Thoughts on the eternal headache that is nuclear power – part 1 of 6

People keep asking me about nuclear power. This might be down to living in NZ, where people who know anything about it are few and far between. Or it might be because they pay me to think about energy systems. I put together the Royal Society of New Zealand’s energy report in 2006 (although I’m speaking purely for myself here). And I have worked with a whole bunch of researchers who worked in the UK nuclear industry. And I don’t work for anyone who’s trying to sell you anything. So, here’s my quick thots, rather than an in-depth, months of research kind of analysis that you’d normally pay me a decent wage for. And it’s going to look like this:
1) What’s the issue
2) What’s wrong with nuclear power from a technological point of view
3) What’s wrong with nuclear power from a economic point of view
4) Why thorium isn’t as easy as you’ve been told
5) What’s wrong with nuclear power – in a real sense and why none of this matters to New Zealand
6) Why the UK has some hard choices to make

It turns out I’ve a fair amount to say on this topic, but the TL;DR version comes down to this: The Trojan nuclear power plant in Oregon was designed with potentially-explosive tanks of hydrogen mounted on the roof of the control room. How anyone ever thought that was a good idea, I’m baffled. But hey, given that the nuclear industry is so highly regulated and committed to safety, you’d think that someone would have spotted that little design flaw before building the plant, right? Wrong. You’d think that someone would have checked this before connecting the plant to the grid and turning it on? Wrong. In fact, it ran for thirteen years before anyone noticed, at which point I expect some harsh language was used.

Getting over technophilia and recognising how multifaceted this is:
The whole debate about energy is far more complicated than people think. There’s a strong tendency, especially amongst geeks, to say “technology X will save the day”. Technology X may be better than all the other technologies, for one particular measure, in isolation. But we want our energy system to:
1) give us power at the lowest cost;
2) have low greenhouse gas emissions;
3) and be safe;
4) and be utterly reliable;
5) and grow as fast as we need;
6) and not look ugly;
7) and not make us dependent upon dodgy foreign regimes;
8) and a whole bunch of other criteria that I haven’t thought of yet, but someone will raise.

And we’re talking about national (or international) energy systems, so none of this exists in isolation, even for an island like New Zealand.

So let’s just look at one tiny part of this debate and see how people are not thinking hard enough. One part of the problem is that we need electricity with lower greenhouse gas emissions. To compare emissions, we need to look at the total life-cycle emissions of each kind of generation, from building the generating plant, getting the fuel, making the electricity, and then getting rid of the waste and the plant at the end of its life. And not surprisingly, lots of people have done this kind of analysis, especially to compare nuclear plants with renewables. Let’s look at what everyone looks at, Wikipedia, and see what they say:

“nuclear power plants produce electricity with about 66 g equivalent lifecycle carbon dioxide emissions per kWh, while renewable power generators produce electricity with only 9.5-38 g carbon dioxide per kWh…. Renewable electricity technologies are thus two to seven times more effective than nuclear power plants on a per kWh basis at fighting climate change”. So if you want to get your hands on a kiloWatt-hour of electricity, then nukes will have higher emissions of greenhouse gases than renewables (according to this estimate).

So, pretty clear, yes? Simple numbers, renewables have lower emissions than nukes, so renewables good, right?

Wrong. This is entirely the wrong question. It misses the context. It ignores the fact that we’re already burning lots of coal, and coal is God-awful when it comes to emissions. For coal plants, you’re looking at around 1000 g per kWh. So, replacing coal with nukes saves you 933 g per kWh, replacing coal with renewables saves you 960-990 g per kWh. Renewables are not “two to seven times more effective… at fighting climate change”. It’s all much of a muchness between nukes and renewables for fighting climate change. What matters is getting rid of coal.

And, of course, there’s more to this than just fighting climate change.

Tomorrow – why nuclear power stations keep surprising engineers.

8 thoughts on “Thoughts on the eternal headache that is nuclear power – part 1 of 6”

  1. I’m fascinated as to the need to store H2 in a nuclear power plant.

    Was it an exotic coolant/moderator? Or to inflate a balloon / airship based escape pod for the operators?

    Or did the plant produce quantities of H2 from coolant/cladding reactions or similar, and they felt it was better to store it than flare it?

    1. It turns out that the hydrogen was used by the plant and delivered from elsewhere. Here’s the NRC regulation notice:

      “Hydrogen is used on pressurized water reactor (PWR) plants for (1) providing a cover gas in the volume control tank, and (2) for cooling the main turbine generator.”

      The volume control tank is used to control the volume of the water in the cooling loop, so they use hydrogen to keep down the levels of oxygen in the water. For cooling turbines, I presume you get much lower drag than air cooling and more cooling than putting the turbine in a vacuum.

      But yeah, enough hydrogen to be equivalent to over 200 kg of TNT. On the control room roof.

  2. One thing you missed explaining (probably because its obvious to you, but it may not be to others) is why the Control Room is so damn important.

    I am currently working at NZ power company, but generally don’t go to Generation sites. I really only got to understand how a power plant functions from the management site until I had some work to do at the power plant.

    They had a nice DVD fronted by the CEO (which was a good way of stressing its importance) explaining why the Control Room needed to know where I was at all times.

    As well as dealing with the management of the plant, the Control Room was spending 24 hours a day being prepared for stuff about to go wrong, which involved knowing where everything, everyone, and all work happening, at all times.

  3. Lifecycle carbon dioxide emissions per kWh

    “nuclear power plants produce electricity with about 66 g[…]”[…]For coal plants, you’re looking at around 1000 g per kWh[…]So, replacing coal with nukes saves you 933 g per kWh

    For large values of 66, small values of 1000, or where 0=1, presumably. (I’m guessing small values of 1000, since 1000 seems to have fewer significant digits than the other two values.)

    I can’t help thinking “The perfect is the enemy of the good” here, as in many other parts of life. It also appears to me that at (over) 10:1 savings, procrastinating for years about what to do while continuing to do the least desirable thing (viz, burning coal) is plausible more damaging than anything else which might be done, by orders of magnitude.

    Aside from that, optimisation is hard. Especially where you have no agreement on what you are supposed to be optimising for most, and what may be acceptably traded off to enhance the things you are optimising for.


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