Sweden adopts new fossil-free target, making way for nuclear : news

[–] laxsill@infosec.pub 34 points 1 year ago* (last edited 1 year ago) (1 children)

I think some local context is worth it (I'm Swedish). This is a result of the fairly new parliamentary coalition in Sweden between the right wing conservatives and the fascist party. The position of the fascists range from that climate change is a hoax to climate policy doesn't work. The conservatives have generally just used nuclear power as a copout so they won't have to acknowledge that they lack any climate policy. They also have several open climate change deniers in parliament.

Since they took power, they've been shutting down project after project, budget after budget relating to climate policy (edit: especially when to comes to solar and wind power, and deforestation), especially after completely shutting down the department for environmental policy. So my guess is that this is mostly a way to cancel the old plan to make Sweden fossil free.

[–] Kempeth@feddit.de 8 points 1 year ago

Thank you for the context. This is exactly the reason I voted to exit nuclear here in Switzerland back in 2017. I'd have been happy to keep nuclear (it's not ideal but trading a problem that needs solving in a decade for one that needs solving in a century is an improvemnt) but I felt it was used as a crutch to kick the sustainability issue down the road. And it sure looks like I was right.

They dragged their feet some more in 2018-19 but 2020 was the first year where the previous record from 2015 of 340MW of additional capacity was surpassed and since then each year we're building a good chunk more than the year before. We still got a huge ways to go but it feels good no longer being the back end of the train.

But as soon as the new climate law was voted in the regressives in the country started crying for more nuclear again...

[–] voidbanana@feddit.nu 25 points 1 year ago (2 children)

It's a waste spending time and money on nuclear today. Building a nuclear plant takes a decade and costs more than renewables. Better to go all in on renewable sources, especially wind and solar power.

Sweden, like many other countries, already experience a huge interest in, and investments and production of renewables. Why not build on that? It's less expensive, has faster time to market, and results in a more resilient power grid when large single points of failure can be avoided.

What is sorely needed in Sweden is making it easier to getting approval for building wind turbines, especially at sea where noise and light pollution is a non-issue, and power grid improvements to support distribution from these new production sites. One area where government support could be really useful is investing in large scale energy storage to be able to deal with peak load.

[–] Hirom@beehaw.org 11 points 1 year ago* (last edited 1 year ago)

The power grid and stockage capacity aren't quite ready yet for 100% renewable. There's already a 5 year backlog (and growing) to connect new renewable projects and it's only going to get harder to manage as share of intermittent renewable increase.

Baseload power will be needed for a long time to complement intermittent renewable, better nuclear than coal and gas.

[–] VoxAdActa@beehaw.org 10 points 1 year ago (2 children)

We need to go 0 carbon yesterday. If you can assure me that in the 12 years it'll take to build a nuclear plant we can have built an equal GW-amount of stable renewables that can serve the same area with the same 100% uptime, sure. But every moment we rely on any amount of oil/gas/coal to cover the renewable gaps is another moment we won't get back in the fight against effectively permanent climate change.

Just like with literally everything else involved in the climate change equation, we needed to have been phasing out oil/gas/coal for nuclear 10-15 years ago. But because we dragged our feet and listened to the pleasing lies from the fossil fuel industry, we're fucked now. We're just fucked. Our kids are fucked, our grandkids are fucked, but maybe we have a chance to un-fuck the future for our great-grandkids, but only if we stop dicking around and actually DO SOMETHING EFFECTIVE. Like ditch all the fossil fuel plants right the fuck now. Can renewables completely replace all the fossil fuel plants? No? Then we need fucking nuclear.

[–] tryptaminev@feddit.de 3 points 1 year ago

So how does it go in that equation, that you need to wait for 12 years until you have the nuclear plant built, with having 0 fossil energy replaced until then?

In the meantime you can scale Solar and Wind, where you continously can build it up. Also at much smaller costs, so you can build three times the raw power, that you could with the nuclear plant. Also you create an incentive, to not just think in terms of creating a supply that meets the demand, but also to adjust the demand to the supply, which is perfectly possible and a hardly tapped potential. Mostly because it requires the demand side to stop being comfy and actually improve their energy usage.

I agree, that we need to be effective. And it is more effective to have replaced much more energy supply in a shorter timeframe, while also getting the demand to adjust, than to wait around for 12 years, until then being able to replace the equivalent in oil or coal plants.

[–] Denaton@programming.dev 2 points 1 year ago

I agree that the world need to go greed several years ago, we are past of no return and are just breaking before the crash, now it's only how hard we will hit the bricks.

But Sweden is a tiny county compared to other countries and ain't the problem when it comes to the climate change, sure everyone should draw their straw to the ant hill, but prolonging 12y in Sweden isn't the problem, it's the bigger counties that need the big changes..

[–] Anarchie99@feddit.de 23 points 1 year ago (2 children)

I really hoped we wouldn't import the reddit nuclear circlejerk.

[–] awsamation@kbin.social 21 points 1 year ago (1 children)

Which, the "nuclear is evil and any power that isn't solar, wind, or hydro deserves literal death" circlejerk?

[–] LordR@kbin.social 16 points 1 year ago (2 children)

The biggest problem with Nuclear Power Plants is their price and the fact that they are centralized. While they might produce a good amount of baseline electricity, their energy is more expensive than solar and wind.

Obviously solar and wind also have disadvantages like fluctuating production but that could be solved by building battery storage. In another comment line I commented about Aqueous Hybrid Ion Batteries that could be used that way, they are heaavier than other battery types but environmentally friendly and could therefore easily be used in buildings.
The main advantage of solar combined with batteries is that it will help regular people instead of a huge company. A decentralized energy production would also help in wars or with natural catastrophies.

[–] VoxAdActa@beehaw.org 11 points 1 year ago (1 children)

The main advantage of solar combined with batteries is that it will help regular people instead of a huge company. A decentralized energy production would also help in wars or with natural catastrophies.

Oh, right. The "the only solution is to completely topple capitalism and government and nothing else will do" circlejerk.

Unless you actually believe solar panels aren't manufactured, marketed, installed, and maintained primarily by the electric companies, in which case, it's the "I refuse to do any actual research on my positions" reddit circlejerk, with a dash of the "what do you mean that not everyone can live an off-grid mountain-man life?" circlejerk.

[–] LordR@kbin.social 12 points 1 year ago (1 children)

You do realize that solar panels are usually installed and maintained by small companies and not multi-billion dollar companies, right?

That means that it's more likely for the profits to stay in the local economy.

It's quite funny how you assume things about me though and thinking that I I don't do any research. How about you showing some research?

[–] VoxAdActa@beehaw.org 3 points 1 year ago (2 children)

You do realize that solar panels are usually installed and maintained by small companies and not multi-billion dollar companies, right?

According to whom? You? Every solar panel installed in my county was done by local contractors on the behest of either the electric company or Tesla.

[–] LordR@kbin.social 10 points 1 year ago

In my country it is mostly small local companies installing solar panels. And I think in most of Europe it's the same.

[–] Denaton@programming.dev 8 points 1 year ago

Hi, Swedish here, since the topic is on Sweden, the installment is made by small companies not big electric companies like Vattenfall. We also have subvented solar panels.

[–] awsamation@kbin.social 6 points 1 year ago (2 children)

It only helps regular people as long as nothing breaks.

You're still beholden to the huge company that's making the panels, or the company that's installing and maintaining them. On property panels are only as decentralized as your personal ability to install maintain and repair them. Off property panels are only as decentralized as the conglomerations that own every solar farm and wind farm.

You aren't "getting away from huge companies." You're just increasing the minimum footprint and ecological disruption needed to generate the power needed for modern life. Let alone the amount of increase needed if EVs are ever going to have a chance at challenging ICE for majority market share.

[–] LordR@kbin.social 8 points 1 year ago

Solar panels are living quite long lifes. The people installing those panels are, at least in my country, mostly in small companies. You are right anout the production though but there will probably grow more and more manufacturer's as they don't need Billions like the Energy Companies that build Nuclear Power Plants.

[–] tryptaminev@feddit.de 6 points 1 year ago (1 children)

nuclear plants usually have a significant ecological footprint and it only growths stronger with climate change.

If the rivers they are typically placed at, carry less water, which we can see all over the world to happen, they stress the rivers ecology further and are at risk of needing to be shutdown, or slow cooking the river dead. That in return has consequences for peoples access to usable water, as the intact ecosystem in the water cycle is vital for the quality of water.

So while the current CO2 emissions might be lowest, which also does not account for the change in energy production for the plants creating solar panels or wind turbines, the local impact is much more severe than that of a solar or wind power plant.

[–] OmnipotentEntity@beehaw.org 2 points 1 year ago* (last edited 1 year ago) (2 children)

A nuclear reactor can range anywhere from 30-50% thermal efficiency, which is similar to a coal fired power plant, because Carnot engines and ain't thermodynamics a bitch. Coal and nuclear power plants also both need massive heatsinks and are normally situated by rivers. So while your comment implies that this is somehow worse than what we already have, it's not!

Also a nuclear power plant has a much smaller ecological footprint than many renewable sources of energy simply because it is relatively compact in terms of land use as compared to the amount of energy it produces. Solar requires converting acres of land into solar farms. Wind requires installing wind mills, and while they do kill a lot of birds and that's a shame, it is a little sensationalized imo, and this particular talking point against windmills is probably a scarecrow argument from fossil fuel companies. Instead, I'll focus again on land use. You can't really have land conservation for wildlife where solar and wind exist because they would disrupt most types of habitat.

Finally, hydro. You have to flood several square miles of perfectly good land to make a reservoir lake, destroying wildlife habitats.

But back to the main point. A 1 GWe nuclear power plant requires around 3 GWt of cooling, this is a rate of about 300 gallons (40 cubic feet) of water boiled per second (the true value used will be slightly higher due to inefficiencies, but this is ballpark correct), which sounds like a lot, and it is on a human scale, but for a typical river, this is a rounding error. If you go to the Wikipedia page for a list of US Rivers by discharge and scroll all of the way to the bottom, even the smallest rivers on this list, such as the St. John's River, which is described in its own page as "The drop in elevation from headwaters to mouth is less than 30 feet (9 m); like most Florida waterways, the St. Johns has a very slow flow speed of 0.3 mph (0.13 m/s), and is often described as 'lazy'," has a typical flow rate of 15,000 cu ft/s.

As an aside, we, of course, use river water for other things, and this use is considerably larger, for instance, irrigation uses, livestock uses, and so on. We essentially consume the entire Colorado river, which no longer flows to the sea. "Due to water diversions, flows at the mouth of the river have steadily declined since the early 1900s. Since 1960, the Colorado has typically dried up before reaching the sea, with the exception of a few wet years." There is no nuclear power plant on the Colorado river.

[–] tryptaminev@feddit.de 3 points 1 year ago

you are absolutely right, that the water usage is an equal issue for coal, oil and other plants. I find it important though to not think in terms of coal vs nuclear, but considering the triangle of options. Forbthe US with its overall low population density water stress might not be an urgent issue. In western Europe it definetely is. For Germany about two thirds of water use are attributable to the energy sector, with the rest being equally divided between industry and households.

Over the last summers multiple plants in western Europe had to drastically lower their output, or in rare cases be shut down. France is discussing to allow for higher river temperatures next to plants, fully aware that this will be the ecological end of the rivers.

As you said there is no nuclear plant on the colorado river. But this raises another issue of water availability. you want the plants to be reasonably close to energy users, so the transportation losses are minimized. And the energy users are also using more water from rivers etc. so you want the plants at already stressed ecosystems.

For the land use of solar, it might be even beneficial as the shading helps to grow crops with less water usage or to protect ecosystems from increases in solar heat.

Due to its size the US has fantastic conditions to transform to renewable energy. The availabe space allows for good integration of renewable plants into the local ecosystems, minimizing their impact. At the same time there will always be wind somewhere in the US in the same wake as their will always be sun somewhere during the day. So with a well connected grid the necessity for base load providers can be reduced better, than in smaller grids.

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[–] packadal@beehaw.org 15 points 1 year ago

I really hoped we wouldn't be as close minded as on Reddit.

Nuclear, like anything, has advantages and drawbacks.

The question is: are those advantages overcoming the drawbacks ? (This is obviously an oversimplification, as there are lots of questions, even nested within this simple one, like "will the advantages overcome the drawbacks for the lifetime of this project?"

[–] LordR@kbin.social 19 points 1 year ago (1 children)

How about investing all that money in actual renewable energy sources? If you already have some Nuclear Power Plants keep them running until you can replace them, but then replace them with renewables.

Renewables can help home owners and renters (solar panels and batteries), while Nuclear Power Generation will only help big energy companies in the long run.

[–] nameless_prole@kbin.social 16 points 1 year ago (2 children)

It's time for people to stop ignorantly railing against nuclear.

[–] Sir_Osis_of_Liver@kbin.social 18 points 1 year ago* (last edited 1 year ago)

Or, now hear me out, people actually know the history of the most recent projects and are reacting based on information.

Olkiluoto-3 was supposed to cost €3B, and ended up being approximately €11B.
Flamanville-3 was supposed to cost €3.3B and will likely end up costing in excess of €20B.
Hinkley Point C was supposed to cost £16B, but will likely end up about £27B.

It's the same in the US:
V.C. Summer 2&3 was supposed to be $9B, but was cancelled while under construction, once total costs were projected to hit $23B.
Vogtle 3&4 was supposed to be $12B, but is currently in the $30B range.

These projects ended up being up to 12 years behind schedule. And that was in a low interest rate era. With higher interest rates, these kinds of schedule overruns will be devastating.

As it was, Framatom (Areva) and Électricité de France needed government bailouts and EdF is being re-nationalized by the French government due to the sad shape of its finances. Westinghouse ended up in creditor protection due to the fallout from the V.C. Summer project, and was sold off by parent company Toshiba.

[–] LordR@kbin.social 13 points 1 year ago (1 children)

Yeah, after believeing big oil way to long, let us now believe the propaganda of the Nuclear Energy Industry because that will turn out to be way better...

[–] chaogomu@kbin.social 14 points 1 year ago (1 children)

Almost all of the anti-nuclear talking points are paid for by big oil. So it's a case of continuing to listen to fossil fuel paid propaganda, or actually looking at reality and a clean power source that can meet all of our energy demands for the next thousand years.

[–] LordR@kbin.social 10 points 1 year ago (4 children)

Ballooning costs for Nuclear Reactors and those reactors being built up to 12 years later than scheduled are simply facts. There is a decision to either build smaller solar and wind and decentralize power generation and invest into the power grid or waiting decades for new Nuclear Plants to get built.

[–] interolivary@beehaw.org 10 points 1 year ago* (last edited 1 year ago) (2 children)

Solar and wind can't replace nuclear energy. You can't get 24/7 output from renewable sources, and you can't store extra energy when you produce it (and you can't just beam energy thousands of kilometers when there's overproduction somewhere but underproduction somewhere else), so you need a source with a stable output alongside sources that sometimes don't produce anything.

[–] Sir_Osis_of_Liver@kbin.social 9 points 1 year ago* (last edited 1 year ago) (2 children)

Right now Sweden has adequate baseload, they are well positioned to go with more renewable.

UHVDC and HVDC links can be used to transmit power over thousands of kms. I think the longest line currently is in China a 1100kVDC line that stretches over 3300kms.

Even with conventional AC transmission, power generated in Churchill Falls and James Bay eventually ends up in population centres in Southern Canada and New England.

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[–] LordR@kbin.social 4 points 1 year ago (1 children)

You can store electricity pretty well either with Pumped-storage hydroelectric plants or with batteries (that recently got way cheaper and more efficient. If you start adding batteries to buildings with solar panels, the buildings can provide electricity for themselves for longer periods of times which will lower energy costs for households.

If you build more Nuclear Power Plants, it is big corporations that profit and not the regular people. I prefer to help regular people.

[–] interolivary@beehaw.org 6 points 1 year ago* (last edited 1 year ago) (1 children)

Far as I know current battery technology just isn't up to it because it relies on rare earth materials that are extracted with processes that are absolutely terrible for the environment and are, well, rare.

[–] LordR@kbin.social 3 points 1 year ago (1 children)

That's true for batteries that have to be lightweight. There are salt water batteries that do not require any (or a lot) rare earth materials. They are about twice as heavy if I remember correctly, but for a house that doesn't matter a lot. And the good thing is that the more batteries are used in houses, the better and more efficient they get.

[–] interolivary@beehaw.org 4 points 1 year ago (2 children)

Salt batteries?! Huh, that's neat, I learnded a thing today thanks to you.

Dug up some info on them. Apparently their problem is that they don't have high discharge or charge currents and they need some energy to keep their temperature, but in cases where those are OK they definitely seem promising.

[–] LordR@kbin.social 4 points 1 year ago

I just figured out that they are called "Aqueous Hybrid Ion Battery" in English, so they are not the molten ones.

I didn't find a lot about them, but this website seems to have an overview about them (although they are the main manufacturer of the batteries, so they are probably biased): https://www.aquionenergy.com/technology/aqueous-hybrid-ion-ahi/#What_Are_Saltwater_Batteries_and_How_Are_They_Different

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[–] chaogomu@kbin.social 7 points 1 year ago (1 children)

This talks about those ballooning costs.

https://rootsofprogress.org/devanney-on-the-nuclear-flop

Spoiler, most of it has been inflicted by regulatory sabotage.

Here are some deep dives by a guy who's been researching this shit for years. There are dozens of articles about how fossil fuel lobbyists have constantly attacked nuclear power.

https://atomicinsights.com/how-did-leaders-of-the-hydrocarbon-establishment-build-the-foundation-for-radiation-fears/

https://atomicinsights.com/how-did-an-oil-shale-investor-hamstring-his-atomic-energy-competition-ancient-but-impactful-smoking-gun/

A great write-up about the oil industry funding the anti-nuclear environmental movement

https://www.forbes.com/sites/kensilverstein/2016/07/13/are-fossil-fuel-interests-bankrolling-the-anti-nuclear-energy-movement/

[–] Sir_Osis_of_Liver@kbin.social 4 points 1 year ago (1 children)

"Regulatory sabotage" is the latest talking point put out by the nuclear lobby. It's a fabrication. Regulations were built based on incidents and accidents in the past. Building nukes on the cheap would be like building deep-sea submersibles without certifications. It'll work fine, until it doesn't.

Certification and licensing only make-up a tiny percentage of a plant's upfront costs. Typically it'll be dumped in with engineering/design costs and those would be down around 15% of capital costs, depending a lot on the project.

The French government has traditionally been very pro-nuclear, and the industry has broad support from the population aside from the Green movement. They have had extensive incentive programs for the industry, both domestic and for export. And yet, they have had no better luck in building plants on time and budgets. Flamanville-3 is the poster child for overbudget nuclear projects. Construction started in 2007, was supposed to be on-line in 2012, but is currently projected to be completed in 2024. The budget went from €3.3B to an estimated €20B as of a 2019 French court audit.

The "oil industry" doesn't care about nuclear at all. Oil fired generators haven't been a thing since the oil shocks of the 1970s. The few that are still around are typically used as backup or peakers, as they're ridiculously expensive to run.

The coal industry would be so inclined, but in the US, coal plants have dropped from ~65% of generation to less than 20% of generation over the last 30 years. New plants are almost as expensive to build as nuclear, and as the plants get to end of life, they're being decommissioned rather than refurbished. The writing is on the wall.

Of the fossil fuel industries, only natural gas is competitive, and the plants are far, far cheaper to build than about anything else. They are the preferred type of new generation for utilities that have access to gas. Only regulation or government mandates really slow down new gas plants.

[–] chaogomu@kbin.social 5 points 1 year ago

If regulatory sabotage isn't real, what do you call the prohibition against multiplexing? Or the requirement for a contingency plan for a Double-Ended-Guillotine-Break of the primary loop piping? That second one cannot actually be simulated in reality because steel doesn't break like that. And yet, it's one of the most expensive design requirements that nuclear power plants must comply with. It also comes at the expense of safety standards that would actually work, because you cannot design for reality and this fiction on the same page.

Then there are stories like this one

A forklift at the Idaho National Engineering Laboratory moved a small spent fuel cask from the storage pool to the hot cell. The cask had not been properly drained and some pool water was dribbled onto the blacktop along the way. Despite the fact that some characters had taken a midnight swim in such a pool in the days when I used to visit there and were none the worse for it, storage pool water is defined as a hazardous contaminant. It was deemed necessary therefore to dig up the entire path of the forklift, creating a trench two feet wide by a half mile long that was dubbed Toomer’s Creek, after the unfortunate worker whose job it was to ensure that the cask was fully drained.

The Bannock Paving Company was hired to repave the entire road. Bannock used slag from the local phosphate plants as aggregate in the blacktop, which had proved to be highly satisfactory in many of the roads in the Pocatello, Idaho area. After the job was complete, it was learned that the aggregate was naturally high in thorium, and was more radioactive that the material that had been dug up, marked with the dreaded radiation symbol, and hauled away for expensive, long-term burial.

Another type of sabotage is called “backfitting”;

The new rules would be imposed on plants already under construction. A 1974 study by the General Accountability Office of the Sequoyah plant documented 23 changes “where a structure or component had to be torn out and rebuilt or added because of required changes.” The Sequoyah plant began construction in 1968, with a scheduled completion date of 1973 at a cost of $300 million. It actually went into operation in 1981 and cost $1700 million. This was a typical experience.

And one final bit of regulatory sabotage, but one that I think was accidental, every nuclear plant has the exact same annual licensing fees regardless of power capacity. This means that there's an incentive to build the largest, most complex plant possible, because you can put out more power for the same regulatory fee. The problem lies in the trap of thinking bigger and bigger, you suddenly have a reactor with parts that need special infrastructure to produce those parts, which is expensive, then you need special equipment to transport them, which is expensive, and special equipment to install them, which is expensive. And then, when the plant is built, it has way more capacity than is actually needed by the surrounding communities.

[–] cleanuponaisle13@kbin.social 3 points 1 year ago (1 children)

It only takes 7 years to build a nuclear plant, and "ballooning costs" only arise due to people being afraid of and simultaneously dependant upon nuclear power once it's built. There wouldn't be ballooning costs if the power plants were built and then decommissioned according to schedule. The increased costs come from maintaining plants for far longer than necessary.

[–] LordR@kbin.social 4 points 1 year ago

Just below Sir_Osis_of_Liver posted an overview of new Nuclear Power Plants that went way over budget and schedule. The additional costs are massiv.

[–] MrSpArkle@lemmy.ca 2 points 1 year ago

The cost of not creating new nuclear plants is building more coal and natural gas plants.

[–] NumbersCanBeFun@kbin.social 17 points 1 year ago* (last edited 1 year ago) (1 children)

I'm okay with using Nuclear power in a limited capacity. There is a great channel on YouTube that goes by the name of Plainly Difficult. Extremely well done documentaries on nuclear related incidents. In my observations, most issues are due to human related error, poor inspection process or a failure to follow a safety procedure.

[–] zalack@kbin.social 25 points 1 year ago (1 children)

A lot (all) nuclear accidents also occurred with older reactor designs.

Traditional nuclear reactors were designed in such a way that they required management to keep the reaction from running away. The reaction itself was self-sustaining and therefore the had to be actively moderated to stay inside safe conditions. If something broke, or was mis-managed, the reaction had a chance of continuing to grow out of control. That's called a melt-down.

As an imperfect analogy, older reactors were water towers. The machinery is keeping the water in an unstable state, and a failure means it comes crashing down to earth

Newer reactrs are designed so they they require active management to keep the reaction going. The reaction isn't self-sustaining, and requires outside power to maintain. If something breaks or is mismanaged, the reaction stops and the whole thing shuts down. That means they can't melt down.

As an imperfect analogy, newer reactors are water pumps. If power is interrupted nothing breaks catastrophically, water just stops moving.

[–] exRedditor@beehaw.org 7 points 1 year ago (2 children)

Correct me if im wrong. I think most of the fears come from positive void coefficient reactors which some of the older reactors have like the RBMK which Chernobyl had. Unlike today where they are negative void coefficient.

[–] OmnipotentEntity@beehaw.org 17 points 1 year ago

Hi! I'm a nuclear engineer. I just wanted to do a small drive-by clarification/lecture.

There are a lot of feedbacks that are considered when designing a nuclear reactor, it's not just a single void coefficient. There are thermal feedbacks, feedbacks related to the decay of fission products, feedbacks related to the burnup of fuel, the burnup of the neutron poisons, the activation of the water in the primary loop, etc etc. When designing a nuclear reactor, all of these effects must be examined. Generally, this involves finding the transfer function and confirming that all the poles of the transfer function have real part less than 0. (This is where the "negative" part comes in, they're complex numbers in general, but as long as the real part is less than zero this corresponds to a decaying exponential.)

An aside on criticality. We are quite fortunate in that due to a quirk of nuclear physics, fission reactors are possible. We call the time difference between one fission and the next from the neutrons produced a "generation." If we had to react on the timescales of a "generation" based on the simple model where one fission leads directly to another, then we'd have to react in milliseconds, and this just wouldn't be possible to make a reactor safe, even with an extremely well designed system of feedbacks. However, some fission products will decay and release a neutron, these so-called delayed neutrons make controlling a nuclear reactor on human time scales possible (minutes and hours instead of milliseconds), and it makes these feedback loops far more stable. So we aim to keep the criticality below 1 for "prompt" neutrons, and slightly above 1 for delayed neutrons, then we rely on the feedback systems (primarily thermal and fission products) to keep the criticality oscillating very slowly around 1.

For specifically Chernobyl, there is a more broad idea that we concentrate on in reactor design, that of overmoderation vs undermoderation. Reactivity has a relative peak at a particular amount of moderation, and we want to design the reactor in such a way that it can never get more moderated than that peak, because that would give a positive feedback loop if increasing the power led to a concomitant decrease in moderation (which is normal, the density of liquid water decreases with increasing temperature). Because Chernobyl was graphite moderated and steam cooled, we had an especially bad case of this where the core flooded and was massively overmoderated, and in order to get the water out of the core they attempted to turn the reactor all of the way up and boil it out, but in doing so this caused the reactivity to go massively supercritical as the moderation was reduced from absolutely smothering the reaction to just right. It was so supercritical that it was supercritical only with the prompt neutrons, so-called prompt supercriticality, which is why you read things like the power went up 1000x in a second.

The United States does not, and did not even at the time, allow certification of designs where it is possible for this to occur. All reactors must have negative reaction coefficients for all major feedbacks in all operating scenarios, and, in fact, due to this stringent process there are only 4 reactor types that the NRC has currently certified for new nuclear reactors (with 3 more currently under review), (and each design has to be certified jointly with the location where it will be built, so something like Fukushima, where the backup generators are in the basement in a flood zone, would not pass certification review in the US.)

Anyway, I hope this was interesting and educational.

[–] intothemild@lemmy.ml 9 points 1 year ago (1 children)

You're correct, but the two groups that are anti nuclear are Boomers and The Greens parties.

Boomers are easy, they grew up with a few nuclear incidents, including reactor issues as well as the USSR stuff.

The Greens is paradoxal, youd think they were pronuclear, at least in the interrum. But they are anti nuclear because of a variety of reasons. So you see situations like in Germany recently where the Greens forced the government to get rid of nuclear reactors, and in their place, comes more Gas reactors.. Greens want 100% renewable, but don't seem to understand that they should be fighting for 0% fossil first .. then when that's obtained go for 100% renewables.

Because every time you remove a nuclear reactor, the only firm power replacement is a fossil fuel reactor.

I say this as a lifelong Greens voter, my political party have a small, and vocal group of idiots.

(In case you're wondering, yes the anti nuclear Greens are usually boomers)

[–] Kempeth@feddit.de 2 points 1 year ago (1 children)

I'm one of those guys. I voted to ban nuclear here in 2017.

I absolutely would love to put 0% fossil before 100% renewable. But as long as nuclear was a choice little more than token efforts were made to expand renewable capacity. Then we banned it and suddenly solar installations are sprouting like mushrooms. Before the ban we put in 330MW per year. The increase in the increase in solar was this much last year (670->1000MW)!

This month we had another vote in a climate bill and as soon as that was accepted the regressives came out and called for more nuclear and complained how all that solar and wind is going to ruin ~~christmas~~ the landscape. I'd love to have renewables AND nuclear but somehow it always ends up being an OR...

Just to be clear: This isn't an attack on pro-nuclear folks. I get your point and in theory you're right. I just never seen it put into practice...

[–] uint8_t@feddit.de 2 points 1 year ago (1 children)

the installed capacity is a nice number but unless you also install batteries AND take capacity factor into account, you're replacing load following dispatchable generation with intermittent ones that is backed by literal fossil fuels

I mean just look at the carbon intensity of a German kWh

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[–] ahriboy@kbin.social 7 points 1 year ago* (last edited 1 year ago) (5 children)

Meanwhile Germany is decommissioning nuclear energy. I was triggered when plasmatrap.com energy costs are almost €473 per year.

[–] tryptaminev@feddit.de 7 points 1 year ago (1 children)

Germany would have decomissened its nuclear plants and have them replaced duely with renewable if it wouldn't have been for Merkel to first extend the plants lifetime and drastically block new renewables, followed by shortening the plants lifetime back to the original plan, but without building up renewables as was planned originally.

The whole maneuver did cost a couple billions fed to the energy companies, without achieving any improvement in the defossilation.

Now extending the plants lifetime again, would have cost billions again, without them actually helping in the energy crisis sparked by the war in Ukraine, because the plants would have required extensive maintenance now. So it would have been another maneuver not doing anything, but wasteing money.

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