5 minute theories: Small nuclear reactors

Browse By

We all care about the world energy crisis. There are many ideas being discussed, but now some people in the UK are promising to solve the issue, as early as 2030, by putting a nuclear reactor into a shrinking machine and dotting lots of them around the country. So, will it work?

Solar energy and wind energy are unreliable, hydroelectric power is expensive and damaging, big nuclear reactors are scary, and fossil fuels are demonic. It is becoming clear that new solutions are needed now more than ever to secure a safe supply of clean energy to power our homes. This has paved the way for some interesting, perhaps far-fetched, ideas regarding what to do about this.

Small nuclear reactors (or SMRs: small modular reactors, if you’re in the know) are a subject of heated discussion right now. Last November, speaking at a summit of experts in finance, manufacturing and nuclear engineering, the UK Energy Minister, Richard Harrington, promised £32mn of funding to get them off the ground. He promised images of the sun-impoverished UK exporting energy to countries around the globe.

Here is a nuclear reactor:

Engineering spaghetti.

The underlying mechanism is much simpler than it may initially seem. The reactor is fuelled by very unstable, heavy atoms that have a tendency to break apart easily. These are known as fissile materials, like the word ‘fissure’. When they split apart in the reactor, they lose some mass and because E = mc^2, this mass goes to a lot of energy. One fuel tank of uranium contains as much energy as 1.7 million tanks of petrol. It is the same energy that nuclear bombs use, but the reaction is much quicker in that case.

This energy then turns to heat, which is used to generate a flow of steam that drives a turbine. This is how energy is generated. Afterwards, the system is cooled by water circulated through pipe; the steam from the turbine is passed over these pipes so that it condenses to be heated and passed through the turbine again.

It is a large, albeit rather clunky, system that efficiently generates a lot of power without taking up large amounts of land and without a whisper of CO2.

Things can go wrong though if the system overheats as there are very few ways of shutting it off quickly. The water inside the reactor then has to cool off over a period of days due to its size and the high pressure in the reactor makes explosions likely in the event of an error. If the safety systems have even slight flaws in them, you can end up with a runaway reaction. This is what happened in the 1986 Chernobyl Disaster.

Small modular reactors show promise as being the much-needed revamp that reactors have been waiting for since the 1960s. Their smaller size makes them easier to maintain and manufacture. They are also more convenient as they can fit easily on the back of a truck for transportation, and a reduced chance of errors will lead to far less consequential dangers. Indeed, simpler versions of those proposed are already used to power submarines and aircraft carriers.

The new reactors can supposedly generate around 300MW of power which is enough to meet the instantaneous demands of all homes in Bristol. Pulling this off has eluded researchers for a while now, but it is a proven technology and there are working units in Russia already. Rolls Royce is an example from a group of companies leading the drive to get these reactors regulated and implemented in the UK.

The idea is simple- apply what Henry Ford did for the car to nuclear reactors: take a largely individual and cumbersome manufacturing process and convert it to the form of a production line. This would mean that the manufacturer could make the reactor for another company to purchase, transport to site, and use. It would also make the manufacturing process much quicker, without an approval process needed for every single construction.

This could be a problem though. It seems like a recipe for a decentralised business model in which accountability is less enforceable. If companies churn out reactors, there will be an increasing number of them with the responsibility resting on an increasingly local set of authorities. This makes them harder to regulate and keep track of, which really isn’t something to be taken lightly. You could imagine it as authorities (and aspiring terrorists) being presented with a long list of potential bombs to oversee.

Also, if more companies become able to construct reactors, there will be an increasing mix of designs and variations that will be hard to maintain and source parts for. A lowered cost for their construction may lead to less experienced companies taking on the challenge. It will also lead to companies trying to compete for customers, potentially cutting corners and trying to find cost reductions in ways that compromise safety.

And, after all this, it is ultimately still nuclear power. The waste produced by nuclear power is highly toxic and polluting; no-one knows what to do with it other than bury it. Nonetheless, there are pros and cons to every method of energy production regardless. SMRs have similar benefits to renewables and thus seem just as likely to cover our needs: quite a high chance, but still decades away. These reactors, however, have the potential to do so with a fraction of the land area and, as a result, environmental impact.

Would you want one in your backyard though?

The future is still uncertain, but it’s definitely worth a thought.