...At the bottom on the ninth...Nasa hits a homer!

Henry Spencer wrote:

That's not the question; the question is how small the *North Koreans* can
make a nuclear weapon. And the answer, almost certainly, is "not very".
Really small nuclear weapons take an experienced weapons lab. They can
probably do better than the Manhattan Project did, because some of the
basic ideas of how to do better are now public knowledge, but their best
will still be big and heavy, for a while.

Hopefully they haven't gotten any of our secrets from our labs.

robert casey wrote:


Hopefully they haven't gotten any of our secrets from our labs.


At best they might do a levitated core boosted plutonium device, but I'm
betting they would go the U-235 gun assembly device route as that's a
lot easier to make, and if you did it right you could probably make it
light enough for a missile to carry.
The explosive lens for a plutonium device is fairly high-tech,
particularly if you want to make the warhead fairly small in diameter.
When Pakistan and India did their nuclear weapons, they went the
enriched U-235 route, and North Korea is supposed to have gotten a lot
of their nuclear tech from the Pakistanis.
As to what the Iranians are up to? If anything, they'll probably go the
U-235 route also.
It's nowhere near as efficient as building a breeder reactor and making
plutonium from an economic point of view, but it's far, far simpler in
terms of needed technology.

Pat

In article ,
Scott Dorsey wrote:
That's not the question; the question is how small the *North Koreans* can
make a nuclear weapon. And the answer, almost certainly, is "not very"...

This is true. The thing is, even if they don't have heavy-lift capability
in a missile, it's still not all that difficult to put it in a shipping
container on the dock and let Yang Ming take it to the US. It's not very
rapid, but it's a much more likely scenario as far as actual nuclear
deployment goes.

It's a scenario for a different mission, though. Specifically, it's a
scenario for *attacking* the US, as opposed to *deterring* the US.

Bombs in cargo containers do not make good *threats*, especially if you
don't have very many bombs. There's too much chance of them being
discovered by mundane means like customs inspections. Moreover, when even
one is discovered, that would almost certainly be seen as an act of war...
so you can't pre-deploy them.

What you want for a threat is a weapon that remains under your direct
control until you have to use it, and has a short travel time and is
difficult to intercept once you do. Like a ballistic missile.

If you're sufficiently crazy to actually want to attack the US, smuggled
bombs may be the best route. But for deterring the US -- e.g. to tell
them not to interfere as you reclaim a few "lost provinces" -- missiles
are the weapon of choice. Which is why so many unpleasant states are so
obsessed with ICBMs, despite the difficulties and costs involved. It's
not because they can't figure out that cargo containers are cheaper than
ballistic missiles; it's because cargo containers don't do the job they
want done.
--
spsystems.net is temporarily off the air; | Henry Spencer
mail to henry at zoo.utoronto.ca instead. |

On Thu, 6 Jul 2006 22:47:43 GMT, in a place far, far away,
(Henry Spencer) made the phosphor on my monitor
glow in such a way as to indicate that:

If you're sufficiently crazy to actually want to attack the US, smuggled
bombs may be the best route. But for deterring the US -- e.g. to tell
them not to interfere as you reclaim a few "lost provinces" -- missiles
are the weapon of choice. Which is why so many unpleasant states are so
obsessed with ICBMs, despite the difficulties and costs involved. It's
not because they can't figure out that cargo containers are cheaper than
ballistic missiles; it's because cargo containers don't do the job they
want done.

Which is why a defense against same (contra many SDI critics for the
past couple decades) makes sense.

In article ,
Rand Simberg wrote:
...But for deterring the US -- e.g. to tell
them not to interfere as you reclaim a few "lost provinces" -- missiles
are the weapon of choice. Which is why so many unpleasant states are so
obsessed with ICBMs, despite the difficulties and costs involved...

Which is why a defense against same (contra many SDI critics for the
past couple decades) makes sense.

Unfortunately true. Sooner or later it *will* be needed, although there
may be room for debate about how soon.

One advantage of building an effective light-attack defense early, though,
is that it is probably the single best way to make a lot of those people
forget about ICBMs -- *far* more effective than diplomatic maneuvers.
ICBMs *are* difficult and expensive to acquire; once they are no longer
unstoppable, once quite small ICBM forces are no longer credible threats,
they become a lot less interesting.

Whether the current US missile-defense system can meet this requirement,
though, is less clear. Mind you, even with doubts about its
effectiveness, having it does help: after all, it *might* work...
--
spsystems.net is temporarily off the air; | Henry Spencer
mail to henry at zoo.utoronto.ca instead. |

In article . net,
robert casey wrote:
...probably do better than the Manhattan Project did, because some of the
basic ideas of how to do better are now public knowledge, but their best
will still be big and heavy, for a while.

Hopefully they haven't gotten any of our secrets from our labs.

Or from Russian or Chinese labs -- the US has no monopoly on this stuff.

What one could hope for, of course, is that their spies decided to start
by stealing the secrets of US project management. That will guarantee
that North Korea will never be a threat. :-)
--
spsystems.net is temporarily off the air; | Henry Spencer
mail to henry at zoo.utoronto.ca instead. |

In article ,
Pat Flannery wrote:
At best they might do a levitated core boosted plutonium device, but I'm
betting they would go the U-235 gun assembly device route as that's a
lot easier to make...

Trouble is, although it's easier to design and build, it's also very
wasteful of fission fuel, since it does no compression. Which is why the
US made very little use of gun bombs after Hiroshima -- the same supply of
U-235 went much farther in implosion bombs. My suspicion is that there's
now enough public knowledge about making implosion work that it would be
appealing just for the sake of needing less U-235 per bomb.
--
spsystems.net is temporarily off the air; | Henry Spencer
mail to henry at zoo.utoronto.ca instead. |

Henry Spencer wrote:

Pat Flannery wrote:


At best they might do a levitated core boosted plutonium device, but I'm
betting they would go the U-235 gun assembly device route as that's a
lot easier to make...



Trouble is, although it's easier to design and build, it's also very
wasteful of fission fuel, since it does no compression. Which is why the
US made very little use of gun bombs after Hiroshima -- the same supply of
U-235 went much farther in implosion bombs. My suspicion is that there's
now enough public knowledge about making implosion work that it would be
appealing just for the sake of needing less U-235 per bomb.



Yeah, but it's simple and you can do it via enriched reactor fuel with
very low technology and be pretty sure the damn thing is going to go off.
That's why Pakistan threw us the curve ball and went for the U-235
bomb....economicly, as far as using your money wisely, a complete
disaster area.
But there's was a good reason that "Little Boy" was the first atom bomb
we used- that being that we pretty much had the assurance that it had
around a 99.9% chance of successfully detonating over the target.
That's what really threw us the curveball regarding the other potential
nuclear powers.. we assumed that they would go the plutonium route
rather than the clumsy U-235 route...and the inherent greater simplicity
of that means of developing a nuclear weapon via a U-235 gun system...
even though the far greater technologic simplicity of the U-235 way
means that accomplishing that end could be done quicker, and with lower
input cost or time for a limited nuclear arsenals.
Going the U-235 way meant they could get the bomb minus the difficulty
of building a breeder reactor, extracting the plutonium from its U-238
input, or designing a symmetric implosion lens to compress the
subcritical plutonium pit.

Pat

Pat Flannery wrote:

Yeah, but it's simple and you can do it via enriched reactor fuel with
very low technology and be pretty sure the damn thing is going to go off.
That's why Pakistan threw us the curve ball and went for the U-235
bomb....economicly, as far as using your money wisely, a complete
disaster area.

Pat; "U-235 bomb" != "gun type bomb". It's quite feasible to build an
implosion weapon from Oralloy.

D.
--
Touch-twice life. Eat. Drink. Laugh.

-Resolved: To be more temperate in my postings.
Oct 5th, 2004 JDL

On Fri, 7 Jul 2006 02:56:26 GMT, in a place far, far away,
(Henry Spencer) made the phosphor on my monitor
glow in such a way as to indicate that:

In article ,
Rand Simberg wrote:
...But for deterring the US -- e.g. to tell
them not to interfere as you reclaim a few "lost provinces" -- missiles
are the weapon of choice. Which is why so many unpleasant states are so
obsessed with ICBMs, despite the difficulties and costs involved...

Which is why a defense against same (contra many SDI critics for the
past couple decades) makes sense.

Unfortunately true. Sooner or later it *will* be needed, although there
may be room for debate about how soon.

One advantage of building an effective light-attack defense early, though,
is that it is probably the single best way to make a lot of those people
forget about ICBMs -- *far* more effective than diplomatic maneuvers.
ICBMs *are* difficult and expensive to acquire; once they are no longer
unstoppable, once quite small ICBM forces are no longer credible threats,
they become a lot less interesting.

Whether the current US missile-defense system can meet this requirement,
though, is less clear. Mind you, even with doubts about its
effectiveness, having it does help: after all, it *might* work...

In fact, that was a point that a lot of critics missed in the
eighties, when they insisted that anything less than a perfect defense
was useless, or even counterproductive. But part of the idea was to
put enough doubt in the minds of a Soviet war planner to take an
attempted first strike off the table, even if the defense didn't knock
down every single missile.