核反应堆及其工作原理

核反应堆及其工作原理

日本地震引发的核泄漏危机使得人心惶惶，网上各种瞎扯的消息铺天盖地，与其在假消息中挣扎，倒不如来普及一下科学知识。核反应堆究竟是什么东西？它的工作原理是怎样的？今天我们就来图解福岛核电站故障。

核反应堆相关词汇表：

core 核心

control rod s 控制棒

reactor vessel反应堆

suppression pool 抑压池

primary containment vessel 第一层安全壳（反应堆外壳）

secondary containment building 第二层安全壳

turbine涡轮

condenser冷凝器

backup steam generator备用蒸汽发电机

Normal operation

正常状态

In operation since the early 1970s, Japan's Fukushima Daiichi nuclear plant uses six boiling water reactors, which rely on uranium nuclear fission to generate heat. Water surrounding the core boils into steam that drives turbines to generate electricity.

The reactor vessel is surrounded by a thick steel-and-concrete primary containment vessel, equipped with a water reservoir designed to suppress overheating of the vessel.

反应堆由一个钢与混凝土构成的厚实外壳（第一层安全壳）保护着，另外还配有一个蓄水库，防止反应堆过热。The suppression pool is designed to protect the primary vessel if the core gets too hot. Valves release steam into the pool, where it condenses, relieving dangerous pressure.

当核心过热时，抑压池可以起到保护第一层安全壳的作用。这时阀门会打开，水蒸气就能进入抑压池内冷凝，减缓压力过大造成的危险。

Earthquake damage

地震时

The earthquake initiated a rapid shutdown of the reactors, but the disaster cut power to controls and pumps, and the tsunami disabled backup generators. New diesel generators were delivered after batteries used to control the operation of the reactor were exhausted.

周五的地震切断了各种控制系统和水泵的电力供应，而海啸又使备用发电机组无法工作。在控制反应堆运作的电池报废后，不得不启用第二套柴油发电机。

Since the quake hit, fuel rods in the cores of reactor 1, 2 and 3 have overheated because of a lack of cooling water.

自地震以来，由于冷却用水的缺少，1、2、3号反应堆核心中的燃料棒一直处于过热状态。

Control rods were inserted into the cores to stop fission, but cores need several days to cool down. 控制棒已经插入，但是核心需要好几天时间来冷却。

Trying to cool the reactors

尝试冷却反应堆

Cores in units 1, 2 and 3 heated up to the extent that the zirconium covering the fuel reacted with steam, releasing hydrogen gas. Hydrogen collected in the secondary containment buildings, where it exploded, blowing the tops off units 1 and 3, and damaging the cooling system of unit 2.

1、2、3号反应堆核心的温度升高到了一定程度，使得覆盖在燃料棒上的锆元素与水蒸气产生了反应，释放出了氢气。氢气在第二层安全壳内聚集，最终爆炸，将1号和3号的顶盖炸飞，损毁了2号的冷却系统。Primary containment vessels in units 1 and 3 are reportedly intact, but a structure in unit 2 has cracked, preventing water from fully covering the core.

报道中称1号和3号的反应堆外壳是完好的，但是2号反应堆中的某个构架被炸坏了，致使水无法完全淹没核心。

Attempting to cool the cores, engineers are flooding cores and their containment vessels with seawater and boric acid, which acts to dampen fission reactions.

为了冷却核心，工程师们灌入掺了硼酸的海水，让核心及安全壳浸没在其内，以起到抑制裂变反应的作用。

Two worst-case scenarios

两种最坏的情况

If engineers are unable to cool a damaged fuel core, enriched uranium can melt into a pool of radioactive lava. The meltdown can burn its way out of the containment vessel or send radioactive steam out through cracks in the system.

如果工程师们无法成功冷却受损燃料核心，浓缩铀会像一滩具有放射性的熔岩，烧穿安全壳，或者让具有放射性的水蒸气从系统裂缝流入外界。

Cooling the spent fuel is critical, for if it becomes exposed, a zirconium fire can break out and spew massive amounts of radiation.

冷却用过的核燃料至关重要，因为一旦它暴露在外，就可能引发锆火灾，从而排放出大量放射物质。According to nuclear analyst Kenneth D. Bergeron, the containment vessels at Daiichi are stronger than Chernobyl but not as robust as Three Mile Island.

据核分析师Kenneth D. Bergeron所言，日本福岛第一核电站的安全壳的结实程度比切尔诺贝利的好，却没三里岛的好。

关于切尔诺贝利、三里岛以及这次福岛的核泄漏事故对比，来引用微博网友“功夫猫”的一句经典总结：

举个例子来说，切尔诺贝利那是坐便器和厕所都炸了，溅人一身；三里岛那个是下水道里面冒个泡，厕所里面一股臭气，但是没跑到厕所外面；福岛这个是厕所里面不断冒泡硫化氢太多炸了，臭气大量外溢，但是屎还没出来。。。