Highest yields of nuclear weapon today

[turin]

@PhysicsMan:

What you say would apply to really small parts only. While there would certainly some chunks that could completely burn up in the atmosphere, this phenomenon would not hold true for any sizable parts. Anything some hundred meters across would certainly not completely burn up. Think about when the MIR-space station, a much more fragile and rather small construct, went down, there were left-over parts which crashed into the ocean.

An asteroid of the same size as the MIR-station is multitudes more massive and would wreak serious havoc, even if it only hits the sea. The Tunguska event for instance was, according to all credible theories, created by an object no larger than a few dozen meters, but it created a blast effect of roughly 10-15 MT. As "StingrayOZ" implies, even an object smaller than that, say 1-5 m would still be equal to a tactical nuke in terms of destructive power.

So in order to disintegrate a large asteroid sufficiently as to avoid these issues you need an extraordinary powerful device, certainly magnitudes larger in destructive power than even the largest nukes theoretically feasible. And then there is still the issue of launch and guidance capabilities.

 

[PhysicsMan]

@PhysicsMan:

What you say would apply to really small parts only. While there would certainly some chunks that could completely burn up in the atmosphere, this phenomenon would not hold true for any sizable parts. Anything some hundred meters across would certainly not completely burn up. Think about when the MIR-space station, a much more fragile and rather small construct, went down, there were left-over parts which crashed into the ocean.

An asteroid of the same size as the MIR-station is multitudes more massive and would wreak serious havoc, even if it only hits the sea. The Tunguska event for instance was, according to all credible theories, created by an object no larger than a few dozen meters, but it created a blast effect of roughly 10-15 MT. As "StingrayOZ" implies, even an object smaller than that, say 1-5 m would still be equal to a tactical nuke in terms of destructive power.

So in order to disintegrate a large asteroid sufficiently as to avoid these issues you need an extraordinary powerful device, certainly magnitudes larger in destructive power than even the largest nukes theoretically feasible. And then there is still the issue of launch and guidance capabilities.

well, it's not quite that straightforward (the size comparison with Mir or anything else) because a major determining factor whether something will melt in atmosphere is not even its size but its material composition. If it's made of lighter elements, like a rock is (which is actually very common for asteroids) then it will be burned very efficiently, even if it's big dimension-wise, like Mir. See, Mir obviously contained lots of metals and alloys, some specifically made to withstand high temps, so many of its pieces weren't burned off, of course. Which brings me to the next point - if the falling meteoroid is composed of metals (usually iron) then it will be a different story, and what you said would apply.
And you were absolutely correct in a previous post, saying that there are much smarter ways to deal with this problem. If the object is detected early enough then even a slightest alteration of its course would be enough to avoid a collision, and would require something much simpler and easier than a nuclear device (except the delivery mechanism, which will not be simple nor cheap).

 

[Duffy]

Two parts to this post

1) How much would a surface blast of a nuclear device actually accomplish in the vacuum of space?
2) Pound for pound I think the W-80 war head found on the AGM-129A and the now out of service Tactical Tomahawk ???-109A.290 lbs with150 kt .
I know the yield is nothing like the Tsar 50mt but that was 54,000 lbs.

 

[Ozzy Blizzard]

Leveling a city (depending on whos city) may indeed be practical under certain circumstances

IIRC before the penetrating capability of modern weapons the 1MT weapons were kept in the arsenal after MIRV ICBM's in order to destroy hardened underground bunkers. A 1MT surface burst will apply massive energy into the earth, however as the weapons were able to penetrate further less yield was necessary.

 

[AMERICANMAN]

To my knowledge HKSDU is right: There is no upper boundary (other than the impractical) of a yield.

You can simply add stage after stage in the termonuclear device, and since the triggering factor is the X-ray pressure (from the detonator, another small nuke) which traveles at the speed of light, there is no way that the bomb can pull it self apart before every stage has been triggered.

To my knowledge the largest bomb ever detonated was the "Tzar Bomba", which was a 3 stage termonuclear yielding 50 MT.

Vanunu's photographs also showed the processing of what appeared to be large hollow hemispheres of lithium deuteride--parts for a thermonuclear bomb with a destructive power of about 200 kilotons. . He was talking about Israel

 

[GI-Gizmo]

SS-18 Mod 6 & B53 Hedge Stockpile

Since the Russian R-36M2 (NATO SS-18 Mod 6 Satan) ICBM force, carrying a single 20mt warhead, was retired in 2009 the current active highest yield nuclear warhead is the US B53 gravity bomb with a 9mt warhead. Although the B53 is not in active service, it is part of the US enduring stockpile, hedge stockpile readiness level. A B53 can be ready for service within a matter of minutes, it is not connected to a delivery system (aircraft, usually a bomber), but can be very quickly. Most warheads on the higher yield end nowadays are around 1mt, although there are some 5mt warheads in active service.

 

[Palnatoke]

Vanunu's photographs also showed the processing of what appeared to be large hollow hemispheres of lithium deuteride--parts for a thermonuclear bomb with a destructive power of about 200 kilotons. . He was talking about Israel

That is consisent with what little I know about bombs.

The "primitive" solutions used in the "thin man" and the "fat man" was hard on implosions, where the thin man used a pistol type of impolsion mechanism in which a ball (of U235 - I think) was physically shoot into another ball of uranium and in that way critical mass is achived by compression. Fat man used expolsives that imploded a solid spherical ball of U235(- I think).
Both of these methods are inferior and those bombs burned less than 10% of the avaliable fuel (uranium).

A better impolsive design (can't remember why) is achived by imploding a spherical shell (made of the fission material) into it's (empty) center. furthermore an even better design is achived by filling the void of the sphere with fusion fuel (as far as I remember a mix of hydrogen and litihum) this is reffered to as a "primed" atom bomb. The trick of this contraption is that while the primary energy creation is by the uranium/plutonium being imploded to critical mass (and then burned) in the center of the sphere, some fusion fuel is present (before getting blown apart) and this fuel starts to fusion, and by that a significant amount of reaction willing neutrons is created. These participate in the burning of the fission material resulting in a better consumption of the fission material, (the energy output of the fusion process is insignificant).
Such a "primed" atombomb is belived to be the goal of 2nd tier nuclear powers (like Israel and pakistan).

For completeness; a thermonuclear device basically consist of a solid ball of plutonium. this ball is surrounded by a solid sphere of fusion material (hydrogen-litihum). Around this is a mantel (sphere) of f.ex. Uranium. When the detonator (a small yield atombomb) explodes it creates a massive "shower" of X-rays. These X-rays perfectly compresses (or implodes) the thermonuclear device (kept together by the uranium mantel). When the pressure/temperature reaches a critical level the fusion material starts to fusion. The primary result of the fusion process is that the innermost solid ball of plutonium is bathed in reaction willing neutrons - not only jump starting the chain reaction, but continually feeding it. This results in a (near) complete burn of the fission material (also some or all of the mantel). Furthermore these devices has variable yield (one can adjust the amount of fusion material and thereby adjust the yield). It's important to note that the main source of energy is the fission process (90-95% or so) the fusion process main purpose is only to provide neutrons to speed up the fission process (though do yield some energy).


Correction: "Boosted" bomb instead of "Primed" bomb.

 

[kato]

Fat man used expolsives that imploded a solid spherical ball of U235(- I think).

Nope. Layered design, neutron source at the core (Polonium-Beryllium), hollow Plutonium (Pu239) sphere around it, encased in an outer Uranium layer as the Neutron reflector (U238). The whole thing was imploded, with the neutron source initiating fission in the imploded Pu239 core, and the Uranium layer serving to keep the fission going.

Was ineffective in so far as the neutron source had a half-life measured in days, and the neutron reflector wasn't big enough. That uranium was used for the reflector isn't unusual or "primitive"; you usually use either uranium or lead, lead being used if you want a "cleaner" bomb.

Oh, and Fat Man used 20% of its fissile material (the Plutonium), not 10%.

The casing layer used as a neutron reflector isn't used to "hold it together", but to lower the critical mass of the contained material by 50-60% by reflecting escaping neutrons into the mass to cause more fissions.

 

[Palnatoke]

Nope. Layered design, neutron source at the core (Polonium-Beryllium), hollow Plutonium (Pu239) sphere around it, encased in an outer Uranium layer as the Neutron reflector (U238). The whole thing was imploded, with the neutron source initiating fission in the imploded Pu239 core, and the Uranium layer serving to keep the fission going.

Was ineffective in so far as the neutron source had a half-life measured in days, and the neutron reflector wasn't big enough. That uranium was used for the reflector isn't unusual or "primitive"; you usually use either uranium or lead, lead being used if you want a "cleaner" bomb.

Oh, and Fat Man used 20% of its fissile material (the Plutonium), not 10%.

The casing layer used as a neutron reflector isn't used to "hold it together", but to lower the critical mass of the contained material by 50-60% by reflecting escaping neutrons into the mass to cause more fissions.

"]Nope. Layered design, neutron source at the core (Polonium-Beryllium), hollow Plutonium (Pu239) sphere around it"

Yes.
,"encased in an outer Uranium layer as the Neutron reflector (U238). The whole thing was imploded, with the neutron source initiating fission in the imploded Pu239 core"

Yes

"and the Uranium layer serving to keep the fission going."

If you mean that the uranium layer's inward momentum negates the initial neutron-assisted fission from blowing the plutonium pit apart (holding the thing together) then yes. I don't think the uranium mantel is consumed in this design.

"The casing layer used as a neutron reflector isn't used to "hold it together", but to lower the critical mass of the contained material by 50-60% by reflecting escaping neutrons into the mass to cause more fissions"

To my knowledge it is - in all designs (that's why you use uranium, which is heavy with good metalic properties). Reflection of neutrons is also important (and easy, Beryllium is f.ex. a good reflector). But the key to any design is to somehow keep the fission fuel together as long as possible so the chain reaction can consume as much as possible before chain reaction ends, by the fuel being blown apart. in some designs it is possible to burn the mantel as well (if made by a fission material).





Tkz for the 20%. correction

 

[Wall83]

Since the Russian R-36M2 (NATO SS-18 Mod 6 Satan) ICBM force, carrying a single 20mt warhead, was retired in 2009 the current active highest yield nuclear warhead is the US B53 gravity bomb with a 9mt warhead. Although the B53 is not in active service, it is part of the US enduring stockpile, hedge stockpile readiness level. A B53 can be ready for service within a matter of minutes, it is not connected to a delivery system (aircraft, usually a bomber), but can be very quickly. Most warheads on the higher yield end nowadays are around 1mt, although there are some 5mt warheads in active service.

Hm didnt the 20MT SS-18 Satan missile retire along time ago?

 

[kato]

Hm didnt the 20MT SS-18 Satan missile retire along time ago?

Taken off alert force in 2007, roundabouts, along with the 1 MT MIRV variants. The R-36M2 anyway. Original R-36M version retired in 1978, replaced by R-36MUTTH, retired in 1990, replaced by R-36M2.