From v04.n841 Thu Jul 30 13:40:13 1998 Date: Wed, 29 Apr 1998 18:01:05 -0700 (PDT) From: Anthony Jackson Subject: Rules for Nukes Hm...I'm not convinced by some of the results I get here... comments on how I did these rules? I'm not entirely convinced by these results... (These rules based on the 'effects of nuclear weapons' FAQ from www.fas.org/nuke/hew/Nwfaq/Nfaq5.html) These rules for nuclear weapons attempt to address the effects of nuclear weapons in a method which is computationally reasonably simple; as such, they are fairly low resolution, but are easily more accurate than the rules given in VE2. With minor modifications these rules can be applied to conventional explosives as well. Basic rules: damage for nuclear weapons are not rated in dice -- they are just given flat numbers which indicate the approximate kill radius for the desired damage type (this radius is expressed as a GURPS range modifier). There are three scores involved: 'flash' (direct thermal effects), 'concussion' (shockwave effects), 'radiation' (expected radiation wounds), and 'space' (thermal shock effects in space). With the exception of 'space', these numbers probably have some basis in reality. Description of effects: Flash: direct effects due to thermal radiation; while actual absorbed energy is linear in warhead yield, the actual effect is nonlinear because a higher yield weapon generates a pulse with greater duration. Flash damage can be lethal at extreme ranges, but is almost irrelevant against any hard target. The thermal pulse also scales roughly evenly with the likelihood of flash-blindness. Concussion: the direct shockwave effect. Concussion is not particularly directly lethal against soft targets (such as humans), but is significantly more effective against buildings and other rigid targets. Radiation: acute radiation dose. For large weapons, the kill radius for radiation is significantly lower than for other effects. Space: effect in space. This is mostly a pulse of soft Xrays, with an _extremely_ short duration; destructive effects are primarily a function of thermal shock, in which sudden heating causes shattering of materials. Ignore other damage ratings in space, they have no particular effects. How a weapon is described: weapons are given three ratings, their 'flash', 'concussion', and 'radiation' ratings. In all cases, add the range penalty (from weapon to victim) to the relevant weapon rating to determine effects. The table below indicates the relevant ratings for weapons from micronukes to citybusters. Weapons Table: Yield Flash Conc Rad Space Yield Flash Conc Rad Space 0.001kT 7 9 11 7 0.01 kT 10 11 13 10 0.1 kT 13 13 14 13 1 kT 15 15 15 16 10 kT 17 17 16 19 100 kT 20 19 17 22 1 MT 22 21 18 25 10 MT 25 23 19 28 100 MT 27 25 21 31 1 GT 30 27 22 34 Size Damage Modifier table: Siz DM Siz DM Siz DM Siz DM Siz DM Siz DM - -6 .1 -5 .15 -4 .2 -3 .3 -2 .5 -1 .7 +0 1 +1 1.5 +2 2 +3 3 +4 5 +5 7 +6 10 +7 15 +8 20 +9 30 +10 50 +11 70 etc. Buildings count as having a DM of *2, and apply damage _per hex_. Multiply damage from blast effects by the DM for the size of the target vehicle. Damage Table DN -3 -2 -1 0 1 2 3 4 5 6 7 8 9 *6 Flash nil 1d-3 1d 3d 6d 9d 6d*2 6d*3 6d*5 6d*7 6*10 6*15 6*20 (*10) Concu nil 1d-4 1d-2 1d 2d 3d 6d 6d*2 6d*5 6*10 6*20 6*45 6*100(*100) Shrap nil 1d-2 1d 1d+2 3d 6d 9d 6d*2 6d*3 6d*5 6d*7 6*10 6*15 (*10) Rads 1 10 100 1000 10k 100k 300k 1M 3M 10M 30M 100M 300M (*1k) Flash damage: flash damage has quite unimpressive penetration, though it is lethal enough against unprotected flesh. DR is multiplied by 5 against flash damage; clothes will divide damage by 5 (after DR), though if the flash does at least 5 points of damage they will catch fire. Flash damage is treated as _impaling_ damage, giving x2 damage against flesh, and penetrating open-weave armor fairly easily. In addition to normal DR effects, reduce flash damage by a number of levels equal to the vision penalties for haze. Flash damage for blinding: assume you are blinded for 5 turns per point of damage, and dazzled (-3 DX) for 1 minute per point of damage. A successful HT roll subtracts 5 seconds * margin of success. Anyone actually looking at the flash should make a HT roll at -1 per point of damage, on a failure you are blinded (heal as a normal disabling injury), on a critical failure the effect is permanent. On a success you will have a blind spot in your vision with the size and shape of the cloud, this will also heal as a disabling injury (this effect can be ignored at effect levels of -10 or lower, the spot is no longer large enough to be relevant). Space: treat space damage identically to flash, except that damage is also treated as HESH (10% of damage vs 1% of DR, do not multiply DR). Make a HT roll for the vehicle, at -1 per 10% of the vehicle's DR from the attack, to avoid becoming unsealed. Concussion: the damage shown here is really only appropriate for concussion vs soft targets (such as humans); rigid objects (such as buildings) are far more vulnerable to concussion. In general, whenever a rigid object is hit by concussion compare (5*damage) with the target's hit points + DR; if the damage is greater, the target will basically disintegrate. DR is applied _after_ the size DM against concussion. Concussion is less effective for ground bursts -- reduce concussion rating by 1 for a near-ground blast, by 2 for a blast actually against a surface. Knockback from concussion: concussion can throw you a _long_ way -- the 1d of damage from a +0 level effect is 160 mph. Assume knockback distance is equal to (damage / (10 * weight in tons)). Hitting a solid object will do more damage than the initial concussion -- multiply by 2. Shrapnel: the biggest hazard of concussion to humans is bits of building, etc. The listed shrapnel damage is reasonably typical if you are in a city. Radiation: this is direct radiation level. Specialized weapons can increase or decrease this by a factor of around 100. Example: 100 kT tactical nuclear weapon, airburst, over an urban area; there is a military depot two miles away (range=19). Looking at our weapons table, we find a 100 kT weapon is: flash 20, concussion 19, radiation 17. Thus, the modified effects are flash +1, concussion +0, radiation -2. A flash rating of +1 corresponds to 4th degree burns on exposed flesh, and will do 6d impaling to exposed soldiers; fortunately, they wear heavy cloth (DR 1) which almost fully covers them, so they have DR 5 against this, and divide the penetrating damage by 5; even after impaling multiples, anyone who wasn't facing the blast merely takes 6 points of damage and is set on fire, plus secondary glare will probably blind them all for over a minute. That 6d impaling is also sufficient to ignite various wooden structures on the base, and just about anything made of cloth; it has no detectable effect on most vehicles. A couple of seconds later the shockwave hits, doing 1d direct concussion damage, and about 1d+2 damage from flying particles; as a side effect this puts out any fires, though it is likely to pretty much sand away charred cloth. There are a number of jeeps in the motor pool (size +4, 1 ton, 200 hp) which take 3d damage; even checking against 1/5 their hit points this isn't a serious problem, but they get thrown about. In addition, there are a couple of wood-frame buildings with DR 4 HT 20 per hex; at 2d per hex they are likely to take 5+ and crumble. Finally, exposed troops take 10 rads, which doesn't worry them overly. Now, a mere 700 yards from the blast there is an APC (14 tons, DR 60, hp 700, size +4). This is a range modifier of only -15, so it takes +5 flash +4 concussion +2 radiation. The flash damage is 6d*5, which fails to penetrate armor. The concussion damage is 6d*2, *5 for size, or about 210 points; 1050 exceeds (HP + DR), so the vehicle comes to pieces. If it had been rigid enough to take it, it would have been moved 1.5 yards, and the crew took 100,000 rads...