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Hi, does anyone of a list of what materials offer in shielding. Eample for every piece of wood 1" thick = *** in shielding rating, concrete 1" of concrete = *** in shielding rating. I know there is a formual for this as I saw it years ago in a old CD manual.
 

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DONT TREAD ON ME
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The halving thickness of concrete is 2.4", the halving thickness of packed earth is 3.6". A halving-thickness is the thickness of a material which reduces by half the dose of radiation that passes through it. So with one halving thickness the amount of radiation penetrating the material is 1/2 the amount it would be if you were to be standing in the open. So if you had 10 halving thicknesses the amount of radiation penetrating the material is 1/1024 (protection factor "PF" of 1024) the amount it would be if you were to be outside. How much Protection Factor is needed for you depends on the area you are in. FEMA prescribes a minimum Protection Factor of 40 but it areas of heavy fallout many in a PF40 shelter would either be incapacitated or die due to the amount of radiation they have received. Considering how easy it is to increase your protection factor there is no reason not to have a protection factor of 1024. I am not sure on the halving thickness of led or other metals are, but the more dense a material the less gamma rays can penetrate.
 

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Here is an excerpt from a shelter guide I wrote about 10 years ago for a military base in the mid-west. Keep in mid you will need some type of device (i.e. CDV-777 kit) to measure radiation.

7.4. Protection Factor.

7.4.1. The effectiveness of a shelter as a radiological countermeasure is often expressed as a protection factor (PF). The PF is the ration of the dose that would be received outdoors, without any protection, to the dose received in the shelter.

7.4.2. Each shelter has a pre-computed PF, which is an estimate of the protection offered, by the shelter.

7.4.3. The actual shelter protection factor is determined by the following:

7.4.3.1. As soon as a dose rate inside the shelter can be determined, compare it with an outside reading taken at or near the same time. This outside dose rate is divided by the inside dose rate to determine the actual protection factor.

7.4.3.2. Once an actual or verified PF is determined, there is no need for outside monitoring because the outside dose rate can be calculated by multiplying the inside dose rate by the protection factor.

7.4.3.3. To determine the “true” protection factor of a shelter, you must take the following steps:
1. Obtain both the inside and outside radiation levels. (These readings should be taken simultaneously for the computations to be valid).

2. The formula is as follows:
a. The outside reading (OR) is_____________

b. The inside reading (IR) is_______________

c. Use this formula: OR÷IR= True Protection Factor


Hope this helps :confused:

Chili
 

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Preparing...
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If there was a nuclear attack how long would you need to stay underground before the amount of radiation is not dangerous and you can leave the bunker?
If it is a very long time what would you do?
How do you know if a nuclear bomb is going to go off, because terrorists are very quiet about when they will attack?
Any ideas would be good.
Thanks
 

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chrisday4064
If there was a nuclear attack how long would you need to stay underground before the amount of radiation is not dangerous and you can leave the bunker?
You will need some way of measuring the amount of radiation you have absorbed. The following i gathered from a website "Bruce Beach Nuclear Survival Resources & Ark II Fallout Shelter Site" What these are is total amounts of radiation you have received (absorbed). There are literally hundreds of charts out there, that will tell you (as an estimated guess) how much radiation you will get if a bomb is detonated near you. But you have to know how close, wind speed, prevailing wind and a lot of other things. It is much simpler of you have a device that measures radiation. Start here
http://www.radmeters4u.com/ You need to educate your self on the different types and uses of each. The chart below is talking about "total accumulated dose" So from start to finish how much you have received.
The following is interpreted from attached "official" and other "expert" sources. These sources often provide a 'range' for effects, but I have simplified this to a single number to make the table easier to memorize - and you should memorize it. You can then 'extrapolate' for your self the relative severity of effects of a number between a higher and lower number.

o 600R -- means 100% chance of fatality is expected.
Some much earlier - but last within two weeks.

o 400R -- means 50% will die within one to three weeks.
Those that don't die are going to be VERY sick and wish that they would. After a few days some may feel better but will often then turn, sicken and die in a few weeks.

o 200R -- lots of sickness, and radiation sickness is pretty terrible (Think of cancer treatment without pain killers.)
Lots of vomiting - hair falling out - and all that.
Not nice

o 50R -- No fatalities at this level. There is a difference of opinion, as to whether the sickness at this level is physical. Some think, as for example in this very authoritative study, that at this level the sickness is psychosomatic. Whatever its cause it is very general.

o 30R -- Most everyone will feel some sickness -
- maybe just "punky" and it may be "just" psychomatic
but it certainly would not be beneficial for children
and pregnant mothers. Even this level is a thousand times higher than the maximum general population exposure permitted under peacetime standards.
 

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If there was a nuclear attack how long would you need to stay underground before the amount of radiation is not dangerous and you can leave the bunker?
If it is a very long time what would you do?
How do you know if a nuclear bomb is going to go off, because terrorists are very quiet about when they will attack?
Any ideas would be good.
Thanks
they say that 2 weeks would be enough time for the fall out to reach a "safe" level. BUT..... theres no guarantee how long it would take for the fall out to settle and there are loads of factors that meen until it happens, there is no real way of knowing whether it would be an air or surface burst (surface bursts make more fall out), the direction of the wind during and after an attack, the power of the bomb used, the general weather etc etc.

and it depends on how many blasts there are.......

there might be one so everyone takes shelter 2 weeks but just before the 2 week period is up there might be another one, and so on and so on.

so even though they say 2 weeks, idealy as a MINIMUN id say be ready for 6 months. the 2 weeks is only guidelines for fallout decay, it doesnt include food and water shortages etc after an attack.
 

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The navy and commercial nuclear industry use the following values for 1/10 thickness:

Lead: 2"
Steel: 4"
Water/oil: 24"

Those values are for gamma shielding, equivalent Cobalt-60 (1.17 and 1.33 MeV gammas, 2 per decay).

The equation for figuring out how much you need is:

Du=Ds(10expN)

where:
Du = Dose Rate Unshielded
Ds = Dose Rate Shielded
10expN = 10 to power of N, where N = actual thickness/tenth thickness

So say you had a radiation dose rate of 1000 mrem/hour, and wanted to know how much shielding it would take to lower your dose rate to 1 millirem per hour, and you were using steel sheets (since lead is toxic).

You need to find the upper portion of the N part of the equation...

LOG(Du/Ds)=Actual thickness/tenth thickness

Actual thickness = tenth thickness (LOG (Du/Ds))

4LOG(1000/1) = 12"

The easy dummy check of the math shows 1000 mrem, reduced by 1 tenth to 100, by another tenth to 10, by another tenth to 1... thats 3 tenth thicknesses, multiply by 4" per tenth thickness = 12".

If you like doing math or playing "what if" you can use this equation and use not so rounded off math friendly numbers, but I wanted to keep it short and simple, and prove it worked.
 
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