Reply to: Nuclear power

[ace00]

And can I just add:
Legal Surgery - always take this option if given the choice
here to help

[ace00]

hello, does it still work?
what about that global warming then?

[zeitghost]

Are you mad?

You can't make pits out of thorium.

Stone me, you can out of U233, but there may be some slight side effects:

This is an entirely different waste profile.

Noticeably missing are the plutonium and the minor actinides.

Noticeably evident is the U233.

The Los Alamos National Laboratory (LANL) in the USA did successfully manufacture an experimental nuclear bomb, and in the process, they amply demonstrated that U233 is far more difficult to construct into nuclear bombs than Pu239 or minor actinides.

The reason lies chiefly in the uranium-232 (U232) contamination that occurs naturally in all U233.

Like most unstable radioactive isotopes, U232 decays into a string of various atoms over time.

U232 and some of its daughter decay products emit very strong gamma radiation.

Unlike Pu239, U232 emits more gamma over time, and becomes more dangerous.

This makes any handling of U232, and by extension any waste material from the thorium fuel cycle, virtually impossible to handle.

To put it into perspective for the reader, a critical mass of plutonium waste product can be handled with a standard glove box, whereas a critical mass of U233 (approximately 5 kilograms) would contain enough U232 content (approximately 1%), that after 10 years, lead shielding of 17 meters in thickness would be required for handling.

Without this lead shielding, any human being within approximately 1.6 kilometers (1 mile) of U232 would suffer lethal exposure within 5 minutes.

Furthermore, because a critical mass of U233 would be so easily detectable, the bomb making facilities would have to be constructed several miles below the surface of the earth.

U232’s gamma emissions also have a destructive effect on electronics.

So, although it is technically possible to construct a bomb from U233 waste material generated by the thorium fuel cycle, it is exponentially more difficult, dangerous and expensive than using Pu239.

[TimberWolf]

Check out the earthquake forces experienced at the Fukushima plants: Fukushima faced 14-metre tsunami

...but available figures put the maximum acceleration as 507 gal from east to west at unit 3

1 gal =1 cm/s², so that's 5g's of side-to side acceleration

3g in the vertical direction too. So as well as getting shaken about like a rag doll in an earthquake, you'd feel pretty heavy too. Though perhaps these accelerations, in any particular direction, only last fractions of a second. Like being pulled backwards and forwards and up and down at some unspecified frequency.

[TimberWolf]

Anyway, don't forget that "waste" heat could be used to provide central heating and hot water for houses, even heating under motorways to prevent them freezing.

Flippin' heck - I've practically designed this thing already!

Also, to address doodab's question, earthquakes have _less_ of an effect on tunnels than on surface structures - see article here :

I suppose you could use surface water pressure to force hot water most of the way back up to the surface too, so there's potentially cheap pumping to the surface available as well as hot water. Combined systems already exist in flat land. You'd have thought being sited on a coast, and deep underground, would be away from the fresh water table too, because you are at (or well below) sea level.

[doodab]

Also, to address doodab's question, earthquakes have _less_ of an effect on tunnels than on surface structures - see article here :

Good to know. I've always wanted a secret bunker.

[OwlHoot]

No disadvantages?

What about efficiency, which effects cost.

A 1GW reactor might need say 2GW of thermal energy to remove. I'm not sure how multiple cooling circuits address that, but even if they did, multiple circuits reduce efficiency, since the primary cooling circuit would presumably be warmer than would a single cooling circuit. Efficiency being 1- Temp_Cold/Temp_Hot

It's also hotter underground meaning another efficiency hit and energy needed to cool equipment and humans

Even if a vertical tunnel chimney were used to vent super hot steam, I imagine a lot of it would fall back down as hot rain before it escaped, unless there were a mega updraught, reducing efficiency.

People disposing of spent fuel rods seem to spend a lot of time figuring out good places to bury spent waste, so I imagine the same headaches will exist for reactor sites.

Fair point about the efficiency; but multiple cooling circuits allow easier and safer maintenance and are more flexible, in terms of switching from one reactor to another if any have to be temporarily shut down for maintenance. Also, being at lower temperature/pressures, the secondary and tertiary ones can be more compact and of a lower spec generally.

Anyway, don't forget that "waste" heat could be used to provide central heating and hot water for houses, even heating under motorways to prevent them freezing.

Flippin' heck - I've practically designed this thing already!

Also, to address doodab's question, earthquakes have _less_ of an effect on tunnels than on surface structures - see article here :

Experience shows that underground structures, especially deep ones, are far less vulnerable to earthquakes than superficial ones. The latter are endangered by earthquakes due to the fact that the motion of the ground can be amplified by the response of the structure to such an extent that the induced strains damage the structure. The earthquake waves can also be amplified within soft superficial strata. In addition, loose water-saturated soil may loose its strength (so-called liquefaction), and this can lead to landslides or failure of foundations and retaining walls. In contrast, deep buried structures, especially flexible ones, are not expected to oscillate independently of the surrounding ground, i.e. amplification of the ground motion can be excluded. This is manifested by the relatively low earthquake damage of tunnels.

[OwlHoot]

True, but gravity does work in your favour in that you can open some valves and flood the place.

Exactly.

If the overheating is only temporary (as in a week or two for short-lived isotopes to decay, having stopped the main reactions) then flooding it with water might be fine, given enough temporary expansion space for the resulting steam and maybe heat exchangers to condense it as far as possible.

Otherwise the best bet would be simply to collapse a few hundred yards of tunnel round the sizzling glowing mess (in the event of meltdown say), along with quick setting liquid concrete and several foot thick steel plugs etc as necessary, and start drilling a new tunnel parallel to the first where a replacement reactor could be sited.

This assumes a tree-like system of tunnels, with main "trunk" passages and reactor passages branching off these.

[TimberWolf]

[stek]

Hartlepool Nuclear Power Station - Wikipedia, the free encyclopedia

Torness and Sizewell too

[shaunbhoy]

That is assuming that in times of a crisis you can find any of us

Or afford the rate you have negotiated for your services!!!

[DodgyAgent]

We could always try dropping bucketloads of Agents though. They are, after all, all wind and piss!!

That is assuming that in times of a crisis you can find any of us

[shaunbhoy]

You cannot drop buckets of seawater from helicopters onto a reactor to cool it if it is underground

We could always try dropping bucketloads of Agents though. They are, after all, all wind and piss!!

[doodab]

What happens to underground caverns during an earthquake? Are they safe places to be?

[DimPrawn]

You cannot drop buckets of seawater from helicopters onto a reactor to cool it if it is underground

True, but gravity does work in your favour in that you can open some valves and flood the place.