We all know what to do if a terrorist/Iraq/North Korea sets off a nuclear explosion nearby, right?

You probably don\'t have a clue. The Bush Administration has been careful not to overstate the risks or inflame public fears about what America and the West faces. However, from my long study of nuclear proliferation, we targets - I mean citizens - need a bit of education just in case on how to handle ourselves and on what to expect from our government. I\'ll confine myself to the United States but the physics apply everywhere.

First, a terrorist or rogue state would be hard pressed to build anything more powerful that a Hiroshima-class weapon - 20 kilotons. Beyond that would be a big step up in difficulties in engineering and in necessary quantities of materials. Probably it would be smaller but 1 kiloton is hardly a fizzle and is pretty easy to do once the materials are in hand. That\'s relatively good news. The good news/bad news is that a ground burst is probably the method of detonation. That\'s good in that it substantially limits the radius of direct blast effects but bad news in that it will create a lot of lethal, local fallout. Fallout was not present at Hiroshima or Nagasaki because those weapons were dropped from airplanes and set off at a height that maximized the blast effects on the ground.

Let\'s talk about the initial blast. You probably won\'t have any warning. A device could be smuggled in via ship or truck so unlike a missile, would not be detected in advance. Your first awareness may be a flash of light brighter than any you\'ve every seen before. If you see such a flash, cover your exposed skin and fall to the ground. DON\'T look at it - it can permanently blind you at long distances, especially at night. That light can last a couple of seconds and can burn exposed skin at considerable distances. Fires will be started in paper and similar light flammible materials. A shock wave will follow that will send flying debris and can knock you off your feet and throw you hundreds of feet - or until you hit a wall at 30 mph. A 100 mph wind follows the shock wave at a 1 mile radius. \"Duck and cover\" means you\'ve covered your skin and hit the ground.

Assume you\'ve survived the initial radiations and blast - and you probably will if you\'re over a mile away. However you\'ll probably get radiation sickness from the 200 rem you get from the fire ball at one mile but that will take a week or two to present - with medical/nursing care you\'ll be OK in a month or two - the next thing to worry about is fallout.

A ground burst is the nasty way and the way a terrorist will find the easiest. The 700 ft diameter crater will of course be very hot so stay away - there will be few if any survivors to help within a half to one mile so don\'t be a fruitless hero. Of the 31,000 people within 0.6 mile radius of ground zero at Hiroshima, less than 2,000 walked away. Fallout can be lethal for many miles downwind so that is your next big concern.

Fallout is the dirt that is sucked up into the mushroom cloud then mixed with the condensation from the weapon debris. The weapon was vaporized and as it cools, it mixes with sucked-up dirt, coating it with intensely radioactive fission products - about 2.5 lbs (1.1 kg) - that will eventually fall back to earth. The closer (and faster) they fall, the higher will be the radiation dose rates on the ground. Some of the fallout will occur in a circle around ground zero (GZ) but most will be carried on the prevailing winds away from the point of detonation.

You can see local fallout - its dirt from the sky. If that\'s happening, move in a direction perpendicular to the winds. If you\'re east of the GZ and the winds are from the west, move north or south. It may only take a move of a few miles to get you out of the path of the fallout if the winds are steady at all elevations. You may be able to see the black cloud that is the source of the fallout but maybe not. If you\'re under fallout within 30 minutes of the explosion, you need to move - NOW. The dose rates will be so high that you could get a lethal dose from 15 minutes of exposure.

The US government has coverage 24/7/365 of a team that will make fallout predictions. The local emergency organization will be the first to notice the blast, of course, and they are supposed to call the state which in turn calls Lawrence Livermore National Labs (LLNL) with as much info as possible including making a guess on kilotonnage based on damage radius, etc. LLNL has continuous metrological data feeds and can come back almost instanteously with initial predictions. One should expect broadcasters to be able to get evacuation instructions out to the public within 1 hour. Therefore, as soon as the mushroom cloud forms, turn on a radio or TV and listen for instructions. Fallout that can give a one day lethal radiation dose could cover 50 to 100 square miles although it could be less. The National Guard has units in each region that have special training for such an event and will be on the scene within hours to get measurements and help with evacuations.

That\'s the simple version. A little knowledge helps to prevent the panic of the unknown so keep your cool and listen for instructions. Our government at all levels has made good preparations and will be converging on the scene to help within an hour but you will have to help yourself and your neighbors over the first day or so. No need to stockpile food or crawl into a hole in the ground for weeks - it will a lot different from the Cold War scenarios.

The books to read are \"The Effects of Nuclear Weapons\" by Glasstone - Government Printing Office and \"Nuclear War Survival Skills\" by Kearny. The former is a science and engineering treatise and the standard reference book; the latter is a bit dated and is focused on \"The Big One\" but has some things of interest in our different scenario.

http://www.ki4u.com/free_book/s73p904.htm