Re: Bomb anniversary

[Guest guest]

Inger,

There is are differences between the radiation of a nuclear bomb and a failing nuclear reactor.

Bombs first.

The first and probably most important is the amount of material involved. A bomb uses a special type of enriched Uranium (238 I think) or Plutonium. With both of these, not a lot of material is needed for the bombs and much of it is destroyed in the explosion. That relatively small amount is scattered over a very large area.

Fallout is different as well. Nuclear bombs work best if they airburst, or explode in the air. This maximizes the effect and range of the blast. Because the explosion is in the air, most of the radioactive material never reaches the ground in concentration. The radiation that kills people immediately and much of what contaminates the ground is radiation released during the nuclear reaction. Most of that radiation around ground zero fades within days to weeks.

Long range fallout can be a problem too. That is because dust and smoke is sucked up from the ground by the fireball of the nuclear blast, the mushroom cloud. Radioactive material from the bomb's core can stick to this material and then settle to the ground a long distance off. However, the concentration is very low, but can be dangerous. for a time.

A groundburst nuclear weapon is a bit different. Radiation tends to last a lot longer there because there is more dirt and such to mix with. That traps more material on the ground making nuclear craters dangerous for a lot longer than ground zero of an airburst.

Underground blast can stay radioactive for a very long time because there is nowhere for the material to disperse to. Some of the 1950's underground nuclear test sites are still leaking small amounts of radiation.

Another factor is that the materials used in bombs have shorter half-lives than the material used in reactors. This is because the material being less stable is easier to split and for the chain reaction to continue.

Reactors.

The amount of material used if far greater. The exact amounts for bombs varies and is classified, but it is probably only a few pounds. A reactor on the other hand, uses hundreds of pounds if not tons.

This nuclear fuel is make of more common, though still enriched uranium, though some use and produce plutonum. This type of Uranium is much more stable than that used in bombs and so has a much longer half-life.

Duration of the release is also different. Nuclear bombs release their material and energy in an instant. Chernobyl burned and released for many hours. As a result, rather than a few pounds of durable fallout like in bombs, this was tons of persistant material.

I also think there was more "diversity" in the type of radioactive material from Chernobyl. Bomb fuel has to be as pure as possible for maximum effect. Plant fuel also is pure, to start with, but over time as the Uranium is spent it produces other types of radioactive materials, like Strontium 90, which is really nasty stuff.

So, Chernobyl was worse because of much longer release time of more stable and persistant material than you would typically find in a nuclear bomb. Another reason for this is because most nuclear bombs are designed to be "clean" or to have the minimum radioactive fallout and the quickest clearing of ground zero. This is not so much for humanitarian reasons, but because the lower residual radiation reduces the hazard to one's own troops if they had to move into the area. It also reduced down wind fallout which could spare allied nations or your own from catching a lot of radiation.

If anyone is really interested, I do have some charts I could copy some information from on how far out radiation can travel. The book that has the information on ground contamination is lost somewhere around here. Haven't needed it for ages so its in storage.

This has been pretty simple but covers the basics.