What if we had commercial fusion power?

[PeterDonis]

If the core explodes

A fusion reactor can't explode. Neither can a fission reactor, for that matter. A nuclear explosion of either type requires a very precise set of conditions, which simply cannot be met in a power reactor.

 

[rbelli1]

Neither can a fission reactor, for that matter.

https://en.wikipedia.org/wiki/Chernobyl_disaster

This one did. It was not a nuclear explosion but it certainly was an explosion.

BoB

[Moderator's note: fixed link]

 

[PeterDonis]

It was not a nuclear explosion but it certainly was an explosion.

Ok, when you said "core explodes" that made me think you were talking about a nuclear explosion. The Chernobyl explosion was a steam explosion due to the coolant flashing to steam because of uncontrolled reactivity. (There was also a graphite fire that released radioactive material.) Even that can't happen in a fusion reactor because there is no such thing as uncontrolled reactivity: any disturbance causes the fusion reaction to shut down, not grow.

 

[phyzguy]

SYes fusion reactors will be safer than fission rather than completely safe.
BoB

The problem is that fission reactors are already safer than other power generations methods, but nobody believes this, so saying fusion power plants are safer will probably fall on deaf ears. By any rational measure, fission plants are far safer than coal burning plants, and clearly safer than hydroelectric power plants. This Wikipedia page attempts to quantify the impact. A single hydroelectric dam failure killed over 170,000 people in China. By comparison, nobody is documented to have died from the radiation release at Fukushima.

 

[russ_watters]

...exploding fusion cores will not be a Chernobyl level event. Or maybe not even possible at all.

Here's the problem with using the word "core" in this context: You're using it to mean "the central or most important part", which is one of the dictionary definitions. But for fission reactors, the "core" refers to the pile of radioactive material inside the central or most important part of the reactor. A fusion reactor doesn't have a pile of radioactive material in the it. So using the same word for both implies something false about the construction of fusion reactors.

 

[russ_watters]

The problem is that fission reactors are already safer than other power generations methods, but nobody believes this...

This, unfortunately, is true:
https://news.gallup.com/poll/2167/energy.aspx

Among the results:
In 2016, polling had the lowest favorability perception of nuclear power in 20+ years of polling; 44%.
Is nuclear power safe? 57% yes -- fairly steady.
Increasing nuclear power: "Necessary" or "too dangerous" (odd choices...) 46-48%

https://en.wikipedia.org/wiki/Public_opinion_on_nuclear_issues
Global support:
Solar: 97%
Hydro: 91%
Coal: 48%
Nuclear: 38%

 

[artis]

I want to share a few thoughts, please don't pick on me for those.

1) Not to sound judgemental or anything but I hardly doubt that the society or the average citizen will ever care if he is even capable of understanding the peculiar technical differences between a core meltdown that is contained within the core vessel or Chernobyl type accident or a standard nuclear bomb explosion. The videos posted on internet where Fukushima outer reactor buildings exploded from accumulated Hydrogen gas to many were "nuclear explosions".
Given how we are glued to facebook and "smart"phones and all kinds of kinky little gadgets plus the complexity of modern life, well good luck with trying to make society think about complicated nuclear science stuff.2) If we want to be very technical and precise then no one should also ever call Chernobyl a "meltdown" because it was not. In fact it was (hope i get my facts straight) a reactor whose reactivity got out of control due to operator error and added by design specifics like positive void coefficient aka positive feedback of power which led to core thermal power increasing 100 of times above max limit causing the approximately 1600 pressure tubes where fuel rods were inserted to rupture and water upon loosing pressure flashing into steam causing a massive steam explosion after which a second explosion happened the causes of which are still debated(and probably forever will be) which then accompanied by panic and lack of correct information in the hours after the accident caused mayhem and chaos. Theoretically this is what the news should read about this accident. But the news care about views so to them Chernobyl Fukushima it's all the same.

Also the wise thing to say to public would be that due to the big differences in design Chernobyl was unique and cannot happen in any western made PWR or BWR type reactor and not even in the Soviet, later Russian made VVER type reactors which are similar to western PWR types.Also I read that often , even the mods here write that "Chernobyl would have benefited from a containment structure like the ones (reinforced concrete domes) around western reactors" but if we wish to be technically correct then is this statement accurate? I am no expert so please correct me if necessary but western type reactor containment is mainly two fold, first the reactor vessel itself then the outer dome for extra protection, but western reactors are designed such that the worst thing that can happen is a partial or full core meltdown within the core vessel which is then contained within the vessel ideally or in worst case within the reinforced dome.
Chernobyl was not a meltdown but an explosion the power of which is estimated to be up to 10 or more tons of TNT, would a western type reinforcment structure have withstood such a shockwave and gas pressure occurring in a matter of few seconds? I sort of doubt so.

For me the logical conclusion is that the RBMK-1000 reactor in the worst case scenario has the capability to go "boom" with a force that modest chemical explosives would envy so constructing a containment for such a "device" would be impractical and extremely expensive so the logical thing here would have been to not build the RBMK-1000 in the first place. Or build it and go with the risk which is what happened.

 

[artis]

Someone here said earlier that we are better off with the devils that we know than the ones we don't. I think it explains why many people fear anything nuclear- they simply don't know much about, it's just bedtime horror stories for them and so just like death , the unknown frightens us. Only unlike death which we have no control over and can't know what's on the other side with nuclear we can actually learn and understand and we have and the safety of modern reactors is a testament to that.

Reading many papers over the years I can say for sure that back when nuclear was at it's infancy the so called "meltdowns" actually happened a lot more than they have in the past say 30 years. There have been various accidents in some early test reactors like the SL1 and some others but back then the media was realistic so there was no hype , now it's the other way around the technology is much much better and we have only had one major problem with Fukushima yet the "fake news" money ad revenue driven social media is all hyped up about anything they can touch.
Also back in the day , for example when Chernobyl went into "bomb mode" the news actually hired some physicists and nuclear experts and only then dared to even speculate about what has happened , somehow I don't see such attention to detail now. One last word I want to say, I think Fukushima could have been entirely avoidable because unlike in Chernobyl where everything went wrong and it happened in a matter of 10 seconds on a reactor that was already into supercritical mode, Fukushima simply could not get backup generators working in time or at all. Given Japan's geographical location , also the location of the power plant itself sitting right next to ocean and the climate change induced increase in weather events which was already well established science and fact in 2011 I think it is simply negligence that they did not move the diesels further uphill and all of this would have been avoided, relocating some backup diesels is nothing in terms of investment money if one considers the loss after an accident like this.

 

[PeterDonis]

climate change induced increase in weather events which was already well established science

The tsunami that flooded the backup switchgear at Fukushima was due to an earthquake well offshore. It wasn't a weather event and had nothing to do with climate change. Please keep this thread focused on things relevant to the topic.

 

[artis]

Ok, point accepted , I forgot that the tsunami was after an earthquake now I remember all the videos of shaking office stuff in Japan.
Still it could have been also a weather event and with the diesels and related stuff being at such a low grade the result would probably been the same so in terms of mismanaging risks I still stand by my point. In fact this was addressed in many papers by people with expertise in the field so I'm just agreeing to expert opinion

 

[russ_watters]

A large number of posts have been deleted, a member will not be returning to the thread, and it is re-opened.

The mods recognize this is a public policy discussion and a speculative one at that; speculating about opinions of people who are not participating in the thread and may believe things that are factually wrong or unreasonable. For that reason it is critical to distinguish between your own beliefs/claims/statements of fact and those you are attributing to speculated opponents of fusion 30 years from now.

We'll give this one more try...

 

[russ_watters]

Someone here said earlier that we are better off with the devils that we know than the ones we don't. I think it explains why many people fear anything nuclear- they simply don't know much about, it's just bedtime horror stories for them and so just like death , the unknown frightens us.

This irrationality also applies to planes, as another example. Commercial air travel has gotten so safe we in the US recently had our first fatality in nine years (1, due to an uncontained engine failure). Except for non-fatal accidents in the US and fatal ones abroad, it was out of the news. But an awful lot of people are still afraid to fly, and those numbers aren't changing much.

Tellingly, 16% of Americans actually believe it is safer to drive than fly. Or after flipping and subtracting out the unsure, only 47% - half - believe it is safer to fly than drive. Wow.

This is the sort of irrationality the nuclear industry is up against. In my first post, I speculated that this is not going to be an issue for fusion, but clearly that's just a prediction/guess. Who knows that minor word twist the public might seize on to generate an irrational fear.

https://flyfright.com/statistics/
https://today.yougov.com/topics/lifestyle/articles-reports/2014/03/19/fear-flying

 

[mfb]

A fusion reactor would need to store a lot of tritium but only a small fraction would be volatile. The rest is in the blanket or can be stored in a solid chemical compound. Decay heat is easy to handle passively. In addition I don’t see which event would be a threat to it.

I expect some opponents of fission to oppose fusion for the same irrational reasons, with the same rhetoric. Power plant operators might call it fusion power but the opponents will probably use the existing words - refer to atoms, radioactivity and so on. As long as a significant fraction of the population would vote to “ban all atoms” it is easy to scare people of fusion.

 

[rbelli1]

“ban all atoms”

I don't like the chemicals either.

BOB

 

[russ_watters]

I expect some opponents of fission to oppose fusion for the same irrational reasons, with the same rhetoric. Power plant operators might call it fusion power but the opponents will probably use the existing words - refer to atoms, radioactivity and so on.

It's so tough to know for sure, but it's as good a bet as any that the existing trigger words could still be applied. Another for the list: radiation (nevermind the electric heater under your desk).

 

[mfb]

The Germans have “Atomstrom”, literally “atomic electricity” - quite ironic for an energy source that comes from the nucleus and doesn’t rely on atomic transitions (unlike coal, oil, solar power, ...)

 

[artis]

Russ mentioned an old but valid point about flying being safer in numbers than driving a car, I think the problem here is partly psychological and not so much statistical or lack of information. A plane is controlled by a pilot and in these days by computers etc so the passenger has no control over what is happening meanwhile in a car you have almost full control over every minor detail , even though due to human factor cars on a highway filled with them are less safe than a plane for people driving a car feels (I believe) emotionally safer.

The same goes for nuclear. Coal is basically nothing but a big oven and a large chimney this is something we can all relate to even those who have very little science understanding because we all have had something to do with ovens, especially our ancestors for whom it was the primary way of surviving.
Nuclear on the other hand is something relatively new, after all there are still people around who were young when we made our first bombs and reactors.
Secondly nuclear just like electronics is sort of the "genie in the bottle" , Nobody except those who read much about or work with it know much about it so there is this unknown factor plus the feeling that you cannot control it.
Thirdly the fact that nuclear was first brought into the world as a bomb of unparalleled power and destruction has probably left a huge imprint into the average mind , Hollywood has only helped this myth. Because when you say nuclear- the mouth almost wants to continue with the word - bomb.

I think these factors combined with the addition of some stupid mishaps and blatant disregard (Chernobyl, Mayak plant, maybe even TMI and to some extent Fukushima) have made people fear the word nuclear.
What I want to say is the word fission is very close to the word fusion , just two letter difference , so good luck with explaining that to the average Joe and telling him his potatoes will not become mutant ninja turtles.I think only time and education plus (sadly) running out of other options will make society change its mind.

 

[mfb]

We have other options. So far they are much more expensive than fission. By the time fusion is an option (around the end of the lifetime of fission reactors built now, hopefully) they might be cheaper than both.

 

[artis]

What "other options" exactly were you referring to?I personally think that we should approach wisely everything we have, I think the smart thing to do would be to keep pushing renewable energy like wind and solar to it's maximum (without overkilling it) while at the same time closing coal plants and swapping them (the so called base load) with more nuclear and if not possible then natural gas. It's not that we need to close all coal plants at the same moment it's just that we need to reduce enough emissions in order to keep climate change steady while we are still working on better solutions.

I live in a smaller country and we supply almost entirely ourselves with 3 medium size hydro plants so our energy is already emissions free, sadly not everyone has that option, some African countries due to their sunny weather and remotely populated areas could maybe almost fully support themselves from wind and solar alone with some small base load for backup.

 

[mfb]

What "other options" exactly were you referring to?

A lot of solar+wind with a lot of storage, or excessive solar+wind and large grids with less storage. Hydro, geothermal energy and a bit of biomass where available/useful. Currently too expensive in most places but that might change.

 

[artis]

Well Hydro is very stable and if the dam is maintained correctly also long term. Our biggest Hydro plant is operating non-stop since 1965 with an output of 1000 MWe, so basically it gives the same output as a standard PWR or BWR nuclear reactor.
The problem is that there are only so many rivers around the globe and I think most have already been used? At one point it was a good business model here to build smaller hydro plants , but those small plants really aren't useful to my mind , their total add to the grid is something like maybe 3/5% while their environmental impact outweighs the gain in electricity.
I believe Russia and some other large countries still have some Hydro potential especially on the large rivers in Siberia etc, with HVDC it would even be productive to bring that power closer to population centers, just an idea.I guess the "storage" is a problem when it comes to solar and wind because realistically how do you store thousands of MW for hours? pumped hydro maybe something else? I think batteries at least at current level is a no-go.But when I said we must approach our energy usage wisely I though in every possible way, one example that comes to mind is electric transport, even Elon Musk brought this up in one interview that even if the electricity that powers an electric car is produced in a coal plant it is still better to use that electricity rather than gasoline or diesel because burning fossil fuels in large ovens or machines like gas turbines has a higher thermal efficiency than doing that in small individual engines so still we are getting more energy out for the same amount of CO2 emitted. So speaking about this I wonder why I see so few , almost none electric locomotives in USA? We here in Europe use almost entirely only electric trains both freight and passenger, Also I advocate for electric public transport like trams and trolleys.

I think if we want to be realistic about this we need to do all these minor things because just sitting here waiting for a miracle ain't going to cut it. Fusion I believe is still 50 years into future, given all the testing and commercial application issues etc let's be real 2050 seems more a realistic point by which time if all else is kept as is we will already be in trouble.

 

[Astronuc]

Thirdly the fact that nuclear was first brought into the world as a bomb of unparalleled power and destruction has probably left a huge imprint into the average mind , Hollywood has only helped this myth. Because when you say nuclear- the mouth almost wants to continue with the word - bomb.

Actually, there were nuclear reactors before the bomb. Chicago Pile 1 (CP-1) was the first nuclear reactor. Ref: https://en.wikipedia.org/wiki/Chicago_Pile-1

The plutonium for the Trinity test (first nuclear explosion) and the 'Fat Man' bomb came from the first large scale production reactor, B-reactor, as Hanford.
https://en.wikipedia.org/wiki/B_Reactor

The achievements of the reactors was known only to a few, and not to the public. "Neither university nor city officials were told that an experiment that even its creators judged as risky was taking place in the heart of the second-largest city in the United States." So, as far as the public knew, the first application of nuclear energy was the bombs dropped during World War II.

With respect to electric railroads, there is the Northeast Corridor (NEC) in the US.
https://en.wikipedia.org/wiki/Northeast_Corridor
https://en.wikipedia.org/wiki/Railroad_electrification_in_the_United_States

Capital cost and traffic density are factors in the consideration of electrification.

MetroNorth Commuter Railroad operates on the NEC as well as on intersecting routes in NY and CT. NJ Transit operates similarly in the state of New Jersey (NJ). I believe Chicago has some electrified railways, and many cities, e.g., San Diego, Houston, Seattle, Denver, Los Angeles, Boston, . . . have electrified light rail systems.
https://en.wikipedia.org/wiki/Light_rail_in_North_America#Table_of_United_States_light_rail_systems

The OP is about "What if we had commercial fusion energy", which implies that we have perfected controlled fusion energy generation that is commercially viable. There are issues of tritium supply, if that's the typical system, and somewhat less so if the system uses d+d fusion. For neutronic reactions, there is the matter of transmutation (activation) of structural materials, as well as radiation effects, and how to dispose of the material. Replacing and disposing of activated components will be an economic consideration. Production of special nuclear materials is yet another concern.

 

[artis]

I knew about the "Fermi" Chicago pile and others it's just that my point was about what the public knew and still knows, many still don't know about the existence of these reactors because when more information became available these were already old old news.

Well since you are an expert I would then like to ask you , how exactly in the D-T fuel will tritium be recovered because not only does the reactor has to produce it by neutron bombardment but I also read that tritium is very hard to recover especially from a complicated vacuum vessel so would't it be the case where the actual tritium input for the reactor to continue operation needs to be larger than simply what's needed for x amount of fusion to take place because it also needs to account for the tritium lost to the walls etc? In the popular science literature this is not discussed as much as other factors related to tokamaks and fusion.

 

[Astronuc]

Well since you are an expert I would then like to ask you , how exactly in the D-T fuel will tritium be recovered because not only does the reactor has to produce it by neutron bombardment but I also read that tritium is very hard to recover especially from a complicated vacuum vessel so would't it be the case where the actual tritium input for the reactor to continue operation needs to be larger than simply what's needed for x amount of fusion to take place because it also needs to account for the tritium lost to the walls etc? In the popular science literature this is not discussed as much as other factors related to tokamaks and fusion.

One can find some references searching for "tritium recovery at ITER".

For example, https://nucleus.iaea.org/sites/fusi...website/talks/November 15 Sessions/Willms.pdf

The recovery depends on the form of the Li used to generate T. Recovery of the T leaking out of the plasma and diffusing into the structural material is more complicated, so I don't know how that is addressed at this time. Ostensibly, there would have to be a T recovery system built into the first wall, or between first wall and rest of structure.

 

[artis]

The question is more about whether it will be possible to recover all the deposited and otherwise lost tritium while maintaining a somewhat decent schedule and uptime or maybe there will be a point after a certain amount of operation where a lot of both structural and technical elements will have to be swapped out for new ones while the old ones go to tritium recovery and recycling and some to burial or something like that? But this probably signals a rather lengthy down time while all this is changed.

 

[Astronuc]

The question is more about whether it will be possible to recover all the deposited and otherwise lost tritium while maintaining a somewhat decent schedule and uptime or maybe there will be a point after a certain amount of operation where a lot of both structural and technical elements will have to be swapped out for new ones while the old ones go to tritium recovery and recycling and some to burial or something like that? But this probably signals a rather lengthy down time while all this is changed.

I believe the goal is continual recovery, but that would be system dependent. If the reactor has to be shutdown, and components removed, then that will have to be considered in the operating cycle.

There is this article - Tritium recovery from an ITER ceramic test blanket module — process options and critical R&D issues
https://www.sciencedirect.com/science/article/pii/S0920379600001836

However the article must be purchased if one is not a subscriber.

 

[mfb]

You can breed on average more than one tritium nucleus per fusion reaction, sacrificing a bit of the power produced: ${}^7Li + n \to {}^4He + T + n$ (-2.47 MeV). Some tritium loss is okay. A power plant will find some sweet spot between breeding and power. Initially power plants might want to breed more to fuel new power plants.

 

[etudiant]

One issue for the experts.
The time to build for large reactors of any type, whether fusion or fission, in the US as well as in Europe has become so long as to prevent them from getting built there at all, although China and India still seem to manage more reasonable schedules for large new fission plants.
Small reactors might be a more acceptable approach for the 'Western World', more easily managed in an emergency and more readily built on an industrial scale.
There are several small fission reactor designs under study to serve this potential opportunity, but I've not seen any small scale fusion designs, even conceptually.
Is small scale fusion inherently impossible or is it simply much more difficult?

 

[mfb]

We don't know how to build it smaller. A smaller plasma has a larger surface area compared to its volume - it loses its energy faster, it gets more difficult to bring it to a stage where fusion releases enough energy to keep it hot. There might be ways to achieve this with smaller reactors but we don't know how.

Fission has a minimal size of the core as well but this minimal size is much smaller.

 

[etudiant]

We don't know how to build it smaller. A smaller plasma has a larger surface area compared to its volume - it loses its energy faster, it gets more difficult to bring it to a stage where fusion releases enough energy to keep it hot. There might be ways to achieve this with smaller reactors but we don't know how.

Fission has a minimal size of the core as well but this minimal size is much smaller.

Guess the square cube law is not a friend of small fusion designs.
Would a stellarator such as the German Wendelstein 7 be less impacted?