[ajross]

Nuclear is emphatically not an instant-on hot backup. Plants take time to spool up, and very importantly time to cool down. Fukushima happened because you can't just turn a reactor off, it produces energy that has to go somewhere while the intermediate fission products decay over hours-to-days.

[troupo]

> Nuclear is emphatically not an instant-on hot backup. Plants take time to spool up, and very importantly time to cool down

All modern nuclear plants work in load following mode with ability to change ant the rate of 3-5% of their rated capacity per minute.

Graph and text on page 8: https://www.oecd-nea.org/upload/docs/application/pdf/2021-12...

> Fukushima happened because you can't just turn a reactor off,

Fukushima happened because the plant was hit with both an earthquake and a flood significantly exceeding its operational parameters (already extremely high)

[ajross]

> Fukushima happened because the plant was hit with both an earthquake and a flood significantly exceeding its operational parameters (already extremely high)

That's exactly the incorrect analysis that caused the meltdown!

That use of "and" and "both" is simply wrong. It wasn't an unforseeable collision of two events, it was a single event (an earthquake) with a predictable correlate (a tsunami). It's not like people didn't know that tsunamis follow earthquakes, and no one who does know that would make the argument you just did.

[troupo]

https://news.ycombinator.com/item?id=38304582

[VaxWithSex]

Nobody seems to get that these operational parameters were set and approved and told to be save and then they were still exceeded, lol.

[troupo]

This was literally the definition of a black swan event: "an event that comes as a surprise, has a major effect, and is often inappropriately rationalized after the fact with the benefit of hindsight"

[hef19898]

No, Japanese authorities and TEPCo knew tgat earthquakes and tsunamis could happen, and usually together. They planned for it, they simply planned insufficiently, so quite the opposite of a black swan.

[troupo]

The definition of a catastrophic one-in-a-lifetime event: you can't plan for it.

Fukushima had been in operation since 1971. You truly really believe that there were no earthquakes in the meantime, and the only reason for failure in 2011 is that they didn't plan for the largest earthquake and one of the worst tsunamis in Japanese history?

[hef19898]

Just found another highlight from the executive summary:

>> Prior to the earthquake, the Japan Trench was categorized as a subduction zone with a frequent occurrence of magnitude 8 class earthquakes; an earthquake of magnitude 9.0 off the coast of Fukushima Prefecture was not considered to be credible by Japanese scientists. However, similar or higher magnitudes had been registered in different areas in similar tectonic environments in the past few decades.

Now, tell me again, how the Fukushima earthquake and tsunami were totally impossible to predict events?

And it gets better:

>> In addition, a number of trial calculations were performed by the operator before the accident, using wave source models or methodologies that went beyond the consensus based methodology. Thus, a trial calculation using the source model proposed by the Japanese Headquarters for Earthquake Research Promotion in 2002, which used the latest information and took a different approach in its scenarios, envisaged a substantially larger tsunami than that provided for in the original design and in estimates made in previous reassessments. At the time of the accident, further evaluations were being conducted, but in the meantime, no additional compensatory measures were implemented. The estimated values were similar to the flood levels recorded in March 2011.

So, in 2002 they predicted pretry accurately the strength of potentail tsunamis. And then they did nothing for next nine years. The USSR knew about the control rod issue of RBMKs, and as TEPCO in Japan, did nothing until Chernobyl. See the inherent risk of nuclear power here? Because both, Chernobyl and Fukushima were pretty much predictable (as the risk was prpoerly identified before both accidents) and preventable if people in charge, and the organizations, would have put counter measures in place.

Edit: And now you can google the material difference between common and special causes.

>> The common cause failures of multiple safety systems resulted in plant conditions that were not envisaged in the design.

[hef19898]

Well, according the IAEA, the planning against, and risk evaluation of, earthquakes and tsunamis for the Fukushima Daiichi NPP were insufficient:

>> The seismic hazard and tsunami waves considered in the original design were evaluated mainly on the basis of historical seismic records and evidence of recent tsunamis in Japan. This original evaluation did not sufficiently consider tectonic-geological criteria and no re-evaluation using such criteria was conducted.

Source:

https://www-pub.iaea.org/MTCD/Publications/PDF/Pub1710-Repor..., page 48.

Stop speculating and assuming, stop thinking from first principle and do the following instead:

- read text books on basic engineering, electricity generation and grid operation

- read some basics regarding nuclear reactors (or, in all seriousness, watch Chernobyl which provides some really good basic explanations)

- read the publicly available incident reports from the IAEA on thebaccidents of your choosing

All the questions you might have about any nuclear accident are answered in those reports. Those reports are prepared and investigated by experts in their field, going painstackingly over documents, event logs, design documents, meeting minutes (like a real and thorough investigation you know). Try understand all of that, and then draw whatever conclusion you want. Because by doing that, we have a basis for discussion, one rooted in reality in facts, as opposed to the headline-talking points fairytale stuff we have now, where people without any basic knowledge how things work draw assumptions from some headlines...

Once HN was a place where people applied critical thinking to topics, and where curious to learn from people knowing more (of which you find a ton around here). Since COVID, more and more people seem to think some general smartness allows them to understand even the most complex issues better than anyone else based on headlines, opinion pieces and social media talking points. I hope we can return to how things were before, it is getting really frustrating at times.

Edit: Some general engineering advice: Those once in a life time event are actually planned for, the USSR had rules for that in the 70s as well. The approach od identifying those risks was formalized as Failure Modes and Effects Analysis, FMEA. They are done for the design, production and operation, for processes, in order to identify those risks, the likelihood, the criticality and the ability to detect them. Following that, mitigation actions are defined and put into place. And, very important, they revisited regularly.

This wasn't done neither for Chernobyl nor Fukushima (just because the formal process didn't exist back then doesn't mean engineers didn't do those exercises, and the USSR had regulations in olace basically asking for the same thing. Regulations that were ignored by everyone for Cherbobyl unit No. 4). The IAEA reports for Chernobyl and Fukushima point thaz insufficient planning out explicitely, as do the USSR reports on Chernobyl. And if you think those fuck ups only happened in the distant past, the Boeing 737 Max can basically be traced back to the same root cause. Because these failures are not as much about people as they are about organizations. Hence processes and rules to follow in safety critical industries, and other large scale organizations. The cowboy style of operating in a start-up doesn't translate well to those places.

[hef19898]

There is basically nothing correct in your statement.

[avar]

In this scenario you could just run the nuclear plant all the time, but just direct its electric production to heating a giant pool of water or whatever.

Then when the grid needs more power you do less of that, and instead send electricity to the grid.

[ajross]

Yes, but the point is that the problem is isomorphic to wind or solar: you get power when you don't want it. So nuclear isn't backstopping any particular need, it has the same drawbacks. The reason gas plants are used as peaker plants is that they can be turned on and off more or less instantly.

[avar]

You're just assigning magical value to "turn it off".

That's only a big deal with fossil fuels due to the fuel cost, the fuel cost of nuclear is marginal.

Yes, I agree that it's stupid to build a (big) nuclear power plant only to use it to boil an Olympic sized swimming pool most of the time.

But that's stupid because we're over-relying on "green" energy that can't provide baseload power.

It's even more stupid with fossil fuels, now you also need an entirely different backup infrastructure, but the fossil one pollutes much more than nuclear.

[hnaccount_rng]

The problem with your logic is, that nuclear is _only_ competitive with a 100% utilization rate/capacity factor. Only with these 90+% capacity factors do you get to competitive rates per kWh produced. Otherwise the initial CapEx is just too large, especially in a non-zero rate environment, as these plants are _already_ scoped/calculated/financed to 40 years. At 90+% capacity factor! That amount of CapEx is basically impossible without either very high earning potential (that’s why TSMC works. Everyone will just pay their price) or government backing (because then you don’t have to care about financing and optionality costs and can just pay for it with taxes). Neither one will be possible, at least in western societies

(And yes this ignores a certain amount of externalities, like the tendency of requiring large scale evacuations in their surroundings every second decade, but we can set that aside, as it’s irrelevant for the economic argument above)

[phil21]

At some point society will realize comparing power pricing to the lowest cost per kwh on a given day is a silly waste of time.

What matters is what is the most realistic mix of power generation and storage for 24x7 reliability. This can of course look very different depending on the situation. Many will argue for distributed storage (e.g. home batteries) - but that just means poor people don't get reliable electric service.

I really don't find that solar is "too cheap to meter" during peak sunlight very interesting. Who cares. What I find interesting is that I can turn a dial on my nuclear power plant to whatever it is I feel like at any time, and have it operating at that capacity within an hour or three.

Since we have such a dial, if you owned both the solar and the nuclear plants you would very likely combine them in a manner that maximizes profits while maintaining continuous service. Short of clouds, regional solar and wind prediction is extremely good to the point that modern nuclear plants may as well be load following. Add in a bit of battery for those minutes (hours max) that surprise you and you're good to go on that front.

You still will need some gas peaker plants for those crazy once-in-a-decade days you don't want to overbuild nuclear capacity for, but you could drastically reduce this infrastructure from what is effectively a 1:1 ratio today.

[avar]

I'm speaking in terms of what we should do. I realize this isn't workable in practice for various reasons.

The main reason is that we price pollution and radiation control into nuclear plants, but fossil fuel plants get a free pass.

[acchow]

Or powering GPU compute centers. When the grid needs more power, these dynamically power down (raise LLM generation prices)

[tuatoru]

Electrolyzing water to make hydrogen for ammonia (fertilizer) and industrial chemical feed stocks, please.