why does a nuclear bomb have to be so big?

Question

what if you use less of the uranium and what not for the bomb why wouldnt they make it more of common size bomb, or is there just no point to it.

Answer 1

There is a certain minimum amount of nuclear material required to achieve a critical mass. However, it is not required that it react with extreme efficiency so it could be moderated to produce a very small explosion, compared to other nuclear weapons. However, nuclear weapons are extremely expensive to make and they have incredibly bad side effects in the form of radiation so as you noted there would be little point in making such a bomb.

Answer 2

Some background on what a nuke needs and does first.

It takes 7.4 kg of uranium to produce a nuclear explosion. When understanding nukes think in kilotonnes. A single Kilotonne yeild can knock a place like Pittsburg flat if if was detonated on the ground, however it would never touch the subburbs. Detonate the same nuke 1 kilometer (half a mile) above Pittsburg and you get to destroy all of the people in pittsburg plus all of the surrounding sub-burbs.

However there is and never has been a 1 kilotonne nuke. Nukes that are built today are in the hundreds to thousands with fully redundant systems that allow a nuke to still hit its target even with most of it blown off. Plus they come with 6 to 20 warheads that can spread out you allow maximum kill zone by emulating a bomb called the daisy cutter. An example would be, a nuclear missle approaches its target, target sets off a missle defence system, the missle already knows about missle defense systems so it starts dropping warhead "seeds" around the target. The target is vapourized from all sides rather than taking a direct strike.

Why the huge explosions? Because they are bombs and the intention of a bomb is to kill your target. Why use a bomb? Capture resources and/or a location that may or may not allow for furthering a campaign goal.

you might want to look up MAD, or Mutually Assured Destruction. It was assumed that all the USA and Russia had to do was make bigger badder bombs than the next guy until it became very clear that if they ever did go to war there would not be anything left on earth. Hence MAD. So the tactic changed, both countries would destroy everything but the goal would be to see how many people they could cram underground while the earth was lit up like a Christmas tree. this went on for about eight year until the Russians tested themselves a new SUPER nuke and accidentally cracked the crust of the earth. So they quit for various reasons;

1) it's really expensive
2) a glow in the dark universe isn't as much fun
3) vodka is impossible without potatoes.

Answer 3

Initially, the threat of total destruction by these massive bombs actually helped prevent war, at the fear of these ugly weapons being used. Now, I believe Bush administration talked about bunker nuclear bombs. I don't recall if that meant they should be bigger, or smaller and more able to penetrate ground and whatnot. But if they were to make it a common size bomb, no need to make it nuclear at all. We have plenty of smaller bombs, so we could use those rather than develop smaller nukes.

Answer 4

Economic and psychological reasons aside, for a warhead comprised of HEU, a certain minimum mass needs to put together. The actual figures vary on how much you need, but this varies depending on how enriched you are. Regardless it's in the Kilogram range. Anything lower than this and nothing will happen.

Now, in order to get the bomb to go off when you want it (Hmm...let's see, peaceful application...uh, how about blowing up a meteoroid) you need to make sure that at no time before you want it to blow there is a critical mass. This is achieved by splitting the warhead into two pieces and separating them. Then, when you want the thing to blow up our meteoroid, you smash the two halves together very hard and voila. Big bang.

Answer 5

There's a minimal mass of fissible material needed for a nuclear reaction to occur. The smallest warhead ever created was the W54 for the Davy Crockett nuclear recoilless rifle. The reason most nuclear bombs are so big is to create a much larger explosion.

Answer 6

Nuclear bombs don`t needed to be big, a nuclear bomb of a size of a hand bag can level a city already. The reason for making it big is to simply scare off the other countries around you, and let them know that sanctions or threats are not welcome.

Answer 7

Technically it doesnt have to be. I've taken a few classes in college on nuclear science. Its big because of the controll features in it (so it only goes off when it is suppossed to)

Answer 8

Even the least amount needed for the chain reaction causes an explosion larger than almost all regular bombs.

Answer 9

To sustain a fissionable chain reation

Answer 10

Well I think its because it can possibly destroy the entire planet and as far as I know the earth isn't that small.