top of page
  • Writer's pictureRiver Champeimont

Does more nuclear energy lead to more nuclear weapons?

Updated: Feb 13, 2021

If you have read my last article about nuclear power, you have seen that nuclear energy still has major advantages until we are able to store electricity on a large scale, and can therefore be of great help to tackle climate change in the next 20 years. But should we promote the deployment of nuclear power everywhere in the world, especially in countries that do not have nuclear technology today? Isn’t there a risk that some countries use the technology to develop nuclear weapons?

This is a very tricky question because it involves some political intuition and not only pure scientific facts, unlike my previous articles about nuclear power on which I “only” needed to gather scientific facts and learn the state of the art on the subject. I will be giving you my own thoughts and I will try to state honestly the facts we know about proliferation and the arguments for both sides, but there are no absolute truths on such subjects, so feel free to disagree in comments.

Born in darkness

Let’s first note that, sadly, nuclear fission was first used to make bombs before it was used to produce electricity. As you know, nuclear weapons were first used in World War II in 1945, while the first nuclear power plant was built in 1951 in Russia and provided electricity for the first time in 1954. The United States quickly followed with the first town to be powered with nuclear energy in 1955, that is 10 years after they had used their nuclear bomb.

BORAX-V: One of the first nuclear reactors built in the United States

In the case of nuclear power, development of the initial technologies was done in parallel and in cooperation with the military, which was using nuclear technology both for weapons and for propelling military ships and submarines. The result is that we have inherited technological choices that were initially designed not to prevent nuclear weapons proliferation, but to ease the development of nuclear weapons by re-using the technology and the fissile material (enriched uranium, plutonium).

How nuclear weapons can be made

Uranium enrichment

Natural uranium found in mines is composed mainly of uranium-238 (99.3%) and of far less uranium-235 (0.7%), that are tightly mixed together. Uranium enrichment is the process of increasing the uranium-235 ratio. To use the uranium as nuclear fuel in light-water reactors, it is necessary to increase it to between 3% and 5%. Light-water nuclear reactors are the most widely used design in the world. It was mainly developed in the United States and later adapted by France for all its nuclear reactors. This technology is also used in nuclear-propelled submarines.

Centrifuges used to enrich uranium

The proliferation issue here is that the same enrichment technology can be used to enrich uranium to much higher ratios (like 80%) which allow to make Hiroshima-like nuclear weapons. The typical risk is that a country can pretend to develop enrichment technology for energy purposes, and then switch to military-grade enrichment levels. For these reasons, nuclear reactors using this technology are often exported without the enrichment technology, and the country buying the nuclear power plant needs to buy the enriched fuel from a country that already performs enrichment.

Plutonium reprocessing

Some reactors, called heavy-water reactors, used in Canada for instance, can actually use the natural uranium “as is” without any enrichment. The advantage is that this technology can be exported to countries which we don’t trust to develop uranium enrichment, without requiring them to depend on other countries for enriched uranium. However, there is another proliferation risk here. These reactors produce more plutonium in their used fuel, which can then be extracted and used to make nuclear weapons. For example, the bomb dropped on Nagasaki used plutonium that was generated this way (in a reactor specifically built for this purpose, not in a nuclear power plant, but the nuclear reaction to make plutonium here is the same).

The current situation with nuclear proliferation

A major step towards the reduction of nuclear weapons was the Non-Proliferation Treaty (NPT) in 1970, and was ratified by most countries in the world, the majority of them having no nuclear weapons. The countries recognized as possessing nuclear weapons then were the United States, Russia, the United Kingdom, France and China.

The goals of the treaty were to prevent any new country from getting nuclear weapons, and to reduce, and eventually destroy, all existing nuclear weapons in the current nuclear countries. In exchange, countries with nuclear technology agreed to help other countries develop civil nuclear energy too.

As you already know, the promise to eliminate nuclear weapons entirely has never been fulfilled. However, there was some success with the reduction of the number of nuclear weapons, as you can see in the chart below. Also, South Africa has completely eliminated its nuclear weapons, as well as some former USSR countries when the USSR was dissolved (Russia kept the nuclear weapons).

Number of nuclear warheads of the United States and the USSR.

Another failure of the treaty was that new countries have actually acquired nuclear weapons:

  • India, Pakistan and Israel refused to sign the treaty, and developed nuclear weapons (or made it ambiguous whether they did in the case of Israel)

  • North Korea signed the treaty but violated it by developing weapons and detonating test nuclear bombs.

The frustration with the lack of success of the NPT at eliminating all nuclear weapons has led some countries to propose an alternative treaty, the Treaty on the Prohibition of Nuclear Weapons, which would ban nuclear weapons completely, just like what is already in effect for biochemical weapons or anti-personnel landmines. By this treaty, signatories promise to never try to develop or use any nuclear weapons. This new treaty went into force very recently, on January 22nd, 2021. However, no current nuclear weapons country has agreed to sign it, so its effect is limited to containing some nuclear proliferation, but it will not lead to any reduction in the arsenal of existing nuclear powers.

Also very recently, as a result of policy change following the inauguration of Joe Biden as the new president of the United States, the US and Russia have agreed to extend the New START treaty for five years, in which both nations agreed to reduce the number of nuclear missile launchers.

Does more nuclear energy lead to more nuclear weapons?

Let’s now get to the hard question, which is whether promoting more nuclear energy in the world increases the proliferation risks.

The current anti-proliferation political system

First, we need to remember that in the Non-Proliferation Treaty (NPT), countries without nuclear weapons agreed not to develop them in exchange for both elimination of those in nuclear countries (which did not happen) and helping non-nuclear countries access civil nuclear power. So the access to civil nuclear power plays a role as an incentive for countries to follow the rules of the NPT. Without this reward, there is basically no counterpart for non-nuclear countries. To get access to civil nuclear technology, signatories need to accept the controls of the IAEA (International Atomic Energy Agency) that checks that nuclear technology is not diverted to military uses.

In theory, countries which don’t respect the Non-Proliferation Treaty (NPT) cannot import nuclear technologies and fuel, as those are controlled by the Nuclear Suppliers Group (NSG) which includes all nuclear power technology suppliers. For this reason, Pakistan, India and Israel are banned from the NSG (this is one of the reasons why Israel has no nuclear power plants although it probably has nuclear weapons). But China agreed on a civil cooperation with Pakistan anyway, and the United States did the same with India. So in practice the ban is subject to geopolitical strategies of big powers.

The nuclear know-how risk

If a country wants to develop nuclear weapons, it needs some knowledge on how to operate nuclear facilities in practice. A strategy for a country to develop nuclear weapons can therefore be to first pretend to develop nuclear power for pacific uses, in order to develop nuclear technology, accumulate know-how and uranium stockpiles. Then, it can break the treaty and repurpose all of these for nuclear weapons.

North Korea is an example of this kind of strategy. It had built an experimental nuclear reactor which used non-enriched uranium, but then extracted some of the plutonium of military uses. The IAEA discovered it in 1992, but the evil was already done, as they now had the plutonium. And as you know, they have since developed actual nuclear weapons.

This is also how India made its first nuclear weapons, by extracting the plutonium produced in a research heavy-water reactor that was built with the help of Canada and the United States. This happened before the IAEA safeguards were put into place, so we could argue that it would not be so easy today.

A last argument against the promotion of nuclear power around the world is the problem of nuclear latency or nuclear hedging. Some countries like Japan have very advanced civil nuclear technology, with both uranium enrichment and plutonium reprocessing used regularly for civil power plants. This means that it would be very easy for them to use these working facilities to enrich uranium to military grade, and to combine it with the extracted plutonium* to make a bomb. Some countries are suspected to rely on a strategy called “hedging” which means that they don’t actually build nuclear weapons, but they are making sure they could build them if they feel it becomes necessary, for example if a rival country develops them. If a lot of countries become “ready” like this, it can make development of nuclear weapons more likely if one country starts a cascading effect.

*Erratum: It is in fact not possible to extract military grade plutonium from nuclear reactors in service in Japan, because the plutonium has to be extracted quickly which is not possible with their type of reactor. It would therefore be necessary to build a reactor designed precisely for the purpose of generating military plutonium.

What about nuclear power at home?

For the reasons I have explained, one may argue that it might be a bad idea to promote nuclear power all around the world. But what about promoting nuclear power in industrialized countries that already have nuclear technology?

An anti-nuclear argument could be that the local nuclear industry wants to sell nuclear plants abroad, so by doing that, it exports the technology and increases the proliferation risks. If we stopped using nuclear power entirely, our nuclear industry would disappear (that is itself an hypothesis), so it wouldn’t be able to export its technology any more and lead to the risks of technological diversion described above.

However, I find this argument moderately convincing, because other nuclear powers might just take the market instead of our local nuclear industry, and might even be more irresponsible. This argument would be valid if there was a way to agree to phase out nuclear power all around the world, which seems unlikely.

Is thorium the solution?

Some people lament that it’s the choice of uranium as the nuclear energy source which leads to these problems. According to thorium proponents, if nuclear power had been designed from the start for pacific uses only, different technological choices would have been made, and thorium would have been chosen instead of uranium. Without uranium, there would be no risk related to uranium enrichment, and plutonium would not exist at all (plutonium is not found in mines like uranium, it appears as the result of transmutation of uranium-238 in nuclear reactors).

However, although this might be true, switching the entire nuclear industry from uranium to thorium would take perhaps 20 to 30 years. This is not impossible, but it makes the case for nuclear energy very weak I think, as by this time renewables will probably be very cheap and large-scale electricity storage might even be possible at a reasonable extra cost. The appeal of nuclear power is that this technology is available right now to fight global warming, in a mix with other decarbonized energy sources, as I explained in my earlier article.


Nuclear proliferation is a complicated subject. I think we cannot just ignore the risks of developing more nuclear power in the world and the risk that some governments would divert the nuclear facilities and materials for military purposes.

Choosing energy sources is a trade-off between the proliferation risks with nuclear power, the global warming risks with fossil fuels, and the economical risks with variable renewable sources (wind and solar). If nuclear power becomes non-competitive in the future thanks to large-scale electricity storage and cheap renewables, there might be a case for eliminating nuclear technology to reduce proliferation risks. But, before this happens, we might still need some nuclear power, and we have to make the best effort to prevent nuclear weapons proliferation.

To learn more

57 views0 comments

Recent Posts

See All


bottom of page