@.@
* The operators were careless and violated plant procedures, partly due
to their lack of knowledge of the reactor's design flaws. Also, several
procedural irregularities contributed to the cause of the accident. One was
insufficient communication between the safety officers and the operators in
charge of an experiment being run that night.
*操作員太過大意且違背了發電廠的操作程序，而部分的原因則是他們不知道反應爐原本
就存在的瑕疵。此外，許多程序上的錯誤也導致了這次意外的發生。其中一個即是安全人
員與那天晚上負責試驗的操作員在溝通上的不良所造成。
*
It is important to note that the operators switched off many of the reactor's
safety systems, which was generally prohibited by the plant's published
technical guidelines.
According to a Government Commission report published in August 1986,
operators removed at least 204 control rods from the reactor core (out of a
total of 211 for this reactor model), leaving seven. The same guidelines
(noted above) prohibit operation of the RBMK-1000 with fewer than 15 rods
inside the core zone.
*最值得注意的就是操作員們關掉了許多在技術指導手冊中被禁止關閉的反應爐安全裝置
。依據一份政府委員會在1986年所公佈的報告，操作員從反應爐核心抽出204隻以上的控
制棒(從RBMK-1000反應爐所擁有的211隻中抽出)，只留下了7隻。如同上文所提到指導手
冊中寫著RBMK-1000型不得在少於15隻控制棒的情況下運作。
有一些核子工程的名詞不知道翻得正不正確
請熟悉核子工程的人在提出來嘍
BTW，這種文章是不是應該要移到翻譯版詢問才對@.@
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