Like most of us (baby boomers) I grew up in a world that already had
nuclear weapons. We did "Duck and Cover" drills in school, and I
thought I had a fair notion about how these things worked.

But this photo (second one on this page) of the PU core of the
"Fat Man" implosion device - it's so small...fit's in your hand.




http://simplethinking.com/home/nuclear_weapons.htm

The majority of the energy release is nearly instantaneous, the mean
time from neutron release to fission can be of the order of 10
nanoseconds, and the chain reaction builds exponentially. The result is
that greater than 99% of the very considerable energy released in an
atomic explosion is generated in the last few (typically 4-5)
generations of fission -- less than a tenth of a microsecond.*

This tremendous energy release in a small space over fantastically short
periods of time creates some unusual phenomena -- physical conditions
that have no equal on earth, no matter how much TNT is stacked up.


A fascinating collection of high speed photos...

http://simplethinking.com/home/rapat...hotographs.htm

http://simplethinking.com/home/rapatronic_2.shtml

and the "rope tricks"...
http://simplethinking.com/home/rapatronic_3.shtml

On 2/23/2012 8:08 PM, Richard wrote:
Like most of us (baby boomers) I grew up in a world that already had
nuclear weapons. We did "Duck and Cover" drills in school, and I
thought I had a fair notion about how these things worked.

But this photo (second one on this page) of the PU core of the
"Fat Man" implosion device - it's so small...fit's in your hand.




http://simplethinking.com/home/nuclear_weapons.htm

The majority of the energy release is nearly instantaneous, the mean
time from neutron release to fission can be of the order of 10
nanoseconds, and the chain reaction builds exponentially. The result is
that greater than 99% of the very considerable energy released in an
atomic explosion is generated in the last few (typically 4-5)
generations of fission -- less than a tenth of a microsecond.*

This tremendous energy release in a small space over fantastically short
periods of time creates some unusual phenomena -- physical conditions
that have no equal on earth, no matter how much TNT is stacked up.


A fascinating collection of high speed photos...

http://simplethinking.com/home/rapat...hotographs.htm

http://simplethinking.com/home/rapatronic_2.shtml

and the "rope tricks"...
http://simplethinking.com/home/rapatronic_3.shtml
Very impressive photos. I don't recall seeing them before.

Still the critical component is not described. It is the mechanism to
trigger the conventional explosive segments all at the identical time.
The key word being - identical. The failure of these devices in the last
North Korea test probably caused the dud. Until Iran is able manufacture
the devices and get them to work properly, all the uranium in the world
will not get them the bomb.

Paul

On Thu, 23 Feb 2012 20:37:59 -0800, Paul Drahn
wrote:

On 2/23/2012 8:08 PM, Richard wrote:
Like most of us (baby boomers) I grew up in a world that already had
nuclear weapons. We did "Duck and Cover" drills in school, and I
thought I had a fair notion about how these things worked.

But this photo (second one on this page) of the PU core of the
"Fat Man" implosion device - it's so small...fit's in your hand.




http://simplethinking.com/home/nuclear_weapons.htm

The majority of the energy release is nearly instantaneous, the mean
time from neutron release to fission can be of the order of 10
nanoseconds, and the chain reaction builds exponentially. The result is
that greater than 99% of the very considerable energy released in an
atomic explosion is generated in the last few (typically 4-5)
generations of fission -- less than a tenth of a microsecond.*

This tremendous energy release in a small space over fantastically short
periods of time creates some unusual phenomena -- physical conditions
that have no equal on earth, no matter how much TNT is stacked up.


A fascinating collection of high speed photos...

http://simplethinking.com/home/rapat...hotographs.htm

http://simplethinking.com/home/rapatronic_2.shtml

and the "rope tricks"...
http://simplethinking.com/home/rapatronic_3.shtml
Very impressive photos. I don't recall seeing them before.

Still the critical component is not described. It is the mechanism to
trigger the conventional explosive segments all at the identical time.
The key word being - identical. The failure of these devices in the last
North Korea test probably caused the dud. Until Iran is able manufacture
the devices and get them to work properly, all the uranium in the world
will not get them the bomb.

Paul

Well, that *is* really a problem. All of the plutonium in the world
won't get them a bomb, but the gun trigger for Little Man could
probably have been made in a good basement shop. That's why it's a lot
scarier for them to have enriched uranium than plutonium. Any goof can
make a gun-trigger uranium bomb, if they have a plan that gives them
useable dimensions.

The US made a few gun-trigger bombs, and the Brits made a few, and
then we both scrapped them. They're dangerous as hell: anything that
will set off the explosive charge, like lightening or a big spark,
can, theoretically, make them go "boom."

Gun triggers won't work with plutonium because the bomb will
self-destruct before the chain reaction is more than a fizzle. BTW. it
takes a much larger uranium pit than a plutonium pit to make a bomb.

--
Ed Huntress

On Thu, 23 Feb 2012 23:53:17 -0500, Ed Huntress
wrote:

On Thu, 23 Feb 2012 20:37:59 -0800, Paul Drahn
wrote:

On 2/23/2012 8:08 PM, Richard wrote:
Like most of us (baby boomers) I grew up in a world that already had
nuclear weapons. We did "Duck and Cover" drills in school, and I
thought I had a fair notion about how these things worked.

But this photo (second one on this page) of the PU core of the
"Fat Man" implosion device - it's so small...fit's in your hand.




http://simplethinking.com/home/nuclear_weapons.htm

The majority of the energy release is nearly instantaneous, the mean
time from neutron release to fission can be of the order of 10
nanoseconds, and the chain reaction builds exponentially. The result is
that greater than 99% of the very considerable energy released in an
atomic explosion is generated in the last few (typically 4-5)
generations of fission -- less than a tenth of a microsecond.*

This tremendous energy release in a small space over fantastically short
periods of time creates some unusual phenomena -- physical conditions
that have no equal on earth, no matter how much TNT is stacked up.


A fascinating collection of high speed photos...

http://simplethinking.com/home/rapat...hotographs.htm

http://simplethinking.com/home/rapatronic_2.shtml

and the "rope tricks"...
http://simplethinking.com/home/rapatronic_3.shtml
Very impressive photos. I don't recall seeing them before.

Still the critical component is not described. It is the mechanism to
trigger the conventional explosive segments all at the identical time.
The key word being - identical. The failure of these devices in the last
North Korea test probably caused the dud. Until Iran is able manufacture
the devices and get them to work properly, all the uranium in the world
will not get them the bomb.

Paul

Well, that *is* really a problem. All of the plutonium in the world
won't get them a bomb, but the gun trigger for Little Man

That should be "Little Boy," the Hiroshima bomb. We had never tested a
gun-tirgger bomb before we dropped Little Boy.

--
Ed Huntress

could
probably have been made in a good basement shop. That's why it's a lot
scarier for them to have enriched uranium than plutonium. Any goof can
make a gun-trigger uranium bomb, if they have a plan that gives them
useable dimensions.

The US made a few gun-trigger bombs, and the Brits made a few, and
then we both scrapped them. They're dangerous as hell: anything that
will set off the explosive charge, like lightening or a big spark,
can, theoretically, make them go "boom."

Gun triggers won't work with plutonium because the bomb will
self-destruct before the chain reaction is more than a fizzle. BTW. it
takes a much larger uranium pit than a plutonium pit to make a bomb.

On Thu, 23 Feb 2012 23:53:17 -0500, Ed Huntress wrote:

On Thu, 23 Feb 2012 20:37:59 -0800, Paul Drahn
wrote:

On 2/23/2012 8:08 PM, Richard wrote:
Like most of us (baby boomers) I grew up in a world that already had
nuclear weapons. We did "Duck and Cover" drills in school, and I
thought I had a fair notion about how these things worked.

But this photo (second one on this page) of the PU core of the "Fat
Man" implosion device - it's so small...fit's in your hand.




http://simplethinking.com/home/nuclear_weapons.htm

The majority of the energy release is nearly instantaneous, the mean
time from neutron release to fission can be of the order of 10
nanoseconds, and the chain reaction builds exponentially. The result
is that greater than 99% of the very considerable energy released in
an atomic explosion is generated in the last few (typically 4-5)
generations of fission -- less than a tenth of a microsecond.*

This tremendous energy release in a small space over fantastically
short periods of time creates some unusual phenomena -- physical
conditions that have no equal on earth, no matter how much TNT is
stacked up.


A fascinating collection of high speed photos...

http://simplethinking.com/home/rapat...hotographs.htm

http://simplethinking.com/home/rapatronic_2.shtml

and the "rope tricks"...
http://simplethinking.com/home/rapatronic_3.shtml
Very impressive photos. I don't recall seeing them before.

Still the critical component is not described. It is the mechanism to
trigger the conventional explosive segments all at the identical time.
The key word being - identical. The failure of these devices in the last
North Korea test probably caused the dud. Until Iran is able manufacture
the devices and get them to work properly, all the uranium in the world
will not get them the bomb.

Paul

Well, that *is* really a problem. All of the plutonium in the world
won't get them a bomb, but the gun trigger for Little Man could probably
have been made in a good basement shop. That's why it's a lot scarier
for them to have enriched uranium than plutonium. Any goof can make a
gun-trigger uranium bomb, if they have a plan that gives them useable
dimensions.

The US made a few gun-trigger bombs, and the Brits made a few, and then
we both scrapped them. They're dangerous as hell: anything that will set
off the explosive charge, like lightening or a big spark, can,
theoretically, make them go "boom."

Gun triggers won't work with plutonium because the bomb will
self-destruct before the chain reaction is more than a fizzle. BTW. it
takes a much larger uranium pit than a plutonium pit to make a bomb.

Somewhere on the web -- I think I found it on Wikipedia -- there's a
discussion about early thoughts on gun-trigger plutonium bombs, along
with a picture of some ten prototypes that were scrapped. They were very
long and very skinny, to try to get the velocity up enough to avoid the
effect that you mention.

Apparently they originally thought that a gun-triggered Pu bomb would
work, and it was one of the big names (Oppenheimer or Feynmann) in
physics that re-did the calculations and figured out that it was a no-go.

--
My liberal friends think I'm a conservative kook.
My conservative friends think I'm a liberal kook.
Why am I not happy that they have found common ground?

Tim Wescott, Communications, Control, Circuits & Software
http://www.wescottdesign.com

On Fri, 24 Feb 2012 12:25:24 -0600, Tim Wescott
wrote:

On Thu, 23 Feb 2012 23:53:17 -0500, Ed Huntress wrote:

On Thu, 23 Feb 2012 20:37:59 -0800, Paul Drahn
wrote:

On 2/23/2012 8:08 PM, Richard wrote:
Like most of us (baby boomers) I grew up in a world that already had
nuclear weapons. We did "Duck and Cover" drills in school, and I
thought I had a fair notion about how these things worked.

But this photo (second one on this page) of the PU core of the "Fat
Man" implosion device - it's so small...fit's in your hand.




http://simplethinking.com/home/nuclear_weapons.htm

The majority of the energy release is nearly instantaneous, the mean
time from neutron release to fission can be of the order of 10
nanoseconds, and the chain reaction builds exponentially. The result
is that greater than 99% of the very considerable energy released in
an atomic explosion is generated in the last few (typically 4-5)
generations of fission -- less than a tenth of a microsecond.*

This tremendous energy release in a small space over fantastically
short periods of time creates some unusual phenomena -- physical
conditions that have no equal on earth, no matter how much TNT is
stacked up.


A fascinating collection of high speed photos...

http://simplethinking.com/home/rapat...hotographs.htm

http://simplethinking.com/home/rapatronic_2.shtml

and the "rope tricks"...
http://simplethinking.com/home/rapatronic_3.shtml
Very impressive photos. I don't recall seeing them before.

Still the critical component is not described. It is the mechanism to
trigger the conventional explosive segments all at the identical time.
The key word being - identical. The failure of these devices in the last
North Korea test probably caused the dud. Until Iran is able manufacture
the devices and get them to work properly, all the uranium in the world
will not get them the bomb.

Paul

Well, that *is* really a problem. All of the plutonium in the world
won't get them a bomb, but the gun trigger for Little Man could probably
have been made in a good basement shop. That's why it's a lot scarier
for them to have enriched uranium than plutonium. Any goof can make a
gun-trigger uranium bomb, if they have a plan that gives them useable
dimensions.

The US made a few gun-trigger bombs, and the Brits made a few, and then
we both scrapped them. They're dangerous as hell: anything that will set
off the explosive charge, like lightening or a big spark, can,
theoretically, make them go "boom."

Gun triggers won't work with plutonium because the bomb will
self-destruct before the chain reaction is more than a fizzle. BTW. it
takes a much larger uranium pit than a plutonium pit to make a bomb.

Somewhere on the web -- I think I found it on Wikipedia -- there's a
discussion about early thoughts on gun-trigger plutonium bombs, along
with a picture of some ten prototypes that were scrapped. They were very
long and very skinny, to try to get the velocity up enough to avoid the
effect that you mention.

Yeah, in theory you can make a gun trigger for plutonium. I've seen
values of barrel length ranging from a few hundred meters to a
kilometer.

In fact, when N. Korea exploded its first bomb in a tunnel, I wondered
(and still do) if that's what they tried.


Apparently they originally thought that a gun-triggered Pu bomb would
work, and it was one of the big names (Oppenheimer or Feynmann) in
physics that re-did the calculations and figured out that it was a no-go.

Right. They pursued both trigger mechanisms until they realized that
gun triggers weren't going to be practical with plutonium.

In talking with people about this over the years I find that few
people know that the Hiroshima bomb was an untried gun-trigger device,
but that the Nagasaki bomb was an implosion device based on the Gadget
used in the Trinity test.

And it disturbs me a bit that reporters often rely on stories about
the extreme difficulty of building a working spherical-implosion
trigger, not noticing whether it's plutonium or uranium that's being
used for the pit.

I find it scary that Iran went for uranium.

--
Ed Huntress

On Fri, 24 Feb 2012 13:34:07 -0500, Ed Huntress wrote:

On Fri, 24 Feb 2012 12:25:24 -0600, Tim Wescott
wrote:

On Thu, 23 Feb 2012 23:53:17 -0500, Ed Huntress wrote:

On Thu, 23 Feb 2012 20:37:59 -0800, Paul Drahn
wrote:

On 2/23/2012 8:08 PM, Richard wrote:
Like most of us (baby boomers) I grew up in a world that already had
nuclear weapons. We did "Duck and Cover" drills in school, and I
thought I had a fair notion about how these things worked.

But this photo (second one on this page) of the PU core of the "Fat
Man" implosion device - it's so small...fit's in your hand.




http://simplethinking.com/home/nuclear_weapons.htm

The majority of the energy release is nearly instantaneous, the mean
time from neutron release to fission can be of the order of 10
nanoseconds, and the chain reaction builds exponentially. The result
is that greater than 99% of the very considerable energy released in
an atomic explosion is generated in the last few (typically 4-5)
generations of fission -- less than a tenth of a microsecond.*

This tremendous energy release in a small space over fantastically
short periods of time creates some unusual phenomena -- physical
conditions that have no equal on earth, no matter how much TNT is
stacked up.


A fascinating collection of high speed photos...

http://simplethinking.com/home/rapat...hotographs.htm

http://simplethinking.com/home/rapatronic_2.shtml

and the "rope tricks"...
http://simplethinking.com/home/rapatronic_3.shtml
Very impressive photos. I don't recall seeing them before.

Still the critical component is not described. It is the mechanism to
trigger the conventional explosive segments all at the identical time.
The key word being - identical. The failure of these devices in the
last North Korea test probably caused the dud. Until Iran is able
manufacture the devices and get them to work properly, all the uranium
in the world will not get them the bomb.

Paul

Well, that *is* really a problem. All of the plutonium in the world
won't get them a bomb, but the gun trigger for Little Man could
probably have been made in a good basement shop. That's why it's a lot
scarier for them to have enriched uranium than plutonium. Any goof can
make a gun-trigger uranium bomb, if they have a plan that gives them
useable dimensions.

The US made a few gun-trigger bombs, and the Brits made a few, and
then we both scrapped them. They're dangerous as hell: anything that
will set off the explosive charge, like lightening or a big spark,
can, theoretically, make them go "boom."

Gun triggers won't work with plutonium because the bomb will
self-destruct before the chain reaction is more than a fizzle. BTW. it
takes a much larger uranium pit than a plutonium pit to make a bomb.

Somewhere on the web -- I think I found it on Wikipedia -- there's a
discussion about early thoughts on gun-trigger plutonium bombs, along
with a picture of some ten prototypes that were scrapped. They were
very long and very skinny, to try to get the velocity up enough to avoid
the effect that you mention.

Yeah, in theory you can make a gun trigger for plutonium. I've seen
values of barrel length ranging from a few hundred meters to a
kilometer.

In fact, when N. Korea exploded its first bomb in a tunnel, I wondered
(and still do) if that's what they tried.


Apparently they originally thought that a gun-triggered Pu bomb would
work, and it was one of the big names (Oppenheimer or Feynmann) in
physics that re-did the calculations and figured out that it was a
no-go.

Right. They pursued both trigger mechanisms until they realized that gun
triggers weren't going to be practical with plutonium.

In talking with people about this over the years I find that few people
know that the Hiroshima bomb was an untried gun-trigger device, but that
the Nagasaki bomb was an implosion device based on the Gadget used in
the Trinity test.

And it disturbs me a bit that reporters often rely on stories about the
extreme difficulty of building a working spherical-implosion trigger,
not noticing whether it's plutonium or uranium that's being used for the
pit.

I find it scary that Iran went for uranium.

Well, I think the major difference between the nuclear programs of N.
Korea and Iran is than Iran wants to blow up Jews, but N. Korea just
wants to extort foreign aid from the West and convince their home-boys
that the leadership has really big balls.

So for N. Korea Pu is the best, because they can scare the hell out of
the dimwits with money, but the real experts won't be rattled. Whereas
for Iran U-235 is the best, because they may actually be able to vaporize
parts of Tel Aviv.

--
My liberal friends think I'm a conservative kook.
My conservative friends think I'm a liberal kook.
Why am I not happy that they have found common ground?

Tim Wescott, Communications, Control, Circuits & Software
http://www.wescottdesign.com

On Fri, 24 Feb 2012 13:34:07 -0500, Ed Huntress wrote:

In talking with people about this over the years I find that few people
know that the Hiroshima bomb was an untried gun-trigger device,
but that the Nagasaki bomb was an implosion device based on the Gadget
used in the Trinity test.

Uranium gun was believed to be so reliable that they felt they didn't
need to test it.


I find it scary that Iran went for uranium.

Well, there's no other way though: the only way to get plutonium is to
refine it from spent fuel created in a conventional U235 reactor. In
short, neutrons from U235 fission hit the normally inert U238 and convert
it to Pu239 http://en.wikipedia.org/wiki/Plutonium

In article ,
says...

On Thu, 23 Feb 2012 23:53:17 -0500, Ed Huntress wrote:

On Thu, 23 Feb 2012 20:37:59 -0800, Paul Drahn
wrote:

On 2/23/2012 8:08 PM, Richard wrote:
Like most of us (baby boomers) I grew up in a world that already had
nuclear weapons. We did "Duck and Cover" drills in school, and I
thought I had a fair notion about how these things worked.

But this photo (second one on this page) of the PU core of the "Fat
Man" implosion device - it's so small...fit's in your hand.




http://simplethinking.com/home/nuclear_weapons.htm

The majority of the energy release is nearly instantaneous, the mean
time from neutron release to fission can be of the order of 10
nanoseconds, and the chain reaction builds exponentially. The result
is that greater than 99% of the very considerable energy released in
an atomic explosion is generated in the last few (typically 4-5)
generations of fission -- less than a tenth of a microsecond.*

This tremendous energy release in a small space over fantastically
short periods of time creates some unusual phenomena -- physical
conditions that have no equal on earth, no matter how much TNT is
stacked up.


A fascinating collection of high speed photos...

http://simplethinking.com/home/rapat...hotographs.htm

http://simplethinking.com/home/rapatronic_2.shtml

and the "rope tricks"...
http://simplethinking.com/home/rapatronic_3.shtml
Very impressive photos. I don't recall seeing them before.

Still the critical component is not described. It is the mechanism to
trigger the conventional explosive segments all at the identical time.
The key word being - identical. The failure of these devices in the last
North Korea test probably caused the dud. Until Iran is able manufacture
the devices and get them to work properly, all the uranium in the world
will not get them the bomb.

Paul

Well, that *is* really a problem. All of the plutonium in the world
won't get them a bomb, but the gun trigger for Little Man could probably
have been made in a good basement shop. That's why it's a lot scarier
for them to have enriched uranium than plutonium. Any goof can make a
gun-trigger uranium bomb, if they have a plan that gives them useable
dimensions.

The US made a few gun-trigger bombs, and the Brits made a few, and then
we both scrapped them. They're dangerous as hell: anything that will set
off the explosive charge, like lightening or a big spark, can,
theoretically, make them go "boom."

Gun triggers won't work with plutonium because the bomb will
self-destruct before the chain reaction is more than a fizzle. BTW. it
takes a much larger uranium pit than a plutonium pit to make a bomb.

Somewhere on the web -- I think I found it on Wikipedia -- there's a
discussion about early thoughts on gun-trigger plutonium bombs, along
with a picture of some ten prototypes that were scrapped. They were very
long and very skinny, to try to get the velocity up enough to avoid the
effect that you mention.

Apparently they originally thought that a gun-triggered Pu bomb would
work, and it was one of the big names (Oppenheimer or Feynmann) in
physics that re-did the calculations and figured out that it was a no-go.

The problem was that the plutonium coming out of the breeders was of a
different isotopic mix than the sample on which they based the
calculations.

Ed Huntress wrote:



Well, that *is* really a problem. All of the plutonium in the world
won't get them a bomb, but the gun trigger for Little Man could
probably have been made in a good basement shop. That's why it's a lot
scarier for them to have enriched uranium than plutonium. Any goof can
make a gun-trigger uranium bomb, if they have a plan that gives them
useable dimensions.
Anybody that has more than a gram of 239 Pu ALREADY has enriched uranium.
You need "weapons grade" enrichment, meaning about 90% 235U) to build a
breeder reactor to make 239 Pu. It has to be a fast neutron reactor
to transmute the 238 U at the edge of the core to 239 Pu, and that requires
a high proportion of 235 U for the chain reaction to continue. (I'm not a
reactor physicist, but that's my understanding.) So, if they have
kilograms of 239 Pu, they MUST have tons of pretty pure 235 U.

Jon

On 2/24/2012 6:04 PM, Jon Elson wrote:
Ed Huntress wrote:



Well, that *is* really a problem. All of the plutonium in the world
won't get them a bomb, but the gun trigger for Little Man could
probably have been made in a good basement shop. That's why it's a lot
scarier for them to have enriched uranium than plutonium. Any goof can
make a gun-trigger uranium bomb, if they have a plan that gives them
useable dimensions.
Anybody that has more than a gram of 239 Pu ALREADY has enriched uranium.
You need "weapons grade" enrichment, meaning about 90% 235U) to build a
breeder reactor to make 239 Pu. It has to be a fast neutron reactor
to transmute the 238 U at the edge of the core to 239 Pu, and that requires
a high proportion of 235 U for the chain reaction to continue. (I'm not a
reactor physicist, but that's my understanding.) So, if they have
kilograms of 239 Pu, they MUST have tons of pretty pure 235 U.

Jon


I wonder where they got the 235U?

On Fri, 24 Feb 2012 18:11:39 -0600, Richard wrote:

On 2/24/2012 6:04 PM, Jon Elson wrote:
Ed Huntress wrote:



Well, that *is* really a problem. All of the plutonium in the world
won't get them a bomb, but the gun trigger for Little Man could
probably have been made in a good basement shop. That's why it's a lot
scarier for them to have enriched uranium than plutonium. Any goof can
make a gun-trigger uranium bomb, if they have a plan that gives them
useable dimensions.
Anybody that has more than a gram of 239 Pu ALREADY has enriched
uranium. You need "weapons grade" enrichment, meaning about 90% 235U)
to build a breeder reactor to make 239 Pu. It has to be a fast neutron
reactor to transmute the 238 U at the edge of the core to 239 Pu, and
that requires a high proportion of 235 U for the chain reaction to
continue. (I'm not a reactor physicist, but that's my understanding.)
So, if they have kilograms of 239 Pu, they MUST have tons of pretty
pure 235 U.

Jon


I wonder where they got the 235U?

Any peaceable nuclear reactor needs U-235 to fire the reaction -- it's
just that the common type (non-breeder) doesn't need much.

I'm not so sure about the absolutely needing a breeder reactor -- AFAIK,
you get Pu from ordinary reactors, just in small quantities. In fact,
(again, AFAIK), part of the reprocessing of nuclear fuel is getting the
Pu out.

--
My liberal friends think I'm a conservative kook.
My conservative friends think I'm a liberal kook.
Why am I not happy that they have found common ground?

Tim Wescott, Communications, Control, Circuits & Software
http://www.wescottdesign.com

That's the first good news I've heard in a long time.

I hope Iran does not develop or purchase a nuke. Too
many targets they would love to destroy. Israel, USA,
etc.

Christopher A. Young
Learn more about Jesus
www.lds.org
..

"Paul Drahn" wrote in message
...
The failure of these devices in the last North Korea test
probably caused the dud. Until Iran is able manufacture
the devices and get them to work properly, all the
uranium in the world will not get them the bomb.

Paul

In article , says...

On 2/23/2012 8:08 PM, Richard wrote:
Like most of us (baby boomers) I grew up in a world that already had
nuclear weapons. We did "Duck and Cover" drills in school, and I
thought I had a fair notion about how these things worked.

But this photo (second one on this page) of the PU core of the
"Fat Man" implosion device - it's so small...fit's in your hand.




http://simplethinking.com/home/nuclear_weapons.htm

The majority of the energy release is nearly instantaneous, the mean
time from neutron release to fission can be of the order of 10
nanoseconds, and the chain reaction builds exponentially. The result is
that greater than 99% of the very considerable energy released in an
atomic explosion is generated in the last few (typically 4-5)
generations of fission -- less than a tenth of a microsecond.*

This tremendous energy release in a small space over fantastically short
periods of time creates some unusual phenomena -- physical conditions
that have no equal on earth, no matter how much TNT is stacked up.


A fascinating collection of high speed photos...

http://simplethinking.com/home/rapat...hotographs.htm

http://simplethinking.com/home/rapatronic_2.shtml

and the "rope tricks"...
http://simplethinking.com/home/rapatronic_3.shtml
Very impressive photos. I don't recall seeing them before.

Still the critical component is not described. It is the mechanism to
trigger the conventional explosive segments all at the identical time.
The key word being - identical. The failure of these devices in the last
North Korea test probably caused the dud. Until Iran is able manufacture
the devices and get them to work properly, all the uranium in the world
will not get them the bomb.

Except that with uranium you can use a simple gun. The imploding-sphere
design is necessary to work around the properties of plutonium, which
has to form a critical mass much more quickly than uranium or you get a
fizzle. Uranium just has to have two pieces slammed together really
hard.

By the way, this timing "magic" was achieved with 1940s electronics.
Shouldn't be any problem today.

If Pakistan can do it Iran can do it, don't pretend that it's beyond
them.

"J. Clarke" wrote:

By the way, this timing "magic" was achieved with 1940s electronics.
Shouldn't be any problem today.


It was done with a high speed switching component that is still
restricted.


--
You can't have a sense of humor, if you have no sense.

"Michael A. Terrell" wrote in message
m...

"J. Clarke" wrote:
By the way, this timing "magic" was achieved with 1940s
electronics.
Shouldn't be any problem today.
It was done with a high speed switching component that is still
restricted.

http://en.wikipedia.org/wiki/Krytron

/djgo7

Jim Wilkins wrote:

"Michael A. Terrell" wrote in message
m...

"J. Clarke" wrote:
By the way, this timing "magic" was achieved with 1940s
electronics.
Shouldn't be any problem today.
It was done with a high speed switching component that is still
restricted.

http://en.wikipedia.org/wiki/Krytron


That's it. i figured that you and maybe Don Nichols would know, but
I was waiting to see if anyone else knew. An EE on another group managed
to pick up one surplus.


--
You can't have a sense of humor, if you have no sense.

In article ,
"Michael A. Terrell" wrote:

"J. Clarke" wrote:

By the way, this timing "magic" was achieved with 1940s electronics.
Shouldn't be any problem today.


It was done with a high speed switching component that is still
restricted.

Yes, but krytrons are also a 1940s technology, and far easier to
duplicate than say an ultracentrifuge. And I bet one can buy them from
non-US sources.

Joe Gwinn

On 3/3/2012 11:37 AM, Joseph Gwinn wrote:
In articlesoednaiXKq79VNDSnZ2dnUVZ_vidnZ2d@earthlink .com,
"Michael A. wrote:

"J. Clarke" wrote:

By the way, this timing "magic" was achieved with 1940s electronics.
Shouldn't be any problem today.


It was done with a high speed switching component that is still
restricted.

Yes, but krytrons are also a 1940s technology, and far easier to
duplicate than say an ultracentrifuge. And I bet one can buy them from
non-US sources.

Joe Gwinn

With high speed solid state electronics commonly available who needs
ancient tube technology?

Richard wrote:

Like most of us (baby boomers) I grew up in a world that already had
nuclear weapons. We did "Duck and Cover" drills in school, and I
thought I had a fair notion about how these things worked.

But this photo (second one on this page) of the PU core of the
"Fat Man" implosion device - it's so small...fit's in your hand.


Its so big because it is hollow. The chemical implosion
crushes it and mixes it with the neutron trigger in the center,
starting the chain reaction.

Modern devices have a solid 239 Pu sphere in the center that
is compressed to about 2 X normal density to create the
critical mass. The reaction is started by a pulse linac
shooting protons at a target timed just right so the neutrons
get there at the instant of maximum compression. The Swan device
uses only two exploding wire triggers and 2 explosive lenses
of varying propagation rate that form a spherical explosion
front. They have a "driver" and a tamper to enhance the compression
and delay the flying apart of the compressed pit.

Some of these Swan devices are only a little bigger than that
"pit" in your picture!

Jon

"Richard" wrote in message
...
Like most of us (baby boomers) I grew up in a world that already had
nuclear weapons. We did "Duck and Cover" drills in school, and I
thought I had a fair notion about how these things worked.

But this photo (second one on this page) of the PU core of the
"Fat Man" implosion device - it's so small...fit's in your hand.




http://simplethinking.com/home/nuclear_weapons.htm

The majority of the energy release is nearly instantaneous, the mean time
from neutron release to fission can be of the order of 10 nanoseconds, and
the chain reaction builds exponentially. The result is that greater than
99% of the very considerable energy released in an atomic explosion is
generated in the last few (typically 4-5) generations of fission -- less
than a tenth of a microsecond.*

This tremendous energy release in a small space over fantastically short
periods of time creates some unusual phenomena -- physical conditions that
have no equal on earth, no matter how much TNT is stacked up.


A fascinating collection of high speed photos...

http://simplethinking.com/home/rapat...hotographs.htm

http://simplethinking.com/home/rapatronic_2.shtml

and the "rope tricks"...
http://simplethinking.com/home/rapatronic_3.shtml

Neat shots. I keep saying I am going to go to the Atomic Energy Museum in
Las Vegas, it's near one of my homes. I saw several of the above ground
tests as a kid in the 50s.

Steve

On Fri, 24 Feb 2012 06:10:02 -0800, "Steve B"
wrote:
BIG SNIP

Neat shots. I keep saying I am going to go to the Atomic Energy Museum in
Las Vegas, it's near one of my homes. I saw several of the above ground
tests as a kid in the 50s.

Steve

Hey Steve,

Well worth the visit. Figure on about 2 hours to see most of it.

The method of taking pix they took during testing is explained, and
very interesting stuff about the "inventor" of the method.

Brian Lawson,
Bothwell, Ontario.

"Brian Lawson" wrote in message
...
On Fri, 24 Feb 2012 06:10:02 -0800, "Steve B"
wrote:
BIG SNIP

Neat shots. I keep saying I am going to go to the Atomic Energy Museum in
Las Vegas, it's near one of my homes. I saw several of the above ground
tests as a kid in the 50s.

Steve

Hey Steve,

Well worth the visit. Figure on about 2 hours to see most of it.

The method of taking pix they took during testing is explained, and
very interesting stuff about the "inventor" of the method.

Brian Lawson,
Bothwell, Ontario.

Would that be Edgerton? Wasn't he the inventor of some huge strobe used on
USAC bombers during WWII?

Steve

On 2/24/2012 6:08, Richard wrote:
Like most of us (baby boomers) I grew up in a world that already had
nuclear weapons. We did "Duck and Cover" drills in school, and I
thought I had a fair notion about how these things worked.

A nice technical document:
http://nuclearweaponarchive.org/Nwfa...1.html#Nfaq4.1

On 2012-02-24, Kristian Ukkonen wrote:
On 2/24/2012 6:08, Richard wrote:
Like most of us (baby boomers) I grew up in a world that already had
nuclear weapons. We did "Duck and Cover" drills in school, and I
thought I had a fair notion about how these things worked.

A nice technical document:
http://nuclearweaponarchive.org/Nwfa...1.html#Nfaq4.1

great article, I love it!

i