Nukes

[Belial666]

First of all, I usually dislike plot-device powers. I also like statting things up. Therefore, nukes. Nukes are not plot-device powerful, seeing as a nuclear bunker can survive a nuke... but can't survive a much smaller bunker-busted bomb. Sure, the Hiroshima bomb was strong enough to turn people into atomic shadows at ground zero but left some of the heavier buildings still standing.

Let's extrapolate from that; against attacks, thick exterior walls defend as objects at +10, with a stress track 10 boxes long. Vault doors and similar heavy fortifications defend as objects at +12 with a stress track 12 boxes long. They can't take consequences or use FP. Since the bomb took out all of the first but some of the latter survived, we need it to be an attack that the first can't resist at all but that the latter might. A +15 attack means defense of 10 will never resist it but defense of 12 might roll a +4 in a 1 out of 81 chance. Since heavy walls and thick iron objects survived more often than not, the blast would have been a bit lower weapon rating so that it only took out such structures half the time. This means weapon 9, for an average chance to take out such things or weapon 8 for a 33% chance - and still level anything less than fortified structures 99% of the time. And this is for ground zero of the blast.

Now, a nuke also has the big flash and the radiation as secondary results that don't really harm buildings but do a number on humans. So we need to stat this up a bit. Here's an example;


40-kiloton nuke [20 shifts effect, 200 zones radius]
Effect: weapon 8 at +15 attack. In addition, a nuke creates a 6-shift fire and a 6-shift radiation environmental hazard for the scene.
Dissipation: nuclear attacks dissipate fairly rapidly. Drop weapon rating, attack rating and hazard strength by 2 for every 1/4 of the radius.
Special 2: nuclear attacks are almost always a surprise as you usually can't see the blast coming. You still defend normally against hazards.

Given that explosive damage increases by the cubic root of explosive energy, explosive radius increases by the square root of energy and that +2 weapon rating in the DFRPG means an order of magniture more damage, here's a further extrapolation;


4-megaton nuke [24 shifts effect, 800 zones radius]
Effect: weapon 10 at +19 attack. In addition, a nuke creates a 7-shift fire and a 7-shift radiation environmental hazard for the scene.
Dissipation: nuclear attacks dissipate fairly rapidly. Drop weapon rating, attack rating by 3 and hazard strength by 2 for every 1/4 of the radius.
Special 2: nuclear attacks are almost always a surprise as you usually can't see the blast coming. You still defend normally against hazards.


Do note that either bombs will kill a human being at ground zero, period. (the fire hazard autotags your full consequences and hits at +14 even if you miraculously survive the blastwave). But supernatural creatures tough as buildings might survive - as they should.

[13th~Nineteen]

But would it take out a Skin Walker?

[tetrasodium]

But would it take out a Skin Walker?

(click to show/hide)

Morgan

thinks it did

[Belial666]

Well, the Skinwalker has enough shifting points to take on mythic-level abilities but the only one that matters is mythic toughness. 10 stress boxes, 3 armor, 0 defense vs weapon 8, 15 attack means 10 stress goes over to consequences - so at least moderate and serious from the blastwave. Then the fire hazard hits at +10 (autotagging the two consequences) and the radiation at +6. Assuming superb endurance, the skinwalker survives that exchange but gets a few more hits.

Now, the skinwalker could attempt to escape. But the nuke just turned the area into a burning, radioactive wasteland. A Way to the Nevernever would only lead to a similar environment now. The skinwalker could attempt to run - but shifting away its toughness to get speed would kill it. The only question is whether it can move a hundred zones to get out of the highly radioactive and burning area before it runs out of stress boxes.

It gets toasted unless it gets really, really, really lucky. And as a monster with negative refresh, it's not supposed to start with Fate Points so it won't get lucky.



Equally tough monsters that are immune to fire or that radiation won't affect them (such as golems) will probably survive the nuke. So would ghosts, those undead whose catch isn't fire, and anything physically immortal (not necessarily immune to damage - they just need to be immune to death). A wizard who is paranoid enough to make a potionlike defensive item at 16 shifts that conjures a 20-ft-thick steel dome or a 16-shift Ward around him in case of nuclear explosion will also survive. But what wizard is paranoid enough to make something like that?
_{*goes off to finish his version of Dresden's crystal shield*}

[BumblingBear]

I find it amusing that with a handful of fate points, my character could probably survive a nuke.

Perhaps he could shut himself in a lead line refrigerator?

::lol::

[Richard_Chilton]

Um, you might want to checkout http://en.wikipedia.org/wiki/Effects_of_nuclear_explosions

Things like the radius of "Urban areas completely levelled (20 psi/140 kPa)" implies more than 20 stress levels - that goes for kilometers when a 20 MT bomb is dropped.

A good rule of thumb is:
Hit by a nuke = dead.
Almost hit by a nuke = almost counts in horse shoes and nuclear weapons, so near misses equal death.

There's the blast wave.  There's the fire storm.  There's the lack of air to breath.  Then there's the buildings falling on you - or rather fragments of building.  That's not talking about the fatal blast of radiation - no, nukes = death.

Richard

[Belial666]

Urban areas completely levelled (20 psi/140 kPa)" implies more than 20 stress levels

140 kPa = 1,3 atmospheres or 20 psi. It is comparable to suddenly being exposed to the pressure of 40 feet of water or being hit by a speeding truck.

Now, some relevant numbers;

Effects of high overpressure;
20 psi overpressure severely damages or demolishes heavily built concrete buildings
35-45 psi overpressure may cause 1% fatalities to humans (but universal injuries)
55 to 65 psi overpressure may cause 99% fatalities to humans

Distance from ground zero in feet and mortality rate for hiroshima bomb;
0 - 1000          93.0%
1000 - 2000    92.0%
2000 - 3000    86.0%
3000 - 4000    69.0%
4000 - 5000    49.0%
5000 - 6000    31.5%
6000 - 7000    12.5%
7000 - 8000    1.3%
8000 - 9000    0.5%
9000 - 10,000   0.0%

Cause of immediate death for hiroshima:
Burns            60%
Falling debris  30%
Other            10%

Cause of immediate death for nagasaki:
Burns              95%
Falling debris      9%
Flying glass        7%
Other                7%

So a 40-kiloton nuclear explosion is not automatically lethal. 7% of people within 1000 feet of ground zero did survive, despite gamma radiation, blastwave and the firestorm that followed. There have been people that survived the bombing of Hiroshima, traveled to Nagasaki, and survived the bombing of Nagasaki as well. I feel rather justified with the mechanics I gave the 40-kiloton nuke now. I might even have given it marginally too high effects.


EDIT:
This probably means that the skinwalker hunting Morgan might have survived if it had its modular points into toughness. OTOH, it might have had all its points into speed to catch up with Morgan or it was a weaker version than the one hunting Dresden.

[Sanctaphrax]

Mixed feelings here. I like the idea, but I feel as though the blast should become gradually less lethal as you move away from ground zero rather than having a D&D-style blast radius.

How would you handle the long-term effects of radioactivity? I'm told that people still get sick in Hiroshima today from lingering radiation.

[Belial666]

Blast and Hazards don't only affect creatures. They affect the area itself.

Just like a 10-shift fireball can add the aspect "House On Fire" to the scene in addition to causing damage to its occupants, so a nuke would affect the area. The blast would replace existing aspcets by the overall scene aspect of "Apocalyptic Wasteland". The firestorm would leave behind the aspect "Scorched Earth" and the radiation hazard would leave behind the aspect "Highly Radioactive".

Then the GM could occasionally compel the "Highly Radioactive" aspect to cause radiation-related stress or consequences just like he could compel a "House On Fire" aspect to burn the occupants.

[EldritchFire]

Blast and Hazards don't only affect creatures. They affect the area itself.

Just like a 10-shift fireball can add the aspect "House On Fire" to the scene in addition to causing damage to its occupants, so a nuke would affect the area. The blast would replace existing aspcets by the overall scene aspect of "Apocalyptic Wasteland". The firestorm would leave behind the aspect "Scorched Earth" and the radiation hazard would leave behind the aspect "Highly Radioactive".

Then the GM could occasionally compel the "Highly Radioactive" aspect to cause radiation-related stress or consequences just like he could compel a "House On Fire" aspect to burn the occupants.

Dang, I love the simplicity of FATE.

-EF

[Todjaeger]

A few things when discussing nuclear devices...

The Hiroshima and Nagaski devices were both comparatively small atomic devices with a yield in the range of 16 - 20 kilotons.  That is roughly comparable to an atomic device which can be fired via tube artillery, or deliveryed via SRBM system.

Another key difference is that both devices were airbursts, with detonation occuring at ~10,000ft if I remember correctly.  That means that a person or building at 'Ground Zero' is still going to be nearly two miles away from the blast.

Regarding structures, while some of the buildings did indeed remain standing, they were all damaged and suffered some degree of structural compromise.

Lastly, when the devices went off, the temperature was briefly the same as on th surface of the sun which is why people were scorched into 'shadows' on the ground.  Unless the supernatural creature or being is able to shrug off 20,000 tons of explosive force, 10,000 degree temperatures, and the radiation which goes along with an atomic blast, then I would say "no" it/they wouldn't survive.

Now if the device is scaled up to a hydrogen/thermonuclear device, it changes even further.  A 2 megaton device, which is one of the standard sizes used for single warhead ICBMs is the rough equivalent of 2 million tons of explosives and the temperature at the blast is going to be somewhere in the neighborhood of 2 million degrees.  By way of comparison, the 1980 eruption of Mount St. Helens was also of roughly 2 megatons force.  During the eruption, trees as far as 19 miles away that were not shielded from the blast by local terrain were shorn off at the base of the trunk and knocked over.  Over 200 square miles of trees were knocked down as a result of the blast.  Also, due to the collapse of the crater, Mount St. Helens dropped close to a thousand feet in height.

Treating such a device as something ~7 times as damaging as a shotgun blast but covering a large area is a bit insufficient, especially if someone/something is close to the blast area.  The pressure wave is capable of propelling debris like projectiles, with a shotgun-like effect miles away from the location of the blast.  In the example I used of the Mount St. Helens eruption, the channeled blast extended out past 19 miles, but with 'only' sufficient force to kill trees by debrading with debris and scorching them, instead of outright knocking them over.  Therefore, if looking for a 20 stress type of hit, that might be applicable for someone/something which is about 20 miles from a 2 megaton device going off.  Keep in mind also that a 20 stress hit isn't going to result in an automatic Taken Out result for anything with even Mediocre (+0) Endurance as long as they can take Consequences.

In short, there is a tremendous amount of energy in such devices, making a nuclear weapon very much a 'plot device' and should be treated as such.

[Belial666]

Another key difference is that both devices were airbursts, with detonation occuring at ~10,000ft if I remember correctly

Actually, the airburst was 580 meters off the ground for Hiroshima. People at ground zero were 580 meters from the bomb. Some of them did survive, if barely.

Unless the supernatural creature or being is able to shrug off 20,000 tons of explosive force, 10,000 degree temperatures

Not 20.000 tons of explosive force - 20.000 tons of explosive. Which produced a 140 kPa blastwave, roughly equivalent to a 16-ton truck hitting per square meter (average frontal surface of a human). And it was ~3400 degrees, not 10.000, lasting a millisecond. It was just enough to ignite wood but not to melt most metals - even the relatively soft ones.

A 2 megaton device, which is one of the standard sizes used for single warhead ICBMs is the rough equivalent of 2 million tons

So, 100x more explosive. That means, according to fairly simple explosion calculations, 4.6 times greater radius and 4.6 times greater explosion strength. 1000x more explosive (a 20-megaton bomb) would mean 10 times greater radius and 10 times greater explosion strength than a 20-kiloton one.

Keep in mind also that a 20 stress hit isn't going to result in an automatic Taken Out result for anything with even Mediocre (+0) Endurance as long as they can take Consequences.

A 20 kPa blastwave will shear off trees and collapse 99% of all manmade buildings. Most humans are killed at three-four times as much overpressure. Simply put, it is four times easier for a bomb to collapse major buildings than it is to kill a human.
The human can (and usually will) be killed by the firestorm that comes after the blastwave; over 70% of the victims in Hiroshima and Nagasaki died from the fire rather than sharpnell or overpressure. Thus, they did survive the initial blastwave, due to luck, situational cover or sheer toughness on their part.





All in all, the Hiroshima bomb was barely strong enough to outright kill most humans at ground zero. A 2-megaton bomb will have roughly 4,6 times the lethality and a 20-megaton bomb will have roughly 10 times the lethality. Therefore, not plot-device powerful by any means.

[Haru]

I find it amusing that with a handful of fate points, my character could probably survive a nuke.

Perhaps he could shut himself in a lead line refrigerator?

::lol::

Nice

But you'd only need one fate point if you can invoke it for effect.

Putting numbers like that on a nuke is like stating out god to die the death of a thousand tiny cuts, only here it is the opposite, the survival by a thousand tiny... shields. Ok, the metaphor falls apart a bit, but I think you know what I mean. In my opinion things on a scale like that should be a plot devise effect and should therefore be countered by plot devise effects (for example by invoking a refrigerator).

[Sanctaphrax]

I disagree completely with everyone saying that nukes should be a plot device.

What does that even mean? Do you tell your players that they die, no defence possible?

If you want to use nukes in your game, you need to assign numbers of some kind.

[Haru]

If you want to use nukes in your game, you need to assign numbers of some kind.

Why?

To me it is more a situation like "there is a nuke about to blow up in 20 minutes. You better find a way to get out of here asap or you are going to blow up with it". I for one would be pretty disappointed if someone in the centre of the explosion would survive, just because he could stack a ton of fate points against an attack of a certain number. I would have no problem with a cool invoke for effect, but just number crunching for a nuke seems kind of silly.