Small Modular Reactors: wishful thinking on a grand scale

Take a large number of scientists who have grown up with the firm belief that nuclear power is the future of energy, face them with the fact that nuclear power is proving to be undeliverable in anything like the scale, time and cost that has been originally envisaged in UK Government plans, and what do you get? Wishful thinking about 'small modular reactors' or 'smrs'! You can see this in the article in the Times by Lady Judge at :
http://www.thetimes.co.uk/edition/business/when-it-comes-to-nuclears-future-its-time-to-think-small-ntnqhvnrr

She says that:
'The plan to focus on building large reactors was originally conceived before Fukushima, while I was chairwoman of the UK Atomic Energy Authority, and when fossil fuel prices were expected to keep going up. Large nuclear plants, however, are expensive and take a long time to build. In the interim, one answer is small modular nuclear reactors. Being small is useful because they can be built in one place and transported to another, such as the site of one of the coal plants that we are in the process of shutting down, or even an industrial park. Modular, in this context, means that more plants can be added easily on an existing site. The flexibility and lower cost of small reactors is a way of getting greater private sector involvement, without the more complex financing arrangements needed for a larger plant'

The impression you get from this is that the idea of large nuclear reactors is some sort of fairly recent deviation, and that somehow there was some golden era when (presumably) smrs were abandoned through some mistake. The advantages of smrs are stated as if there is evidence for this.
There is no evidence at all for this, and indeed the notion that smrs would ever be cheaper than large reactors flies in the face of engineering logic.

Nuclear reactors in the UK (and in the rest of the world) have been steadily scaled up from around 200 MWe in size to begin with, up to around 500 MWe in the 1960s, and then up to over 1000 MWe in the 1980s and 1990s. Contrary to the impression given in Lady Judge's article, this was not a recent decision or trend. And there are sound engineering reasons for this, including one very simple one: for complex machines with moving parts and the need to ensure (safe) functioning of each unit each unit needs much the same input for design as a much larger unit.

By way of comparison, if you want to build a gas fired power station to generate, say, 500MWe of power, people don't lash together dozens of small gas turbines - that would be financial madness. You have smaller gas turbines when the circumstances demand it, you do not do it out of choice because they generate much cheaper power at much bigger scales. To minimise costs developers will prefer to build one large unit, and they can take several years to build, although of course there is much more certainty about the costs and timescale of building gas fired power stations compared to nuclear power plant. Given that nuclear reactor sets will need much more safety care compared to gas fired power plant, there is no way in this universe that the principles applied to gas turbines are suddenly going to be reversed in the case of nuclear reactors - indeed the reverse is likely to be the case - ie there is even more pressure to upscale nuclear reactors compared to gas-fired power plant.

Sometimes we hear talk about the nuclear powered submarines built by Rolls Royce. But these generate no more than a few MWe of power and whilst we don't know how much they cost exactly, the submarines cost billions of pounds each. Rolls Royce may well be keen to get down to earning money through doing research in smrs, but will they be able to contribute to a project that is cheaper than Hinkley C? I think not.

There is of course no comparison to be made with solar pv cells. They are very small, passive items, with no unit specific design costs. They can be assembled along massive production lines allowing big economies of scale and where you can also get very big supply chain economies of scale - on the basis of just 250-300 watts each. You can, and solar pv companies do, produce hundreds of thousands of units a year. This is simply on a different dimension to nuclear reactors.

The moral of this story maybe that it doesn't matter how clever people are, they can still have unlikely beliefs. The fact that so many scientists appear to subscribe to the nonsense about smrs says something about how being clever doesn't protect you from believing in rubbish, not that smrs are somehow a cost-effective prospect. Never in the history of humankind, (so far as I am aware) have so many clever people subscribed to such an inherently ludicrous concept before!