A single kilogram of uranium produces about 2 million times more energy than 1 kilogram of coal. Some may consider that a spectacular feat since you don't have to heat uranium to make that happen; it heats itself through a process called fission. Nuclear reactors cause atoms in some materials to split, unleashing the energy stored in those atoms. Though the advantages of nuclear energy are numerous, there are still significant drawbacks and cons of nuclear energy.

A common type of nuclear reactor core houses thousands of metal rods that hold uranium fuel. As nuclear fission occurs (the splitting of atoms), the fuel releases heat that causes water surrounding the rods to boil and produce steam which rotates a turbine to make electricity. A nuclear power plant operates with practically no carbon emissions, but it is not necessarily classified as renewable energy or clean energy because of the nuclear waste that is left behind.

It is important to note that nuclear reactors designed for producing electrical power are very distinct from the nuclear components and designs used to make nuclear weapons. The uranium used in nuclear power reactors is low-enriched meaning it does not have the density of uranium-235 that would be found with weapons grade uranium.

A meltdown occurs when a reactor core overheats and radioactive fuel escapes. If that hot fuel melts through barriers designed to keep it in, radioactive material could escape into the area outside the reactor. The Three Mile Island nuclear reactor in Pennsylvania experienced a partial meltdown in 1979, safety measures have tightened since this concerning incident. In 1986, the Chernobyl reactor in Russia sent radioactive material as far as Sweden and large swathes of the surrounding region are still considered uninhabitable today. More recently, three reactor building explosions and three core meltdowns occurred at Japan's Fukushima nuclear plant after an earthquake and tsunami rocked the country in 2011. The accident contaminated air, water, homes and farms and displaced 160,000 people. In 2015, extremely low levels of radiation from the Fukushima mishap were recorded on North American shores. As of April 2015, radiation wasn't considered high enough to significantly threaten marine or human life.

These meltdowns and nuclear accidents vary greatly in their severity and longevity, and new nuclear plants are continuing to be designed with the utmost safety in mind. Safety has improved greatly just within the last decades. The Chernobyl disaster was largely a result of mismanagement and improper safety that lead to faulty containment of radiation, and it has rendered the area around Chernobyl uninhabitable by humans for almost four decades. However, the most recent accident in Fukushima, Japan demonstrates the progress in safety and nuclear technology. A natural disaster severely damaged the reactor, and it did cause leakage, but the area has mostly recovered in only a few years.

Electricity sent to customers from the nuclear power plant is the good news; the bad news – nuclear waste – sits in secure storage sites around the country. All American nuclear power plants collectively produce around 2,000 metric tons of radioactive waste yearly. You can't simply toss this waste into a landfill because radiation can harm living creatures and the environment. Thousands of years can pass before plutonium and some other elements in this waste lose their radioactivity. It's also expensive and risky to transport nuclear waste to its final destination over public roads. Despite ongoing efforts and the expenditure of $10 billion, the nation's proposed central storage site at Yucca Mountain in Arizona is still not approved for construction. As of April 2015, the United States is still depending on scattered interim storage sites.

It's expensive to build new nuclear power plants because of several factors. To construct a large nuclear reactor, you need thousands of components, thousands of workers, costly materials, such as high-quality steel, and systems that provide the reactor with ventilation, cooling, communication and electricity. According to the Union of Concerned Scientists, the cost for a nuclear power plant hovered around $9 billion as of 2008. The UCS estimated that, if plans proposed in 2009 had been built, the taxpayers would have been on the hook for as much as $1.6 trillion. Post Cold War-era design methods are one of the biggest cons of nuclear power generation, and it's why plants cost so much. Because older designs were not standardized, builders would customize new plants their own way. As plants got bigger, their costs scaled up as well because they needed more expensive materials. Newer modular designs that use mass-produced materials could reduce plant construction costs. Nuclear power plants are relatively inexpensive to operate after they're built.

There are numerous drawbacks and dangers associated with nuclear energy, but in the transition away from fossil fuels it could be a key component of global action to reduce carbon emissions. The biggest hurdle to tackle with nuclear energy production might not actually be the cost, waste, or safety – because we are constantly making huge strides in all of these respects; instead, perception of risk is actually very difficult to handle.

Coal plants and natural gas burning produce billions of tons of carbon dioxide, methane, and greenhouse gas emissions each year. These emissions will continue to have long term, and increasingly immediate, impacts on health, society, and economies, but fossil fuel power plant safety and air pollution from these forms of energy are directly resulting in hundreds of thousands of deaths annually. Renewable energy sources and nuclear energy both cause significantly fewer casualties (scaled for the amount of energy produced), but the disasters and casualties within the nuclear industry often draw more public attention because of their larger and more singular nature (i.e. meltdowns and failures like Chernobyl). In reality nuclear power stations draw about as much risk as renewable energy sources, and large-scale implementation of nuclear fission (and maybe nuclear fusion someday) could actually provide a cleaner source of energy to help combat climate change.

There is no perfect answer to the climate crisis, and innovation across all sectors of energy – solar power, wind energy, geothermal, and nuclear fuel – will prove invaluable in protecting our world.