Comment by AustinDev | Hacker News Reader

Comment by AustinDev | Hacker News Reader

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You're likely not an electrical engineer by training so I will assume you don't know much about power generation and distribution. (It's worth noting my training in this field is nearly 2 decades old so I'm a bit rusty but I still follow several publications in the field) Engineers have been warning about inertia and voltage control being neglected as renewable penetration has soared. These aren't normally of much concern when you are spinning a large mass to generate AC power.

> fyi, the root cause of the Spain blackout (not blackout) is not yet known.

While the final official reports may not be out initial data has been released and indicates frequency and/or voltage oscillations got out of hand causing generation disconnection and cascading blackouts. Renewable penetration in that area of the grid likely contributed to the brittleness especially in voltage control and inertia management.

"Inertia management is increasingly critical for grids with high renewable penetration. Many such systems now implement inertia floors to limit the maximum rate of change of frequency during disturbances. While inertia is often considered primarily for frequency stability, it also plays a crucial role in preventing loss of synchronism between different parts of the grid. As conventional synchronous generation decreases, careful monitoring and management of system inertia becomes essential to maintain stability during disturbances." [1]

>"healthy mix of generation" is quite funny to read, thinking about nuclear and coal which are not too healthy for the people living close to the plants :-D

I'll give you coal as unhealthy but natural gas is much cleaner and nuclear is entirely clean, save waste management which is a solved problem.

How does nuclear effect residents living nearby? I'm not aware of any reporting of systemic illness near any of Europe's nuclear plants but, I may just be ignorant of the latest research. Care to provide a link?

[1] https://www.powermag.com/understanding-the-april-2025-iberia...

Thanks for your factful reply :)

Regarding the nuclear risk - it is driven by incidents. If the plant had not incidents, there would be no risk.

E.g. the childhood leukemia risk is double inside a 5km radius, and there is no good explanation for this (except the occasional release of radioactive exhaust in case of incidents). (https://www.bfs.de/DE/bfs/wissenschaft-forschung/wirkung-ris..., link is in German, sorry)

Same is true for the nuclear plant workers. Their cancer risk grows linearly with their exposure - which I assume is also an effect of minor incidents, especially if you exclude lung cancer (smoking was quite popular in the 20th century...). See e.g. https://www.aerztezeitung.de/Medizin/Krebsrisiko-im-Kernkraf...

The childhood Leukemia link is something I didn't know. Very interesting.

On the worker front it makes sense that there is some linear correlation. I wonder how radiation exposure for workers compares to say a fighter jet pilot with 10,000 hours. In a fighter jet you have very little if any protection from radiation present at higher altitudes.

In the context of interia and frequency syncing, I'm guessing nuclear has pretty high capacity, given that the physical-thermal generation side is decoupled from the electricity generation side.

I.e. you can control the amount of thermal you're feeding your turbines, to get the electrical output characteristics you want?

You're correct, nuclear power plants have high inertia and significant flexibility in managing their output due to the decoupling of the thermal generation from the electrical generation.

Yet they did not help to stabilize the network in Spain, and had to be shut down.

12:03 – 12:07 CEST – first period of oscillations in the grid detected and mitigated. 12:19 – 12:21 CEST – second period of oscillations in the grid detected and mitigated. Since then the grid appeared stable, with no oscillations detected. 12:32:57 – 12:33:17 CEST – a series of generation trips in southern Spain, the first near Granada, the second near Badajoz and the third near Seville causes a loss of 2200 MW in generation capacity. Frequency decreased and voltage increased. 12:33:18 – 12:33:21 CEST – grid frequency of the Iberian Peninsula drops below 48.0Hz. Automatic load shedding is activated.

https://en.wikipedia.org/wiki/2025_Iberian_Peninsula_blackou...

Looks like the first few oscillations were successfully mitigated. I'm not sure what type of generation got cutoff that led to the cascade. Not sure how reliable this infrastructure map is but that area seems to have a pretty good mix of Natural Gas, Hydro Storage and Solar. https://openinframap.org/#9.14/37.4625/-5.8656

Exactly, and as a consequence of the automatic load shedding, the fission reactors shut down for safety reasons, and had to be cooled using their Diesel generators, which wasn't nice to watch: https://www.lavanguardia.com/vida/20250428/10625069/nucleare...

Which unfortunately meant they were unable to support the "reboot" of the network. That was started in the evening to avoid working hours (we were lucky and hat our electricity back at 18:30, while some people had to wait quite a bit longer). The reboot used mostly hydro, gas, and as much electricity as possible from France and Marocco. (well summed up in https://en.wikipedia.org/wiki/2025_Iberian_Peninsula_blackou...)

I wonder whether there could be a safe mode during load shedding that would not require a complete reactor shutdown. If that were the case, nuclear could have a stabilizing effect same as gas or hydro.

I am quite eager to learn about what really went wrong. We enjoy really cheap consumer prices for electricity (we use it to heat and cool, like in the US), thanks to solar and wind. I hope investing in batteries and network reliability will be enough to mitigate the problems.

>Exactly, and as a consequence of the automatic load shedding, the fission reactors shut down for safety reasons, and had to be cooled using their Diesel generators, which wasn't nice to watch

The shutdown is due to an abundance of caution and is regulatory (in the US). When the grid falls below a certain threshold of stability the reactors are programmatically shutdown. (At least that's how it worked 20 years ago.) They have significant inertia but that only goes so far, as you mentioned until we see the final report we won't know for sure if the shutdown was manual or programmatic.

Depending on how long the Reactors were shutdown down Xeon poisoning could have also been why they took longer to start back up. Xeon poisoning is one of the attributes of our current fission technology that makes Nuclear less able to cope with instability compared to combustion generation.

>I am quite eager to learn about what really went wrong. We enjoy really cheap consumer prices for electricity (we use it to heat and cool, like in the US)

Air conditioning is a great application of Solar especially in the sunbelt. It just makes so much sense. When it is daylight and the Sun is unobstructed A/C draws a lot of power likewise Solar is at peak efficiency. I've never been to Spain but, if you all believe in A/C I may have to stop by next time I'm sailing the Med.

Yes. That is all very important but we have time and time again seen spinning metal grids collapse in similar ways as the Iberian grid.

Instead caused by plants tripping, bugs in software, lack of maintenance etc.

Again. Let’s wait for the final report before drawing any conclusions.

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