切尔诺贝利核事故
维基百科，自由的百科全书
-{T|zh-tw:車諾比核能電廠事故;zh-cn:切尔诺贝利核事故;zh-hk:切爾諾貝爾核能電廠事故;zh-sg:切尔诺贝利核事故}-
-{zh-tw:車諾比核能電廠事故;zh-cn:切尔诺贝利核事故;zh-hk:切爾諾貝爾核能電廠事故;zh-sg:切尔诺贝利核事故}-起因於1986年4月26日凌晨1點23分發生在烏克蘭普里皮亚特（Pripyat, Ukraine）的一起核泄漏事故。車諾比事件被視為歷史上最嚴重的核能發電廠意外事故。由於車諾比發電廠沒有保護掩體，導致受到核輻射塵污染的雲層漂往前蘇聯西部的部分地區、西歐、東歐、斯堪地那維亞半島、不列顛群島和北美东部部分地區。此外，在烏克蘭（Ukraine）、白俄羅斯（Belarus）及俄羅斯（Russia）境內遭受到嚴重的汙染的地區，超過336,000名的居民被迫撤離。依據前蘇聯的官方報告，約60%受到輻射塵污染的地區皆位於白俄羅斯境內（Belarus）。但根據2006年的TORCH報告指出，半數的輻射塵都落在前述的三個前蘇聯國家以外。這次災難所釋放出的輻射線劑量是投在廣島的原子彈的400倍以上。
這次的意外引起眾人對於前蘇聯核能發電工業上的安全顧慮，也減緩了一系列的核能工程進度，同時也促使了前蘇聯政府的資訊較為透明化。蘇聯瓦解後的獨立國家包括俄羅斯、烏克蘭、白俄羅斯仍持續地在因車諾比事件所造成的汙染清理及健康照護上付出許多代價。因車諾比事件所造成的死亡人數更是難以精確的算計，而在前蘇聯時期的刻意隱瞞之下，也使得在追查犧牲者方面的工作更為困難。前蘇聯政府當局不久後也禁止醫生在死亡證明上提及因"輻射線"而死亡。然而，潛在的死亡因素，特別是癌症，仍尚未發生，而這些在將來也都難以證明是因車諾比事件所引起。然而估計與實際的數據差別是相當大的，一份由國際原子能總署（International Atomic Energy Agency, IAEA）和世界衛生組織（World Health Organization, WHO）所主導的車諾比論壇在2005年所提出的車諾比事件報告中，有56名犧牲者是直接受輻射線的影響而死亡（47名救災人員，9名罹患甲狀腺癌的兒童），而據估計，在660萬人中，最後約有9000人會死於某一種類型的癌症（一種被誘發的疾病）。就此，綠色和平組織所估計總傷亡人數是9萬3千人，但引用在最新出爐的一份報告中的數據指出發生在白俄羅斯、俄羅斯及烏克蘭單獨的事件在1990年到2004年間可能已經造成20萬起額外的死亡。
目录 |
[编辑] 廠房
切尔诺贝利核电站（北緯51度23分14秒東經30度6分41秒）是位於乌克兰普里皮亞季（-{Прип'ять}-，Pripyat）殖民地，切尔诺贝利市西北11英里（18千米），離乌克兰與白俄羅斯邊界10英里（16千米），及烏克蘭首都基輔（-{Київ, Kiev}-）以北70英里（110千米）。核电站由四個核反应堆組成，每個能產生1吉瓦特的電能（3千2百兆瓦特的熱功率），核事故時四個反應堆共提供了乌克兰10%的電力。廠房的工程始於1970年代，1號反應堆於1977年啟用，接著2號於1978年、3號於1981年、4號於1983年亦相繼啟用。還有兩個反應堆（5號及6號，每個能產生10億瓦特）在事故時仍建造中。
廠房的四個反應堆都是屬於同一類型，稱為RBMK-1000。
[编辑] 事故
1986年4月26日星期六，當地時間早上1點23分58秒，切尔诺贝利核电站的第四個核反應堆—即切尔诺贝利4號—發生了一次突如其來的蒸汽爆炸，引發了火警、一連串的爆炸和核熔毀。
[编辑] 起因
關於事故的起因，官方有兩個互相矛盾的理論。第一個是在1986年8月公佈，完全把事故的責任推卸到核电站操作員。第二個則是發佈於1991年，認為事故由於壓力管式石墨慢化沸水反應堆（簡稱RMBK）的設計缺陷引致，尤其是控制棒的設計。雙方的調查團都被多方面遊說，包括反應堆設計者、切尔诺贝利核电站職員及政府。現在一些獨立的專家相信兩個理論都並非完全正確。
另一個促成事故發生的重要因素是職員並沒有收到反應堆問題報告的事實。根據Anatoli Dyatlov—一名職員所述，設計者知道反應堆在某些情況下會出現危險，但蓄意將其隱瞞。（造成這情況是因為廠房主管基本由不具备RMBK資格的員工组成：廠長V.P. Bryukhanov，具有燃煤發電廠的訓練和經驗。他的總工程師Nikolai Fomin亦是來自一個常規能源廠。Anatoli Dyatlov, 3號和4號反應堆的副總工程師只有“一些小反應堆的經驗”，VVER反應堆的小版本即蘇聯海軍的核潛艇的設計。）
在細節中，
- 反應器有一個危險高正面空係數。簡單地說，這意味著如果蒸汽氣泡形成在反應器冷卻劑中，核反應加速，如果沒有其它干預，將會導致逃亡反應。更壞的話，在低功率輸出，這個其它因素未補償正面空係數，會使反應器不穩定和危險。反應器在低功率的危險對工作人員是與預計相反和未知數。
- 反應器的一個更加重大的缺陷是在控制棒的設計。在一個核反應堆，控制棒被插入反應堆以減慢核反應。但是，在RBMK反應堆設計，控制棒部份是空心的；當控制標尺被插入時，最初的數秒鐘冷卻劑被控制棒的空心外殼偏移了。因為冷卻劑（水）是中子吸收體，反應堆的輸出功率實際上上升。這情況也是與預計相反，而反應堆操作員亦不知情。
- 操作員粗心大意並違犯了規程，部分是由於他們未察覺反應堆的設計缺陷。一些程式的不規則促成了事故發生。另一原因是安全幹事和負責該夜實驗操作員之間的通訊不足。
重要注意的一點，是操作員關上了許多反應堆的安全系統，除非安全系統發生故障，否則這是技術指南所禁止的。
1986年8月出版的政府調查委員會報告，操作員從反應堆核心至少拿去了204枝控制棒（這類型的反應堆共需要211枝），留下七枝。同樣指南（上文提及）是禁止RBMK-1000操作時在核心區域使用少於15枝控制棒。
[编辑] 經過
1986年4月25日，4號反應器預定關閉以作定期維修。並決定在這場合作為測試反應堆的渦輪發電機能力的機會，在電力損失情形下發充足的電供給反應堆的安全系統動力（特別是水泵）。像切爾諾貝爾，反應堆有一對柴油發電器可利用作為待命，但並不能瞬間地起動—反應堆將因此被使用轉動渦輪，到時渦輪會從反應堆分離和在自己的慣性之下力量轉動，而測試的目標是確定當發電器起動時，渦輪是否在減少階段能充足地供給泵浦動力。測試早先在其它單位執行成功（所有安全供應起動）而結果是失敗的（那是渦輪產生了不足的力量在減少階段供給泵浦動力），但另外的改進提示了對其它測試的需要。
為了在更安全、更低功率地進行測試，切爾諾貝利4號反應器的能量輸出從正常功率的3.2吉瓦特減少至700兆瓦特。但是，由於實驗開始的延遲時，反應堆控制員太快地減低能量水平，實際功率輸出落到只30兆瓦特。結果，中子吸引而成的裂變產品氙-135增加了（這產品典型地在更大的功率情況下，在一台反應堆中消耗）。力量下落的標度雖是接近由安全章程允許的最大限制，但員工組的管理者選擇不關閉反應堆並繼續實驗。後來，實驗決定“抄捷徑”和只上升功率輸出到200 兆瓦特。為了克服剩餘氙-135的中子吸收，遠多於安全章程數量的控制棒由反應堆拔出。在4月26日上午1點05分，作為實驗一部分，被渦輪發電機推動的水泵起動了；水的流量由於這行動而超出了安全章程的指定。水流量在上午1點19分增加了—因為水也會吸收中子，在水流量的進一步增加需要手工撤除控制棒，導致一個極不穩定和危險操作條件。
上午1點23分04秒，實驗開始了。反應堆的不穩定狀態在控制板沒有顯示任何情況，並且看起來所有反應堆員工並未充分地意識到危險。水泵的電力關閉了，並且被渦輪發電機的慣性推動，水流的速度減低了。渦輪從反應堆分離，反應器核心的蒸汽水平增加。因為冷卻劑被加熱，個別的蒸汽在冷卻劑管道形成。在切爾諾貝利的RBMK石墨緩和反應器的特殊設計有一個高正面空係數，意味著在沒有水時的中子吸收的作用使反應堆的力量迅速地增加，並且在這種情況下，反應堆操作變得逐漸變得不穩定和更加危險。上午1點23分40秒操作員按下了命令“緊急停堆”的AZ-5（“迅速緊急防禦5”）按鈕—所有控制棒的充分的插入，包括之前不小心地拿走的控制棒。這是否作為緊急措施，或只是簡單地在實驗完成時作為關閉反應堆定期方法，並不清楚（反應堆預定被關閉作為定期維修）。這通常意味著緊急停堆的命令是因為意想不到的迅速力量增量的一個反應。另一方面，總工程師Anatoly Dyatlov，在事故時身在切爾諾貝利核電站，他寫在他的書上：
- “在1點23分40秒，集中化控制系統之前……沒有登記能辯解緊急停堆的任何參量變動。依照陳述委任……會集和分析很多材料，在它的報告，沒確定原因為什麼命令了緊急停堆。並沒有需要尋找原因。反應堆簡單地在實驗完成時被關閉。”
由於控制棒插入機制（18至20秒的慢速完成），棒的空心部份和冷卻劑的臨時移位，逃走導致反應率增加。增加的能量產品導致了控制棒管道的變形。棒在被插入以後被卡著，只能進入管道的三分之一，因此無法停止反應。在1點23分47秒，反應堆產量急升至大約30 吉瓦特，是十倍正常操作的產品。燃料棒開始熔化而蒸汽壓力迅速地增加，導致一場大蒸汽爆炸，使反應器頂部移位和受破壞，冷卻劑管道爆裂並在屋頂炸開一個洞。为了減少費用，和它的體積太大，反應堆以單一保護層方式興建。這令放射性污染物在主要壓力容器發生蒸汽爆炸而破裂之後進入了大氣。在一部分的屋頂炸毀了之後，氧氣流入—與極端高溫的反應堆燃料和石墨慢化劑被結合—引起了石墨火。這火災令放射性物質擴散和污染更廣的區域。
由於目擊者的報告和站內紀錄不一致，有一些爭論認為確實的事件是發生在當地時間1點22分30。最後共同同意的版本被描述在上面。根據這種理論，第一次爆炸發生了在大約1點23分47秒，操作員在七秒以後命令了“緊急停堆”。
[编辑] 后事
爆炸发生后，并没有引起苏联官方的重视。在莫斯科的核专家和苏联领导人得到的信息只是“反应堆发生火灾，但并没有爆炸”。因此，苏联官方反应迟缓。在事故后48小时，某些距离核电站很近的一些村庄才开始疏散。政府也派出军队强制人们撤离。当时在现场附近村庄测出了是致命量几百倍的核辐射，而且辐射值还在不停地升高。但这还是没有引起重视。专家宁愿相信是测量辐射的机器故障也不相信会有那么高的辐射。可是居民并没有被告知事情的全部真相，这是因为官方担心会引起人民恐慌。许多人在撤离前就已经吸收了致命量的辐射。
事故后3天，莫斯科派出的一个调查小组到达现场。可是他们迟迟无法提交报告。苏联政府还不知道事情真相。终于在事件过了差不多一周后，莫斯科接到从瑞典政府发来的信息。此时辐射云已经飘散到瑞典。苏联终于明白事情远没有他们想的那么简单。
之后数个月，苏联政府派出了无数人力物力，终于将反应堆的大火扑灭，同时也控制住了辐射。
[编辑] 事故造成的影響
[编辑] 立即影響
由原子爐熔毀而漏出的輻射雲飄過俄羅斯、白俄羅斯和烏克蘭，但輻射雲也飄過歐洲的部份地區，例如：土耳其、希臘、摩爾多瓦、羅馬尼亞、立陶宛、芬蘭、丹麥、挪威、瑞典、奧地利、匈牙利、捷克、斯洛伐克、斯洛維尼亞、波蘭、瑞士、德國、義大利、愛爾蘭、法國(包含科西嘉)[1]) 和英國(UK) [2] [3]。最早的車諾比輻射外洩證據來自瑞典而不是俄國，1986年4月27日瑞典Forsmark核電廠工作人員發現異常的輻射粒子在他們的衣服上，該電廠距離車諾比大約1100公里。根據瑞典的研究發現該輻射物並不是來自於瑞典的核能電廠，他們懷疑是俄國核電廠出了問題。法國政府宣稱輻射雲只飄到德國及義大利的邊界。因為輻射塵的關係義大利規定部份農作物禁止食用例如蘑菇。為了避免引發民眾的恐懼法國政府沒有作類似的測量。
車諾比災變不只污染周圍的鄉鎮，它還藉由氣流幫助沒有規律的往外面散開。根據俄國及西方科學家的報告指出：掉落在俄國的輻射塵有60%在白俄羅斯。而由TORCH 2006的報告指出有一半的易揮發的粒子掉落在烏克蘭、白俄羅斯、及俄羅斯以外的地方。在俄羅斯聯邦布良斯克的南方極大的區域和烏克蘭北方的部份地區都被輻射物質污染。
203人立即被送到醫院，其31人死亡，31人死之中有28人死於過量的輻射[來源請求]。死亡的人大部份是消防隊員和救護員，他們在不知道輻射危險之下，為了使核電廠恢復控制他們暴露在核分裂產生的同位素形成的濃煙之中。 135,000人被撤離家園，其中約有50,000人是車諾比附近的皮里亞克鎮居民。衛生單位預測在未來70年中受到輻射劑量約在5–12艾貝克的人癌症比例將會上升2%。已經有10人因為此次意外而受到輻射照射死於癌症。 Template:Citeneeded
俄國科學家報告說車諾比4號機反應爐總共有180 - 190 噸的二氧化鈾以及核反應產生的核廢料。他們也估計這些物質大約有5%-30%流到外面。但根據曾經到過石棺內反應爐做後續處理的清理人(例如Mr. Usatenko和Dr. Karpan)說反應爐內只剩大約5%-10%的物質。反應爐的照片顯示反應爐完全是空的。因為大火引發的高溫讓許多輻射物質衝向大氣層高空向四面八方擴散。
在災變後負責恢原及整理的工作人員我們將他們稱為"清理人"。清理人在清理的過程中接受到非常高劑量的輻射。根據俄羅斯的估計，大約有300,000到600,000的清理人在災變後的2年內進入離反應爐30公里的範圍內清除輻射污染物。[4]
在被輻射污染地區有許多小孩接受輻射劑量高達50 戈雷(Gy)。這是因為他們在喝牛奶的過程中吸收了當地生產被輻射污染的牛奶，當地牛奶是被碘-131所污染，碘-131的半衰期為8天。許多研究發現白俄羅斯、烏克蘭及俄羅斯的小孩也罹患甲狀線癌比例快速增加。根據日本原子彈爆炸的事後調查統計預期在車諾比地區白血病在未來的幾年內將會增加，但直到目前為止白血病病例的增加數量還不足以在統計學上推斷與輻射外洩有關。 不過有事實證明在車諾比地區的畸形兒出生率升高了There has been a 證實 increase attributable to Chernobyl in congenital abnormalities, adverse pregnancy outcomes or any other radiation-induced disease in the general population, both in the contaminated areas or further afield Template:Cite needed.
[编辑] 長期健康影響
在那次事件之后，主要健康問題與放射性半衰期為8 天的碘有關。現在，有人擔憂半衰期約為30 年的鍶-90和銫-137對土壤造成的污染。最表層土壤中的所含的銫-137被植物，昆蟲和蘑菇吸收，進入當地的食品供應。有些科學家擔心輻射對當地人的影響會持續好幾個世代。
蘇聯當局在事故之後36個小時開始疏散住在車諾比反應爐周遭的居民。[1][2]在1986年5月，即事件發生一個月后，約116，000名住在廠房方圓30 公里(18 英里)內的居民被安置在別處。這個地區經常被稱為疏散區域(Zone of alienation)。然而，輻射影響的範圍其實遠大於方圓30公里。
核電廠爆炸事故對車諾比居民造成的長期影響一直備受爭議。有超過300，000 人因為此次事故被重新安居；數百萬人仍然繼續居住在污染區。另一方面，那些受到對低的劑量輻射影響的大多數的人；在他們中幾乎沒有增加的死亡率，癌症或者先天缺陷的證據；縱使當這樣的證據出現時，其原因的與放射性污染的關聯也是不確定的。
必须被注意的是前苏联警方在灾难中及灾难catastrophe后在旁边设置了障碍物, 科学研究也许还会因为缺乏的民主透明性而被限制. 在白俄罗斯（Belarus）, Yuri Bandazhevsky, a scientist一个质疑官方对切尔诺贝利后果评估和与官方的最大限制1 000 Bq/kg关联的科学家 , 已经宣称成为国家控制political repression的受害者。从2001年到2005年，他在1999年出版关于切尔诺贝利事件官方调查指导的评论报告后因贿赂罪被关押。
[编辑] 食物限制 Food restrictions
1986年四月, 一些欧洲国家(除法国以外) 已经强迫实行食物限制, 特别是菌类和牛奶. 在灾难过后20年, 主要限制制造、运输、消费过程中来自切尔诺贝利放射性尘埃的的食物污染, in particular caesium-137, in order to prevent them from entering the human food chain. In parts of Sweden and Finland, restrictions are in place on stock animals, including reindeer, in natural and near-natural environments. "In certain regions of Germany, Austria, Italy, Sweden, Finland, Lithuania and Poland, wild game (including boar and deer), wild mushrooms, berries and carnivore fish from lakes reach levels of several thousand Bq per kg of caesium-137", while "in Germany, caesium-137 levels in wild boar muscle reached 40,000 Bq/kg. The average level is 6,800 Bq/kg, more than ten times the EU limit of 600 Bq/kg", according to the TORCH 2006 report. The European Commission has stated that "The restrictions on certain foodstuffs from certain Member States must therefore continue to be maintained for many years to come". [2]
Under power provided in the 1985 Food and Environment Protection Act (FEPA), Emergency Orders have been used in the UK since 1986 to impose restrictions on the movement and sale of sheep exceeding the limit of 1 000 becquerels per kilogramme (Bq/kg). This safety limit was introduced in the UK in 1986 based on advice from the European Commission's Article 31 group of experts. However, the area covered by these restrictions has decreased by 95% since 1986: while it covered at first almost 9 000 farms and over 4 million sheep, as of 2006 it covers 374 farms covering 750 km 2 and 200 000 sheep. Only limited areas of Cumbria, South Western Scotland and Northern Wales are still covered by restrictions. [5]
In Norway, the Sami people were affected by contaminated food (the reindeer had been contaminated by eating lichen, which are very sensitive to radioactivity) [6]
[编辑] 車諾比事故後的好處
在事故後，隔離區內變成部份野生動物的天堂。 雖然動物也飽受輻射之苦，但比起人類對牠們的傷受是非常輕微的，所以對牠們而言事故的發生反而是好事。在隔離區內的動物比如說老鼠已適應了輻射，牠們和沒受輻射影響地區的老鼠壽命大約相同。 下列為隔離區內再度出現或被引入的動物山貓，貓頭鷹，大白鷺，天鵝，疑似1隻熊，歐洲野牛，蒙古野馬，獾，河狸，野豬，鹿，麋鹿，狐狸，野兔，水獺，浣熊，狼，水鳥，灰藍山雀，黑松雞，黑鸛，鶴，白尾鵰。[7]
[编辑] 死亡人數估計的爭議
[编辑] 車諾比論壇的報告
In September 2005, a draft summary report by the Chernobyl Forum, comprising a number of UN agencies including the International Atomic Energy Agency (IAEA), the World Health Organization (WHO), the United Nations Development Programme (UNDP), other UN bodies and the Governments of Belarus, the Russian Federation and Ukraine, put the total predicted number of deaths due to the accident at 4,000 [8]. This death toll predicted by the WHO included the 47 workers who died of acute radiation syndrome as a direct result of radiation from the disaster and nine children who died from thyroid cancer, in the estimated 4,000 excess cancer fatalities expected among the 600,000 with the highest levels of exposure. [9] The full version of the WHO health effects report adopted by the UN, published in April 2006, included the prediction of 5,000 additional fatalities from significantly contaminated areas in Belarus, Russia and Ukraine and predicted that, in total, 9,000 will die from cancer among the 6.8 million most exposed Soviets [10].
[编辑] 歐洲議會議員(綠黨)
German Green MEP (member of the European Parliament) Rebecca Harms, commissioned a report (TORCH ,The Other Report on Chernobyl) in 2006 in response to the UN report; it stated that:
"In terms of their surface areas, Belarus (22% of its land area) and Austria (13%) were most affected by higher levels of contamination. Other countries were seriously affected; for example, more than 5% of Ukraine, Finland and Sweden were contaminated to high levels (> 40,000 Bq/m2 caesium-137). More than 80% of Moldova, the European part of Turkey, Slovenia, Switzerland, Austria and the Slovak Republic were contaminated to lower levels (> 4,000 Bq/m2 caesium-137). And 44% of Germany and 34% of the UK were similarly affected." (See map of radioactive distribution of Caesium-137 in Europe) [2]
The IAEA/WHO and UNSCEAR considered areas with exposure greater than 40,000 Bq/m2; the TORCH report also included areas contaminated with more than 4,000 Bq/m2 of Cs-137.
The TORCH 2006 report "estimated that more than half the iodine-131 from Chernobyl [which increases the risk of thyroid cancer] was deposited outside the former Soviet Union. Possible increases in thyroid cancer have been reported in the Czech Republic and the UK, but more research is needed to evaluate thyroid cancer incidences in Western Europe". It predicted about 30,000 to 60,000 excess cancer deaths and warned that predictions of excess cancer deaths strongly depend on the risk factor used; and predicted excess cases of thyroid cancer range between 18,000 and 66,000 in Belarus alone depending on the risk projection model [11] Furthermore it pointed out that many diseases have latencies such that it is very difficult to generate accurate estimates as early as 2006, stating that "most solid cancers have long periods between exposure and appearance of between 20 and 60 years. Now, 20 years after the accident, an average 40% increased incidence in solid cancer has been observed in Belarus with the most pronounced increase in the most contaminated regions." It also quoted the 2005 Forum's report, which documented preliminary evidence of an increase in the incidence of pre-menopausal breast cancer among women exposed at ages lower than 45 years. The TORCH report also stated that "two non-cancer effects, cataract induction and cardiovascular diseases, are well documented with clear evidence of a Chernobyl connection." Quoting the report, Nature wrote that: "it is well known that radiation can damage genes and chromosomes"; "the relationship between genetic changes and the development of future disease is complex and the relevance of such damage to future risk is often unclear. On the other hand, a number of recent studies have examined genetic damage in those exposed to radiation from the Chernobyl accident. Studies in Belarus have suggested a twofold increase in the germline minisattelite mutation rate". [10] [12]
[编辑] 綠色和平組織
Greenpeace claimed contradictions in the Chernobyl Forum reports, quoting a 1998 WHO study referenced in the 2005 report, which projected 212 dead from 72,000 liquidators [13]. In its report, Greenpeace suggested there will be 270,000 cases of cancer attributable to Chernobyl fallout, and that 93,000 of these will probably be fatal, but state in their report that “The most recently published figures indicate that in Belarus, Russia and the Ukraine alone the accident could have resulted in an estimated 200,000 additional deaths in the period between 1990 and 2004.” . Blake Lee-Harwood, campaigns director at Greenpeace, believes that cancer was likely to be the cause of less than half of the final fatalities and that "intestinal problems, heart and circulation problems, respiratory problems, endocrine problems, and particularly effects on the immune system," will also cause fatalities.
[编辑] 避免核戰國際物理學家德國分會成員
According to an April 2006 report by the German affiliate of the International Physicians for Prevention of Nuclear Warfare (IPPNW), entitled "Health Effects of Chernobyl", more than 10,000 people are today affected by thyroid cancer and 50,000 cases are expected. The report projected tens of thousands dead among the liquidators. In Europe, it alleges that 10,000 deformities have been observed in newborns because of Chernobyl's radioactive discharge, with 5,000 deaths among newborn children. They also claimed that several hundreds of thousands of the people who worked on the site after the accident are now sick because of radiation, and tens of thousands are dead [14] [15].
[编辑] 其他研究
- The Ukrainian Health Minister claimed in 2006 that more than 2.4 million Ukrainians, including 428,000 children, suffer from health problems related to the Chernobyl catastrophe [1]. Psychological after-effects, as the 2006 UN report pointed out, have also had adverse effects on internally displaced persons.
- Another study alleged heightened mortality in Sweden [16].
- According to the Union Chernobyl, the main organization of liquidators, 10% of the 600,000 liquidators are now dead, and 165,000 disabled. [17]
- The Abstract of the April 2006 International Agency for Research on Cancer report Estimates of the cancer burden in Europe from radioactive fallout from the Chernobyl accident stated "It is unlikely that the cancer burden from the largest radiological accident to date could be detected by monitoring national cancer statistics. Indeed, results of analyses of time trends in cancer incidence and mortality in Europe do not, at present, indicate any increase in cancer rates - other than of thyroid cancer in the most contaminated regions - that can be clearly attributed to radiation from the Chernobyl accident." [18] [19] However, while undetectable, they estimate, based on the linear no threshold model of cancer effects, that 16,000 excess cancer deaths could be expected from the effects of the Chernobyl accident through the year 2065. Their estimates have very wide 95% confidence intervals. [citation needed]
[编辑] 法國的訴訟
In April 2006, 200 new suits were deposed in France against "X" by the French Association of Thyroid-affected People, leading to a total amount of 400 suits deposed (the first one had been deposed in March 2001). These persons are affected of thyroid cancers or goitres, and have deposed a lawsuit alleging that the French government, led by Prime Minister Jacques Chirac, had not informed enough the population of the risks linked to the Chernobyl radioactive fallout, although east of France and Corsica had been heavily contaminated and that health protection measures had been put in place in nearby countries to prevent consumption of green vegetables or milk by children and pregnant women. Although the 2006 study by the French Institute of Radioprotection and Nuclear Safety alleged that no clear link could be found between the increase of thyroid cancers in France and Chernobyl, it also stated that papillary thyroid cancer had tripled in the following years [20].
[编辑] 與其他事故比較
將車諾比事故被拿來與1984年印度波帕爾化學災變作比較。1984年12月3日印度聯合碳化公司在波帕爾的化學工廠洩漏出40公頓有毒的異氰酸甲酯和其他有毒氣體，該毒氣大約殺死15000人並且使150,000到600,000受到傷害。
以下為其他造成非常多人死亡的人為災害
- 約翰鎮水災，1889年，美國， 2,209人死亡。
- 板橋水庫水霸，1975年，中國，171,000人死亡。
- 1952年英國倫敦煙霧，英國倫敦大約12,000人死亡。
其他的核能輻射災變並沒有造成像車諾比一樣的嚴重災害。民用核能事故包含1964年7月24日美國羅德島查理斯鎮電廠發生添加燃料意外，共1人死亡[21]；1983年9月23日阿根廷布宜諾斯艾利斯實驗設備，共1人死亡[22]；最近1999年9月30日日本Tokaimura核能燃料再處理工廠，共2人死亡[23]。車諾比事故之前的商用核能電廠事故包含1957年英國反應爐火災和1979年美國三哩島核能電廠反應爐熔毀，這兩個事故都沒有人員死亡的記錄。
[编辑] 車諾比事故之後
車諾比電廠的問題並沒有因為4號機組出問題而停止，電廠的4號機組被封閉並且用200公尺長的水泥與其他機組隔開。由於缺乏能源，所以烏克蘭政府讓其他3個機組繼續運作。1991年一場火災又在2號機組發生，烏克蘭政府當局隨後宣布2號機組無法修復因此終止運作。1996年11月1號機組在烏克蘭政府與國際原子能總署的協議下停止運作。2000年11月烏克蘭政府總統Leonid Kuchma在一個正式典禮上閉關了3號機組的運作，因此整個車諾比發電廠就停止發電不再運作。
[编辑] The need for future repairs
The sarcophagus is not an effective permanent enclosure for the destroyed reactor. Its hasty construction, in many cases conducted remotely with industrial robots, is aging badly. If it collapses another cloud of radioactive dust could be released. The sarcophagus is so badly damaged that a small earth tremor or severe winds could cause the roof to collapse. A number of plans have been discussed for building a more permanent enclosure.
According to official estimates, about 95% of the fuel (about 180 tonnes) in the reactor at the time of the accident remains inside the shelter, with a total radioactivity of nearly 18 million curies (670 PBq). The radioactive material consists of core fragments, dust, and lava-like "fuel-containing materials" (FCM) that flowed through the wrecked reactor building before hardening into a ceramic form. By conservative estimates, there are at least four tons of radioactive dust inside the shelter. However, more recent estimates have strongly questioned the previously held assumptions regarding the quantity of fuel remaining in the reactor. Some estimates now place the total quantity of fuel in the reactor at only about 70% of the original fuel load, however the IAEA maintains that less than 5% of the fuel was lost due to the explosion. Moreover, some liquidators estimate that only 5–10% of the original fuel load remains inside the sarcophagus.
Water continues to leak into the shelter, spreading radioactive materials throughout the wrecked reactor building and potentially into the surrounding groundwater. The basement of the reactor building is slowly filling with water that is contaminated with nuclear fuel and is considered high-level radioactive waste. Though repairs were undertaken to fix some of the most gaping holes that had formed in the roof, it is by no means watertight, and will only continue to deteriorate.
The sarcophagus, while not airtight, heats up much more readily than it cools down. This is contributing to rising humidity levels inside the shelter. The high humidity inside the shelter continues to erode the concrete and steel of the sarcophagus.
Further, dust is becoming an increasing problem within the shelter. Radioactive particles of varying size, most of similar consistency to ash make up a large portion of the debris inside the shelter. Convection currents compounded with increasing intrusion of outside airflow are increasingly stirring up and suspending the particles in the air inside the shelter. The installation of air filtration systems in 2001 has reduced the problem, but not eliminated it.
[编辑] Consequences of further collapse
The present shelter is constructed atop the ruins of the reactor building. The two "Mammoth Beams" that support the roof of the shelter are resting upon the structurally unsound West wall of the reactor building that was damaged by the accident. If the wall of the reactor building and subsequently the roof of the shelter were to collapse, then tremendous amounts of radioactive dust and particles would be released directly into the atmosphere, resulting in a devastating new release of radiation into the surrounding environment.
A further threat to the shelter is the concrete slab that formed the "Upper Biological Shield" (UBS), and rested atop the reactor prior to the accident. This concrete slab was thrown upwards by the explosion in the reactor core and now rests at approximately 15° from vertical. The position of the upper bioshield is considered inherently unsafe, in that only debris is supporting it in a nearly upright position. The collapse of the bioshield would further exacerbate the dust conditions in the shelter, would probably spread some quantity of radioactive materials out of the shelter, and could damage the shelter itself.
The sarcophagus was never designed to last for the 100 years needed to contain the radioactivity found within the remains of reactor unit 4. While present designs for a new shelter anticipate a lifetime of up to 100 years, that time is minuscule compared to the lifetime of the radioactive materials within the reactor. The construction of a permanent sarcophagus that can entomb the remains of unit 4 will undoubtedly present a daunting challenge to engineers for many generations to come.
[编辑] 車諾比基金與遮避物計畫
西元1997年在丹佛舉行的七國峰會同意提供資金成立車諾比遮避物基金。遮避物計畫(Shelter Implementation Plan簡稱SIP)將建造1個新的安全遮避構造(New Safe Confinment簡稱為NSC)把原來的遺址轉變成1個符合生態要求安全而穩定的石棺。 原始計畫預估將花費美金7億6千8百萬元。 SIP計畫將由Bechtel, Battelle, 和Electricité de France共同管理並設計，它將包含一個可移動的拱形結構，為了避免輻射，它將在遠離遺址的位置建造完再一步步移到遺址上方。 新的遮避物將是有史以來人類建造最大的可移動建築物。預估它將在西元2008年初建造完成. 尺寸 寬度: 270 公尺 高度: 100 公尺 長度: 150 公尺
[编辑] 切尔诺贝利事件後民众的觉醒
切尔诺贝利核事故引起了国际上的关注。世界范围内人们了解到了这次事故并对此事极为震惊。此后，切尔诺贝利这一名词在不同方面进入了公众的意识里。
[编辑] 參看
[编辑] 外部連結
