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Discussion Starter · #1 · (Edited)
As I understand it, the amount of radiation given off from fallout is directly proportional to the physical amount of it that surrounds you. So if you were to come into contact with a pile of fallout weighting 1kg, you could expect to suffer 1000x more radiation than if you came into contact with 1g of it. Is this correct?

Assuming the above is correct, does that mean that radiation coming from dust in treetops would be most likely be orders of magnitude lower than that coming from the ground?

So in this highly technical diagram, if we assume that the fallout in the area is producing a total of 1000 R per hour while outside, what sort of dose would our little man in red likely be receiving from that single large tree? (assume that the walls completely block all the radiation from the ground sources).

I have heard about skyshine (ground radiation reflected back down to earth) but I'm unsure just how strong this effect is and how it would play out in this particular example.


Plant Tree Natural landscape Terrestrial plant Organism



If you're wondering why I'm asking, its because I'm trying to get a handle on just how and when we can safely move around within certain parts of our bunker in the event that one of our entrances did not have all it's shielding material fully in place.
 

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Heh, if only it were that simple. Yes, you can probably roughly assume that a mass of fallout 1000x greater will produce 1000x the exposure. There's a bit more to the geometry question though because you also have scattering that occurs. The following picture illustrates it better than I can explain it.

Human body Organism Triangle Slope Font


This is also why right-angles are incorporated into fallout shelter design... to prevent radiation from streaming straight through hallways and entrances or scattering into the shelter.

Rectangle Font Drawing Parallel Diagram


Standing inside your shelter, if you look out the entrance tunnel at various angles, what you have line-of-sight to is what you will be exposed to if fallout were to land there.

Plant Building Window Rectangle Stairs


What I would do is use the area in yellow for storage for at least the first 24 hours if you suspect that area may be exposed to higher dose rates. Try to keep people out of that area. After the first 24-48 hours, radiation levels will be reduced by 99% and you can spread out more. Certainly keep younger shelterists in the more protected areas and older adults in the less protected. An area that has line of sight further down the entrance tunnel is less protected, even if it's a greater distance from the entrance tunnel. So the rightmost corner of the green box in the picture above would be better protected than the bottom left corner, even though the bottom left corner may be slightly further away from the tunnel. That's sort of a simplification, but hopefully you get the idea. If there are multiple entrances, that may negate the above. If you wanted a definitive answer, you'd need to talk to an engineer (which I am not).

Ideally what you should probably do is have a radiation monitoring device on-hand so you can check the area just inside the entrance tunnel to see if the exposure in various areas to see if any are significantly worse than anywhere else. Use the worst protected areas for storage, put adults in the next best protected area, and the youngest in the most protected areas and so forth.
 

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Discussion Starter · #3 · (Edited)
Yep I get the idea with how the line of sight works. Standing inside looking out you can only really see those tree tops so I hoped the radiation dose would be small.

In the event that the door isn't shielded, I was indeed planning to keep everyone away from it as much as possible, especially in the early hours. The only snag here is that one of my vent pipes is directly opposite this door so I may need to do certain operations in this area (closing/opening vents, fixing/replacing fans or filters etc). Though I suppose that as long as I can keep these exposures very brief it won't be a problem.

For the record I do now wish I had of put in a right angle turn. The problem was that I did rush this project somewhat as I expected the ukraine war to escalate quickly and I rather stupidly assumed that there would only be one detonation to worry about. This would have made my sandbag idea very workable (ie close doors, wait for blast, then fill tunnel with sand before fallout arrives). However if another blast happens while I'm putting the sandbags in place... well then we could all be toast.

Short term I think my plan will be to wait for the blast, wait 7 hours and only then fill the tunnel (if no further blasts are felt). Long term I need to just add the right angle somehow.
 

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Yep I get the idea with how the line of sight works. Standing inside looking out you can only really see those tree tops so I hoped the radiation dose would be small.
I think the amount of "treeshine" and scattered skyshine making it into your shelter will probably be minimal in your case.

In the event that the door isn't shielded, I was indeed planning to keep everyone away from it as much as possible, especially in the early hours. The only snag here is that one of my vent pipes is directly opposite this door so I may need to do certain operations in this area (closing/opening vents, fixing/replacing fans or filters etc). Though I suppose that as long as I can keep these exposures very brief it won't be a problem.

For the record I do now wish I had of put in a right angle turn. The problem was that I did rush this project somewhat as I expected the ukraine war to escalate quickly and I rather stupidly assumed that there would only be one detonation to worry about. This would have made my sandbag idea very workable (ie close doors, wait for blast, then fill tunnel with sand before fallout arrives). However if another blast happens while I'm putting the sandbags in place... well then we could all be toast.

Short term I think my plan will be to wait for the blast, wait 7 hours and only then fill the tunnel (if no further blades are felt). Long term I need to just add the right angle somehow.
Why would you wait 7 hours? Your dose from fallout radiation is "front loaded" (like mortgage interest). Meaning you receive the vast majority of your dose at the beginning of your exposure. Let's say if you don't place the sandbags at all it drops your protection factor down to a PF100 shelter. I have no idea what it is in reality but this is a pretty extreme example. Outside, we start around 1000 rad/hr so your in-shelter dose starts at roughly 10 rad/hr. If you started placing sandbags at 7 hours in, you're going to be exposed to a dose rate somewhere between the in-shelter dose rate and an unprotected dose rate. Let's just average the two and say your in-tunnel dose rate is 48.8 rad/hr at 7 hours and it takes you an hour to place sandbags. You're going to pick up ~45 rad on top of the 16 rad you received in-shelter during the first 7 hours. Over the remaining 329 hours of the next two weeks, you only pick up another 1.7 rad with the improved protection (let's assume it's a perfect PF1000 shelter with the sandbags). Total dose = 66.5 rad.

But guess what... If you did nothing and accepted the imperfect protection, your total shelter dose over two weeks would be 34 rad. Granted it reduces everyone else's dose to a total of ~18 rad, but honestly an additional 16 rad in this example is completely trivial and not worth you picking up 3x that trying to improve the shielding. So if you're expecting fallout, I think you should probably have the sandbags placed beforehand. Don't plan on placing them after fallout arrives because you'll just end up with an unnecessary and preventable exposure.

Now, full disclosure, this is all very oversimplified as it assumes fallout from all detonations arrive at all the same time, after 1 hour, etc. However, the principles apply to real world application. Don't expose yourself to an unnecessary dose chasing perfect protection by filling the tunnel with sand after fallout has already arrived. The amount of in-shelter dose you'll be preventing by doing that will be trivial.

You could plan for a sandbag wall outside of the entrance. Or, you could even build a concrete wall that looks like soil-filled planter outside the entrance if you're going for an incognito look. Or, just keep yourself and others out of that area for the first day or two.
 

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Discussion Starter · #5 ·
Oh yeh the ideal is indeed to have the sand bags in place well before any explosion. But I'm thinking about a scenario in which we are literally only given a 2 minute warning via text message in the middle of the night or something similar. In that instance trying to do the sandbags beforehand may be too risky.

I understand the point you're making, but I think it is indeed a bit of an over simplification to say that the sandbags would change the shelter from PF 1000 to 100. That could be a good ballpark average but the reality will be that, half the shelter gets almost no rads, and the other half gets a high dose. That would mean we would be forced to use only half the available space, and with 8 people in an already very small room, that is not at all ideal. For example, right now we have 3 folding bunk beds but the only possible way to fit all of these in requires that one bunk be directly opposite the entrance door.

I should say that unless I'm seriously injured, it will not take me an hour to place the sand bags. I think 5-10 minutes is more likely.

The main thing that holds me back from building a right angle extension is what to do about a roof for that new piece. A lightweight roof is easy to make but has a very high chance of being destroyed by any blast winds. A heavy duty roof that could withstand a high PSI would be far harder to construct. Your planter idea has got me thinking though...

If were to place that fake concrete planter outside the entrance, say 2ft away and there was no 'roof' between this and the entrance, that would mean fallout could land in that little gap. Am I right in assuming that fallout landing here would be of minimal threat because its only a small area that it could collect in? The entrance is actually raised off the ground a bit too so I imagine only a tiny amount would actually be able to beam in anyway.
 

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Oh yeh the ideal is indeed to have the sand bags in place well before any explosion. But I'm thinking about a scenario in which we are literally only given a 2 minute warning via text message in the middle of the night or something similar. In that instance trying to do the sandbags beforehand may be too risky.
Yeah, I keep forgetting you're in the UK and over there you don't get much warning.

I understand the point you're making, but I think it is indeed a bit of an over simplification to say that the sandbags would change the shelter from PF 1000 to 100. That could be a good ballpark average but the reality will be that, half the shelter gets almost no rads, and the other half gets a high dose. That would mean we would be forced to use only half the available space, and with 8 people in an already very small room, that is not at all ideal. For example, right now we have 3 folding bunk beds but the only possible way to fit all of these in requires that one bunk be directly opposite the entrance door.

I should say that unless I'm seriously injured, it will not take me an hour to place the sand bags. I think 5-10 minutes is more likely.
Just throwing numbers out there... I have no idea how many bags you had or what their size/weight was. I don't think any of the adults will be sleeping in the first 24 to 48 hours so their bunks wouldn't need to be set up. Once that period is past, you'd probably be fine with their legs closest to the door.

The main thing that holds me back from building a right angle extension is what to do about a roof for that new piece. A lightweight roof is easy to make but has a very high chance of being destroyed by any blast winds. A heavy duty roof that could withstand a high PSI would be far harder to construct. Your planter idea has got me thinking though...

If were to place that fake concrete planter outside the entrance, say 2ft away and there was no 'roof' between this and the entrance, that would mean fallout could land in that little gap. Am I right in assuming that fallout landing here would be of minimal threat because its only a small area that it could collect in? The entrance is actually raised off the ground a bit too so I imagine only a tiny amount would actually be able to beam in anyway.
Correct. What you're blocking out is what's on the ground outside that gap. The small amount of fallout that lands inside the wall won't make that much difference.
 

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Re: the planter idea. You don’t need to get your shelter roof over to planter/partial blast wall. Just make enough space to walk around it and enter the entprance. And the planter 3-4 feet tall and say 3 feet deep, to get 3 feet of dirt between the entrance and whatever height.

and can’t you put some/all the sandbags inside the shelter. (You don’t want to leave them outside to get wet and gain weight). Some sand bags in the tunnel are better than none and who says they can’t be stacked against the door inside too. (Just thinking if you weren’t home or hurt,)
 

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Oh yeh the ideal is indeed to have the sand bags in place well before any explosion. But I'm thinking about a scenario in which we are literally only given a 2 minute warning via text message in the middle of the night or something similar. In that instance trying to do the sandbags beforehand may be too risky.

I understand the point you're making, but I think it is indeed a bit of an over simplification to say that the sandbags would change the shelter from PF 1000 to 100. That could be a good ballpark average but the reality will be that, half the shelter gets almost no rads, and the other half gets a high dose. That would mean we would be forced to use only half the available space, and with 8 people in an already very small room, that is not at all ideal. For example, right now we have 3 folding bunk beds but the only possible way to fit all of these in requires that one bunk be directly opposite the entrance door.

I should say that unless I'm seriously injured, it will not take me an hour to place the sand bags. I think 5-10 minutes is more likely.

The main thing that holds me back from building a right angle extension is what to do about a roof for that new piece. A lightweight roof is easy to make but has a very high chance of being destroyed by any blast winds. A heavy duty roof that could withstand a high PSI would be far harder to construct. Your planter idea has got me thinking though...

If were to place that fake concrete planter outside the entrance, say 2ft away and there was no 'roof' between this and the entrance, that would mean fallout could land in that little gap. Am I right in assuming that fallout landing here would be of minimal threat because its only a small area that it could collect in? The entrance is actually raised off the ground a bit too so I imagine only a tiny amount would actually be able to beam in anyway.
5 gal bucket of grain is close to a sandbag, as are water jugs, Generally, for fallout, it’s pretty close to pounds of mass per sq foot of opening. Fallout takes time to travel and fall out, you should have at least an hour.

Are you really sure blast is an issue?

Cover the planter with a tarp, and you can decon it in seconds.

As far as sky shine, I’ve never seen an accurate formula- they are acknowledged to be off by a factor of up to 10 ( luckily, the effect is overestimated.) It is clearly proportional to the sky solid angle exposure (in Steradians)
 

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Discussion Starter · #9 · (Edited)
5 gal bucket of grain is close to a sandbag, as are water jugs, Generally, for fallout, it’s pretty close to pounds of mass per sq foot of opening. Fallout takes time to travel and fall out, you should have at least an hour.

Are you really sure blast is an issue?

Cover the planter with a tarp, and you can decon it in seconds.

As far as sky shine, I’ve never seen an accurate formula- they are acknowledged to be off by a factor of up to 10 ( luckily, the effect is overestimated.) It is clearly proportional to the sky solid angle exposure (in Steradians)
I do have 25litre water jerry cans, but their density is lower than the sand and its harder to fill gaps due to their shape.

I actually think the most likely scenario is that we'll get zero blast effects where we are, but because the UK is a tiny densely populated island there is no way to be certain on that.
 

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Discussion Starter · #10 ·
Re: the planter idea. You don’t need to get your shelter roof over to planter/partial blast wall. Just make enough space to walk around it and enter the entprance. And the planter 3-4 feet tall and say 3 feet deep, to get 3 feet of dirt between the entrance and whatever height.

and can’t you put some/all the sandbags inside the shelter. (You don’t want to leave them outside to get wet and gain weight). Some sand bags in the tunnel are better than none and who says they can’t be stacked against the door inside too. (Just thinking if you weren’t home or hurt,)
Yeh I already have the sand bags setup so I can fill the entry tunnel from the inside. Unfortunately it would be hard to shield the door from the inside as its quite high up from the interior wall of the shelter and there is currently nothing in front of it to place sand bags onto. Although in a pinch we could move our other supplies to that area to create a base to put the sand bags on. Not ideal but then nothing about a nuclear war would be :)

The planter idea does seem like the best solution right now as it both makes the shelter safer, easier to use and frees up more interior space (no need to store sandbags)
 

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When you do the planter, add some poles so you can slope a piece of canvas from a point over the shelter area to well past the planter. Make it a very steep slope on the canvas and use a long reach extendable pole with a broad pad on the end to shake the canvas from the highest point to past the planter every so often. This will walk any calculation of fallout off the canvas and away from the living area. It can be done from well inside the shelter.

If you have any type of power, AC or DC available, you can also do a fluffer that will fluff the canvas with an air blower to do the same thing. Even a D-battery powered inflatable air bed could be used to fluff the canvas to walk the fallout off over the end past the planter.

If it is a one and done, where a local device detonates, fallout arrives and stops, and the decay period begins, you can also arrange fabric or light material so the same kind of blower can force it to swirl out of the area. You want air around the edges being drawn by the air input from the device like a vortex vacuum so the powerful full flow will carry the material from the slower moving air coming in at the edges out with the rest.

Again, this would only be practical for a short time frame unless you have unlimed timed power for the blower.

I am heading in to get my birthday lunch, but when I get back I will work up some drawings to illustrate what I mean, if someone does not explain it better while I am gone.

Just my opinion.
 

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With the propensity of fire during such an event there will likely be no trees or structures to hide in.
And with wind everything in the atmosphere will travel into every nook and cranny in sight.
Ideally garden area should be prepared before hand with a water proof membrane and a layer of dirt that is completely expendable so that it can be easily removed to start growing food ASAP. Or a green house with an alternate roof to shed falling debris.
 

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Discussion Starter · #13 ·
When you do the planter, add some poles so you can slope a piece of canvas from a point over the shelter area to well past the planter. Make it a very steep slope on the canvas and use a long reach extendable pole with a broad pad on the end to shake the canvas from the highest point to past the planter every so often. This will walk any calculation of fallout off the canvas and away from the living area. It can be done from well inside the shelter.

If you have any type of power, AC or DC available, you can also do a fluffer that will fluff the canvas with an air blower to do the same thing. Even a D-battery powered inflatable air bed could be used to fluff the canvas to walk the fallout off over the end past the planter.

If it is a one and done, where a local device detonates, fallout arrives and stops, and the decay period begins, you can also arrange fabric or light material so the same kind of blower can force it to swirl out of the area. You want air around the edges being drawn by the air input from the device like a vortex vacuum so the powerful full flow will carry the material from the slower moving air coming in at the edges out with the rest.

Again, this would only be practical for a short time frame unless you have unlimed timed power for the blower.

I am heading in to get my birthday lunch, but when I get back I will work up some drawings to illustrate what I mean, if someone does not explain it better while I am gone.

Just my opinion.
The canvas sounds like a pretty good idea. My only concerns would be that having it setup beforehand might mean it'll be blown away by blast winds, or if it we set it up just after a detonation, I'm putting us at risk by leaving the door open in a similar fashion to the sand bag idea (ie another blast could occur). But then again, this idea is so cheap and easy that it certainly wouldn't hurt to have it setup before hand, on the off chance it doesn't get blown away.

I suppose that making a strong roof between the planter and the shelter itself wouldn't be so hard as long as the gap it had to fill was very small. Could probably weld something out of thick steel and then use chemical anchors to bolt it in place to both structures.
 

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It will depend on what you make the planter out of.

concrete/cinder blocks, fill the empty spaces with either concrete or sand. Depending on height, rebar at the corners might be good. Or you could section the planter with the same concrete blocks for extra support. Gravel in the bottom few feet, dirt above. Using block means you will have two flat areas at the top. To make iit pretty, flat concrete pavers or brick. Flower pots could be placed along that ledging. Pretty, but useful, either to hold down tarp (flammable) or corrugated metal.

brick walls would need concrete footing. But you could also build up the ground some lowering the height. (Brick facing on concrete block is nice, and the dirt area doesn’t need to be as wide).

here in the USA metal sheeting is often used raised beds. (Think large galvanized animal waterer).
Plant Wood Rectangle Outdoor furniture Table

Plant Wood Grass Groundcover Landscape


Plant Natural foods Leaf vegetable Fines herbes Ingredient


Well watered soil would add extra protection from both radiation and fire.

wouldn’t suggest a wooden planter due to fire, most of the planters with wood on the outside is for looks and extra support as metal bracing is used inside the planter.
 
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