This article is part of The Conversation’s worldwide series on the Future of Nuclear. You can read the rest of the series here, and a counterpoint to the views expressed in this article here.

Nuclear power is likely the least well-understood energy source in the United States. Just 99 nuclear power plants spread over 30 states provide one-fifth of America’s electricity. These plants have provided reliable, affordable and clean energy for decades. They also carry risk - to the public, to the environment and to the financial solvency of utilities.

Risk is the product of the probability of an occurrence and its consequence. The probability of dying in a car accident is actually quite high compared to other daily events, but such accidents usually claim few individuals at a time, and so the risk is low. The reason nuclear energy attracts so much attention is that while the probability of a catastrophic event is extremely low, the consequence is often perceived to be extremely high.

Nuclear power and public risk

In the US, commercial nuclear plants have been operating since the late 1960s. If you add up the plants’ years in operation, they average about 30 years each, totaling about 3,000 reactor years of operating experience. There have been no fatalities to any member of the public due to the operation of a commercial nuclear power plant in the US. Our risk in human terms is vanishingly low.

Nuclear power’s safety record is laudable, considering that nuclear plants are running full-tilt. The average capacity factor of these plants exceeds 90%; that means 99 plants are generating full power over 90% of the time.

If you compare that to any other energy form, there’s a huge gap. Coal is a mainstay of electricity generation in this country and has a capacity factor of around 65%. Gas is about the same; wind’s capacity factor is around is 30%, and solar is at 25%.

While the probability of a nuclear catastrophe is extremely low, it is only part of the risk calculation. The other part of risk is consequence. The world has been host to three major nuclear power generation accidents: Three Mile Island in 1979, Chernobyl in 1986 and Fukushima in 2011. To the best of our knowledge, Three Mile Island, while terribly frightening, resulted in no health consequences to the public.

Chernobyl was an unmitigated disaster in which the reactor vessel – the place where the nuclear fuel produces heat – was ruptured and the graphite moderator in the reactor ignited, causing an open-air fire and large releases of radioactive material. This reactor design would never have been licensed to operate in the Western world because it lacked a containment.

The scientific consensus on the effects of the disaster as developed by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) has identified 66 deaths from trauma, acute radiation poisoning and cases of thyroid cancer. Additional deaths may occur over time, as understanding the causes of death is a statistical rather than a deterministic process. Considering that the authorities didn’t alert the neighboring communities for many hours, the long-term health consequences of that reactor accident are surprisingly small.

And then there was Fukushima Daiichi. At least three of the reactors have sustained core damage, and there is potentially damage to the reactor vessel as well. At this time, no deaths have been attributed to radiation release at Fukushima, but an estimated 1,600 people died as a result of evacuation, and land contamination was widespread.

So if you look at these cases together, in Chernobyl, you had a reactor core on fire and open to the air; in Fukushima, three reactors lost all power during full operation and sustained major core damage, resulting in substantial radioactivity release in one of the most densely populated countries in the world.

These accidents had serious, lasting consequences that aren’t to be trivialized, but the consequences are nothing like what has been feared and glorified in movies over the past 50 years. What we’ve learned about public risk during that time is that the forecasted nightmares resulting from nuclear accidents, even in serious accidents, simply haven’t come to fruition. At the same time, as a society, we’ve come to accept - or at least look the other way from - thousands of traffic- or coal-related deaths every year in the US alone.

Waste containment: risk and storage

The production of energy in any form alters the environment. Coal and natural gas generate particulates, greenhouse gases and the like. In 2012, coal plants in the US generated 110 million tons of coal ash. Nuclear waste created by power generation is in solid form, and the volume is minuscule in comparison, but extremely toxic. Even the production of wind and solar energy generates waste.

Fuel for nuclear plants is in the form of fuel assemblies or bundles, each containing tubes of a zirconium alloy that hold hundreds of ceramic pellets of uranium oxide.

Each fuel assembly provides power for four to five years before it is removed. After removal, the fuel is considered to be waste and must be safely stored, as its radiotoxicity level is extremely high. Unprocessed, it takes about 300,000 years for the radiation level of the waste inside an assembly to return to background levels, at which point it is benign.

Vertical casks of nuclear waste being monitored.US Nuclear Regulatory Commission

Due to the cancellation of the Yucca Mountain site in Nevada, there is no place designated for long-term nuclear waste storage in the US, and utilities have resorted to constructing on-site storage at their plants. These storage containers were not designed to be permanent, and the Nuclear Regulatory Commission (NRC) is now licensing these temporary facilities for up to 100 years.

Many cheered when the Yucca Mountain project was shuttered, but waste still must be stored, and clearly it is safer to store the waste in a single, permanent depository than in 99 separate and temporary structures.

Monitored, retrievable storage is the safest approach to nuclear waste storage. Waste sites could be centralized and continuously monitored, and built in such a way that waste canisters could be retrieved if, for example, storage technology improves, or if it becomes economical to reprocess the waste to recover the remaining uranium and plutonium created during operation.

If we are to keep using nuclear power even at the present rate, our risks related to waste will increase every year until storage is addressed thoughtfully and thoroughly.

Infrastructure: same plant, different century

At the dawn of commercial nuclear power, the prospect of cheap, plentiful energy produced forecasts that nuclear energy would be too cheap to meter - we’d all be ripping the meters off our houses. But as plant designs evolved, it became clear that ensuring safety would increase the cost of the energy produced.

Every accident taught us something, and with every accident the NRC unveiled a new set of regulations, resulting in a system of plants that are, from the perspective of a few decades ago, much safer. Such tight regulatory oversight, while needed, drives up cost and means that utilities undertake significant financial risk with each nuclear plant they build.

Decades ago, the idea that the NRC would be granting 20-year license extensions to power plants was unheard of. Today, 75% of plants have received them. Now there’s talk about a second round of license extensions, and the NRC, the US Department of Energy and the industry are engaged in talking about what it would take to get a third. We’re talking about 80 or even 100 years of operation, in which case a plant would outlive the Earth’s population at the time it was built.

The Indian Point plant, about 50 miles from New York City, is seeking to extend its operating license for another 20 years.Tony Fischer/flickr, CC BY

In the shorter term, life extension makes sense. Most of the plants in the United States are Generation 2 plants, but Generation 3 is being built all over the world. Gen 2 plants are proving very robust, and existing plants are quite economical to operate. Gen 3 plants, like Vogtle now being built in Georgia, boast better safety systems, better structural components and better design.

Would I rather have one of those than the one I have now? Absolutely. The risk of operating such a facility is simply lower. At US$4.5 billion to $10 billion, Gen 3 plants are very expensive to build, but we must either accept that capital outlay or find another source of electricity that has all the benefits of nuclear energy.

How much risk do we accept?

As a society, we accepted over 32,000 traffic accident deaths in 2013, and no one stopped driving as a result.

I think most people would be surprised to know that in 2012, seven million people globally died from health complications due to air pollution and that an estimated 13,000 US deaths were directly attributable to fossil-fired plants.

US deaths from coal represent an annual catastrophe that exceeds that of all nuclear accidents over all time. In fact, nuclear power has prevented an estimated 1.84 million air-pollution related deaths worldwide. Natural gas plants, increasingly being constructed around the country, are highly subject to price volatility and, while cleaner than coal, they still account for 22% of carbon dioxide emissions from electricity generation in the US. This is not to mention the illogical use of this precious resource for electricity generation versus uses for which it is more uniquely suited, such as heating homes or powering vehicles.

And until the capacity factor for renewables increases dramatically, the cost drops and large-scale storage is developed, they are simply not equipped to handle the bulk of US energy needs nor to provide electricity on demand.

Through the NRC’s oversight and the work of researchers all over the world, we have applied lessons from every global nuclear event to every American nuclear plant. The risk inherent in nuclear plant operation will always be present, but it is one of the world’s most rigorously monitored activities, and its proven performance in delivering zero-carbon electricity is one that shouldn’t be dismissed out of fear.

This article is part of The Conversation’s worldwide series on the Future of Nuclear. You can read the rest of the series here, and a counterpoint to the views expressed in this article here.

Gary Was does not work for, consult to, own shares in or receive funding from any company or organisation that would benefit from this article, and has no relevant affiliations.