Why Aren’t Nuclear Reactors Built Underground?

Notice I haven’t asked why aren’t “power stations” built underground (obviously far too big). Yet building Nuclear Reactors underground has the potential to solve at least three, costly, problems…

1. Safety: Had 3 Mile Island, Chernobyl, or Fukushima occurred just 10 meters underground, it’s my estimate that almost no radioactive particles would have become air-born. This of course is assuming they also had a sealable shaft entrance. It would also make it impossible for almost any missile (let alone a hijacked aeroplane) to breach the containment.
2. Decommissioning: This is the single biggest cost of nuclear power (i.e. dismantling the radioactive structure once the reactor core, has suffered too much Transmutation to remain structurally sound). Because in the UK all new, nuclear reactors, are being privately built, Nuclear Liabilities Funds are being legally imposed to cover the long-term costs (both for new builds and older ones the government has sold years ago). The idea being that after about 30-50 years of use, the money continuously invested will have grown substantially, even if only in government bonds
en.wikipedia.org... However there would be little to no need to dismantle an underground structure. Throughout Britain there are the remains of Roman building that were constructed with half-baked bricks 2000 years ago. It stands to reason that using modern concrete, and stainless steel reinforcement bars, we could build today an underground structure that would remain fully intact long-after 2000 years. By which time robotic armies, or some other world changing technological developments should have come into being.
3. Waste: Most nuclear power stations were not designed to become long-term depositaries of nuclear waste, and yet that is how they are being used, because the anti-nuclear lobby, opposes the storage of waste in the most geologically sensible places
(I guess that would give them even less to argue about given existing nuclear kills 4000 times less people, per unit of electricity, than coal,
Image Representation: www-958.ibm.com...
Statistics: nextbigfuture.com...
And worldwide nuclear has killed less than hydroelectric dam failures).

The dam failures killed an estimated 171,000 people[1]; 11 million people lost their homes. It also caused the sudden loss of 18 GW of power[citation needed] , the equivalent of roughly 9 very large modern coal-fired power stations or about 20 nuclear reactors, equalling about 1/3 the peak demand on the UK National Grid en.wikipedia.org...

Anyhow: Building a power stations, long-term nuclear waste storage, on the same power station site, would prevent most if not all nuclear waste transportation (obviously expensive due to numerous safety concerns). It would mean nuclear waste could be dealt with the next few thousand years, as and when it’s made.

What Do You Think?
A. The only reason I’ve ever heard for not building reactors underground is they (could) be harder to inspect. I say “could” because I see absolutely no reason not to have a cavity space between the nuclear reactor, and the underground structure it’s contained in. Such a space need be no more than a 1-2 meters.
B. It’s obvious that some heat will be lost from a 10-15 meter transport trip for the reactors boiling water, coolant. However this heat would be very little if the reactors coolant was transported in a vacuum sealed pipe (just like double glazing).
C. Another obvious improvement to reactors would be: To place a “matt” of e.g. lead, iron or even concrete, directly beneath any Reactor Core, that possess a theoretical way of going into meltdown (some reactors like The Pebble Bed Reactor en.wikipedia.org... are prevented from doing so by non-other than the laws of physics). The purpose of this “matt” would be to dilute any fuel that came out of the reactor in the event of meltdown (because the amount of nuclear energy, nuclear fuel releases is directly proportionate to the fuels concentration i.e. proximity) AND it could also prevent the “China Syndrome” by further reducing fuel proximity, through directing the molten reactor fuel away from the reactor (i.e. at sloping angels) (i.e. into pre-constructed concrete containers) each of which would have volume for no more than e.g. a 10th-20th of the original, maximum core meltdown, mass, possible.
If by the end of reactors useable life, it never goes into meltdown (as happens literally over 99% of the time) then this “matt” of e.g. valuable lead-iron can be recycled for new builds, or sold as scrap.

reply to post by Liberal1984


i seem to remember that concrete has a life of one thousand years not two .
but i have been retired from the construction industry for some time now , so i could be wrong .

as for building the reactors underground , i think you have a good point , here in the uk we have quite a few excavations left over from the mining of rock salt , and they could be ideal for such a purpose .

Because you need to vent radioactive water vapor to the atmosphere.

Because you can't have your nuclear power station enclosed as the workers would be breathing high levels of hot particles.

Your cooling ponds storing your old nuclear fuel are hot and also evaporating LARGE quantities of water keeping them cool.

Like we saw in New York a few months ago.....when things go bad you need to be able to Emergency Shut Down your reactor and vent massive quantities of radiation into the atmosphere.

People don't want them below ground where the water table is.

tom.farnhilli seem to remember that concrete has a life of one thousand years not two

Standard concrete yes. But add more lime to it, and you increase its hardness & durability. E.g. fire cement can be harder than most stones. Likewise I advocate stainless steel bar, as opposed to ordinary steel (as that rusts and expands over large amounts of time).

Pervius I’m grateful to your critical thinking. If you can answer back, we might just be able to solve the problems raised…

Because you need to vent radioactive water vapor to the atmosphere.

So provide an emergency chimney!!! The water isn’t normally radioactive, unless it’s certain types of Boiling Water Reactor designs (Pressurised Water Ones don’t).

Because you can't have your nuclear power station enclosed as the workers would be breathing high levels of hot particles.

That doesn’t make much sense. If the core is on fire, they will die anyway (unless they run away for a few days, like in Fukushima)
Also having the reactor underground would be the best way to deprive a fire of oxygen. And there’s zero reason (I know of) why the reactor can’t be designed to operated from above ground. After all in no nuclear do people e.g. get inside it, and move leavers around!!!

Your cooling ponds storing your old nuclear fuel are hot and also evaporating LARGE quantities of water keeping them cool.

Then Have two chimneys for the ponds: One short one (to let air in) and another long one (to let moisture filled air out). This will work as wet air is (counter intuitively) lighter than dry air (but it’s not so counter intuitive when you see clouds floating high above).
Alternatively: Only put the fuel rods into storage once they become ready for it (it generally takes 4-5 years for the amount of heat produced to be of a level that can be easily absorbed from conduction as opposed to convection).

People don't want them below ground where the water table is.

If you have a lead-iron-concrete “meltdown matt” the core meltdown will never reach the water table, as the little heat produced (after fuel dilution) will be in equilibrium to that lost from conduction.
Furthermore: In all core meltdowns to date, the water table has been contaminated, and this is in any case, far less of a human-environment welfare issue than it particles air born. Water is about as good as absorbing radiation as standard concrete, it moves slowly, particularly once it’s no longer pumped (from the water table) –after the accident.

Underground construction is a rarity in today's society.

From a practical standpoint - we should be building damned near everything under the ground (spare, of course, for farms/green houses and solar/wind power plants). It's safer, reduces energy requirements (particularly regarding climate control), and the construction far more robust.

Why it isn't done is due to the lack of 'subterranean construction companies' - which are few and far between due to the fact that many people are rather fixated on the traditional concept of above-ground construction. Without experienced contracting agencies; you have increased construction costs along with a higher chance of encountering mid-construction design conflicts/challenges. First-time designs, also, automatically pioneer operational flaws and construction oversights (such as condensation accelerating galvanic corrosion due to an unforeseen deficiency in the ventilation application).

I'm a huge proponent of building things under ground, and developing ways to "have our cake and eat it to" (by allowing natural sunlight into the spaces and making the spaces feel less like a crypt). I expect the market for it will be growing substantially over the next few decades. The main obstacle to practical solar power for homes is in the sheer amount of power used for climate control purposes (though there is also considerable issue with storing power during peak generation times for use through the rest of the day).

There has been some talk of starting to build new structures under the ground in Chicago - because they have, literally, run out of room. The costs of building higher are simply unacceptable and the only place left to go is down.

Honestly - if I were to invest in stock, I'd pick a company specializing in underground construction/excavation with smart, ambitious leadership.

Because the last thing this planet needs is more nuke reactors, and fantasy robot armies to tend to them in the future. The solution is simple: cease and desist with insane tech.

Shar_Chi
Grow up, or get real (just whichever comes first). What is wrong with nuclear whenever physics guarantees it can be done safely? There is already the Pebble Bed Reactor and Integral Fast Neutron Reactor both of which are guaranteed against melt down by the laws of physics.

I know...
The Boiling Water Reactor (designed in 1965 and operational by 1971 and which saw 3 it’s designers resign 35 years ago because of its stupid location, and pathetic flood defences newsfeed.time.com...–-35-years-ago/ ) was a bad idea. I never supported it, and wanted it closed before the disaster too. I know Chernobyl happened because they deliberately over rid its safety systems, and 3 Mile Island was caused by ridiculously incompetent plant operators. I know the regulatory US system is a disaster waiting to happen, and nuclear's beyond bad whenever it goes wrong.

But...
The mistakes of the past were inevitable along the road of finding mankind the perfect energy source. By improving the technology -using knowledge existing already; there are indeed ways the laws of physics can override the potential for human error.

Meanwhile: we have brown coal, plus Mountain Hill Top Mining en.wikipedia.org... , and even black coal killing 4000 times more people, and will kill a lot more if (or when) the climate is unbalanced for the next 10,000 from the new constructions due over the next 40 –constructions that would otherwise consume world coal reserves.

We have a planet approaching 7 billion, and we need more electricity not the same amount –current renewables are insufficient and likely to stay this way. Overall electricity should be cheap, or inflation rises and manufacturing jobs (in particular) go abroad.
The Stars that made every atom in you and me (accept hydrogen) provided the answers we need: Thorium, Uranium and Plutonium. We also have stockpiles of Depletive Uranium and Plutonium which could provide Britain all its energy for over 500 years, and which would otherwise be used in war. There are reactors which can use these energetic substances for the purpose the universe intended…

GE and Hitachi plan new reactor to burn UK plutonium stockpile
Multibillion pound plant at Sellafield would convert UK's nuclear power plant residue into fuel www.guardian.co.uk...

Nuclear waste has killed almost nobody, and in any case can vastly reduced & recycled through Reprocessing see UK advert explaining the benefits here: www.tvspots.tv...

Meanwhile: Accidents can & will become less likely as technology advances, if not altogether eliminated –barring (perhaps) the most trivial.

Summary...
Only if the truly paranoid are in charge of this world, are we unlikely to have progressed much, in 2000 years. Either this; or we'll be killed by the pollution and problems you're half solutions might, (kind of) provide!!! Electricity that's killed 4000 times less than that from coal isn't bad! Are you going to e.g. campaign twice as hard to ban hydroelectric too? (Given that’s killed more than twice as more). Dare you to answer back -I'm confident I can ruin your arguments, with nothing but truth & logic.

Aim64C

Why it isn't done is due to the lack of 'subterranean construction companies' - which are few and far between due to the fact that many people are rather fixated on the traditional concept of above-ground construction.

So basically smaller reactor sizes would be a good way of increasing feasibility, as then digging project can be proportionately smaller?
There is much to be said for smaller reactors, with smaller construction times. However nuclear power stations should always be big because they are easier to defend, and public opposition is generally small wherever they already exist.