Hinkley Point C: Building Britain's first nuclear reactor in 30 years

Interesting, thank you for that.

Do you have a source for that and any context (eg: "not power" time being used for "experiments" related to UK military nuclear uses, etc)?

That's one of the reasons. Others include, but are not limited to:

1. The EPR is a FOAK build of a new design

All of the EPR instances were started before any other instances were completed. FOAK (First of a Kind) builds are notoriously more difficult, costly and risky than NOAK (Nth of a Kind) builds.

Think how much more a prototype of car costs than one you get off the assembly line. The difference is not quite that pronounced, but it's there.

2. No nuclear industry/workforce

I think the article goes into this, but a lot of the cost of HPC, Olkiluoto and Flamanville (as well as Vogtle-3/4) is simply for rebuilding nuclear expertise both in industry and in the workforce.

China also buit both EPRs and AP-1000s, and they did it quite a bit more quickly and cheaply, because they have an experienced workforce and industry at hand. They current have 20+ reactors under construction. That makes a huge difference as we know from experience. Just in Germany, the difference between one-off reactors and the Konvois that were built at the same time in series was around 2x.

However, even in China the EPR took longer than other reactors. Partly due to it being a FOAK design, but also for the third reason:

3. The EPR is too complicated

For various reasons, the EPR is far too complicated, and in the end not a good design. Which is one of the things you find out in FOAK builds (see point 1).

That's not me saying this, it's the manufacturer, EDF. They have abandoned the EPR design, all new French reactors will be the vastly simplified EPR2. I haven't been able to find out whether Sizewell C and subsequent will also be EPR2 or whether the UK will stick with its heavily modified EPR.

One example is that the EPR has quadruple independent cooling systems. This is in order to maintain triple redundancy while doing maintenance on the cooling system, so being able to do that maintenance without having to take the reactor offline. Considering the German PWRs were above 90% capacity factor with "just" triple redundancy, this seems to be gold-plating. Nice-to-have if you can pull it off, but it appears they couldn't pull it off.

Also, all those cooling systems have to be active in order to comply with German nuclear regulations. The somewhat silly reason is that German regulators both (a) had no experience with passive cooling systems and (b) had a prescriptive approach to regulation, rather than a requirements-based approach. So "you must build a cooling system like this" rather than "your cooling system must be able to do this".

It's is also obviously a bit redundant considering that Germany no longer operates nuclear power plants and isn't exactly currently in the market for an EPR.

The Westinghouse AP-1000 uses at least some passive cooling, which is not only more reliable but also simpler, smaller and cheaper and makes the total plant a lot smaller.

Once you've built one, the EPR is apparently a great reactor (the Fins are very happy with theirs), and should last a long time, but it's just a pain to build.

We only have so many lochs/valleys, realistically we will need to rely on batteries after about 20GWH or so.

The UK’s average nuclear load factor for 1970 to 2017 was 67.4 per cent. Furthermore, France demonstrated the correlation of nuclear downtime in the summer of 2022 when it was too summery, compounded with overrunning maintenance. At its lowest point, France’s nuclear availability sat at around 40% of maximum capacity for about a month.

All single power generators need to be backed up for downtime.

thanks for additional contribution! Agree, AP-1000 is extremely cool, China already has 4 reactors with it and more are in building phase