Decontaminate radioactive fallout

you can survive a nuclear event!

All the steps you need to take when you emerge from your shelter after a nuclear detonation and decontaminate radioactive fallout from yourself and your shelter.

Decontaminating Radioactive Fallout – published on September 9, 2020

The key factors:

  • You need to take shelter during and immediately after a nuclear event, but be equipped to decontaminate radioactive fallout.
  • Personal decontamination needs to happen every time you leave and re-enter your shelter.
  • Area decontamination requires that the fallout is removed from the area you spend the most time – your underground shelter.
  • Only healthy people without compromised immune systems should perform the initial area decontamination above ground.
  • Your total dose of radiation matters. You need to track it with a dosimeter and chart it every time you leave the shelter.

We will clearly explain these factors in this article.

Radioactive fallout

This is a quick primer on nuclear fallout from the article on NBC air filtration systems:

Radioactive fallout consists of small particles of dust and ash that are created during a nuclear detonation. These particulates are thrown up into the atmosphere by the blast, and then fall back to earth. Fallout has different sizes and timelines. Local fallout is an acute danger that starts shortly after the detonation and consists mostly of the larger particles. It can extend far beyond the other effects of a nuclear detonation (direct radiation, blast, and heat waves). What makes it an acute danger is the amount of radiation. It has more mass than the finer particles and can accumulate rapidly on flat surfaces. Global fallout is a chronic danger. It comes from the finer particles are thrown up into the upper atmosphere that can take months or years to fall out.

The radiation source is the particulates that “fall out” of the atmosphere. Remove these particulates from your immediate area, and you remove the radiation source. The best method to do this is to wash down (and away) with water. This guide assumes you have water pressure. Pressure washers are good at blasting particulates off of a surface, but they don’t use very much water and we need the run-off to flow away from your shelter. Avoid using them unless you are low on water. If you do not have an abundance of water under pressure, other methods will work. Sweeping with a broom and blowing with compressed air or a leaf blower will work as well, but you must have effective personal protection if you are going to start blowing radioactive particulates around. Water rinsing is best.

Water can remove the particulates, but it can also bring them to you. You need to mitigate this by making your shelter the high ground with effective drainage that takes the runoff at least 100 feet (30 meters) from where you spend your time. The three radiation variables that we can manipulate are time, distance and shielding. Our shelter is the shielding, we get distance from removing the fallout, and we need to utilize our initial time outside of the shelter to remove the fallout.

Personal decontamination

Your shelter is the green zone, safe for human habitation. Outside is the red zone, unsafe or unknown and assumed to be unsafe. There needs to be protocols in place for how you protect yourself when you enter the red zone and how you protect the green zone when you return. You need to have a decontamination airlock in your shelter. See the article on shelter airlocks to understand how to use the airflow from your NBC air filtration system to purge an airlock. You also need to have the personal protective equipment and know how to safely donn and doff it. That will be covered in a future article.

Airlock protocol

In the interest of completeness, the airlock protocol from the article on shelter airlocks is copied here:

This is the protocol for egress (exiting the shelter) from the inside:
    1. Open the inner door and enter the airlock.
    2. Securely latch and seal the inner door.
    3. Ensure there is filtered air purging the airlock by checking the differential pressure gauge reads a minimum of 0.3 inches (7.62 mm) of water gauge.*
    4. Donn your personal protective equipment. Ensure that everything is properly fitted and functioning correctly.
    5. Open the outer door, check that the area is clear of threats, exit the shelter, and secure the outer door shut.

*If there is a situation outside the shelter that only becomes apparent right as or after you open the outer door, the airlock must be purged prior to opening the inner door and re-entering the shelter. Structural fires, incoming rounds, or observation of an intruder on the property are several examples.

This is the protocol for ingress (entering the shelter) from the outside:
    1. Open the outer door and enter the airlock.
    2. Ensure that the inner door is securely latched and sealed.
    3. Securely latch and seal the outer door.
    4. Ensure that there is filtered air purging the airlock by checking the differential pressure gauge reads a minimum of 0.3 inches (7.62 mm) of water gauge. Overpressure = airflow.
    5. Start the timer.
    6. Remain in the airlock for the placarded dwell time while performing a personal decontamination procedure as outlined in the article on decontaminating radioactive fallout (this article, the procedure is below).

The US Military has different levels of personal protection ranging from MOPP1 to MOPP4. MOPP stands for Mission Oriented Protected Posture. The levels range from all items being either carried or available to all items being worn. All items include a gas mask, a chemical protective undergarment (activated carbon filled long underwear) a chemical resistant hood, overgarment , and gloves.

Civilian protective equipment

For this discussion, we are going to outfit you with protective equipment that can be readily sourced by civilians.

Here is the scenario: there’s been a nuclear detonation that has deposited fallout at your location. You are returning from outside your shelter and entering in through the airlock and bringing a small bag of medicine that you retrieved from your home. You have a Tyvek suite on with the drawstring of the hood tightened down over a full face respirator with Chemical, Biological, Radiological, and Nuclear (CBRN) filters. You also have on rubber gloves and waterproof rubber boots.

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The mission is to re-enter the shelter while minimizing the exposure to the fallout that is on your protective equipment, weapons, and the medicine. The medicine will be removed from the bag and the bag will be rinsed and left in the airlock. The plastic on the mask and filter cartridges can be wiped down, but not exposed to direct water spray from the shower. Remember that all filters have a clean side and a dirty side. Do not let toxins (fallout) migrate from the dirty to the clean side. This means protecting the inside of the mask from whatever is on the outside. Wiping it down is permissible, but do not let any part of your mask get wet.

Be careful where fallout can accumulate

If we have a working airlock with a shower to decontaminate ourselves with, avoid the urge to shake or brush the fallout off of your protective equipment in the approach to your shelter. To decontaminate radioactive fallout, we need all of the particulates to be taken away from the shelter, not on the ground right outside the door.

Initial decontamination

We are going to decontaminate in two stages. For the first stage we will keep our protective gear on for the entire dwell time while we wipe everything down with damp rags. This should remove most of the fallout from our protective equipment. Then we will remove our mask, store it, and use the shower to perform a more thorough decontamination. Here are the steps for initial decontamination:

  1. Enter the airlock from the outside and securely latch and seal the outer door from inside the airlock.
  2. Check that the inner door is latched and sealed and that there is airflow through the airlock.
  3. Start the timer.
  4. Wipe down your rifle and hang it up (away from the spray of the shower). The same goes for your sidearm, magazines, and any other equipment that was outside of your suit.
  5. Starting at the top and working downward, wipe down your hood, mask, and suit with a damp cloth. Drop the rags on the floor near the drain.

Note that when you have been outside, your suit can be covered in radioactive fallout. Wiping down your suit and mask will not remove all of the fallout, but it will moisten it and mitigate it from becoming airborne. Keep your suite and mask on until the dwell time is complete. Once you have performed the initial decontamination, you can sit down, but try and have as little contact as possible with the inside of the airlock.

Final decontamination

When the timer indicates the protocol dwell time is up, perform these steps:

  1. Loosen the drawstring of your hood and remove your mask.
  2. Stow it on the mask hook (away from the spray of the shower) and place a plastic bag over it to further protect it from the shower’s spray. It will need to be wiped down again and cleaned as per the manufacturer’s directions. Reminder: always save the manuals and keep them with the equipment or in the manual storage location in your shelter.
  3. Starting at the top and working downward, rinse off your suite with the shower.
  4. Rinse the walls of the airlock (except for the wall with the equipment hooks). Start at the top and work your way down. A handheld shower head is the best type of shower for a decontamination airlock.
  5. Rinse and wring out the rags used in the initial decontamination.
  6. Rinse the floor of the airlock.
  7. If you have adequate water, send enough water down the drain to flush the water trap below the shower (about two gallons, 7.5 liters).
  8. Remove your gloves, boots, and suit. Stow them in the airlock.

We want to rinse the suit off while we wear it because it is easier to control when it is worn. But if you need to remove your suit as soon as possible, you can rinse it after you remove it. The airlock should be rinsed out completely before doffing your suit.

This is a lengthy process with a lot of steps. It may seem like overkill now, but after an event, your priorities will change. The world will seem like a different place and you will be more focused on the new dangers that you face. If you have planned everything correctly, it will not take long to decontaminate radioactive fallout.

Shelter decontamination

Radioactive fallout can emit radiation for weeks or months. The level of radiation is highest when the fallout is first deposited and decreases over time. Because of this, when there is an event, get inside your shelter immediately and stay there as long as possible.

This article is on decontamination. We have an upcoming article on radiation levels that will make recommendations on when it is safe to go outside the shelter and how long you should stay there. If you do not have the equipment to measure the radiation, the standard time used by the Swiss is two weeks underground. After that, every healthy adult comes out for 20 minutes a day and washes to decontaminate radioactive fallout. You need to be taking your potassium iodide, wearing your dosimeter, and logging your time outside. Remember, the three variables of radiation that we can manipulate are time, distance, and shielding. This time in the red zone can vary as needed, but it needs to be limited as much as possible. Initially, tasks outside the shelter need to be combined and planned. Make a list of everything you need to bring back into the shelter and how you will decontaminate these items in the airlock. Be sure and budget time to do an initial reconnaissance of your property when you leave your shelter.

Strategic landscaping

In the article on emergency egress options, we discuss battlespace preparation and creating the cover around your escape hatch for tactical surfacing. Now we are going to introduce strategic landscaping as it pertains to beneficial watershed. You need water to run off the surface of the backfill of your shelter and into ditches or pipes so that the fallout is washed away from your shelter. The time to do this is when you backfill your shelter. Note that the backfill may depress over time and we need the high ground to be right over the shelter.

The runoff is the key. You cannot just make it wet. You are not watering a garden. In fact, we want to avoid having water soak into the backfill over our shelter so that the radioactive fallout is trapped in the earth right above the shelter. To properly decontaminate radioactive fallout, we need it to run off and take the particulates with it.

This is a good time to make a mental note that you should not have flat ground, or worse a depression right over your shelter. Water needs to run off and away from your shelter. Some directed watershed is in order. Pipes, ditches and French drains should be utilized to ensure a good runoff when you backfill your shelter. You need to create the high ground and the proper surface for the water to run off and not soak in. There are several options that will accomplish this:

  1. Build your home, a garage, or a shed over your shelter.
  2. Seal the surface of your backfill with asphalt or concrete. There are many shelters that are under concrete slabs.
  3. If you require a lawn over your shelter, have tarps and weights or stakes ready to cover the shelter backfill. You still need to create a slope. Tarps over a depression in the grade will not keep the fallout and rainwater or wash water from soaking into the backfill. This is the worst place outside of your shelter where it can accumulate.

Any one of these steps can make decontaminating the ground over your shelter much easier and safer.

Shelter decontamination steps

After you perform the recon of likely avenues of approach and are ready to decontaminate your shelter, these are the steps, in priority that should be done. It is assumed that you have water pressure.

  1. Check screen on ventilation pipes. Do not spray water or compressed air into the pipes. Everything must be done to get whatever particulates that is on the screen out and onto the ground where they can be washed away.
  2. Decontaminate the ventilation pipes. Your ventilation pipes should have a 180 degree turn or a rain hood at the top. Take a water hose and wash the complete exterior of the pipes and the ground around them.
  3. Decontaminate the portals. The doors and hatches should be weather tight and can be directly sprayed off. We will not open them initially because we want the most return possible of fallout removal from our investment of precious time outside the shelter. You need to wash large areas first. Spray down the doors, hatches, their frames, and the area around them.
  4. Decontaminate the top of the shelter. This is where our strategic landscaping will pay off. Wash every inch of the surface of the backfill and ensure that your watershed is working. Be methodical and sequential. Start at the high points. Work your way down. Check drainage pipes and ditches for obstructions. The water with the fallout must be taken far away from where you spend most of your time.
  5. Decontaminate any important equipment and storage locations. If you have sheds with equipment and tools, these are next.

If you do not have water pressure, compressed air or a leaf blower will help. But you must have your protective equipment on and fitted correctly. The worst place to have radioactive fallout is in your lungs. When it’s there, all of the radiation coming out from each particle is impacting your body at zero distance and with zero shielding for as long as it is radioactive. That is all of the variables that we normally can manipulate (time, distance, and mass) maxed out. The survival rate for someone with lungs that have radioactive particles embedded in them is very low. Water is the key. It prevents the fallout from becoming airborne and takes it away from your shelter when it drains off of your watershed. Hit the play button to see some real radiation:

Each shelter needs to have its watershed evaluated and optimized to remove the fallout particulates. It may be raining when an event happens. You do not want to omit this important safety consideration. This is battlespace preparation against the ravages of radiation poisoning.

Decontaminate your home

Once the shelter has been cleared of fallout, your home is next. Start with the top and work your way downward. Your home should have a prescribed watershed so that rainwater is taken away from the foundation. That’s the reason we put eves and gutters on homes.

The same procedures outlined above for your shelter can be used on your home. Remember that we are initially concerned with getting the most return for our time spent outside the shelter. Hit the large flat surfaces of the roof, walls, and surrounding ground first.

Vehicle decontamination

If you need to evacuate the area, vehicle decon gets moved ahead of shelter and home decon. Remember, we need to remove the fallout as far away from the place we will spend the most time. No sense in decontaminating our home if we will not be there. We don’t even care if the watershed from our vehicle decon takes it away from our home. Get the vehicle clean, and hit the road.

Just like the home, we will start at the top using water to wash away the fallout particulates. Pretend you are pre-rinsing your vehicle for cleaning and hit every surface. The exception to doing this is when you are leaving in the vehicle right away. You want to avoid having a wet vehicle on a dry. We do not want road dust (radioactive fallout) sticking to the vehicle. There’s almost zero radiation shielding in vehicles.

The air intakes for the ventilation system in most vehicles should not have fallout in them if the vehicle has not been driven after the event. But if you use the heater or air conditioner, it will bring fallout into the cabin from the road. Evacuating by vehicle after an event will be covered in a future article.

Special considerations

  1. Pets: the protocol for cats and dogs is to be decontaminated in the airlock with the shower. A water heater in your shelter will make this more comfortable for them. Start at the top and work your way down. Don’t worry about shampoo. We are rinsing the dust (fallout) out of their fur. Other pets will need special considerations. The fallout must not be allowed into the green zone.
  2. Children: these are small humans. Suit them up and decontaminate them as such. They should not be involved in the initial fallout removal.
  3. Elderly: these are humans with accumulated knowledge. Listen to them, suit them up, and decontaminate them as such. They should not be involved in the initial fallout removal.
  4. People with compromised immune systems: this includes people undergoing treatment for cancer (chemotherapy and radiation treatment), primary immune deficiency, and acquired immune deficiency diseases (AIDS, HIV, diabetes, etc.). These should be the last of your tribe to leave the shelter.

Children and pets cannot always understand why they are being kept indoors. Try and keep them occupied when inside and safe when outside.

Avoiding radioactive fallout

  1. Take your potassium iodide daily.
  2. Don’t go outside of your shelter.
  3. Time and document all trips outside the shelter.
  4. Plan your tasks and combine them.
  5. Wear a radiation meter.

The take-away

Sometimes the only winning move is to not play the game. Your shelter should be able to support life for several weeks. Staying buttoned up inside the green zone is the best way to stay safe. When you emerge, you need to decontaminate radioactive fallout.

Next article:  Nuclear, Biological, and Chemical air filtration systems

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