Nuclear Explosion Effects

[Raellus]

I know we have several related threads, but I thought it might be useful to have one thread dedicated to the various effects of nuclear explosions. I also have a couple of specific questions re said that I'm hoping someone has the expertise to answer for me.

Which would be more effective against an oil refinery, a ground strike or airburst?
(Guessing air burst)

Which would be more effective against oil wells, a ground strike or airburst? (Guessing ground strike)

It's been shared before, in several threads, I believe, but I think it's worth sharing the famous nukemap simulator again.

https://nuclearsecrecy.com/nukemap/

Also, here's a really interesting piece about recovery time after a nuclear disaster. The parts on the rebuilding of Hiroshima and Nagasaki, I think, are particularly useful to the T2k ref:

https://davidson.weizmann.ac.il/en/o...clear-disaster

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[chico20854]

And here are some more sources:

The granddaddy of them all, that has all the gnarly scientific details and formulas that the nukemapper site uses is The Effects of Nuclear Weapons, 640 pages...

Some other ones are:

The Effects of Nuclear War, which was used by GDW when drafting Howling Wilderness

The Medical Implications of Nuclear War, another brick at 638 pages...

Survival of the Relocated Population of the US After a Nuclear Attack

an answer to your specific question, Raellus: Minimizing Damage to Refineries from Nuclear Attack

The Effects of a Nuclear Attack on Rail Activity Centers

And how to plan a nuclear war (!!!):

The US Nuclear War Plan: A Time for Change, which goes into details about things like the "hardness" of various targets and what it means to say "Well, X Target got nuked".

and (this is a repost from the original site, which gave me a security error), Stuart Slade's Nuclear Warfare 101

and

The US Army's FM 101-31-1, Nuclear Weapons Employment Doctrine and Procedures, which gets into the nitty-gritties of how to determine which weapon to use to achieve the objective.


Longer term I've been toying with the idea of a piece on the nuclear phase of the war... but the above documents combine to equal some seriously depressing reading.

[rcaf_777]

The Early-Time (E1) High-Altitude Electromagnetic Pulse (HEMP) and
Its Impact on the U.S. Power Grid, Prepared for Oak Ridge National Laboratory
2010

Appendix
E1 HEMP Myths

"Cars dying: Some say that all vehicles travelling will come to a halt, with all modern vehicles damaged because of their use of modern electronics (and one movie even had a bulk, non-electronic part dying). Most likely there will be some vehicles affected, but probably just a small fraction of them (although this could create traffic jams in large cities). A car does not have very long cabling to act as antennas, and there is some protection from metallic construction."

[Raellus]

Thanks, Chico. I read the Minimizing Damage to Refineries from Nuclear Attack but didn't see a specific reference to the different effects of air burst and/or ground strikes against oil wells and/or refineries.

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[Southernap]

So what you are thinking of is the Weaponeering. There are a number of books about it which deal with the conventional weapons and I am sure there are books about this for nuclear weapons.

Just remember there are at least 5 types of bursts. High altitude air, air burst, surface burst, sub-surface burst, deep underwater burst.

To me it would work best to have the low altitude air burst against both refineries and oil wells, since the burst wave would do the most damage to all the facilities that would be touched by the pressure wave from an air burst.

[Legbreaker]

Keep in mind that T2k is not the real world and physics are slightly different (take a look at radiation half life IRL and in the game for an example.
There's no reason to think EMP isn't also a little different in the game universe and somewhat nastier than in our own reality.

[Raellus]

A neat infographic, and Top 10 list:

https://www.visualcapitalist.com/lar...ar-explosions/

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[Raellus]

Simulation Shows The Devastating Impact Of A Nuclear War Between The US And Russia

https://www.iflscience.com/environme...AWW7yB2qSAGTXw

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[castlebravo92]

Originally Posted by Southernap

So what you are thinking of is the Weaponeering. There are a number of books about it which deal with the conventional weapons and I am sure there are books about this for nuclear weapons.

Just remember there are at least 5 types of bursts. High altitude air, air burst, surface burst, sub-surface burst, deep underwater burst.

To me it would work best to have the low altitude air burst against both refineries and oil wells, since the burst wave would do the most damage to all the facilities that would be touched by the pressure wave from an air burst.

IRL no one would waste a nuke on an oil field. Pump jacks are not soft targets, there are a ton of them servicing a major field spread out over thousands of square kilometers. Juice isn't worth the squeeze even with 1984 stockpiles. Refineries, though, absolutely. Oil storage, yes, Ports capable of loading or offloading, yes,

You would probably want an airburst to optimize the 12+ psi range, although anything over 5 psi would probably be a hard kill, and anything over 2 psi would be a soft kill for a refinery. 12 psi would mostly guarantee that pretty much everything but some vertical pipe columns would be flattened.

[Raellus]

Most of what I've seen on the topic of the nuclear explosion effects focusses on high-yield strategic weapons. From this, I've tended to extrapolate a scaled-down version of these effects for tactical weapons, and applied that in the T2kU. Based on the linked articles, it appears now that that was in error, and that tactical nuclear weapons have some key differences as far as effects are concerned, especially in terms of radiological impact. The article abstract is as follows:

"In this article, we offer a detailed explanation of nuclear weapons effects and the misconceptions many readers have concerning the ways in which it is possible to use non-strategic nuclear weapons while reducing collateral effects associated with nuclear weapons."

https://www.thedrive.com/the-war-zon...uclear-weapons

Application to T2k 4e

The 4e manual includes 3-4 random encounters in which the PCs run across large surface craters, often containing some standing water, and usually highly radioactive. It's pretty clear that the authors were trying to create a post-nuclear conflict atmosphere for the setting and what better way to do it*. I can't fault them for that but, according to the linked article, such craters would be relatively rare, and not quite as radioactive as portrayed in the game rules.

Question:

*Assuming most tactical strikes are air-bursts, the apparent damage attributable to a nuclear weapon might be much less obvious. After a year or two, damage from a low-yield airburst would probably be indistinguishable from that left behind by heavy conventional fighting, and radiation in the area could be negligible. How would a PC be able to differentiate between the two potential causes of damage, nuclear or conventional, to a given area? If damage was created by a low-yield nuclear airburst, what clues to its actual nature would there be?

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[Raellus]

https://www.scientificamerican.com/a...missile-silos/

This article suggests that America's breadbasket would get a heavy dosing of radioactive fallout. This could provide an alternative explanation for the famine described in Howling Wilderness.

[castlebravo92]

Originally Posted by Raellus

https://www.scientificamerican.com/a...missile-silos/

This article suggests that America's breadbasket would get a heavy dosing of radioactive fallout. This could provide an alternative explanation for the famine described in Howling Wilderness.

The v1/v2 canon attack wasn't large enough.

Aside from hotspots created via runoff, fallout would be well attenuated to safe levels in most areas by 2001 from Nov/Dec 1997 nuclear strikes. Using the 7/10 rule (every 7-fold factor in time results in a 10-fold reduction in radioactivity), if an area was in a 3000 rem/hr fallout region (which is intense fallout), after 7 hours it would be 300 rem/hr, 49 hours, 30 rem/hr, 14 days, 3 rem/hr, 100 days, 0.3 rem/hr, and 2 years, 0.03 rem/hr. At 0.03 rem/hr, you are looking at 1 month of unshielded exposure to accumulate 1 rem.

This is an exaggerated fallout map (in that I modeled airbursts creating fallout) for the T2K target list in North America:



The burgundy red is basically the 3000 rem footprint, the red the 1000 rem footprint, and the light red the 100 rem footprint.

Now, if the attack followed NAPB-90, you would get a dramatically different result:



(I didn't model fallout for this yet, but use your imagination, most of those black dots are ground bursts).

So anyway, timeline bit.

Immediate T2K attack kills around ~9 million + maybe another 9 million die from injuries & fallout over the next 60 days, so around 8% of the population. That means most of the population of the country is still alive, largely unemployed and unproductive, and needs food.

You have 12-18 months worth of grain on hand, but...you also have a world war, and some of that grain would likely be sent overseas to help keep our allies from starving.

But technically you have enough food stored on hand to see you through 2 more harvests, so it's a distribution problem. It's too bad the national transportation network completely collapses around August 1998, which forces the mass urban exodus in search of food. IMHO, this is when the real die off should occur. The North East, for example, produces about 1 calorie in food output for every 10 calories consumed. Ergo, a 80-90% die off is not hard to imagine or justify.

Rolling into 1999, farmers in the Midwest suffer from a lack of fuel, which means little to no mechanization for planting or harvesting. So, in 1997 a single farmer might be able to plant and harvest 2000 acres with a combine. In 1999, that farmer would be able to plant and harvest ~3 acres by hand, maybe as many as 40 acres with draft animals, and more than that if they had farm hand labor.

So you go from 1 farmer feeding >10,000 people to 1 farmer feeding 9 people (low side) to ~100 people (high side, with draft animals). Factor of 2 decrease in productivity. Actually, net fed amount would be less because instead of buying seed, you would need to hold grain back for seeding (and with declining yields, about 20% of your harvest would need to be retained for next year's seeding).

Starting in fall 1998, transportation/distribution grid collapses, country falls into widespread disorder (especially urban areas), and civil government collapses leaving the military in control.

The country as a whole would need a whole lot more farmers to feed itself than it did in 1997. Luckily, you have a lot more unemployed labor to be farmers. Unluckily, as said above, your transportation grid collapses, and you probably don't have a way to get seeds to all those would be farmers.

Hunting, well, most game animals would be hunted to near extinction in a few months. There would be very little game by 2000. Similar problem with animal agriculture - it's an industrial process; most places that raise animals don't have the pasture to raise their animals to maturity - they depend on other farms / pastures for that. So, 1998 = a large cull of animals. Meatpacking is geographically concentrated in the Midwest, and loss of refrigeration = no way to queue up processing backlog, and most of the animal protein would be wasted and never go to feeding anything but buzzards and crows.

There's your 2000-2001 famine in a nutshell, no drought needed really (never mind the fact that the US basically has 3 independent, reliable large scale continental patterns that deliver water for agriculture vs. most other regions have 0-1, so a continental drought affecting North America is not really a very realistic scenario).

[Raellus]

Thanks for the info, Castlebravo. Really impressive research and effect modelling.

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[castlebravo92]

Originally Posted by Raellus

Thanks for the info, Castlebravo. Really impressive research and effect modelling.

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I don't know what came first, me being a nuclear war nerd, or Twilight 2000, but they certainly fed each other. I remember stashing canned food in my mother's garage, just in case, as a kid in the 80s.

[Ursus Maior]

Originally Posted by Raellus

*Assuming most tactical strikes are air-bursts, the apparent damage attributable to a nuclear weapon might be much less obvious. After a year or two, damage from a low-yield airburst would probably be indistinguishable from that left behind by heavy conventional fighting, and radiation in the area could be negligible. How would a PC be able to differentiate between the two potential causes of damage, nuclear or conventional, to a given area? If damage was created by a low-yield nuclear airburst, what clues to its actual nature would there be?

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Just read this and wanted to share some thoughts.

You're correct that most tactical strikes would be air bursts. With (reactivated) B57 and the (almost ubiquitous) B61 probably delivering most of the strikes during the Twilight War. Nuclear bunker busters, such as the B83 nuclear bomb, which could also be dialed into the small kiloton range, would instead be used in ground burst or even subterranean explosions.

For explosions in these low kiloton and up to mid-double digit kiloton ranges, there are some important differences to keep in mind to the much bigger, strategic device explosions: First and foremost, their fireballs do not reach into the stratosphere, making them irrelevant for any discussions on the "nuclear winter" topic as this phenomenon is caused by black soot reaching the stratosphere in relevant amounts to have long lasting effects. Everything not reaching the stratosphere and thus remaining in the troposphere will fall back down onto the surface quickly, within hours or days, and thus have a negligible effect on climate (but not weather, an important difference!).

Second, even though we're talking tactical devices, these explosions are huge and extremely pinpointed. A 20 kt device will leave a crater 25 m deep, 15 m for a 5 kt device and still 6 m deep for the lowest possible yield a B61 can be dialed upon: 0.3 kt. These are no values conventional devices could attain, maybe with the exception of the Mk. 118 demolition bomb. The massive difference of nuclear bombs stems from the high pressure (psi) values reached, I believe, and not so much purely from the blast yield in tons TNT equivalent.

Third, the mode of why craters are formed is different, I believe. A nuclear device produces enormous levels of pressure (psi) an simulations from this site suggest that crater depth does not depend on whether a burst occurs on the surface or in the air. Conventional, "dumb" bombs however tend to explode after hitting the surface and thus in the ground. This changes crater creation dynamics and the amount of matter ejected out of the crater: I would presume a nuclear airburst crater to have a wider crater lip radius (from the center to the outer boundary of the lip) due to the explosion ejecting matter outward to the sides. A conventional explosion might eject matter more into the air as well.

This latter point, the blast wave going to all sides, is what creates the immense pressure waves that destroy the surrounding area. A 0.3 kt blast, still being ca. 335 times larger than a that of a Mark 118 demolition bomb (with its 896 kg warhead) will result in moderate blast damage out to about 300 m to 340 m (depending on air burst optimization (radii or overpressure). Moderate blast damage here means 5 psi overpressure, most residential buildings collapse, injuries being universal, and fatalities being widespread. Light damage, including shattering glass and probably broken off trees, would go out to 1.32 km.

So, the main differences visible to the naked eye between a nuclear and a conventional explosion would simply be the massive damage to the surrounding environment far beyond the immediate crater. When the Saudis used a Mk. 87 bomb on a Yemeni market in March 2016 (with a 428 kg warhead filling) they killed 97 people. Hitting a market in an urban center with a 0.3 kt device would likely kill close to 6,000 people immediately and wound another 20,500 people, many of them would die from maiming and 3rd to 2nd degree burns, which occur out to about 380 m and 480 m respectively. These burns would be also visible on trees, with charring marks at least out to 350 m, but probably more, and knocked over trees out to beyond 1 km in a concentric pattern around the 6.18 m deep crater (that's easily a two story building).

[castlebravo92]

Originally Posted by Ursus Maior

Just read this and wanted to share some thoughts.

You're correct that most tactical strikes would be air bursts. With (reactivated) B57 and the (almost ubiquitous) B61 probably delivering most of the strikes during the Twilight War. Nuclear bunker busters, such as the B83 nuclear bomb, which could also be dialed into the small kiloton range, would instead be used in ground burst or even subterranean explosions.

For explosions in these low kiloton and up to mid-double digit kiloton ranges, there are some important differences to keep in mind to the much bigger, strategic device explosions: First and foremost, their fireballs do not reach into the stratosphere, making them irrelevant for any discussions on the "nuclear winter" topic as this phenomenon is caused by black soot reaching the stratosphere in relevant amounts to have long lasting effects. Everything not reaching the stratosphere and thus remaining in the troposphere will fall back down onto the surface quickly, within hours or days, and thus have a negligible effect on climate (but not weather, an important difference!).

Second, even though we're talking tactical devices, these explosions are huge and extremely pinpointed. A 20 kt device will leave a crater 25 m deep, 15 m for a 5 kt device and still 6 m deep for the lowest possible yield a B61 can be dialed upon: 0.3 kt. These are no values conventional devices could attain, maybe with the exception of the Mk. 118 demolition bomb. The massive difference of nuclear bombs stems from the high pressure (psi) values reached, I believe, and not so much purely from the blast yield in tons TNT equivalent.

Third, the mode of why craters are formed is different, I believe. A nuclear device produces enormous levels of pressure (psi) an simulations from this site suggest that crater depth does not depend on whether a burst occurs on the surface or in the air. Conventional, "dumb" bombs however tend to explode after hitting the surface and thus in the ground. This changes crater creation dynamics and the amount of matter ejected out of the crater: I would presume a nuclear airburst crater to have a wider crater lip radius (from the center to the outer boundary of the lip) due to the explosion ejecting matter outward to the sides. A conventional explosion might eject matter more into the air as well.

This latter point, the blast wave going to all sides, is what creates the immense pressure waves that destroy the surrounding area. A 0.3 kt blast, still being ca. 335 times larger than a that of a Mark 118 demolition bomb (with its 896 kg warhead) will result in moderate blast damage out to about 300 m to 340 m (depending on air burst optimization (radii or overpressure). Moderate blast damage here means 5 psi overpressure, most residential buildings collapse, injuries being universal, and fatalities being widespread. Light damage, including shattering glass and probably broken off trees, would go out to 1.32 km.

So, the main differences visible to the naked eye between a nuclear and a conventional explosion would simply be the massive damage to the surrounding environment far beyond the immediate crater. When the Saudis used a Mk. 87 bomb on a Yemeni market in March 2016 (with a 428 kg warhead filling) they killed 97 people. Hitting a market in an urban center with a 0.3 kt device would likely kill close to 6,000 people immediately and wound another 20,500 people, many of them would die from maiming and 3rd to 2nd degree burns, which occur out to about 380 m and 480 m respectively. These burns would be also visible on trees, with charring marks at least out to 350 m, but probably more, and knocked over trees out to beyond 1 km in a concentric pattern around the 6.18 m deep crater (that's easily a two story building).

All good points. One slight quibble, according to the published data, crater formation scales logarithmically with TNT yield equivalent, regardless of explosive type:



Another thing to point out is that for nukes, blast damage follows an inverse cube law - doubling the effect requires 8x the explosive yield. Lethal radiation from x-rays, gamma-rays, and neutrons, however, doesn't scale well at all.

https://nuclearweaponsedproj.mit.edu...ator/radiation

A 1 kt nuclear explosion will delivery 450 rads between neutrons and gamma rays to an unshielded person at 914 meters, falling off to 0 rads at 3.7 km.

100 kt will only deliver 0.19 rads at 3.7 km (but 45,000 rads at 1 km).

A 1 megaton explosion will deliver 1.9 rads at 3.7 km.

This is "important" because as yields go up, radiation ceases to be much of a factor in prompt deaths and injuries because blast and thermal injuries take over (for example, for the 1 megaton explosion, PSI for an airburst at 2280 meters height, 3.7 km away would be ~12.7 and wind speed would be 360 mph, which would be sufficient to flatten all but the most heavily reinforced structures - fatalities in this zone approach 100% unless underground or in a blast shelter).

Conversely, for that 1 kt explosion @ 120 meter detonation height, overpressure would be 1.9 PSI at 914 meters, and wind speed would be 68 mph. That's enough to break windows and damage wood siding in homes, and cause some injuries and maybe a few fatalities from flying debris. Thermal effects are not sufficient to cause even 1st degree burns.

But 914 meters away from GZ, people are still receiving 450 rads of radiation exposure. The LD50 for radiation exposure is 250-500 rads. So half of the people in a 914 meter radius would die, the other half would have serious radiation injuries. These are deaths & injuries from the bone marrow dying off and immune compromise and subsequent infection as a consequence.

[Raellus]

Originally Posted by Ursus Maior

So, the main differences visible to the naked eye between a nuclear and a conventional explosion would simply be the massive damage to the surrounding environment far beyond the immediate crater. When the Saudis used a Mk. 87 bomb on a Yemeni market in March 2016 (with a 428 kg warhead filling) they killed 97 people. Hitting a market in an urban center with a 0.3 kt device would likely kill close to 6,000 people immediately and wound another 20,500 people, many of them would die from maiming and 3rd to 2nd degree burns, which occur out to about 380 m and 480 m respectively. These burns would be also visible on trees, with charring marks at least out to 350 m, but probably more, and knocked over trees out to beyond 1 km in a concentric pattern around the 6.18 m deep crater (that's easily a two story building).

To be clear, I was not contrasting the effects of a single large conventional bomb and a tactical nuclear weapon, but your points are well-taken.

The war in Ukraine has produced some stunning images of the effect of large volumes of conventional explosives on urban areas- Bakhmut, being an especially good example. Aside from being in color, aerial shots of present-day Bakhmut don't appear all that dissimilar from photos of Hiroshima taken in September, 1945 (it's also worth noting the fact that Bakhmut started with many times more concrete structures than Hiroshima did). To reiterate my point, a couple of years after a battle/campaign like Bakhmut, it would probably be difficult for the average soldier (not in possession of a Geiger counter) to distinguish whether such extensive damage was created by intense conventional warfare or by a tactical nuclear weapon. This would be especially true the further from ground zero one happens to be.

Of course, as you pointed out, there would be other clues, that those more experienced, or with special training perhaps, would likely recognize.

In a T2k campaign, in trying to clue the audience into the fact that the party was entering the outer margins of an old tac-nuke blast zone, I described the damage to a wooded area near a kilometer or two from ground zero as a concentric band of fallen trees all lying pointing roughly in the same direction. I got the idea after seeing photos of some of the forest surrounding Mt. St. Helens (a volcano in upstate Washington) a year or two after the surprise 1980 eruption.

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