Test of ~1KT tactical nuclear weapon, Nevada, January 1951.

 

Tactical nukes have been getting a bunch of ink of spilled lately, so here are some words about nukes and what you might want to panic about if you live in Europe.  Nothing in here is classified and most everything in here is in Wikipedia or other popular websites.  Many people here have great backgrounds in science but I have kept everything at science 101 levels to make typing it easier.

Let’s start with little booms.  These are conventional bombs and explosions.  The explosion comes from a chemical reaction that occurs at high speed.  (Sometimes this reaction is in two parts but for our purposes we can consider everything one reaction.) Damage comes from over pressure from the shock waves, heat causing burns or combustion, and shrapnel.  Shrapnel can come from the casing around the explosive charge like in a hand grenade or artillery shell, or from materials propelled by the shockwaves, like an automobile, wood splinters, or pulverized concrete etc.  Shock waves don’t propagate that well through air which limits their effect to cause damage at distance.

The largest air dropped conventional bombs are about 22,000 lbs. (10 tons) During WWII 41 or 42 were dropped. The MOAB was used by the USAF in Afghanistan. Some ground emplaced explosions have been larger, but have been limited in far reaching impact because of the depth of their emplacement.  That is not to say they were small.  One set off by the British in France during WWI was heard in London. At least one did not detonate is still ticking underground today.

Grand Slam being dropped by RAF, 1945

 

Using nuclear fission (splitting nuclei) or fusion (forcing two hydrogen atoms together with enough force to make a helium atom) releases lots more energy than a mere chemical reaction.  With a theoretical 100% rate of fission one kilogram of uranium-235 releases an explosion equivalent of ~17,000 tons of TNT. The Little Boy bomb dropped on Hiroshima only “fissioned” ~1.4% of the nuclear fuel.

Nuclear and radiological weapons add in radiation to the mix.  Radiological weapons are not nuclear explosions, rather they scatter irradiated material in order to deny people access to an area.  The scattering can be by explosion, mechanical means, wind, water etc.  After 9/11 these type of weapons got some publicity because you don’t need a state actor, any terror group or lone madman can employ this weapon provided they can get their hands on an easily spreadable radiation source.  By their nature these weapons can do local damage only, and that damage will be mitigated by weathering, half-life, and mechanical decontamination.  The primary impact these weapons is psychological since you can’t see, taste, or smell the radiation.   So unless you are planning on a winter vacation in Ukraine and one of these is used in the same town that you are in- you are safe.

Nuclear weapons either split atoms (fission weapons) or push them together to make new elements (fusion weapons) and either way releases huge amounts of energy.  This is the first difference with nuclear weapons to differentiate them from conventional weapons.  Nukes have much more power. More overpressure (shock waves), more heat, more material thrown as shrapnel.  Plus these weapons add in several forms of irradiation.  There is direct radiation from the nuclear reaction, and there is induced radiation where the radiation from the reaction makes other materials radioactive.  Since it is very difficult for weapons to consume 100% of their radioactive materials so the remaining uranium or plutonium is dispersed as well. These materials are best known as fallout.  [If the reaction is a squib or partial squib and not a full reaction then the core materials (uranium or plutonium) will be spread as well.]

Direct radiation is in the area directly around the weapon detonation site.  These are the gamma rays produced during the explosion.  If you survive the heat, overpressure, and shrapnel, this form of high energy can quickly kill you.  (A neutron bomb is a hybrid fission/fusion bomb that releases a greatly enhanced amount of gamma radiation for the size of the explosion.)

Nuclear bombs produce up to three types of fallout: local, tropospheric, and stratospheric. Local fallout is due to the deposition of the larger radioactive particles near the site of the explosion. This fallout is quite intense but relatively short-lived (see squibs above). Tropospheric fallout occurs when the particles stay in the lower atmosphere (think around the height of Mt Everest) and are deposited over a larger area, depending on the local meteorological conditions. Usually this fallout drops in a month or less, in the same general latitude of the burst, and primarily downwind by the direction of dominant winds.  (Local weather like storms would also scrub the particles to the ground.) Stratospheric fallout is made up of the finest particles and are carried into the stratosphere.  These particles can take years to make it back to the surface and can land just about anywhere.  “Small” nuclear weapons don’t produce much of this type of fallout since they don’t have enough power to lift significant amounts of materials high enough into the atmosphere.    Back in the era of Nevadan open air nuclear tests no fallout fell east of the Mississippi River.  This was ensured by not establishing any fallout measuring stations east of the Mississippi River.

Many different radioisotopes are formed during a nuclear explosion, but only a few long-lived isotopes are dominate stratospheric fallout. Cesium-137 and strontium-90, which have 27 and 28-year half-lives dominate most discussions because they absorbed by the body as a calcium mimic and can bio-accumulate. Radioactive Iodine can accumulate in the thyroid and increase cancer risk.  A popular, but not universally accepted, method to reduce risk is to take Potassium iodide pills or iodine treated water to make sure the thyroid full of iodine so the body doesn’t absorb the radioactive iodine.

Will Putin break previously intact international norms? Will Biden get a chocolate or vanilla pudding cup for lunch? What will Giselle do with three Super Bowl rings? Find out in the sequel, “Post-Boom.”