Dear Dr. Zoomie – I’m worried about global warming because I live near the beach. The pro-nucks tell me that nuclear reactors don’t give off any greenhouse gases, but the anti-nukes tell me that you can’t make a safe reactor and we’ll just keep having more meltdowns will contaminate the whole world. What’s the real story?
Thanks – it’s been awhile since I’ve been asked a question that deals with the fate of the world. I guess, for starters, I have to say that I don’t think that nuclear energy is the solution to our problems – but I think that it’s part of the solution. I should also say up front that, while I have never worked for a commercial nuclear power plant (or for any sort of commercial power plant), I did spend 8 years in Naval Nuclear Power, including two years as an instructor and four years on a nuclear submarine. I also spent nearly two weeks in Japan after the Fukushima accident, helping to train emergency responders and medical responders in how to care for patients coming from the contaminated areas. So I think I’ve seen both some of the good and bad that nuclear power can offer – I hope that this helps me to be objective.
So – this is one of those “Do you want the good news or the bad news first?” sort of things. I normally go for the bad news first, so let’s start there. The bottom line is that, in the 70 years since Fermi oversaw the world’s first reactor criticality, the world has had three serious nuclear accidents in the nuclear age as well as a number of near-misses or less serious accidents. The result of these accidents is that large swathes of land in Japan, Ukraine, and Belorussia are currently evacuated and might not be reoccupied for decades. Huge amounts of radioactivity were put into the environment – the fallout cloud from Chernobyl and Fukushima blanketed the Northern Hemisphere, and Fukushima also dumped large amounts of radioactivity into the oceans. The accidents themselves have cost hundreds of billions of dollars and have had a global impact on the way that we view nuclear energy. And – at least in the case of Chernobyl – people have died. I should add that other accidents have killed people as well.
On the other hand, I should also point out that the World Health Organization conducted an extensive study of the people around Chernobyl in 2006 – on the 20th anniversary of the accident – and concluded that fewer than 100 people have died of radiation sickness or from radiation-induced cancer from that accident, and they also concluded that nobody in Japan will die from radiation-induced disease (including cancer) from Fukushima. Nobody got sick or died from the Three Mile Island accident, and only a handful of people have died from any of the other nuclear reactor accidents that have taken place. When we compare the number of deaths per gigawatt-hour of energy produced, nuclear actually stacks up quite favorably to other forms of energy – coal mining, hydrocarbon extraction and processing, and transportation of these fossil fuels are dangerous activities that cause hundreds to thousands of deaths annually; far more than the deaths from these accidents. And that doesn’t even get into the health effects of smokestack emissions, acid rain, and so forth. I’m not trying to say that nuclear power is harmless – just that we have to remember that no form of energy is without risk.
Ah – I hear you say – but if we build more nuclear reactors it’s only a matter of time until the next accident, and the more reactors we build the more accidents there will be. Well – yes and no. If we assume that the risk of an accident is the same for every reactor built then yes, this logic makes sense. But reactors have been getting safer with time – reactors built now are much less likely to suffer catastrophic accidents than those built in the 1980s. And – in case you’re wondering – factors that make reactors less likely to melt down or to have catastrophic accidents include operating at lower pressures (we can’t avoid high temperatures), simplifying the engineering designs, and making use of basic laws of physics to provide cooling in an emergency rather than pumps and other reengineered safeguards that require power to operate properly. Reactors powered by thorium, for example, have a number of features that make them almost impossible to melt down (sorry – this is far too much to get into here, but maybe at a later time; in the interim, http://energyfromthorium.com/ is a site where you can find some information if you’re interested). So if today’s reactors are safer than those built in the past, doubling the number of reactors won’t necessarily double the number of accidents. The bottom line is that some of the newest designs are virtually melt-down proof – not completely so, but pretty close. The bottom line is that the risk of meltdowns might increase, but not as much as one might expect. In fact, if we replace older reactors with the newer designs (in addition to building new ones), the risk of a meltdown might actually drop somewhat.
One last thing that’s touted as being a risk from nuclear reactors is the radioactive waste that they produce – more specifically, where it can be stored safely. At the moment the US has no long-term radioactive waste solution, but this is more a function of politics than of science. Again, there’s not enough space here to go into a full-blown discussion about radioactive waste disposal, but here’s something to consider: about two billion years ago a particularly rich uranium deposit achieved criticality and operated as a reactor for at least 100,000 years in what’s now West Africa. In the time since then, all of the fission products (the nuclear waste) have stayed put, in spite of the fact that the reactor zones are in porous and fractured sandstone and below the water table for most of that time. This bodes well for our ability to safely contain radioactive waste in an engineered facility set in much less-porous rock well above the water table.
The bottom line is that nuclear energy has its drawbacks, as does every form of energy. But these drawbacks are understood and can largely be managed – they certainly don’t call for abandoning nuclear energy altogether. Incidentally, you might also be interested to know that fossil fuels (coal, oil, natural gas) are associated with natural radioactivity due to the geochemistry of uranium. The radiation dose from burning any of these fuels is actually higher than the radiation dose from nuclear energy for every GW-hour of energy produced.
Now let’s look at the other side – the part of your question regarding nuclear energy and global warming. Here the argument is pretty simple – nuclear energy produces a lot of power and virtually no greenhouse gas at all; pretty attractive in a world increasingly worried about global warming. And – yes – some greenhouse gases are produced by the mining, processing, and transportation of uranium. But this pales in comparison to the greenhouse gas produced by fossil fuel plants.
There are other forms of low-carbon energy – solar, wind, tidal, and geothermal power come to mind. But each of these has its limitations – solar power doesn’t work well at night for example, the strongest winds are usually distant from the cities that use the most power, geothermal is only useful in a few location, and tidal power isn’t very useful in the continent’s interior. As of today, nuclear energy is the only form of non-fossil fuel power that can be used anywhere at any time. That’s not to say that nuclear energy is the answer to all of our problems (it isn’t) or that there’s no place for alternative energy sources (there is) – just that for reliable baseline power that can be put virtually anywhere on Earth and that doesn’t emit any greenhouse gases we just can’t get any better than nuclear at the moment. One of these days we might have fusion reactors, solar power satellites, or other exotic forms of energy – but not today and not in the plannable future.