Longlasting radiation catastrophe

[duraluminium]

Greetings everyone!

I have been reading the forums for a while now, however I have just registered and this will make my first post.

While thinking of a science fiction novel that takes place in contaminated setting, originating from our day world, I have found myself stuck on how to provide a scientifically justifiable explenation on how the contamination came to be.

"Mad science Q&A" are abundant on the internet, but read as I might, I can not identify the bellow clearly.

I already did some reasearch on radiation, nuclear disasters, etc. and came up with the frame within which I hope to identify a single radioactive element of the following properties:

a) half-life of 7000+ years (preferabely at least twice that but that's the minimum i hope for)

b) alpha/beta (preferabely both, but if i have to make a pick, then beta) radioactive decay, sufficient to deliver a terminal dose within hours of internal exposure (breathing in unseen dust particles), resulting in death after around 14 to 30 days. Other radiation that is harder to shield from is not desirable

c) Sufficient quantities to cover the entire surface of the Earth (thinking fallout) with more of the dust drifting in the atmosphere. Not necesserily available on Earth in such quantities and can be of an extraterestrial origin - an asteroid of some sort or some other form of cataclysmic delivery (supernova debri, or some quantum experiment involving matter discharge from the sun gone terribly terribly worng, perhaps?)

In addition to the above, I have some general things i want to ask:

Coud (in theory)alpha/beta radiation be held back by a strong enough electromagnetic field?
Radiation does not mess with unshielded electronic devices, right?

Basically I am looking to (semi)scientifically justify a Chernobyl (city of Pripyat) like radioactive environment (with, relatively speaking, more immidiate consequences for the misfortunate individual that strides into it unprotected) that prevents people living in spaces open to radioactive dust, thus calling for more drastic measures, alternating the way people live by forcing them into long term (a few 1000 years) refuge in large confined spaces, but letting them walk around in the open if wearing protective clothing.

Would radiation in the above scenario (before the half-life period is reached) steadily decrese? If it would, how long before the half-life point would it be at human-tolerable levels (i.e. so that the deadly dose exposure time would go from a few hours to a week or something?).

I would really like to get a better picture on how a cataclysmic nuclear event would influence our civilisation on a few thousand year scale. Would we in compharison plunge into a modern medival age (contless hollywood plots) lasting until the half-life point or would we be back on our feet in a few decades / a century? The scene I'd like to give a logical history to would be survival through use of present and future technology, but with limitations (technological, economical and sheer size) on just how much area could be sheltered.

I kindly ask for your suggestions.

Cheers

 

[duraluminium]

Greetings to all again.

It seems I have misunderstood some things I have read...

A correction to b) , looking for Alpha/beta RADIATION.

Can anyone suggest any potential candidates? I am looking at some ANL Factsheets that hold much information presented in a form that comes of quite a lot of use to me, but I do not know which element to search for... and there is no particular index on the site, I am just googling each individual element :(

Cheers

 

[Astronuc]

Here is some information on radioactive decay series.

http://hyperphysics.phy-astr.gsu.edu/hbase/nuclear/radser.html

and data on specific nuclides - http://www.nndc.bnl.gov/chart/
Beta emitters are below the line of black dots, and alpha emitters toward the top right. Place cursor over chart, click and select Zoom 1 for specific details.

The alpha emitters are heavy elements, with polonium being the lightest. Beta emitters are more abundant.

Essentially the only way to have a large volume of alpha and beta emitters dispersed over a large area would be to have a large scale use of nuclear warheads or a catastrophic breach of a repository of spent fuel (e.g. an asteroid striking the repository).

Activity is a function (product) of decay constant and the number of atoms of a particularly radionuclide present.

 

[duraluminium]

Thanks Astronuc,

This narrows my search down to beta emitters i guess.

I'm looking at the links, now, searching for the best candidate... however...

1) Would I be correct to presume that long half-lives go hand in hand with lower levels of radiation?

and

2) Amount of radiation a person would receive depends on the quantities of the material and time of exposure?
What I mean is:

a) A 2 second exposure to a highly radioactive beta emitter that breaks down in 2 seconds would be on pair with twice the exposure time to a radioactive beta emitter that breaks down in 4 seconds, providing they give away the same amount of particles in the space of 2 seconds.

b) 2 second exposure to a highly radioactive beta emitter (of a certain mass) that breaks down in 2 seconds would be on pair with 1 second exposure to twice the mass of the same beta emitter.

If so, the same result could be achievable with more mass of along lived beta emitter as with less mass of short lived beta emitter... correct?

Also... I have stumbled over a few sources that contradict each other. Some say beta radiation is easily stopped by a sheet of aluminum foil... some say that it easily passes through it... Which is it?

Thanks again for your help

Cheers