Problems with Problems With The Orion Spacecraft #9: Stress

Paul F. Dietz wrote:
Pat Flannery wrote:

You heard it here first- a gun assembly nuclear device employing
plutonium, not uranium, as its fissile material.
That was supposed to be impossible due to a unstable isotope of
plutonium (Pu-240) that would cause it to pre-react if gun assembly was
used, and which was supposed to not be separable from the Pu-239.
Well, either the Orion team made a major slip in their report, or by
1964 we knew how to separate Pu-239 and Pu-240.

... or maybe that pre-reacting is perfectly acceptable
in the low yield situation here?

Paul

One of Ted Taylor's 'grails' was finding the least amount of
fissionable material that would explode. Page 54 in the paperback
Project Orion, show he was thinking about this before Orion. IIRC one
of his later statements mentioned a fissionable quantity the size of a
stick of gum. You just have to compress it.

On Mon, 24 Oct 2005 06:56:34 -0500, Jack Linthicum wrote
(in article .com):

IIRC one
of his later statements mentioned a fissionable quantity the size of a
stick of gum. You just have to compress it.

Talk about understating the technical complexities . . . :-/

--
"Fame may be fleeting but obscurity is forever." ~Anonymous
"I believe as little as possible and know as much as I can."
~Todd Stuart Phillips
www.angryherb.net

On 24 Oct 2005 04:56:34 -0700, "Jack Linthicum"
wrote:

One of Ted Taylor's 'grails' was finding the least amount of
fissionable material that would explode. Page 54 in the paperback
Project Orion, show he was thinking about this before Orion. IIRC one
of his later statements mentioned a fissionable quantity the size of a
stick of gum. You just have to compress it.

....I now have this vision of the ultimate stick of practical joke gum,
a gag that would not only make Johnson-Smith a nuclear superpower, but
would once and for all render the exploding cigar totally obsolete.

OM
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Let's face it: Sometimes you *need*
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On 24 Oct 2005 04:34:32 -0700, "Jack Linthicum"
wrote:

You are aware that the original launch point for Orion was either at
Torrey Pines or Point Loma in the San Diego area. They had to leave TP
when their test shots, with C4, distrubed the neighbors. Think what the
real deal, even in a 'shallow silo', would have done for property
values?

....Jack, *please* trim your quotes. Despite Henry's posts being of
superior quality than most, it was completely unnecessary to quote
this one in its entirety.

Note that since you're obviously *not* an idiot -or- a troll, I'm
advising as opposed to my usual nuclear-tipped admonishments I reserve
for both of those undesireables...:-)

OM
--
]=======================================[
OMBlog - http://www.io.com/~o_m/omworld
Let's face it: Sometimes you *need*
an obnoxious opinion in your day!
]=======================================[

Herb Schaltegger wrote:
On Mon, 24 Oct 2005 06:56:34 -0500, Jack Linthicum wrote
(in article .com):

IIRC one
of his later statements mentioned a fissionable quantity the size of a
stick of gum. You just have to compress it.

Talk about understating the technical complexities . . . :-/

--
"Fame may be fleeting but obscurity is forever." ~Anonymous
"I believe as little as possible and know as much as I can."
~Todd Stuart Phillips
www.angryherb.net

You must not be conversant with Ted Taylor. TRy Jamie McPhee's The
Curve of Binding Energy. Taylor goes from a source the size of a
softball (not specified whether the 12, 13 or 20 inch circumference)
page 108, 20 pounds weight page 109, a small cantelope page 148, one
gram was converted to energy in the Nagasaki bomb, page 163, home-made
about the size of a golf bag page 193, the gum reference is to a stick
of U-235 that size which 10% of the energy contained therein would
bring down the World Trade Center, when it was still standing, page 15.

All the nuke people hate Taylor as he kind of makes their brain strains
into easy exercises.

In article , Pat Flannery says...


Here's something _very_ interesting from that Orion .pdf that Rusty found:
http://ntrs.nasa.gov/archive/nasa/ca...1977085619.pdf
If you go over to page 134 of the report (pdf page 146) you will run
into LENS (Low Energy Nuclear Source); a very low yield nuclear device
that will is to be detonated near the pusher plate to check out how it
behaves...nothing unusual in that...except that LENS is a....ready for
this? "the LENS system, which is a very-low-yield "gun-type" plutonium
assembly (see Fig. 7. 10)."

You heard it here first- a gun assembly nuclear device employing
plutonium, not uranium, as its fissile material.

That was supposed to be impossible due to a unstable isotope of
plutonium (Pu-240) that would cause it to pre-react if gun assembly was
used, and which was supposed to not be separable from the Pu-239.
Well, either the Orion team made a major slip in their report, or by
1964 we knew how to separate Pu-239 and Pu-240.

Or they were paying attention to the *Very Low Yield* part.

This is not something we heard here first. It has been publicly known
for about sixty years now, that what happens if you try to build a Pu
gun is that it predetonates, resulting in a very low yield. Normally,
this is undesirable behavior and we thus don't build a plutonium gun.
If a very low yield is what you actually *want*, go ahead and buuld
the gun - it's a simple and reliable, if somewhat heavy, way to get
a very low nuclear yield.


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Paul F. Dietz wrote:


Well, either the Orion team made a major slip in their report, or by
1964 we knew how to separate Pu-239 and Pu-240.


... or maybe that pre-reacting is perfectly acceptable
in the low yield situation here?


From what I read, what would happen is that the plutonium would go
molten and start to vaporize before it could be detonated- you would
probably end up with a dirty bomb more than a true nuclear bomb. I
wouldn't want to be the guys who had to retrieve the pusher plate, as it
would probably have been sprayed with plutonium if that happened.
I was always suspicious of that stated inability to separate Pu-239 and
Pu-240; our isotope separation technology is a lot more advanced
nowadays than in W.W. II.

Pat

John Schilling wrote:

Or they were paying attention to the *Very Low Yield* part.

This is not something we heard here first. It has been publicly known
for about sixty years now, that what happens if you try to build a Pu
gun is that it predetonates, resulting in a very low yield. Normally,
this is undesirable behavior and we thus don't build a plutonium gun.
If a very low yield is what you actually *want*, go ahead and buuld
the gun - it's a simple and reliable, if somewhat heavy, way to get
a very low nuclear yield.



Wouldn't you end up with very inefficient fission and a lot of
unfissioned plutonium getting sprayed around?
They intended to use the LENS for several tests up to and including a
test of a 10 meter diameter pusher plate in a large semi-buried vacuum
chamber around 100 feet in diameter by 250 feet tall.
The way the report describes LENS makes it sound like it's something
that already existed at the time of the report's writing.
It uses a barrel of tungsten or uranium inserted into a cylindrical
reflector assembly.
By varying the speed of impact and the diameter and shape of the
plutonium core, you can vary the energy released.
I don't know what the upper end of efficiency for this system is, but
the report puts the lower end at 1% of the total potential energy
contained in the fissioning plutonium.

Pat

Pat Flannery wrote:

You heard it here first- a gun assembly nuclear device employing
plutonium, not uranium, as its fissile material.
That was supposed to be impossible due to a unstable isotope of
plutonium (Pu-240) that would cause it to pre-react if gun assembly was
used, and which was supposed to not be separable from the Pu-239.

It was impossible in terms of the crash program during WWII to build a
bomb that would fit into a B-29.

Well, either the Orion team made a major slip in their report, or by
1964 we knew how to separate Pu-239 and Pu-240.

With a higher velocity gun, and better ability to calculate the
effects of pre-detonation, all manner of things become possible.

OTOH, there have been references to 'supergrade' plutonium, I.E.
having less -240 than is the norm. I don't know if the -240 is
separated out or if the Pu is produced using methods that create less
-240. (The amount of -240 produced is IIRC, sensitive to irradiation
rates.) However, it's pretty scarce and expensive stuff, and is used
(again IIRC) in special applications and as a 'sweetener'.

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

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

Pat Flannery wrote:

The way the report describes LENS makes it sound like it's something
that already existed at the time of the report's writing.

As Henry pointed out - the Orion folks were somewhat on the optimistic
side in their assumptions and their reports. This had lead people
like bombardmentfarce to believe the program was much further along
than it was in reality.

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

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