Radon Emission from Uranium Deposits

[Mr_Bojingles]

From what I hear Uranium miners are constantly under threat from radiation gas which is released from Uranium mines.

What I learned before is that there are 3 types of radiation. Alpha (helium), Beta (electrons), and gamma (photons). What kind of radiation releases radon gas. If its not radiation what is it? Uranium which gradually decayed into radon which is trapped under ground until the miners release it?

 

[Dr Transport]

If memory serves me correctly radon gas is radioactive itself. I bought a house a few years ago which the radon gas level was way to high and had to have an abatement system installed which just removed the gas making the house habitable again. I forget what the decay mechanism is.

 

[Mr_Bojingles]

Radon is a radioactive gas. Alot of houses build near Uranium deposits have dangerously high radon levels. Especially in the basements. I hear some building materials contain Uranium so give off radiation. I am not sure if that gives off radon though. I read a lot of the houses in Sweden build around 1990 give off high amounts of radiation because of the building materials used.

 

[Morbius]

From what I hear Uranium miners are constantly under threat from radiation gas which is released from Uranium mines.

What I learned before is that there are 3 types of radiation. Alpha (helium), Beta (electrons), and gamma (photons). What kind of radiation releases radon gas. If its not radiation what is it? Uranium which gradually decayed into radon which is trapped under ground until the miners release it?

Mr Bojangles,

It's not "radiation gas"; but "radon gas".

Radon gas really isn't "trapped" underground. Radon is one of the noble gases; it's inert;
and very difficult to "trap". Radon diffuses around in the ground. It frequently will then
seep into the basements of houses. Houses in areas with this problem can mitigate
the problem with a "radon fan":

http://www.infiltec.com/tg3fg20.jpg

http://www.infiltec.com/inf-pixr.htm

The fan - the white cylinder with the tapering top - draws air and radon gas from the
area around the house's foundation and exhausts it up the stack; so that radon
doesn't accumulate in the basement and interior of the house. [ I actually use a
radon fan to cool some electronic equipment that's part of my home
entertainment system - they're very quiet.]

The problem really isn't the radon gas directly. Since radon is inert, your body won't
trap it. You may breathe it in - and there is a finite probability that some of the atoms
will decay and irradiate your tissues with alpha particles. However, it will only be for a
short time, since you will exhale the radon in the next breath.

The real problem with breathing radon, is that it may decay to polonium after you breathe
it in. The polonium, which is not inert; can be trapped by your tissues, and it will sit there
and your tissues will be irradiated by the polonium and its radioactive daughters.

That's why it's best to take the mitigation steps shown in the links above.

Dr. Gregory Greenman
Physicist

 

[Mr_Bojingles]

I meant radon gas not radiation gas. What I am wondering is why Uranium deposits emit radon gas. The only thing I can think of is that its created by the decay of the Uranium. Since its so far down the decay chain id assume that its trapped down there for a long time before decaying further and eventually reaching stable lead.

When you say it diffuses do you mean it spreads and seeps through the Earth surrouding the Uranium deposits? In that case is it just the digging of the Uranium mines that put the workers at risk.

Like you said the problem with radon gases arise when its inhaled. From what I've learned there were a lot more risks for Uranium miners 50 years ago since they didnt take adequate precautions against radiation. Nowadays the mines are well ventilated but the workers still arent completely risk free.

 

[Astronuc]

I meant radon gas not radiation gas. What I am wondering is why Uranium deposits emit radon gas. The only thing I can think of is that its created by the decay of the Uranium.

Radon is an intermediate step in the decay chains of several actinides.

U235 - http://hyperphysics.phy-astr.gsu.edu/hbase/nuclear/radser.html#c1

Th232 - http://hyperphysics.phy-astr.gsu.edu/hbase/nuclear/radser.html#c2

U238 - http://hyperphysics.phy-astr.gsu.edu/hbase/nuclear/radser.html#c3 (at two points)

Uranium is found at low levels in the Appalacian mountains, the western mountain states, and the northern/midwestern US.

http://www.epa.gov/iaq/radon/zonemap.html

Of course, it's higher in certain deposits which are mined for the very reason that the Uranium content makes it economical to mine.

 

[ChrisLeslie]

U-238 and Th-232 are present in most rocks, clay deposits and soils at several tens to hundreds of decays per second per kg. Therefore radon, being eventually a daughter product of the above long lived parents, will be constantly generating and decaying in our environment. Most radon will be trapped within rocks and compacted soils, but some gas near the surface of the ground, or holes in the ground, or near the surfaces of clay bricks and tiles will escape to the air and be a potential and apparently significant health risk if breathed in. Everybody is breathing in some radon, but poorly ventilated underground places may cause radon levels to build up, thereby increasing the health risk. Radon atoms that escape to the atmosphere will decay in a matter of days, on average, eventually to Pb-210 and Po-210 which finds its way back to soils. This process causes an excess of Pb-210 and Po-210 in surface soils and settled dust.

 

[Morbius]

Everybody is breathing in some radon, but poorly ventilated underground places may cause radon levels to build up, thereby increasing the health risk.

ChrisLeslie,

Courtesy of the Health Physics Society at the University of Michigan:

http://www.umich.edu/~radinfo/introduction/radrus.htm

The average dose due to Radon is 200 mrem/yr = 2.0 mSv/yr which accounts for
about 55% of one's annual backgrond radiation dose.

Dr. Gregory Greenman
Physicist