Super-explosives (Non-Nuclear)
mike stone
weapon, but how about the other direction? Is it possible to produce _chemical_
explosives orders of magnitude more powerful than today's?
I am envisaging something like a rifle bullet with enough explosive in it to
demolish a tank or a building, whilst a hand-grenade using the same stuff is
equivalent to ten or twenty tons of TNT
Is this ever likely to be practical? I drool a bit thinking of what James
Mowry could have done with it
--
Mike Stone - Peterborough England
"The English people are like the English beer.
Froth on top, dregs at the bottom, the middle excellent" - Voltaire
Paul F. Dietz
> There's been occasional talk about how much one can miniaturise a nuclear
> weapon, but how about the other direction? Is it possible to produce _chemical_
> explosives orders of magnitude more powerful than today's?
Almost certainly not. Chemical bonds are only so strong.
Paul
Mark Fergerson
Yup. Hmmm. Taking "chemical" to mean "using only chemical-level
energy processes (such as phase changes) as opposed to nuclear energy
processes" and "explosive" to mean "materials capable of suddenly
occupying a much larger volume on command":
S'pose somebody comes up with a way to make metallic H _and_
encapsulate it portably; if the encapsulation is breached, will the H
revert to the gaseous state explosively or more slowly i.e. by
melting+evaporation/sublimation? Also, how much energy will be
released/absorbed in the metallic/diatomic gas transition?
Best I can come up with on short notice.
Mark L. Fergerson
Andrew Higgins
mike stone <mws...@aol.com> wrote in message
news:20010520134447...@ng-cs1.aol.com...
>
> There's been occasional talk about how much one can miniaturise a
nuclear
> weapon, but how about the other direction? Is it possible to produce
_chemical_
> explosives orders of magnitude more powerful than today's?
>
Chemical explosives, no. The most powerful chemical explosives on the
drawing board today (e.g., octanitrocubane) are only 20-30% more
powerful than conventional explosives such as RDX and HMX. Even these
are proving to be a considerable challenge; the synthesis of
octanitrocubane required decades of work by Philip Eaton and his
colleagues at U of Chicago, and they still do not have enough of the
stuff to test its properties. It appears we are reaching the limit of
how much energy can be packed into organic molecules.
As for more powerful, but still non-nuclear, explosives, there are some
theoretical possibilities: atomic hydrogen, metallic hydrogen, and
electronically-excited triplet helium. While all of these compounds
have been synthesized in the lab, there are considerable challenges
(i.e., it could be impossible) to making them meta-stable in a form that
would be useful as a propellant or explosive. Their energy content
would be an order of magnitude more powerful than TNT, but not *orders*
of magnitude more powerful.
--
Andrew J. Higgins
hig...@mecheng.mcgill.ca
Erik Max Francis
> There's been occasional talk about how much one can miniaturise a
> nuclear
> weapon, but how about the other direction? Is it possible to produce
> _chemical_
> explosives orders of magnitude more powerful than today's?
>
> I am envisaging something like a rifle bullet with enough explosive in
> it to
> demolish a tank or a building, whilst a hand-grenade using the same
> stuff is
> equivalent to ten or twenty tons of TNT
In short, not a chance. Chemical fuels/explosives only have ideal
yields on the order of 10^7 J/kg. A bullet with a mass of, say, 15 g
would be able to manage an explosion of only ~100 kJ; a hand grenade
with a mass of, say, 700 g would result in an explosion of ~1 MJ.
By comparison, 20 kt TNT equivalent is 84 TJ.
Others have suggested a few more exotic, but non-nuclear solutions.
--
Erik Max Francis / m...@alcyone.com / http://www.alcyone.com/max/
__ San Jose, CA, US / 37 20 N 121 53 W / ICQ16063900 / &tSftDotIotE
/ \ Once the people begin to reason, all is lost.
\__/ Voltaire
Product's Quake III Arena Tips / http://www.bosskey.net/
Tips and tricks from the absolute beginner to the Arena Master.
George William Herbert
>mike stone <mws...@aol.com> wrote in message
>news:20010520134447...@ng-cs1.aol.com...
>> There's been occasional talk about how much one can miniaturise a
>> nuclear weapon, but how about the other direction? Is it possible to
>> produce _chemical_ explosives orders of magnitude more powerful than today's?
>
>Chemical explosives, no. The most powerful chemical explosives on the
>drawing board today (e.g., octanitrocubane) are only 20-30% more
>powerful than conventional explosives such as RDX and HMX. Even these
>are proving to be a considerable challenge; the synthesis of
>octanitrocubane required decades of work by Philip Eaton and his
>colleagues at U of Chicago, and they still do not have enough of the
>stuff to test its properties. It appears we are reaching the limit of
>how much energy can be packed into organic molecules.
Right. Bond energy and combustion energy are well known,
and good existing explosives already are pretty close to
maximally functional (all the atoms in the molecule are
contributing energetically in the detonation). There are
a few remaining avenues to improve on; more highly stressed
carbon-carbon bonds are one (octanitrocubane is the prime
example, but there are some other possiblities along these
lines out there). But the improvement is not going to
even approach 50% at best. You might increase density a
bit, but energy/mass is nearing the peak. You can get a
moderate improvement if you use cryogenic binary explosives
(frozen oxygen, ozone, or fluorine slush in liquid hydrogen,
for example). But those are impractical to handle and have
low density. LOX/carbon is only moderately denser and still
cryogenic.
>As for more powerful, but still non-nuclear, explosives, there are some
>theoretical possibilities: atomic hydrogen, metallic hydrogen, and
>electronically-excited triplet helium. While all of these compounds
>have been synthesized in the lab, there are considerable challenges
>(i.e., it could be impossible) to making them meta-stable in a form that
>would be useful as a propellant or explosive. Their energy content
>would be an order of magnitude more powerful than TNT, but not *orders*
>of magnitude more powerful.
Also, the metallic nitrogen recently produced may be useful that way.
It appears to be much more stable once the pressure is released,
unlike metallic hydrogen, though that may require cryogenic handling.
-george william herbert
gher...@retro.com
jimirwin
>I am envisaging something like a rifle bullet with enough explosive in
>it to demolish a tank or a building,
How about hypervelocity bullets? Probably have quite a kick, though.
--
Jim Irwin
http://www.holoscenes.com
3-D maps of the Grand Canyon, Yellowstone, Death Valley, and more.
Ray Drouillard
"mike stone" <mws...@aol.com> wrote
>
> There's been occasional talk about how much one can miniaturise a nuclear
> weapon, but how about the other direction? Is it possible to produce
_chemical_
> explosives orders of magnitude more powerful than today's?
>
> I am envisaging something like a rifle bullet with enough explosive in it
to
> demolish a tank or a building, whilst a hand-grenade using the same stuff
is
> equivalent to ten or twenty tons of TNT
>
> Is this ever likely to be practical? I drool a bit thinking of what James
> Mowry could have done with it
> --
> Mike Stone - Peterborough England
Sure... go find some "red mercury" ;-/
Ray
George William Herbert
>On 20 May 2001 mike stone wrote:
>>I am envisaging something like a rifle bullet with enough explosive in
>>it to demolish a tank or a building,
>
>How about hypervelocity bullets? Probably have quite a kick, though.
Fortunately, Newton gives us an equation and we have several free
variables at the same time.
Recoil is conservation of momentum (p = m v). Damage is generally
an energy function (for a class of projectiles and targets where
there will be effective energy transfer, which is not universal
but that would take toooo looooong... we'll simplify). Energy
is ke = 1/2 m v^2
One kilogram at one meter per second has recoil impulse of 1 kg-m/s.
It has KE of 1/2 joule.
One hundred grams at ten meters per second have recoil impulse of
1 kg-m/s and KE of 5 joules.
Ten grams at one hundred meters per second have recoil impulse of
1 kg-m/s and KE of 50 joules.
One gram at one thousand meters per second has recoil impulse
of 1 kg-m/s and KE of 500 joules.
...
0.0001 gram at ten million meters per second has recoil impulse
of 1 kg-m/s and KE of 5 megajoules, about equivalent to one kilo
of TNT.
You can see where this is going. Shortly thereafter, relativity
will start to raise its ugly head, but you get the idea.
There are secondary effects which make very very small
projectiles "difficult" (they want to vaporize at high speeds)
but not impossible, especially if you accept limited ranges.
-george william herbert
gher...@retro.com
John Park
gun when you concentrate that much KE in the projectile. (Sounds as
though it might put limits on the portability and rate of fire of the
weapon at least.)
--John Park
Some Anonymous Jerk
>0.0001 gram at ten million meters per second has recoil impulse
>of 1 kg-m/s and KE of 5 megajoules, about equivalent to one kilo
>of TNT.
Yes, the recol is quite low, but the energy required to launch the bullet is
also 5 megajoules, actually greater due to inefficienty. So that means you need
a propellant that has the equivalent of one kg of TNT per bullet.
--
SAJerk
George William Herbert
>>0.0001 gram at ten million meters per second has recoil impulse
>>of 1 kg-m/s and KE of 5 megajoules, about equivalent to one kilo
>>of TNT.
>
> Yes, the recol is quite low, but the energy required to launch the bullet is
>also 5 megajoules, actually greater due to inefficienty.
That's correct; assuming inefficiencies, you will need a lot more than
5 MJ on the launcher's power supply, in fact.
>So that means you need
>a propellant that has the equivalent of one kg of TNT per bullet.
At speeds above about 2,000 m/s for conventional propellants and
about 10,000 m/s for light gas guns (hydrogen), you run out of oomph
with the internal ballistics problem: the projectile outruns gas free
expansion velocity, and you stop getting any additional accelleration
force on it....
So practically a 10 km/s or faster gun is going to have to be an
electromagnetic launcher of some sort, railgun or whatnot.
You'll have to have a power source and storage unit to build up
power to fire and store the firing current. Stored energy will
have to be some moderate multiple of KE; typical launchers of
these types are 5% to 50% efficient, so the multiplier should
be somewhere between 2 and 20 times the projectile KE.
This is in fact the trick. It's not impossible today to
fit capacitors and a generator for tank-gun like KE ranges
into a tank (KE of around 10 MJ). That's say 3-5 cubic meters
of volume and several tons. If you postulate super-capacitors
in your science fiction, then you could theoretically make
them man-portable. The power source density will affect
rate of fire, but the capacitors have to be small enough
and light enough to fit into a backpack or gun envelope
no matter what the rate of fire is...
-george william herbert
gher...@retro.com
Ross Donelly
You can get the same effect as your bullet or hand grenade using high-tech
artillery. Imagine rail guns, huge lasers, etc in LEO that could shoot on demand.
Simply fire a targeting laser at your building and voila. Instant gratification.
rossd.
Leszek Karlik
disseminated foul capitalist propaganda:
[...]
>> Yes, the recol is quite low, but the energy required to launch the bullet
>>is also 5 megajoules, actually greater due to inefficienty.
>That's correct; assuming inefficiencies, you will need a lot more than
>5 MJ on the launcher's power supply, in fact.
[...]
>So practically a 10 km/s or faster gun is going to have to be an
>electromagnetic launcher of some sort, railgun or whatnot.
>You'll have to have a power source and storage unit to build up
>power to fire and store the firing current. Stored energy will
>have to be some moderate multiple of KE; typical launchers of
>these types are 5% to 50% efficient, so the multiplier should
>be somewhere between 2 and 20 times the projectile KE.
The main problem is delivering that energy to the projectile.
Coils and/or rails will simpy vaporize from the waste heat, unless
they are superconducting. However, superconductors have that nasty
tendency to lose their superconducting properties when enough
current is crammed in them, and then they vaporize in a puff of,
well, not logic but laws of physics. :)
>-george william herbert
Leslie
--
Proszę wyłączyć UseNet, muszę zacząć się uczyć na sesję.
Friar Chuck
mass...that mass, give or take, is about 5 Kg for U235 and 4 Kg for P238. The
exact figure depeands on the enrichment process. The only bullet we are likely
to see this in is one witht he number 155 mm on it (maybe 127)
FC
Ray Drouillard
tongue-in-cheek comment about a mythological "super explosive" that the
Soviets are rumored to have developed. Whether or not it actually exists is
anyone's guess. I guess "no", however :)
BTW, there have been some discussions about "mini nukes". You do need
critical mass, but some isotopes have a smaller critical mass. I don't
remember the details.
Ray
"Friar Chuck" <prof...@teleocity.com> wrote in message
news:3B09CC82...@teleocity.com...
dbt...@sp2n21.missouri.edu
: Sorry to thow in a wrench but to make a nuclear weapon work you need critical
: mass...that mass, give or take, is about 5 Kg for U235 and 4 Kg for P238. The
: exact figure depeands on the enrichment process. The only bullet we are likely
: to see this in is one witht he number 155 mm on it (maybe 127)
IIRC, the critical mass for Americium 240(243?) is on the order of
grams . . . so you can have Dicky Seaton's Mark XX bullets, but it's
going to cost you a few hundred mill.
George William Herbert
Ok, let's refute a bit of both of the above...
The canonical online reference for this sorts of stuff is the
Nuclear Weapons FAQ done by Carey Sublette, found at:
http://www.fas.org/nuke/hew
Regarding unconventional isotopes, see:
http://fas.org/nuke/hew/Nwfaq/Nfaq6.html#nfaq6.2
Americium 241 has an estimated bare critical mass of 84 kg, Am-243
of around 140 kg, based on extremely adjusted simple calculations.
These are much poorer than Uranium.
Californium is probably the material you were thinking of;
I quote from the FAQ directly:
]] I have seen no actual published estimates for californium isotope
]] critical masses, so I have done one-group calculations for the
]] two californium isotopes that are most plausible for weapons use
]] (Cf-249 and Cf-251) as well as the often discussed Cf-252 (see
]] the beginning of this section for more on this method). I used
]] theoretical estimates for the density of californium based on its
]] position in the periodic table, which are fairly reliable, since
]] experimental data is unavailable. The estimation model used tends
]] to underestimate critical mass sizes but should be quite accurate
]] for highly fissile materials like thse isotopes. The calculated
]] bare sphere critical masses are:
]]
]] Cf-249 5.90 kilograms
]] Cf-251 1.94 kilograms
]] Cf-252 2.73 kilograms
]]
]] By using a thick beryllium reflector the critical masses can be
]] reduced to 40% or so of their bare value so that the most fissile
]] of these isotopes, Cf-251, would have a reflected critical mass
]] of 780 grams. This is arguably "in the gram range" since it is
]] less than one kilogram, but it is obviously much, much closer to
]] one kilogram than to one gram. Implosive compression can reduce
]] this further. Just as a powerful and heavy implosion systems can
]] produce low yield nuclear explosions from as little as 1 kg of
]] Pu-239 (yield up to 100 tons, with the implosion system weighing
]] on the order of 1000 kg), a relatively large implosion system
]] could produce a low yield explosion from as little as 200 grams
]] of Cf-251. The yield would be proportionately smaller of course,
]] around 20 tons, and the total mass on the order of 200 kg. The
]] U.S. has tested devices with 20 ton yields using the vastly
]] cheaper plutonium (though much more of it) which only weighed 13 kg.
]]
]] Experience with small nuclear devices indicates that it is
]] impossible to make a nuclear device with a total mass less than
]] the bare sphere critical mass of the fissile material used.
]] Beryllium reflectors and high explosives can reduce the fissile
]] mass required as indicated, but at the expense of adding more
]] weight than is saved. Thus a nuclear device smaller than 2
]] kilograms or so using Cf-251 is almost certainly impossible.
From the engineering section of the FAQ:
http://fas.org/nuke/hew/Nwfaq/Nfaq4-1.html#Nfaq4.1.5.2
The bare critical mass for Plutonium is around 10.5 kilos;
for 93% enriched Uranium, it's around 48 kilos. Note that those
are "bare" masses, for a simple uncompressed sphere at normal density,
without any reflector material in the system. Using the maximum
practical reflector (10 cm Be), Uranium drops down to around 14 kg.
Interpolating from primary sources indicates that with Pu, it's
around four kilos with 10 cm Be.
-george william herbert
gher...@retro.com
dbt...@sp2n23.missouri.edu
: <dbt...@sp2n21.missouri.edu> wrote:
: >Friar Chuck (prof...@teleocity.com) wrote:
: >: Sorry to thow in a wrench but to make a nuclear weapon work you need critical
: >: mass...that mass, give or take, is about 5 Kg for U235 and 4 Kg for P238. The
: >: exact figure depeands on the enrichment process. The only bullet we are likely
: >: to see this in is one witht he number 155 mm on it (maybe 127)
: >
: >IIRC, the critical mass for Americium 240(243?) is on the order of
: >grams . . . so you can have Dicky Seaton's Mark XX bullets, but it's
: >going to cost you a few hundred mill.
: Ok, let's refute a bit of both of the above...
<snip of some good stuff>
This came up a few montsh back wrt spacecraft propulsion;
turns out the isotope is Am 242 and in the words of one paper:
----begin----
In the article, the researchers demonstrate that the fairly rare nuclear
material americium-242m (Am-242m) can maintain sustained nuclear fission
as an extremely thin metallic film, less than a thousandth of a millimeter
thick. In this form, the extremely high-energy, high-temperature fission
products can escape the fuel elements and be used for propulsion in space.
Obtaining fission-fragments is not possible with the better-known
uranium-235 and plutonium-239 nuclear fuels: they require large fuel rods,
which absorb fission products.
----end----
I'd give you the URL, but actually, all you need to do is
google with 'americium' and 'propulsion' for a raft of
papers (most of them with a distinctly press-boosterish
flavor), but apparently this was reported thusly:
Calculations supporting
this conclusion were reported in this month's issue of Nuclear Instruments
and
Methods in Physics Research A (455: 442-451, 2000) by Prof. Yigal Ronen,
of
BGU's Department of Nuclear Engineering and graduate student Eugene
Shwagerous
Now, it's been a few months, more than time enough for
the other shoe to drop, but I haven't heard of anything
from anybody over on sci.space.tech debunking these
claims yet (other than the issue of cost, of course)
George William Herbert
>George William Herbert (gher...@gw.retro.com) wrote:
>: Ok, let's refute a bit of both of the above...
>
><snip of some good stuff>
>
>This came up a few montsh back wrt spacecraft propulsion;
>turns out the isotope is Am 242 and in the words of one paper:
>Now, it's been a few months, more than time enough for
>the other shoe to drop, but I haven't heard of anything
>from anybody over on sci.space.tech debunking these
>claims yet (other than the issue of cost, of course)
You've just heard from someone from sci.space.tech debunking it. 8-)
Metastable Am-242 is the nuclear science equivalent of unidirectionally
solidified single-crystal ion-implanted surface hardened unobtanium.
Nobody even knows how to make quantities of it more than a few atoms
worth at a time, and its nuclear qualities in quantity are virtually
unmeasured.
There's more physics behind it than a warp drive, but nobody's
taking it all that seriously, either. I think it won a grant for
ongoing research from the NASA advanced propulsion research group,
who are covering a wide variety of reasonable but progressive
out to very fringe stuff including plasma energy storage that
appears to be Crystalized Magic.
-george william herbert
gher...@retro.com
dbt...@sp2n21.missouri.edu
: <dbt...@sp2n23.missouri.edu> wrote:
: >George William Herbert (gher...@gw.retro.com) wrote:
: >: Ok, let's refute a bit of both of the above...
: >
: ><snip of some good stuff>
: >
: >This came up a few montsh back wrt spacecraft propulsion;
: >turns out the isotope is Am 242 and in the words of one paper:
: >[...]
: >Now, it's been a few months, more than time enough for
: >the other shoe to drop, but I haven't heard of anything
: >from anybody over on sci.space.tech debunking these
: >claims yet (other than the issue of cost, of course)
: You've just heard from someone from sci.space.tech debunking it. 8-)
: Metastable Am-242 is the nuclear science equivalent of unidirectionally
: solidified single-crystal ion-implanted surface hardened unobtanium.
: Nobody even knows how to make quantities of it more than a few atoms
: worth at a time, and its nuclear qualities in quantity are virtually
: unmeasured.
You don't disagree that the calculated critical mass is on the
order of grams, and indeed, have relied on calculation alone
for the critical masses of other high-mass isotopes.
In fact, you're just saying what was said several months earlier:
it all boils down to cost - a valid criticism, especially wrt
space flight applications. But this is hardly 'debunking' in
the sense that, say, cold fusion or polywater has been debunked.
George William Herbert
>: You've just heard from someone from sci.space.tech debunking it. 8-)
>: Metastable Am-242 is the nuclear science equivalent of unidirectionally
>: solidified single-crystal ion-implanted surface hardened unobtanium.
>: Nobody even knows how to make quantities of it more than a few atoms
>: worth at a time, and its nuclear qualities in quantity are virtually
>: unmeasured.
>
>You don't disagree that the calculated critical mass is on the
>order of grams, and indeed, have relied on calculation alone
>for the critical masses of other high-mass isotopes.
For the other high-mass isotopes, quantities such as density,
neutron cross sections, etc. are available. You can perform
one-group calculations to find critical mass with that.
For Am-242M, those quantities are *not* yet available from
experimental data. They are extrapolated or theorized.
Do you understand the difference? In one case, we're
calculating to derive a physical value from other, experimentally
known values. In the other case, we're calculating to derive
a physical value from theoretically calculated values.
Two steps of uncertainty instead of one.
>In fact, you're just saying what was said several months earlier:
>it all boils down to cost - a valid criticism, especially wrt
>space flight applications. But this is hardly 'debunking' in
>the sense that, say, cold fusion or polywater has been debunked.
It doesn't all boil down to cost. It is not yet experimentally
tested that the metastable state behaves as expected in the macro
universe; it is not yet experimentally tested that the neutron
cross section is what has been proposed, either.
If there's a continuous spectrum from Lensman physics, through
Star Trek physics, through Abucierre Warps and negative-mass
stabilized wormholes, through exotic propulsion like nuclear
salt water rocket or fusion rocket, to laser lightsail, to NERVA,
to chemical rocket... Metastable Am is somewhere around the
Abucierre Wraps and negative-mass stabilized wormholes level.
It is not rigorously or experimentally known to be physically
possible at this time, though it is not excluded by our known
laws of physics. It is not even generally agreed to be
possible yet, unlike NSWR and fusion rockets, which are probably
quite feasible but very hard engineering projects at best.
-george william herbert
gher...@retro.com
Paul F. Dietz
> For the other high-mass isotopes, quantities such as density,
> neutron cross sections, etc. are available. You can perform
> one-group calculations to find critical mass with that.
>
> For Am-242M, those quantities are *not* yet available from
> experimental data. They are extrapolated or theorized.
A quick Google search on am-242m yields:
"Measurements of Neutron-induced Fission Cross Section for Am-242m
from 0.003 eV to 10 keV Using Lead Slowing-down Spectrometer, Thermal
Neutron Facility and Time-of-Flight Method"
http://koken-db.kogaku.kyoto-u.ac.jp/2000/B/NE/00BNE42001.html
"Fission Cross Section Measurements of Am-242m Using Lead
Slowing-down Spectrometer"
http://koken-db.kogaku.kyoto-u.ac.jp/1998/B/NE/98BNE42004.html
"Measurement of Fission Cross Sections for Am-241, 242m and Am-243
With Linac-driven Lead Slowing-down Spectrometer"
http://charm.postech.ac.kr/koba_abs_1.html
"Fission Cross Section Measurement for Am-242m with TOF Methods
in Low Energy Region"
http://wwwndc.tokai.jaeri.go.jp/nds/proceedings/1998/kai_t.pdf
Citation of:
66Fu13 Measurement of the Average Neutron Yield Per Fission for Am-242m S. C. Fultz, J. T. Caldwell,
B. L. Berman, R. L. Bramblett, M. A. Kelly, H. D. Wilson, M. S. Coops, R. W. Lougheed, J. E. Evans,
R. W. Hoff, Phys. Rev. 152, 1046(1966). Nuclear Reactions:Fission 233 , 235 U, 242 Am(n,F), E =
thermal; measured neutrons/fission.
in http://www.pnpi.spb.ru/nrd/temp/tablisot/toi98/ref2/ref66f.pdf
Paul
dbt...@sp2n21.missouri.edu
: <dbt...@sp2n21.missouri.edu> wrote:
: >George William Herbert (gher...@gw.retro.com) wrote:
: >[...]
: >: You've just heard from someone from sci.space.tech debunking it. 8-)
: >: Metastable Am-242 is the nuclear science equivalent of unidirectionally
: >: solidified single-crystal ion-implanted surface hardened unobtanium.
: >: Nobody even knows how to make quantities of it more than a few atoms
: >: worth at a time, and its nuclear qualities in quantity are virtually
: >: unmeasured.
: >
: >You don't disagree that the calculated critical mass is on the
: >order of grams, and indeed, have relied on calculation alone
: >for the critical masses of other high-mass isotopes.
: For the other high-mass isotopes, quantities such as density,
: neutron cross sections, etc. are available. You can perform
: one-group calculations to find critical mass with that.
: For Am-242M, those quantities are *not* yet available from
: experimental data. They are extrapolated or theorized.
: Do you understand the difference? In one case, we're
: calculating to derive a physical value from other, experimentally
: known values. In the other case, we're calculating to derive
: a physical value from theoretically calculated values.
: Two steps of uncertainty instead of one.
Uh, you are saying that calculations of the chemical and
bulk physical properties of various elements have been
grossly innacurate, or have never been done, or that at
least some of the nuclear properties of Am 242 aren't known?
That's news to me :-) And quite a few other people, I
suspect.
: It doesn't all boil down to cost. It is not yet experimentally
: tested that the metastable state behaves as expected in the macro
: universe; it is not yet experimentally tested that the neutron
: cross section is what has been proposed, either.
Which boils down to cost, and which boils down to *confirming*
these properties (I believe you're already wrong about the
neutron cross-section of this isotope as well, but I don't
have a reference handy). I repeat - when this was discussed
several months agoe, -nobody- argued that using Am 242 for
spacecraft propulsion was impractical because it's properties
as stated were wildly incorrect, but rather, like anti-matter
(a material whose properties nobody argues about) is severely
cost-constrained. Easier than antimatter, in fact: not
as costly and the containment problems aren't nearly as
formidable.
: If there's a continuous spectrum from Lensman physics, through
: Star Trek physics, through Abucierre Warps and negative-mass
: stabilized wormholes, through exotic propulsion like nuclear
: salt water rocket or fusion rocket, to laser lightsail, to NERVA,
: to chemical rocket... Metastable Am is somewhere around the
: Abucierre Wraps and negative-mass stabilized wormholes level.
What!?!?!? I'll concede this point when you can actually
point to an Albucierre warp, negative mass, or even a
transitory wormhole . . . something I can already do with
Am 242. Personally, in terms of do-ability, I'd put it
right underneath Zubrin's (way cool) NSWR.
Jordan S. Bassior
>In short, not a chance. Chemical fuels/explosives only have ideal
>yields on the order of 10^7 J/kg. A bullet with a mass of, say, 15 g
>would be able to manage an explosion of only ~100 kJ; a hand grenade
>with a mass of, say, 700 g would result in an explosion of ~1 MJ.
>
>By comparison, 20 kt TNT equivalent is 84 TJ.
>
>Others have suggested a few more exotic, but non-nuclear solutions.
Would a molecular structure catalyzed nuclear reaction -- an explosive "cold
fusion" effect -- be more promising?
(I have fond memories of Doc Smithian "duodec") :)
--
Sincerely Yours,
Jordan
--
"To urge the preparation of defence is not to assert the imminence of war. On
the contrary, if war were imminent, preparations for defense would be too
late." (Churchill, 1934)
--
Paul F. Dietz
> Would a molecular structure catalyzed nuclear reaction -- an explosive "cold
> fusion" effect -- be more promising?
Sure, and so would total conversion catalyzed by fairy dust.
Paul
Leszek Karlik
disseminated foul capitalist propaganda:
[...]
>Sure, and so would total conversion catalyzed by fairy dust.
'Your mission, should you choose to accept it, is to hunt down
and eliminate Tinkerbell. She is a danger to national security.'
> Paul
Jordan S. Bassior
>"Jordan S. Bassior" wrote:
>
>> Would a molecular structure catalyzed nuclear reaction -- an explosive "cold
>> fusion" effect -- be more promising?
Why would the catalysis of a fusion reaction by molecular structure be
impossible to make an explosive effect?
George William Herbert
>George William Herbert wrote:
>> For the other high-mass isotopes, quantities such as density,
>> neutron cross sections, etc. are available. You can perform
>> one-group calculations to find critical mass with that.
>>
>> For Am-242M, those quantities are *not* yet available from
>> experimental data. They are extrapolated or theorized.
>
>A quick Google search on am-242m yields:
Those measurements are all far lower than fission product neutron
typical energy ranges, as far as I can tell. Trying to describe
the critical properties of Plutonium-239 or U-235 from the 10 keV
and down portion of their fission cross spectra are roughly a
non-sequiteur, as it is with metastable Am-242.
I may be wrong, but as far as I am aware none of those experiments
nor any others have yet measured the neutron energy range needed
for fast criticality analysis of the material. And we're not talking
about moderated applications (and I am not aware that the application
in question *could* use moderated criticality...).
I'll admit I'm a skeptic on this concept in general, but that's
because nobody's addressed the specific questions I'd need to
see answered to believe in it. When the question is "What's X?"
and you get back "Aren't Q,R, and P neat?" the credibility of
the initial proposal suffers some... This may just be that they're
working their way around to it. But they really ought to get
to the specific measurements needed...
-george william herbert
gher...@retro.com
Paul F. Dietz
> Those measurements are all far lower than fission product neutron
> typical energy ranges, as far as I can tell. Trying to describe
> the critical properties of Plutonium-239 or U-235 from the 10 keV
> and down portion of their fission cross spectra are roughly a
> non-sequiteur, as it is with metastable Am-242.
> I may be wrong, but as far as I am aware none of those experiments
> nor any others have yet measured the neutron energy range needed
> for fast criticality analysis of the material. And we're not talking
> about moderated applications (and I am not aware that the application
> in question *could* use moderated criticality...).
We're not talking about a moderated application? I thought
we were. Granted, this means you need to cool the moderator,
but only a few percent of the energy in a fission reaction
comes off in the neutrons, so this is not necessarily
a showstopper. And the critical mass with moderation
is typically *much* smaller than for fast fission.
Also, these net results are meant to show that your assertion
about Am-242m (no nuclear data) is incorrect, not that this specific
data is precisely what would be needed. I note that that
last reference is to a paper published in 1966, which means
we've had enough Am-242m to do experiments on for more than
three decades. Given the relevance of this subject to nuclear
weapons, I bet fast neutron fission of this isomer was studied
exhaustively a generation ago, and that most of the
results are in the paper archives, not on the net.
Paul
Leonard Erickson
>
> "Paul F. Dietz" wrote:
> >
> > mike stone wrote:
> >
> > > There's been occasional talk about how much one can miniaturise a nuclear
> > > weapon, but how about the other direction? Is it possible to produce _chemical_
> > > explosives orders of magnitude more powerful than today's?
> >
>
> Yup. Hmmm. Taking "chemical" to mean "using only chemical-level
> energy processes (such as phase changes) as opposed to nuclear energy
> processes" and "explosive" to mean "materials capable of suddenly
> occupying a much larger volume on command":
>
> S'pose somebody comes up with a way to make metallic H _and_
> encapsulate it portably; if the encapsulation is breached, will the H
> revert to the gaseous state explosively or more slowly i.e. by
> melting+evaporation/sublimation? Also, how much energy will be
> released/absorbed in the metallic/diatomic gas transition?
There was a recent article on a metastable form of liquid nitrogen
created at around 2.5 megabars. It's an orange, semiconducting liquid.
And stanble at normal pressures.
I have to wonder what will happen to that it you give it the right sort
of jolt. <g>
--
Leonard Erickson (aka shadow{G})
sha...@krypton.rain.com <--preferred
leo...@qiclab.scn.rain.com <--last resort
Leonard Erickson
>
> Paul F. Dietz said:
>
> >"Jordan S. Bassior" wrote:
> >
> >> Would a molecular structure catalyzed nuclear reaction -- an explosive "cold
> >> fusion" effect -- be more promising?
>
> Why would the catalysis of a fusion reaction by molecular structure be
> impossible to make an explosive effect?
The imposdsibility is the catalyzed fusion... Or at least it's *really*
unlikely.
Having it able to release energy *explosively* is definitely over the
top.
George William Herbert
>> Those measurements are all far lower than fission product neutron
>> typical energy ranges, as far as I can tell. Trying to describe
>> the critical properties of Plutonium-239 or U-235 from the 10 keV
>> and down portion of their fission cross spectra are roughly a
>> non-sequiteur, as it is with metastable Am-242.
>
>> I may be wrong, but as far as I am aware none of those experiments
>> nor any others have yet measured the neutron energy range needed
>> for fast criticality analysis of the material. And we're not talking
>> about moderated applications (and I am not aware that the application
>> in question *could* use moderated criticality...).
>
>We're not talking about a moderated application? I thought
>we were. Granted, this means you need to cool the moderator,
>but only a few percent of the energy in a fission reaction
>comes off in the neutrons, so this is not necessarily
>a showstopper. And the critical mass with moderation
>is typically *much* smaller than for fast fission.
I thought this was an offshoot of the Am-242M foil particle-emitting
space thruster concept discussion, which appears to be a fast neutron
only reaction for obvious reasons... I don't think it can work with
a moderated system. Did I miss a direction change?
Sure, the critical mass with moderation is much smaller than
for fast fission, sometimes less than a kilogram (the DOE criticality
accidents summary report available on the web is a wonderful source...)
for Uranium or Plutonium solutions. I just didn't think that was
physically usable for the thin-Am-foil fission devices.
>Also, these net results are meant to show that your assertion
>about Am-242m (no nuclear data) is incorrect, not that this specific
>data is precisely what would be needed. I note that that
>last reference is to a paper published in 1966, which means
>we've had enough Am-242m to do experiments on for more than
>three decades. Given the relevance of this subject to nuclear
>weapons, I bet fast neutron fission of this isomer was studied
>exhaustively a generation ago, and that most of the
>results are in the paper archives, not on the net.
I don't recall my exact origional wording; I didn't mean
to imply there'd never been any experimentation on it.
Most clearly and specifically, this is an area I have
some moderate knowledge of and have never seen the
applicable range of experimental data to validate the
specific claims made regarding Am-242M foil propulsion
concepts. I didn't intend to argue it had never been
studied at all, but I think with some reasonable basis
that I can argue that I probably should have seen
something in my prior researches if the specific data
in question had been generated. That could be wrong,
obviously; I don't have firm negative data, I have a
lack of the specific data and am hypothesizing an associated
hole in the research. The peripheral data is there
but not directly applicable to the application and
related physics questions at hand, I think.
In rough terms, compare this to your and my reaction
if someone walks up at a science fiction convention
and starts asking about these new liquid iodine / manganese
rockets NASA is talking about launching next year.
While not utterly impossible given known physics,
it's not evidently a good idea from known chemistry
and propulsion engineering and physics, and I would
damn well expect to have heard something about it
in professional discussions prior to hearing someone
bring it up at a sci-fi con. That's not saying it
could never happen or that it's impossible.
But that's not the way you'd think you'd find out
about it if it's something that's actually going
on...
We could ask Carey and Chuck if they've seen it,
if you want to poke around in alt.war.nuclear and
see if they've got spare cycles this weekend...
-george william herbert
gher...@retro.com
Paul F. Dietz
> I thought this was an offshoot of the Am-242M foil particle-emitting
> space thruster concept discussion, which appears to be a fast neutron
> only reaction for obvious reasons... I don't think it can work with
> a moderated system. Did I miss a direction change?
I don't see why moderation should be ruled out for this system.
The fission product nuclei could be directed with a magnetic
field, or used to heat a gas (which Rubbia was talking about,
IIRC), and the fuel assembly surrounded with offset moderating
blankets.
BTW, I vaguely recall the critical mass for 235U in solution
can be as little as 100 grams.
Paul
Mark Fergerson
>
> Mark Fergerson wrote:
> >
> > "Paul F. Dietz" wrote:
> > >
> > > mike stone wrote:
> > >
> > > > There's been occasional talk about how much one can miniaturise a nuclear
> > > > weapon, but how about the other direction? Is it possible to produce _chemical_
> > > > explosives orders of magnitude more powerful than today's?
> > >
> > > Almost certainly not. Chemical bonds are only so strong.
> >
> > Yup. Hmmm. Taking "chemical" to mean "using only chemical-level
> > energy processes (such as phase changes) as opposed to nuclear energy
> > processes" and "explosive" to mean "materials capable of suddenly
> > occupying a much larger volume on command":
> >
> > S'pose somebody comes up with a way to make metallic H _and_
> > encapsulate it portably; if the encapsulation is breached, will the H
> > revert to the gaseous state explosively or more slowly i.e. by
> > melting+evaporation/sublimation? Also, how much energy will be
> > released/absorbed in the metallic/diatomic gas transition?
>
> There was a recent article on a metastable form of liquid nitrogen
> created at around 2.5 megabars. It's an orange, semiconducting liquid.
> And stanble at normal pressures.
Everybody else is saying _solid_ Nitrogen. That's it, I have to
Google it later today.
> I have to wonder what will happen to that it you give it the right sort
> of jolt. <g>
My guess is it will easily qualify as (if not redefine) "explosive".
Mark L. Fergerson
Brian K. White
> Sure, the critical mass with moderation is much smaller than
> for fast fission, sometimes less than a kilogram
This all reminds me of a "Probability Zero" I read a while back.
There was an alien planet where their currency was plutonium coins.
The story ends when one day one citezen finally becomes rich enough.
--
Brian K. White -- br...@aljex.com -- http://www.aljex.com/bkw/
+++++[>+++[>+++++>+++++++<<-]<-]>>+.>.+++++.+++++++.-.[>+<---]>++.
filePro BBx Linux SCO Prosper/FACTS AutoCAD #callahans Satriani
Coridon Henshaw
@news1.rdc1.nj.home.com:
>> Sure, the critical mass with moderation is much smaller than
>> for fast fission, sometimes less than a kilogram
> This all reminds me of a "Probability Zero" I read a while back.
> There was an alien planet where their currency was plutonium coins.
> The story ends when one day one citezen finally becomes rich enough.
Hmmm. Plutonium stock shares. Sounds like a good way to cut several
Microsoft executives down to size.
--
Coridon Henshaw -- http://www3.sympatico.ca/gcircle/csbh
"..To expect a good deal from life is puerile." -- D.H. Lawrence
Carey Sublette
I don't usually read this group but I was just passing through (actually
I was referred to it from a sci.space.x thread).
Yep, light water solutions can have very low critical masses - hence the
idea of the nuclear salt water rocket.
Regarding Am-242m, this idea *requires* a moderated system. Check out
the cross section data on:
http://wwwndc.tokai.jaeri.go.jp/jendl/j32/Tabsigs/Am242M.HTML
AM-242 has an enormous thermal fission cross section - 6400 barns vs 747
barns for Pu-239, its fission spectrum average cross section is about
the same (1.8 barns). The colder the neutrons the better (below room
temp the cross section goes over 10,000 barns I think). If the critical
thickness of a plutonium slab is 5 cm for Pu-239 for fast fission, then
for Am-242m the slow fission cross section would be something like 10
microns.
You could back the Am-242m layer with a cooled hydrogen rich material
for a moderator/reflector, the heating chamber would need to designed so
that neutrons emitted in that direction are also moderated and reflected
back. The neutron per fission is like 2.8 though, so you can lose a lot
of them and keep the chain reaction going.
Carey Sublette
Regular Am-242 also has an enormous fission cross section, but it has an
even larger capture cross section.
Carey Sublette
Simon Morden
In an attempt to google a paper on this, I did see that NaN3 (sodium azide) is used to
inflate airbags (mixed with Fe2O3 to scavenge the free Na), ignited by an electrical spark.
Sodium azide bullets? Would you need a spark, or would impact be sufficient?
Simon Morden
--
________________________________________________________
Moving in a mysterious way ...
Visit the Book of Morden at http://www.bookofmorden.pwp.blueyonder.co.uk
*'Taiga Taiga Burning Bright' in Extremes2 from Lone Wolf *
* From Jan 2001! http://www.dm.net/~bahwolf/extremes2.htm *
George William Herbert
>"Paul F. Dietz" wrote:
>> George William Herbert wrote:
>> > I thought this was an offshoot of the Am-242M foil particle-emitting
>> > space thruster concept discussion, which appears to be a fast neutron
>> > only reaction for obvious reasons... I don't think it can work with
>> > a moderated system. Did I miss a direction change?
>>
>> I don't see why moderation should be ruled out for this system.
>> The fission product nuclei could be directed with a magnetic
>> field, or used to heat a gas (which Rubbia was talking about,
>> IIRC), and the fuel assembly surrounded with offset moderating
>> blankets.
>>
>> BTW, I vaguely recall the critical mass for 235U in solution
>> can be as little as 100 grams.
>
>I was referred to it from a sci.space.x thread).
>
>Yep, light water solutions can have very low critical masses - hence the
>idea of the nuclear salt water rocket.
By the way, a number of experts at LANL have apparently off the record
stated they're not sure if NSWR will "work" as Zubrin proposed;
it apparently is hard to keep the flow sufficiently critical to get
high energy yields out of it. I was and still am considering a proposal
to NASA to take publically available liquid solution critical mass/
physics packages and integrate them into a NSWR simulation environment,
and then do some basic detailed simulations, but even making the proposal
is a lot of effort. The DOE appears to have most or all of the code
required available off the shelf for qualified users, unclassified but
NOFORN if I read the security notes right.
>Regarding Am-242m, this idea *requires* a moderated system. Check out
>the cross section data on:
>http://wwwndc.tokai.jaeri.go.jp/jendl/j32/Tabsigs/Am242M.HTML
>AM-242 has an enormous thermal fission cross section - 6400 barns vs 747
>barns for Pu-239, its fission spectrum average cross section is about
>the same (1.8 barns). The colder the neutrons the better (below room
>temp the cross section goes over 10,000 barns I think). If the critical
>thickness of a plutonium slab is 5 cm for Pu-239 for fast fission, then
>for Am-242m the slow fission cross section would be something like 10
>microns.
>You could back the Am-242m layer with a cooled hydrogen rich material
>for a moderator/reflector, the heating chamber would need to designed so
>that neutrons emitted in that direction are also moderated and reflected
>back. The neutron per fission is like 2.8 though, so you can lose a lot
>of them and keep the chain reaction going.
Yeah, I hadn't re-checked the cross section info.
There were two seperate recent proposals; Carlos Rubbia
proposing essentially just a Am-242m mini-reactor, where
the Am was used prinicpally because it's reactive in small
quantities, not because other reactions don't work. This
would scale down a lot smaller than "typical" NERVA type
motors but I don't see any significant advantage. This is
not a particularly big deal; Am-242m is just useful, not
tremendously advantageous in a completely novel manner,
here.
The other one is the Ronen et al paper; I just spent the better
part of an hour with a grungy web search trying to find it and
finally did...
http://www.elsevier.nl/gej-ng/29/35/25/96/show/Products/NPE/toc.htt
and more specifically:
http://www.elsevier.nl/gej-ng/10/33/34/96/27/42/article.pdf
...for which you'll have to register (free).
This article makes it clear that a moderator (BeO is proposed)
is involved and required, and shows a very different physical
structure for the proposed unit than I had seen in the paraphrased
reports... I hereby retract my previous comments, it's evident
that what I remember seeing was not accurately describing what
the actual paper proposed.
-george william herbert
gher...@retro.com
Paul F. Dietz
There was a proposal from about 10 (?) years ago that had
thin americium wires that rotated through a reaction zone,
then out where they could cool by radiation. This concept
was from LANL, I think, and was designed to reach about
1% c. I don't think it used Am-242m, though.
Perhaps that's what you were thinking of?
Paul
Luke Campbell
> > Sure, the critical mass with moderation is much smaller than
> > for fast fission, sometimes less than a kilogram
>
> This all reminds me of a "Probability Zero" I read a while back.
> There was an alien planet where their currency was plutonium coins.
> The story ends when one day one citezen finally becomes rich enough.
There was a Stanislaw Lem story (IIRC) where a 1000 armed dictator
hoarded too much of the local plutonium currency, and the resulting
explosion blew his arms into orbit and made a pretty ring around the
planet "thus demonstrating the benifits of nuclear disarmament."
How did Lem get his puns to work in english anyway? Did he write in
english, or did he just have very clever translators?
Luke
George William Herbert
I think that one was plutonium wires, but it's been too long.
Somehow, what I saw was a sail drive, where you had the Am-242m
foil spread out with one side coated with something which would
stop the fission fragments from exiting through it, and the other
open to space. The intent was to get a fair thrust to weight ratio
out of the stuff. But that is very clearly not what either of
these two recent proposals were about. I haven't yet chased down
all the references listed in these to see if what I am remembering
is a slightly older concept or if I saw something which was a horrible
popularization which was just Wrong...
-george william herbert
gher...@retro.com
Leonard Erickson
>
> Sorry to thow in a wrench but to make a nuclear weapon work you need critical
> mass...that mass, give or take, is about 5 Kg for U235 and 4 Kg for P238. The
> exact figure depeands on the enrichment process. The only bullet we are likely
> to see this in is one witht he number 155 mm on it (maybe 127)
Try californium. It has a critical mass of under 100 grams, as I recall.
Also, critiocal mass is *greatly* affected by the shape of the mass, and
the surroundings. That's because it's essentially a matter of how many
neutrons can escape versus how many get to react internally.
The critical mass for a spherical lump of Pu238 is around *20* kg. The
critical mass for Pu238 in aqueous solution is *2* kg. And you can make
an infinitely long 1 cm rod of Pu238 (as long as there's no other
neutron source or reflector nearby) of *infinite* length without
reaching critical mass.
Weapons can use sub-critical masses by slamming them together *fadst*
and using implosion charges to compress the metal even further.
Judicious use of neutron reflectors helps.
Leszek Karlik
disseminated foul capitalist propaganda:
[...]
>How did Lem get his puns to work in english anyway? Did he write in
>english, or did he just have very clever translators?
He didn't. He did brilliant puns in Polish, and he simply had very
clever translators (Michael Candel comes to mind).
But you still miss much by not being able to read, say, Cyberiad in
the original version. :>
>Luke
Jim Davies
>[Am-242m]
Dumb question: what's the difference between Am-242m and Am-242?
And can you have U-235m? (etc, etc)
-
Jim Davies
----------
Mind your manners, son! I've got a tall pointy hat!
John Schilling
>Carey Sublette <care...@earthling.net> typed:
>>[Am-242m]
>Dumb question: what's the difference between Am-242m and Am-242?
>And can you have U-235m? (etc, etc)
The 'm' suffix referrs to a metastable nuclear state; the 242 neutrons
and protons are not packed into the minimum-energy configuration, but
are willing to hang around in a particular higher-energy configuration
for a macroscopic timescale - or until disturbed. This can have some
interesting nuclear properties, like an increased propensity for fission.
And yes, there is a U-235m, but it isn't terribly useful for bomb or
powerplant use as it is only stable for an average of twenty-six minutes.
Am-242m has a half-life of 141 years.
--
*John Schilling * "Anything worth doing, *
*Member:AIAA,NRA,ACLU,SAS,LP * is worth doing for money" *
*Chief Scientist & General Partner * -13th Rule of Acquisition *
*White Elephant Research, LLC * "There is no substitute *
*schi...@spock.usc.edu * for success" *
*661-951-9107 or 661-275-6795 * -58th Rule of Acquisition *
George William Herbert
>Friar Chuck wrote:
>> Sorry to thow in a wrench but to make a nuclear weapon work you need critical
>> mass...that mass, give or take, is about 5 Kg for U235 and 4 Kg for P238. The
>> exact figure depeands on the enrichment process. The only bullet we are likely
>> to see this in is one witht he number 155 mm on it (maybe 127)
>
>Try californium. It has a critical mass of under 100 grams, as I recall.
Around a kilogram, we think; detailed measurements are not available
in declassified form (if the military ever made enough to be sure...).
The Traveller Cf rounds were, in the final analysis, fictional,
though they'd been proposed as viable in the real world in the
timescale when Traveller's people picked 'em up and used 'em
in the game. But those were not as accurate analysies, we think now.
>Also, critiocal mass is *greatly* affected by the shape of the mass, and
>the surroundings. That's because it's essentially a matter of how many
>neutrons can escape versus how many get to react internally.
>
>The critical mass for a spherical lump of Pu238 is around *20* kg.
Pu-238 isn't the fissile isotope; Pu-239 is. The critical mass
of Pu-239 is around 10.5 kilos for unreflected spherical geometry.
Pu-238 is only marginally fissile.
>The critical mass for Pu238 in aqueous solution is *2* kg.
Actually, probably less than a kilo, uranium solutions much less
than that have gone critical.
>[...]
>Weapons can use sub-critical masses by slamming them together *fadst*
>and using implosion charges to compress the metal even further.
>Judicious use of neutron reflectors helps.
Yep.
-george william herbert
gher...@retro.com
Mike Van Pelt
>> > > > Is it possible to produce _chemical_
>> > > > explosives orders of magnitude more powerful than today's?
>> > > Almost certainly not. Chemical bonds are only so strong.
>> There was a recent article on a metastable form of liquid nitrogen
>> created at around 2.5 megabars. It's an orange, semiconducting liquid.
>> And stable at normal pressures.
>> I have to wonder what will happen to that it you give it the right sort
>> of jolt. <g>
> My guess is it will easily qualify as (if not redefine) "explosive".
Hmm... Maybe this is E. E. "Doc" Smith's "duodec".
27 rings of 12 each atoms of heptavalent nitrogen, IIRC.
--
Mike Van Pelt /"\ ASCII Ribbon campaign against E-Mail
mvp at calweb.com \ / in gratuitous HTML and Microsoft
KE6BVH X proprietary formats.
/ \
Paul F. Dietz
> Dumb question: what's the difference between Am-242m and Am-242?
> And can you have U-235m? (etc, etc)
The 'm' indicates a nuclear isomer (a long-lived excited
nuclear state.) The halflife for this state to decay
happens to be something like 140 years, since the
wave functions of the initial and final states are very
dissimilar. There is typically a large difference in
angular momentum between isomeric states and the ground
state, which inhibits decay (for Am242, the difference
is 4 hbar).
Whether a nucleus has isomers, and what their halflives
are, depends on details of the structure of the nuclear
ground and excited states. As it turns out, U-235m *does*
exist, but has a halflife of about 26 minutes.
Whether something is called an 'isomer' or just an 'excited
state' is kind of fuzzy.
Paul
Jim Davies
>
>> Sure, the critical mass with moderation is much smaller than
>> for fast fission, sometimes less than a kilogram
>
>This all reminds me of a "Probability Zero" I read a while back.
>There was an alien planet where their currency was plutonium coins.
>The story ends when one day one citezen finally becomes rich enough.
This looks a lot like Robert L Forward's "Self-Limiting", from
Indistinguishable from Magic. I thought that book was required reading
here.
"There are no millionaires on Xanax..."
Leonard Erickson
>
> I messed up the attributions. Anyway...
>
> >> > > > Is it possible to produce _chemical_
> >> > > > explosives orders of magnitude more powerful than today's?
>
> >> > > Almost certainly not. Chemical bonds are only so strong.
>
> >> There was a recent article on a metastable form of liquid nitrogen
> >> created at around 2.5 megabars. It's an orange, semiconducting liquid.
> >> And stable at normal pressures.
>
> >> I have to wonder what will happen to that it you give it the right sort
> >> of jolt. <g>
>
> > My guess is it will easily qualify as (if not redefine) "explosive".
>
> Hmm... Maybe this is E. E. "Doc" Smith's "duodec".
> 27 rings of 12 each atoms of heptavalent nitrogen, IIRC.
No, but if you have "Spacehounds of IPC" (also by Smith) handy, you'll
find that the inhabitants of Titan are using something quite similar as
their strongest explosive.
Leonard Erickson
>
> >Also, critiocal mass is *greatly* affected by the shape of the mass, and
> >the surroundings. That's because it's essentially a matter of how many
> >neutrons can escape versus how many get to react internally.
> >
> >The critical mass for a spherical lump of Pu238 is around *20* kg.
>
> Pu-238 isn't the fissile isotope; Pu-239 is.
I assumed he had the right isotope in his post and didn't check. :-(
> The critical mass
> of Pu-239 is around 10.5 kilos for unreflected spherical geometry.
> Pu-238 is only marginally fissile.
>
> >The critical mass for Pu238 in aqueous solution is *2* kg.
>
> Actually, probably less than a kilo, uranium solutions much less
> than that have gone critical.
I was working from memory of a table in an article in a magazine that's
in storage.
The article mentioned lovely goofs in the early days of the nuclear
program such as neglecting to account for the fact that a large mass of
water (ie a human being) might move between otherwise safe sub-critcal
masses. Oops!
dbt...@sp2n23.missouri.edu
Yikes! Is this the point where I put the flashlight under
me chin and recount the tale of poor Dr. Slotkin (sp)?
Jim Davies
>>The critical mass for Pu238 in aqueous solution is *2* kg.
>
>Actually, probably less than a kilo, uranium solutions much less
>than that have gone critical.
So presumably you can make a dirty terrorist nuke by just tipping a
bucket of nitric acid onto 1 kg of granulated U235?
By remote control, naturally.
Paul F. Dietz
> So presumably you can make a dirty terrorist nuke by just tipping a
> bucket of nitric acid onto 1 kg of granulated U235?
Not really, because the critical mass for uranium in solution
is for a moderated chain reaction, and a moderated chain
reaction cannot cause a substantial explosion. At best,
it can produce a yield comparable to an equal mass of
high explosive. There'd be some radioactivity left
over, but not a lot.
Paul
MA Lloyd
>gher...@gw.retro.com (George William Herbert) typed:
>>>The critical mass for Pu238 in aqueous solution is *2* kg.
>>
>>Actually, probably less than a kilo, uranium solutions much less
>>than that have gone critical.
>So presumably you can make a dirty terrorist nuke by just tipping a
>bucket of nitric acid onto 1 kg of granulated U235?
>By remote control, naturally.
Fortunately no. You'd probably need more uranium for bomb
criticality, but even if you had it the timescale of nuclear
reactions is short compared to most chemical processes.
What'll happen is enough uranium will dissolve to heat the
system very hot, and the acid will boil or decompose. This
is actually what usually happens when you try to assemble
a critical mass. Before you get to the explosive level
enough heat is generated that your uranium melts or vaporizes.
--
-- MA Lloyd (mall...@io.com)
Leonard Erickson
>
> : The article mentioned lovely goofs in the early days of the nuclear
> : program such as neglecting to account for the fact that a large mass of
> : water (ie a human being) might move between otherwise safe sub-critcal
> : masses. Oops!
>
> Yikes! Is this the point where I put the flashlight under
> me chin and recount the tale of poor Dr. Slotkin (sp)?
Doesn't ring a bell...
Captain Button
[ snip ]
> Hmm... Maybe this is E. E. "Doc" Smith's "duodec".
> 27 rings of 12 each atoms of heptavalent nitrogen, IIRC.
Doesn't duodec have its internal explosion wavefront propogate
at lightspeed or some such absurdity?
And over in Blish's "Cities in Flight" books there was TDX,
where the explosion only propogates in a plane perpendicular
to the local gravity. This must be what the special effects
guys in the movies use to make those ring explosions.
--
"Gee, who'd a thunk it? Turns out alien superintelligence is
no match for our Earthly can-do spunk." - Jane Lane, "Daria"
Captain Button - [ but...@io.com ]
Monte Davis
dbt...@sp2n23.missouri.edu
: dbt...@sp2n23.missouri.edu () wrote:
: >the tale of poor Dr. Slotkin (sp)?
: Slotin. Louis Slotin.
Thanks. Here's one reference:
http://www.lavitt.ca/louisslotin/beaver.html
From the article:
----begin----
The chain reaction was stopped when Slotin knocked the spheres apart,
but deadly gamma and neutron radiation had flashed into
the room in a blue blaze caused by the instantaneous ionization of the
lab's air particles. Louis Slotin had been exposed to almost
1,000 rads of radiation, far more than a lethal dose. Kline, who had
been three or four feet away from Slotin, received between 90
and 100 rads, while Graves, standing a bit closer, received an estimated
166 rads.
A surge of heat "swept over the observers, felt even by those some
distance from the source," writes Thomas D. Brock, a retired
University of Wisconsin biologist who has done extensive research on
early atomic-era accidents at Los Alamos. "In addition to
the blue glow and heat, Louis Slotin experienced a sour taste in his
mouth [and] an intense burning sensation in his left hand. As
soon as Slotin left the building, he vomited, a common reaction from
intense radiation." Another commentator suggests that it
was as though Slotin had been fully exposed to an exploding atomic bomb
at a distance of 4,800 feet.
----end----
In another reference from a few years back, one of the
guys in the room said that the glue glow cast no
shadows . . .
dbt...@sp2n23.missouri.edu
: Wild-eyed conspiracy theorists insist that on 30 May 2001 14:29:10 -0700, Mike Van Pelt <m...@web1.calweb.com> wrote:
: [ snip ]
: > Hmm... Maybe this is E. E. "Doc" Smith's "duodec".
: > 27 rings of 12 each atoms of heptavalent nitrogen, IIRC.
: Doesn't duodec have its internal explosion wavefront propogate
: at lightspeed or some such absurdity?
: And over in Blish's "Cities in Flight" books there was TDX,
: where the explosion only propogates in a plane perpendicular
: to the local gravity. This must be what the special effects
: guys in the movies use to make those ring explosions.
A while back Scientific American had a (for them) decent
article on shaped nuclear charges that would - somewhat -
cause the blast to propagate in certain preferred directions.
Matthias Warkus
...and dbt...@sp2n23.missouri.edu <dbt...@sp2n23.missouri.edu> wrote:
> A while back Scientific American had a (for them) decent
> article on shaped nuclear charges that would - somewhat -
> cause the blast to propagate in certain preferred directions.
ObSF:
One of Saberhagen's Berserker stories has a weapon consisting of a
series of nuclear shaped charges exploding one after another. The
effect is like a spear thrust into the Berserker.
On a more serious note, has any attempt to actually build nuclear
shaped charges been made?
mawa
--
Boys, you have ALL been selected to LEAVE th' PLANET in 15 minutes!!
dbt...@sp2n21.missouri.edu
: It was the 1 Jun 2001 16:18:21 GMT...
: ...and dbt...@sp2n23.missouri.edu <dbt...@sp2n23.missouri.edu> wrote:
: > A while back Scientific American had a (for them) decent
: > article on shaped nuclear charges that would - somewhat -
: > cause the blast to propagate in certain preferred directions.
: ObSF:
: One of Saberhagen's Berserker stories has a weapon consisting of a
: series of nuclear shaped charges exploding one after another. The
: effect is like a spear thrust into the Berserker.
: On a more serious note, has any attempt to actually build nuclear
: shaped charges been made?
How would you go about finding out?
Carey Sublette
George William Herbert wrote:
>
> Carey Sublette <care...@earthling.net> wrote:
> >"Paul F. Dietz" wrote:
> >> George William Herbert wrote:
> >> > I thought this was an offshoot of the Am-242M foil particle-emitting
> >> > space thruster concept discussion, which appears to be a fast neutron
> >> > only reaction for obvious reasons... I don't think it can work with
> >> > a moderated system. Did I miss a direction change?
> >>
> >> I don't see why moderation should be ruled out for this system.
> >> The fission product nuclei could be directed with a magnetic
> >> field, or used to heat a gas (which Rubbia was talking about,
> >> IIRC), and the fuel assembly surrounded with offset moderating
> >> blankets.
> >>
> >> BTW, I vaguely recall the critical mass for 235U in solution
> >> can be as little as 100 grams.
> >
> >I don't usually read this group but I was just passing through (actually
> >I was referred to it from a sci.space.x thread).
> >
> >Yep, light water solutions can have very low critical masses - hence the
> >idea of the nuclear salt water rocket.
>
> By the way, a number of experts at LANL have apparently off the record
> stated they're not sure if NSWR will "work" as Zubrin proposed;
> it apparently is hard to keep the flow sufficiently critical to get
> high energy yields out of it.
I suspected this. I had trouble visualizing how this would work
efficiently. A nice thing about propellant/oxidizer liquid fuel, and
solid fuel are that the mixing time and the rate of heat conduction
(respectively) provide a nice way of separating the energetic reaction
from the fuel "feed". For any nuclear rocket to be attractive it will
have to generate v_e much higher than chemical fuel, and water is fairly
lousy propellant (compared to the hydrogen proposed for solid phase
reactor designs) so very high temps are necessary to make it worthwhile.
Of course a moderated aqueous fission rocket could operate in pulse
mode, sort of a micro-orion.
The Ronen concept (I gather) uses fission fragment energy transport to
deposit the fission energy directly in the working fluid to obtain
higher temperatures than is possible with solid phase reactors
(plutonium carbide/carbon for example).
The idea of using the fission fragments directly as reaction mass is a
concept proposed for interstellar spaceflight where extreme exhaust
velocities are essential. Since the fuel mass increases exponentially
when burnout is many times larger than v_e, very costly propellants with
high v_e can make sense for very high burnout velocities.
Carey
George William Herbert
Carey Sublette <care...@earthling.net> wrote:
>George William Herbert wrote:
>> Carey Sublette <care...@earthling.net> wrote:
>> > [...]
>> >Yep, light water solutions can have very low critical masses - hence the
>> >idea of the nuclear salt water rocket.
>>
>> By the way, a number of experts at LANL have apparently off the record
>> stated they're not sure if NSWR will "work" as Zubrin proposed;
>> it apparently is hard to keep the flow sufficiently critical to get
>> high energy yields out of it.
>
>I suspected this. I had trouble visualizing how this would work
>efficiently. A nice thing about propellant/oxidizer liquid fuel, and
>solid fuel are that the mixing time and the rate of heat conduction
>(respectively) provide a nice way of separating the energetic reaction
>from the fuel "feed". For any nuclear rocket to be attractive it will
>have to generate v_e much higher than chemical fuel, and water is fairly
>lousy propellant (compared to the hydrogen proposed for solid phase
>reactor designs) so very high temps are necessary to make it worthwhile.
>
>Of course a moderated aqueous fission rocket could operate in pulse
>mode, sort of a micro-orion.
Even in pulse mode, you run into the same problem that makes
hydride / moderated fission bombs impractical... they dissassemble
fast enough that it's hard to get all that much energy out before
the reaction stops. I've looked a bit into infinite flat plate
solutions for pulsed aqueous fission. I don't have enough tools
to be sure, but it looked a lot like the dissassembly (even in one
dimention, for a truly infinite flat plate pulse unit) will outrun
useful energy production. Warm or even hot steam isn't all that
energetic, we need many Mj/kg to be worthwhile.
There are some possible tricks, I'm not writing it off quite yet.
>The Ronen concept (I gather) uses fission fragment energy transport to
>deposit the fission energy directly in the working fluid to obtain
>higher temperatures than is possible with solid phase reactors
>(plutonium carbide/carbon for example).
He actually proposes both as possible useful technologies,
along with a fission-fragment-MHD electrical power generator.
>The idea of using the fission fragments directly as reaction mass is a
>concept proposed for interstellar spaceflight where extreme exhaust
>velocities are essential. Since the fuel mass increases exponentially
>when burnout is many times larger than v_e, very costly propellants with
>high v_e can make sense for very high burnout velocities.
Yeah, very efficient fission (where the propellant mass is fission
fragments, not other stuff heated by a fission core) and fusion are
in the right v_e ranges for interstellar travel.
-george william herbert
gher...@retro.com
Jordan S. Bassior
>No, but if you have "Spacehounds of IPC" (also by Smith) handy, you'll
>find that the inhabitants of Titan are using something quite similar as
>their strongest explosive.
Smith, being a chemist, seems to have had a _very_ good idea of just what sorts
of hyper-explosives would be possible given a century or so's technological
progress :)
--
Sincerely Yours,
Jordan
--
"To urge the preparation of defence is not to assert the imminence of war. On
the contrary, if war were imminent, preparations for defense would be too
late." (Churchill, 1934)
--
dbt...@sp2n23.missouri.edu
: Leonard Erickson said:
: >No, but if you have "Spacehounds of IPC" (also by Smith) handy, you'll
: >find that the inhabitants of Titan are using something quite similar as
: >their strongest explosive.
: Smith, being a chemist, seems to have had a _very_ good idea of just what sorts
: of hyper-explosives would be possible given a century or so's technological
: progress :)
Yep. Smith got this one right. Like the man says, "Write
what you know about".
Leonard Erickson
Which is why the mining accident in "First Lensman", and the ordinance
plant lab bits in "Triplanetary" are so good. <g>