On a December afternoon in Chicago during the middle of World War II,scientists cracked open the nucleus at the center of the uranium atom and turned nuclear mass into energy over and over again.

第二次世界大战期间，时值芝加哥12月份的一个下午，科学家们敲开了铀原子中心的原子核，一遍又遍地重复将质量转化成能量这一过程。

They did this by creating for the first time a chain reaction inside a new engineering marvel:the nuclear reactor.

他们创造了在世界上尚属首次的连锁反应工程新奇迹：核反应炉

Since then, the ability to mine great amounts of energy from uranium nuclei has led some to bill nuclear power as a plentiful Utopian source of electricity.

自此，人类从铀原子核中提取巨量能源，使一些人将核能视为一种非常充足的乌托邦式电力来源。

A modern nuclear reactor generates enough electricity from one kilogram of fuel to power an average American household for nearly 34 years.

一个现代的核反应堆装填一公斤的核燃料所发的电力足够一个普通美国家庭使用大约34年。

But rather than dominate the global electricity market,nuclear power has declined from an all-time high of 18% in 1996 to 11% today.

但核能并没有占据全球电力市场的主导地位反而从1996年的18%的历史高点下降到现在的11%

And it's expected to drop further in the coming decades.

而且预计在未来的几十年里，还将进一步下滑

What happened to the great promise of this technology?

核能发电这项技术的美好前景到底遭遇了什么？

It turns out nuclear power faces many hurdles,including high construction costs and public opposition.

事实证明，核能发电面临着许多障碍，包括高昂的建设成本和公众的反对声浪。

And behind these problems lie a series of unique engineering challenges.

这些障碍背后还有一系列罕见的工程挑战。

Nuclear power relies on the fission of uranium nuclei and a controlled chain reaction that reproduces this splitting in many more nuclei.

核子能量的释放依赖于铀原子核的裂变和受控的连锁反应，连锁反应在旁边的众多铀原子核中复制了这种裂变

The atomic nucleus is densely packed with protons and neutrons bound by a powerful nuclear force.

密密麻麻包围着原子核的质子和中子，受到强大的原子核力束缚

Most uranium atoms have a total of 238 protons and neutrons,but roughly one in every 140 lacks three neutrons,and this lighter isotope is less tightly bound.

多数铀原子质子和中子的个数加起是283个，但是大约每140个铀原子就有一个铀原子缺少3个中子，这种轻的铀同位素结合地还不太稳定。

Compared to its more abundant cousin,a strike by a neutron easily splits the U-235 nuclei into lighter, radioactive elements called fission products,in addition to two to three neutrons,gamma rays,and a few neutrinos.

与它稳定的亲戚相比，一个中子的撞击轻易地将铀-235分裂成更轻的放射性元素，即裂变产物，裂变产物还包含二到三个中子、伽马射线和一些中微子。