HPC

[Countrypaul]

I can see that as a real problem yes - although it's two 1.6GW nuclear plants co-located so unlikely that both would trip simultaneously, but can imagine the local grid management will be very complex?

Actually does anyone know what size the actual generators are? Surely it can't be one single 1.6GWp turbine/generator?

This makes it look appear there is just one generator per plant
https://www.intelligentcio.com/eu/2017/ ... t-uk-grid/

[Moxi]

I can see that as a real problem yes - although it's two 1.6GW nuclear plants co-located so unlikely that both would trip simultaneously, but can imagine the local grid management will be very complex?

Actually does anyone know what size the actual generators are? Surely it can't be one single 1.6GWp turbine/generator?

Hi Dan, yes thats exactly what it is although unlike older units the rotation is much slower at 1500rpm. so two 1600MW turbine per reactor. I am not sure - because I haven't followed the EPR design developments for the UK market that closely of late, but I believe on tripping the reactor the primary coolant circuit continues to produce steam via the secondary loop and therefore the turbine doesn't drop off the grid immediately and rather it coasts down to a terminal load disconnection point. This is all done in parallel with the auxiliary power systems which immediately on trip take the role of maintaining the primary and secondary cooling circuits so the turbines do not perform any coolant duties after trip and no safety case is linked to such a requirement.

Worth noting that the older PWR reactor runs two turbines in series (IIRC) so a HPT and I/LPT but thats why the PWR normally averages a poor 36% efficiency where as the AGR fleet was generally around 42% - not sure what the EPR claims but its better than a PWR.

There was a good argument for building more AGR's rather than an EPR back in the 90's but that would have needed the UK government to foot the bill - mind you if they had we might be operating at least two new reactors now with another 6 in construction.? All for around the same cost as Hinkley C too. ho hum

Moxi

[Mart]

On Sunday, the 1,600 megawatt Olkiluoto 3 nuclear reactor tripped again, the latest in a series of faults and outages that have plagued the new facility and caused the market to reach out for back-up power to fill the gap.

I can see this being a big problem for HPC also, when losing 3GW instantaneously can crash the grid !

Hi Ken. Can't find it now, but a decade or so back I did have a link to the estimated annual cost of backup for HPC. I think it was £12m, but I may be talking ballcocks.

The issue being exactly what you state, that the grid may struggle if it loses a reactor without warning, in this case 1.6GW, and nuclear power stations may in the case of some reactor issues, also shutdown the partner reactors, so potentially 3.2GW in the case of HPC.

Quite what that backup is, I don't recall, maybe simply paying FF generation to stay in a more ready condition, but I'm entirely making it up now.

Of course RE will also need backup, but that is typically a more planned / expected / slow transition, as weather changes, rather than potentially instantaneous.

[Countrypaul]

On Sunday, the 1,600 megawatt Olkiluoto 3 nuclear reactor tripped again, the latest in a series of faults and outages that have plagued the new facility and caused the market to reach out for back-up power to fill the gap.

I can see this being a big problem for HPC also, when losing 3GW instantaneously can crash the grid !

Hi Ken. Can't find it now, but a decade or so back I did have a link to the estimated annual cost of backup for HPC. I think it was £12m, but I may be talking ballcocks.

The issue being exactly what you state, that the grid may struggle if it loses a reactor without warning, in this case 1.6GW, and nuclear power stations may in the case of some reactor issues, also shutdown the partner reactors, so potentially 3.2GW in the case of HPC.

Quite what that backup is, I don't recall, maybe simply paying FF generation to stay in a more ready condition, but I'm entirely making it up now.

Of course RE will also need backup, but that is typically a more planned / expected / slow transition, as weather changes, rather than potentially instantaneous.

Unexpected failures from RE can share some of the same issues as other sources of power in that it can be down to equipment located after the generation but before the grid. In fact, was it not somethig like that a couple of years ago that resulted in some trains being stranded after the power from a wind turbine farm got cut at the same time as something else and triggered a shutdown of part of the grid?
Found it: https://www.theguardian.com/business/20 ... t-blackout

[Oliver90owner]

It would depend on the time of day in the near future, but back-up would still be required.

Battery storage would soon maintain the grid for a few minutes? Pumped storage would quickly take up the slack as long as it was not depleted or already running to the grid.

Open cycle gas turbines take a few minutes to start generating and any spinning reserve combined cycle gas generation would take longer.

I expect Hinkley would likely only trip the south west, so not quite as much chance of a widespread grid outage - but nevertheless a pita for those in the region!