In article , Paul F Austin
writes

"Dave Eadsforth" wrote in message
...
In article , Paul F Austin
writes

"Dave Eadsforth" wrote ...
Jim Yanik wrote
Any deep mine that had a nuclear explosion nearby deep underground
would
have it's shafts collapse,or become inaccessible,just as effective as
destroying the WMD itself. They might even flood.

At one point, it was feared that an exploding nuke could send a stream
of VERY hot gasses along tunnels, thus spoiling everyone's day.
However, later modelling (and maybe even testing) revealed that an
underground nuclear explosion in an area containing shafts and tunnels
tends to crush them flat, thus sealing them and saving the rest of the
complex further damage. So, the lesson appeared to be; don't build
caverns, stick to tunnels and shafts.

That's interesting. Do you have a cite for that?

I'm afraid not - it was described in a newspaper article many years ago,

During the underground test
era, in one test the blast doors failed. During a UGT, explosive-powered
doors located a short distance from the bomb chamber close after the
prompt
radiation pulse drops off (a few hundred nanoseconds) and before the
blast
wave arrives, to preserve the down-hole equipment. In one test, the doors
failed and the VERY hot gasses (and lots of fission fragments) both
melted
and contaminated the equipment in the test galleries quite far back from
the
bomb chamber.

Was that because the blast hit the tunnel head on? If so, I could
imagine the VERY hot gases etc going straight down the tube. However,
if the complex were built of tunnels that zig-zagged sharply, the nuke
would move enough rock to crush tunnels at 90 degrees to the explosion
and any hot stuff entering a tunnel head on to begin with should be
blocked when a section at 90 degrees to it collapsed.

The test galleries for UGTs were layed out herringbone fashion along a main
tunnel. Each test gallery could "see" the nuclear explosion so that the test
articles could be exposed to both thermal and nuclear (the two blur together
somewhat) radiation.

So; exposed on purpose. If thin tunnels were zig-zagged like a WWI
trench system with bulkheads between, I guess that might help a bit.

The blast doors were build to withstand the
overpressures that the bomb would generate. In the UGT where they failed, it
was the closing mechanism that failed to operate rather than the doors being
breached.

Bet that annoyed some designer...

As I understand it, the argument for building penetrating nuclear weapons is
that the weapon will volatilize any agents (chemical or biological) that are
present before they can leak out.. That seems iffy to me. As far as
"crushing" tunnels, there won't be much crushing going on much outside the
facture zone, which for a full yeild B61 (300KT) is about 900 feet radius.
Any bunker more than a few multiples of that distance away will get a
hellacious shock but if competently designed, should remain intact.

Hmm, nuke has to be accurately targeted then - I suppose they might run
to the cost of GPS guidance for this type of bomb...

But the shock of the explosion would cause those bunkers safely beyond
the fracture zone to rock and roll like hell. I read somewhere that the
interior facilities at Cheyenne Mountain were resting on humungous sized
springs - is that the only option for resilience?

Enthusiasts keep ignoring these unpleasant facts and suppose that
ground-penetrating RADAR or some other MagicTech will give the attackers
x-ray glasses so that they can see more or less where the bunkers really
are. Fat chance. I mentioned up-thread that modern tunneling equipment can
drive a shaft 200 feet a day. With a year to prepare, without superb HUMINT
it's all going to be a mystery to the targeters, even with nukes at their
disposal.

So, what to we conclude when a country orders a set of tunnelling
equipment, ostensibly to build a metropolitan subway, and then gives up
'because the geology is all wrong' (um, wouldn't that have come out of
the original survey?)? Is the kit sitting in a junkyard - or is it now
underground, doing something else?

Cheers,

Dave

--
Dave Eadsforth