A question...

[Humanoid]

Could a United States Aircraft carrier, i.e. The USS George H.W. Bush, withstand a close proximity nuclear explosion? Not of course on top of it, but would it survive the shockwave/be insulated from the radiation?

 

[gf0012-aust]

Could a United States Aircraft carrier, i.e. The USS George H.W. Bush, withstand a close proximity nuclear explosion? Not of course on top of it, but would it survive the shockwave/be insulated from the radiation?

Yes. Depending on a number of factors. But, the US ran a number of nuclear weapons proximity test on all classes of naval vessels that included capital ships and carriers over a number of years.

They are survivable.

 

[AegisFC]

Could a United States Aircraft carrier, i.e. The USS George H.W. Bush, withstand a close proximity nuclear explosion? Not of course on top of it, but would it survive the shockwave/be insulated from the radiation?

Go look up the Bikini Atoll tests from the late 40's, just about all the ships survived just fine.

Take a look at this.
US Navy Course NAVEDTRA 14057 - Damage Control Man

It is an older (the only thing that isn't current from my skimming through it is that they talk about the old Oxygen Breathing Apparatus rather than the SCBA that replaced them for several years now) Damage Controlman training manual, chapters 10 and 11 deal with nuclear blasts and their effects.

 

[localhost127]

what about aircraft below deck - that would still be exposed to the shockwave?

i assume much of that would be a lost cause?. .. or is most of this still classified information from testing?

 

[AegisFC]

what about aircraft below deck - that would still be exposed to the shockwave?

i assume much of that would be a lost cause?. .. or is most of this still classified information from testing?

What about them? They are tied down when not being moved and just about all military electronics are EMI shielded to prevent permanent damage.

 

[localhost127]

let me rephrase:
are modern USN carriers designed to withstand a nuclear blast and effectively continue operations? or are they designed to a point to be able to limp home.

i understand this question is vague - because there are so many variables with regards to the blast's proximity to the carrier (pressure/shockwaves, heat, etc).

 

[Systems Adict]

Interesting posts !

The BIGGEST threat to any modern naval vessel (including the US), from a nuclear blast, isn't the nuclear blast itself, the fallout, shockwave or radiation, it's EMP.

EMP or Electro-Magnetic Pulse has the ability to destroy electronics for tens to hundreds of miles away, dependant on variables such as detonation height, atmospherics, precipitation, etc.

In the tests done in the Pacific in the 40's & 50's, it was able to affect power supplies & radio stations, knocking them out.

While vessels can be 'hardened' against it, having transmitters & receivers powered up & working during a blast is a no-no.

Large whip aerials, radars, etc act like lightning conductors, allowing it to enter the ship, giving it access to sensitive equipment in the ship, via the cable runs.

More over, cable runs on upper decks for things like loud speakers & lights will do the same, possibly with greater effect.

Using screened cabling with a continuous 360 degree braided shield underneath the PVC sheath goes some way to helping, as it acts as a Faraday cage, blocking the waves / power transmitted, by grounding it.


Downside is that all this 'protection' costs a lot to do / install when the ship is being built. Then when the vessel is in service it must be maintained & periodically inspected, to ensure that it is effective.

Cabling on upper decks usually has the addition of being installed in solid drawn conduits, which have specialist glanding at points where cables enter & exit the ships superstructure.

The issues with modern vessels is that some navies feel that this elaborate protection is not required, as after 50 years of détente & living under the threat of the A-bomb, nothing has happened, so they feel it's more cost effective NOT to install it.

However, the Military is still trying to develop the EMP technology into a weapon, as it would allow you to knock out enemy positions / cities, but without the mess & half-life of nuclear fall-out !

As ever, more detailed & corrected info can be found on search engines, or the ever popular Wiki.... (see link below)

Electromagnetic pulse - Wikipedia, the free encyclopedia


SA

 

[Humanoid]

I'm familiar with EMPs, and my limited understanding of nuclear radiation/fallout, is that, if shielded from the blast, the fallout needs to be filtered out of air so that it may be breathed once again. Would an EMP to a capital ship, or carrier, disable such filtrations thereby exposing the crew to fallout?

 

[Beatmaster]

A EMP will destory all electric systems even your pacemaker.
Every systems that uses electric sparks or electronics in general will be BBQed.
So life support systems on a ship will not work exepct for some systems that managed to stay out of the blast due very good shielding but still the ships electronics will be useless at least most of it.
There are ways to shield vital electronics but even then the electonic infrastructure inside a capital ship will be severly damaged because even if the vital points are shielded the Emp is really effective.
At TNO in Delft the netherlands they did a test what a full Emp blast can and cannot do and eventually it turnes out that even if a piece of electronics is properly shielded then its still a +_80% luck thing.
So yes survival in a capital warship is possible history has proven that but with a full emp blast just seconds before the main blast will certainly lower the survival options for the crew with a massive number.
At least that is what all the webpages out there do display.
I do not know or they tested this senario in 2000 or later but i assume that even if the technologic advancement has increased of the past 20 years it would be doubt full that a capital ship and its crew survives a full EMPstrike and seconds later a Abomb blast.
And even if they survive than it would be a small group and the ship will probably survive it but it will be out of action and in need of some serious repair before it acctaully can be used again.


Little update:
When they tested a Nuke blast on the ships 50 years ago many survived right?

Now with the emp blast and the stronger more advanced nuke this senario would be horrible check this link and you will see that if the emp is not shut you down the nuke will because the emp destroyed your protection systems and all other electronics.

Link

 

[gf0012-aust]

I do not know or they tested this senario in 2000 or later but i assume that even if the technologic advancement has increased of the past 20 years it would be doubt full that a capital ship and its crew survives a full EMPstrike and seconds later a Abomb blast.
And even if they survive than it would be a small group and the ship will probably survive it but it will be out of action and in need of some serious repair before it acctaully can be used again.

thats just plain incorrect. the citadels (and in fact all of the ship in modern vessels in the west) are sheilded from NBC. and unless they suffer from a massive kinetic strike, they can still fight.

again, platforms and specific components are shielded from EMP. EMP was a silver bullet 40 years ago.....

 

[Beatmaster]

thats just plain incorrect. the citadels (and in fact all of the ship in modern vessels in the west) are sheilded from NBC. and unless they suffer from a massive kinetic strike, they can still fight.

again, platforms and specific components are shielded from EMP. EMP was a silver bullet 40 years ago.....

Yeah i know you and you are right, most modern navy vessels are protected against this.

Take a look at this tekst and you will see that EMP Hardening is capable to protect your systems but it is not working 100%.\
So i must say you should be right as always ^^, but you are partially right.

The Electromagnetic Pulse (EMP)
Introduction
Nuclear weapons can have devastating effects. Usually, one thinks only of the blast, thermal, and radiation effects as they relate to the human body. However, considering only these factors ignores some of the other devastating effects. One such effect is that of the nuclear electromagnetic pulse (EMP). The effects of the nuclear electromagnetic pulse must be considered and calculated when preparing for a nuclear war.
This essay will try to describe what the electromagnetic pulse is. It will then explore the types of bursts that produce different pulses, and the possible effects of the pulses will be examined. Next, the ways to guard against EMP will be examined. Finally, the policy issues concerning the vulnerability of the United States will be explored. To achieve these goals, three basic sources will be used to describe the technical aspects of the pulse. Once this has been completed, several journal and magazine sources will be used to consider the vulnerability and policy issues. This format will create a technically based essay. From this science base, several observations of vulnerability will be made to evaluate the United States?policy and strategy.

EMP Physics
Early on in the development of nuclear weapons, the presence of the electromagnetic pulse was known. Before the July 16, 1945 Trinity test, Enrico Fermi had tried to calculate the possible electromagnetic fields that would be produced. Unfortunately, the actual effects of the EMP were still not truly known. It wasn’t until the mid-1960s that the true nature of the EMP was better understood. However, even then, many of the possible effects, like other nuclear weapon effects, were not well-known due to the lack of data.1 The basic theory of EMP is now well understood.
In a nuclear detonation, gamma rays are produced. These gamma rays interact with the surrounding air molecules by the Compton effect to produce electrons. In this effect,

"...the gamma ray (primary) photon collides with an electron and some of the energy of the photon is transferred to the electron. Another (secondary) photon, with less energy, then moves off in a new direction at an angle to the direction of motion of the primary photon. Consequently, Compton interaction results in a change of direction (or scattering) of the gamma-ray photon and degradation in its energy. The electron which, after colliding with the primary photon, recoils in such a manner as to conserve energy and momentum is called a Compton (recoil) electron"(2)
These Compton-recoil electrons travel outward at a faster rate than the remaining heavier, positively charged ions. This separation of charges produces a strong electric field. The lower-energy electrons produced by collisions with the Compton electrons are attracted to the positive ions. These ions produce a conduction current. This current is directly related to the strength of the Compton effect. Also, this conduction current flows in a direction opposite to the electrical field produced by the Compton effect. Because of this, the conduction current limits the electrical field and stops it from increasing.(3-5)
Varieties of EMP Explosions
There are three main types of explosions to consider when examining the effects of the electromagnetic pulse. These are near-surface busts, medium-altitude bursts, and high-altitude bursts. Near-surface bursts are those at altitudes up to 1.2 miles, medium-altitude bursts range from 1.2 miles to 19 miles, and high-altitude bursts are those above 19 miles. These altitudes are only rough guidelines, but a better understanding of where each occurs will be gained after examining each type of burst briefly.(6)
The greatest effect on surface bursts is caused by the ground. Unlike in the air, the gamma rays cannot escape the blast in all directions. For this reason, near-surface bursts are also in this category. Although they may not be on the ground, they have similar effects. The ground absorbs many of the gamma rays. This produces an asymmetric field. The resulting field is very similar to that of a hemisphere that is radiating upward. The electrons also are able to return to the burst point through the ground. This makes the area near the center of the burst contain a high concentration of highly ionized particles. This net movement of electrons creates current loops that generate a magnetic field running around the burst point. This is the basic model of a near-surface burst.(7)

When the nuclear explosion occurs in the medium-altitude range, the effects of the ground are much. A medium-altitude range would be away from the ground but below the upper atmosphere. As the height of the burst increases, the asymmetry of the field produced decreases. However, the asymmetry increases, after a point, with altitude due to changes in the atmospheric density. This asymmetry can be seen in Figure One.

Figure One--Approximate variation of an asymmetry factor relative to a surface burst as a function of altitude8

Since the ground is absent, the magnetic field produced in near-surface bursts will be absent. The electric fields will be similar to those of near-surface bursts.(9)

High-altitude electromagnetic pulses (HEMP) produced by high-altitude bursts occur in an area of the atmosphere where the density of the air is low. Because of this, the gamma rays can travel very far before they are absorbed. These rays travel downward into the increasingly dense atmosphere. Here, they interact with the air to form ions as previously described. This region, called the deposition or source region, is roughly circular. It is thick in the middle and thinner toward the edges. It extends horizontally very far creating source regions that are over 1000 miles in diameter.(10) The size of it depends on the height of the burst and the yield of the weapon. The EMP in this source region gets deflected downward towards the earth due to the earth’s magnetic field. Although the fields produced from a high-altitude burst are not as great as those for a near-surface burst, they affect a much larger area.(11) Because of this huge potential, high-altitude bursts could be the most dangerous type of EMP.

EMP Effects
The electrical field produced by the EMP only lasts a very short time before it quickly tails off. The electric field has a rise time of about 1 nanosecond.(12) Even with such a short pulse, the effects can be tremendous. For a high altitude burst, the effects can also be far reaching. By many calculations, one properly placed nuclear bomb detonated above the center of the United States could produce huge electrical fields on the surface of the earth. "The EMP from a single hydrogen bomb exploded 300 kilometers over the heart of the United States could set up electrical field 50 kV/m strong over nearly all of North America"(13). Since EMP is electromagnetic radiation traveling at the speed of light, all of the area could possibly be effected almost simultaneously.
With such a possible threat, it is important to consider what may be affected. "Because of the intense electromagnetic fields (about 10 kV/m) and wide area of coverage, the HEMP can induce large voltages and currents in power lines, communication cables, radio towers, and other long conductors serving a facility"(14). Some other notable collectors of EMP include railroad tracks, large antennas, pipes, cables, wires in buildings, and metal fencing. Although materials underground are partially shielded by the ground, they are still collectors, and these collectors deliver the EMP energy to some larger facility. This produces surges that can destroy the connected device, such as, power generators or long distance telephone systems. An EMP could destroy many services needed to survive a war.

"Society has entered the information age and is more dependent on electronic systems that work with components that are very susceptible to excessive electric currents and voltages."(15) Many systems needed are controlled by a semiconductor in some way. Failure of semi-conductive chips could destroy industrial processes, railway networks, power and phone systems, and access to water supplies. Semiconductor devices fail when they encounter an EMP because of the local heating that occurs. When a semi-conductive device absorbs the EMP energy, it displaces the resulting heat that is produced relatively slowly when compared to the time scale of the EMP. Because the heat is not dissipated quickly, the semiconductor can quickly heat up to temperatures near the melting point of the material. Soon the device will short and fail. This type of failure is call thermal second-breakdown failure.(16)

It is also important to realize how vulnerable the military is to EMP. "Military systems often use the most sophisticated and therefore most vulnerable, electronics available, and many of the systems that must operate during a nuclear war cannot tolerate the temporary disturbances that EMP may induce."(17) Furthermore, many military duties require information to be communicated over long distances. This type of communication requires external antennas, which are extremely susceptible to EMP. Also, some military duties require information-gathering techniques. Many of these techniques use electronic devices connected directly to antennas or radar. Although the devices may be inside shielded buildings, the antennas bring the EMP inside to the electronics. Therefore, the effectiveness of shielding must be examined.

EMP Hardening
There are two things to consider when considering hardening targets against EMP. The first question to answer is whether the hardened system will become useless if shielded. The second question to be answered is whether the target is economically worthwhile to harden. The answers to these two questions are used to determine what devices should be shielded
To explain the first consideration, Makoff and Tsipis give the following simple example. If there was a communication plane with many antennas used to collect and transfer data, it would not be useful if its antennas were removed. However, to harden the plane, the antennas would need to be removed because they provide a direct path to the interior of the plane.(18) It is important to understand how the hardening will affect the performance of the hardened item.

The second consideration is very easy to understand. Some systems, although important, may not seem worthwhile enough to harden due to the high costs of shielding. "It may cost from 30% to 50% of the cost of a ground based communication center…just to refit it to withstand EMP," and, "as high as 10% of the cost for each plane."(19)

There are two basic ways to harden items against EMP effects.20 The first method is metallic shielding. The alternative is tailored hardening. Both methods will be briefly described.

Metallic shielding is used to, "Exclude energy propagated through fields in space."(21) Shields are made of a continuous piece of some metal such as steel or copper. A metal enclosure generally does not fully shield the interior because of the small holes that are likely to exist. Therefore, this type of shielding often contains additional elements to create the barrier. Commonly, only a fraction of a millimeter (22) of a metal is needed to supply adequate protection. This shield must completely surround the item to be shielded. A tight box must be formed to create the shield. The cost of such shielding (in1986 dollars) is $1000 per square meter for a welded-steel shield after installation.(23)

The alternative method, tailored hardening, is a more cost-effective way of hardening. In this method, only the most vulnerable elements and circuits are redesigned to be more rugged. The more rugged elements will be able to withstand much higher currents. However, a committee of the National Academy of Sciences is skeptical of this method due to unpredictable failures in testing.(24) Also, the use of this method is not recommended by the National Research Council. They doubted whether the approximations made to evaluate susceptibilities of the components were accurate. They did concede that tailored hardening may be useful to make existing systems less vulnerable.(25)

United States Policy
There are four issues to examine in the United States policy toward EMP. The effects of EMP must be considered when the United States decides when to launch its missiles to avoid possible EMP damage, how effective their nuclear warheads will be, where to use extra EMP hardening techniques after considering costs, and if development of an EMP device is in its best interest. These issues are very crucial to maintaining the United States deterrence against attack.
The first issue arises from the possible effects of the EMP. When deciding whether to launch missiles in a nuclear war, the United States must be aware of the EMP. A high-altitude burst or local-surface burst used on the United States could negate many of the United States advantages. Although many crucial systems are hardened, "Predicting the effects of EMP on givens systems…are riddled with uncertainty."(26) The first nuclear burst used on the United States might disable some or many key systems. The United States is using simulators to better estimate EMP effects, but even with good EMP hardening technology, many systems, particularly the older ones, may not get hardened. This is because, "The high cost of EMP hardening implies that only the most important systems will be made to withstand the pulse."(27) If some of these less important systems include some missile systems or other offensive systems, it may be worthwhile to use them before they are potentially destroyed.

Once the missiles have been launched, they may still be vulnerable to EMP effects. "Intercontinental missiles and their fire control centers depend heavily on sensitive electronic systems for guidance, radar, and communications as well as to control the functioning of their nuclear warheads."(28) The vulnerability of radar and communication has already been discussed, and because of this, the vulnerability of intercontinental missiles can be seen. Also, EMP from neighboring "friendly" warheads may destroy the warhead, as well. So, once the missile is fired, it is by no means safe from EMP.

Cost also has to be considered. With EMP hardening so expensive, the United States must decide what are reasonable losses due to EMP. These considerations have to include not just military losses. Many of the new military systems are having hardening technology built into them, but much of the civilian world is left unguarded. The single hydrogen bomb alluded to earlier could cause an EMP that would destroy, "In an instant tens of billions of dollars worth of communications equipment and other electronics. Almost all electric power will be knocked out."(29) With the United States?electronic and social base of today, this would be catastrophic. This amount of losses would probably be unacceptable. However, the United States must decide if it is worthwhile to shield all of its vulnerable systems. This scope of hardening would be incredibly expensive. However, after the war, society would need these systems to rebuild itself. With such a potential for destruction, it does not seem wise for the United States to continue development of EMP weapons.

Right now, "The electromagnetic pulse generator is emerging as one of the strongest contenders...to find effective weapons to defeat an enemy without causing loss of life."(30) The motive may be right, but the idea may be bad. It is nice to be searching for a weapon that reduces casualties, but such a weapon could be very destructive if used against the United States. Although the weapon is designed to be used by the United States, the possibility of it being used against the United States may not be as unlikely as it seems. With the extensive technology base of the United States, it seems extremely vulnerable to such a weapon.

Conclusions
The threat of EMP effects is real. The first nuclear bomb detonated over the United States could cause widespread destruction. It should be noted that in EMP tests not all electronics and systems at risk were initially destroyed. Some items did not fail in the first test or even the second. However, eventually they all failed. This poses a problem. The actual effects of EMP are not clear. It is clear that the potential for damage is there. Following this conclusion, the need for EMP hardening is clear.
If the United States is still preparing for war, it must shield itself from the effects of EMP. Theoretically, damage due to EMP could be extensive. Much of this damage may be avoidable if the United States takes measures to harden all its communication systems, power systems, and such. Also, the United States must further explore EMP effects to better prepare for them. This includes informing the United States public about the effects of EMP simulators. If current public opinion continues(31) and all the EMP simulators close, further EMP testing cannot be done. The public must understand that the EMP simulators are not harmful, and that the destruction of the American infrastructure would be devastating. This must be avoided at all costs, but without testing, America is vulnerable to this destruction. This is why the United States must be prepared for the effects of the EMP.

 

[Beatmaster]

O sorry here is the reference to the tekst i wrote: Link

Otherwise i get flamed again...

 

[Falstaff]

O sorry here is the reference to the tekst i wrote: Link

So it is you who wrote this text? May I ask on what occasion you did it? Just out of interest?

One or two thoughts:
As many of the sources are rather old if you deal with the problem these day you'd have to take into account that there is a thing that has to be taken into accout and that's the emergence of glass fibre and wireless means of communication.
Secondly if a EMP passes the cage somehow there are powerful and very tricky means to deal with current peaks inside electronic circuits.

I do agree though that a EMP would probably have devastationg effects on civilian infrastructure.

 

[Beatmaster]

So it is you who wrote this text? May I ask on what occasion you did it? Just out of interest?

One or two thoughts:
As many of the sources are rather old if you deal with the problem these day you'd have to take into account that there is a thing that has to be taken into accout and that's the emergence of glass fibre and wireless means of communication.
Secondly if a EMP passes the cage somehow there are powerful and very tricky means to deal with current peaks inside electronic circuits.

I do agree though that a EMP would probably have devastationg effects on civilian infrastructure.

No no its not my tekst....some other smart guy did wrote the tekst iam just using his info to make my point.
Anyway i mean to say a capital ship worth billions of dollars should have proper protection against all sorts of attacks, but its hard to believe that a capital ship suffers no damage from a indirect emp and nuke attack.
IMHO if complete city's can be destroyed by a nuke than a capital ship should be no problem even with a indirect hit, the blast wave would be so mutch and create a huge tidalwave that will sink any ships near it.

But to get back at the EMP... so you are saying that a capital ship suffers no damage from a EMP blast?


True on a civi population there is no question what damage a emp would do ^^

 

[gf0012-aust]

Yeah i know you and you are right, most modern navy vessels are protected against this.

Take a look at this tekst and you will see that EMP Hardening is capable to protect your systems but it is not working 100%.
So i must say you should be right as always ^^, but you are partially right.

ah, but I'm not stating that they're absolutely EMP protected - my prev was that critical warfighting nodes are shielded. You can't protect everything - you protect the critical gear and systems though.

The article is somewhat selective and liberal in stating its claims.

 

[Falstaff]

The article is somewhat selective and liberal in stating its claims.

And, if I may add this, it leaves out the fact that "hardening" not only means "shielding" but also the use of technologies that are not affected by EMP, e.g. glass fibre comm cables and others.
That's what I wanted to state in the first place, it is somewhat dated in this respect.

Anyway i mean to say a capital ship worth billions of dollars should have proper protection against all sorts of attacks, but its hard to believe that a capital ship suffers no damage from a indirect emp and nuke attack.
IMHO if complete city's can be destroyed by a nuke than a capital ship should be no problem even with a indirect hit, the blast wave would be so mutch and create a huge tidalwave that will sink any ships near it.

From a purely academic POW I'd say that a capital war ship with a robust steel hull (at least of German ships I know that they have to pass extensive blast trials, I guess others as well), NBC protection and vital nodes EMP shielded should be able to withstand a nuclear explosion some km away relatively unharmed.
But that's of course depending on distance, yield and so on.

 

[Beatmaster]

ah, but I'm not stating that they're absolutely EMP protected - my prev was that critical warfighting nodes are shielded. You can't protect everything - you protect the critical gear and systems though.

The article is somewhat selective and liberal in stating its claims.

But if i may ask you lets say for example that a USN aircraft carrier comes close to ground zero lets say seconds before the big bang, what would be the situation for the vessel? i mean what impact would a emp blast have on the nimitz class carrier? would the nuke blast claim more damage and lives with or without the pre-EMP blast?

 

[StingrayOZ]

I think a carrier would generally survive.

Physically they are massive structures that are very strong, designed to withstand 200+ kmph winds and very poor weather (large waves) etc.

a 100-200kt blast the ship would still be floating unless very close (<5km?). There would be a large number of fatalities and injurys by overpressure (hanger etc), but over all much crew survival, ship would be a mission kill. I think the ship would be very tough to sink esp if it was turned front on to the shock wave. I think it would be long term mission kill if within 25km.

Further out.. 25-50 km.

I think primary radar would be offline, coms would be a bit of a mess, anything on deck would be a mess. But these large ships have redundant and back up systems that would see some sort of radar and some coms restored. Things on deck would be jestisoned. It would move out of the blast area at high speed under its own power.

Tanks, heavy armour and ships are actually highly resistant to nukes that they aren't really useful to disable them (unless neutron devices.). As you would need one for each target generally to ensure a kinetic kill.