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☢️ Nuclear Fallout Guide

What to do if there is a nuclear detonation or a radiation release: how to shelter, how long, how to protect food, water and animals, how to clean up, and when potassium iodide (KI) helps. The full manuals — shelter plans, the homemade KFM fallout meter, farm and livestock guides — are in Nuclear-Radiation\.

The three rules

  1. Get inside. Stay inside. Stay tuned. Most deaths from fallout are avoidable just by being behind enough mass in the first day or two.
  2. Fallout is dust. It hurts you from what lands on and near you, so put mass and distance between you and the roof, walls and ground outside.
  3. Time is on your side. Radiation from fallout drops fast — 90% in the first 7 hours, 99% in 2 days.

⚡ The first minutes

First-hour checklist: get people and pets inside; close doors, windows and blinds; take a few minutes to check the house for fires — stamp out smoldering drapes, throw burning furniture outside (FEMA H-20, p. 26); fill containers and tubs while the taps run (rule of thumb); carry food, water, radio, medicines and the toilet bucket to the shelter spot.

📚 Go deeper: FEMA H-20 Protection in the Nuclear Age — warning signals, the flash, fallout timing, fires; FEMA Planning Guidance, 3rd ed. — today's official "Get Inside, Stay Inside, Stay Tuned" advice.

🏠 Where to shelter

Best to worst: a basement (especially a corner below ground level) → the middle floors and center of a large concrete or brick building → a crawl space or interior room of a house → a vehicle (poor). See the FEMA drawing of protection inside different buildings and Fallout shelter.

Cut-away drawing of houses and buildings from a 1-story wood house to a large office building, each room marked with its protection factor: 2 to 3 on the main floor of a wood house, 10 in its basement, up to 200 deep underground Protection factors: 10 means a tenth of the outdoor dose. A 1-story wood house gives only 2–3 on its main floor and 10 in a basement; basements and the middle of big buildings give the most (FEMA Planning Guidance, p. 78).

Most homes in the Illinois Valley are one-story wood frame with no basement. FEMA says these, and vehicles, are not adequate shelter on their own (Planning Guidance, p. 76). Plan now: a nearby building with a basement or thick masonry, a crawl-space shelter you can shield, or an outdoor trench shelter (plans in MP-79, In Time of Emergency, and Nuclear War Survival Skills Appendix A — see the Door-Covered Trench Shelter and Pole-Covered Trench Shelter drawings). Permanent backyard plans: FEMA H-12-1 outside concrete shelter, FEMA H-12-2 aboveground shelter.

"Adequate" means it cuts your dose 10× or more. Concrete, brick, stone and earth stop a lot; wood, drywall and sheet metal stop little (Planning Guidance, p. 76; EPA dose-reduction diagram by building type).

Adding shielding — each of these stops about as much as 4 inches of concrete (FEMA H-20, p. 22):

Material Thickness
Brick 5–6 in
Sand or gravel 6 in
Packed earth 7 in
Hollow concrete block (sand-filled) 8 in (6 in)
Water 10 in
Books or magazines 14 in
Wood (firewood stack) 18 in

Pile it on the floor above you and around the walls of your shelter spot: earth-filled drawers and boxes, water jugs, firewood, books, heavy furniture. Every extra ~4 inches of packed earth roughly halves what gets through — about 3 feet of earth cuts it around 1,000× (Nuclear War Survival Skills, 1979, p. 23: one "halving thickness" of packed earth is 3.6 in; halving-thickness drawing; Radiation protection). Crawl space: shelter under the center of the house, ring yourself with blocks or earth-filled containers, and pile mass on the floor above.

Diagram of ten layers of packed earth, each 3.6 inches thick, about 3 feet in all, with bars showing the radiation getting through halving at each layer from 1,000 down to about 1 Each 3.6 in of packed earth halves what gets through, so about 3 ft cuts it around 1,000 times (a diagram drawn for this guide).

Quick shelters, step by step (FEMA H-20, pp. 23–25; HS-4, p. 67):

  1. Table shelter: a sturdy table or workbench in the most-underground basement corner, loaded on top and walled around with shielding. Crawl in and block the opening. (drawing of a basement table shelter)
  2. Door-roof shelter: walls of dressers or appliances, a roof of heavy doors propped and piled with shielding. Fill drawers and boxes with earth after they're in place — full ones are too heavy to carry.
  3. Crawl-space shelter: cut an access now. Under the middle of the house, wall a spot with blocks or earth-filled containers up to the joists and pile mass on the floor above. Make sure no heavy appliance sits right above you. Dig down so you can sit up.
  4. Last resort: dig a trench beside a slab house and tunnel no more than 4 feet under the slab; shore it and pile shielding on the slab inside.

Drawing of a man in a basement corner stacking boxes of heavy material on top of and around a sturdy workbench to make a fallout shelter A table shelter (step 1): heavy material stacked on and around a sturdy table in a basement corner; dirt in the window wells adds more (OCD H-6, p. 26).

Ventilation: a crowded, sealed shelter gets dangerously hot in warm weather. Kearny's homemade air pump (KAP) — plans in Nuclear War Survival Skills and the ORNL Expedient Shelter Handbook — moves air without bringing in fallout dust (KAP swinging in a doorway; photos of homemade KAPs). In a heat wave, plan on about 4 quarts of water and 10 grams of salt per person a day and as few clothes as practical (NWSS 1979, p. 62).

📚 Go deeper: FEMA H-20 — shielding table and home expedient shelters; FEMA HS-4 Citizen's Guide — rating and upgrading your house; Expedient Shelter Handbook ORNL-4941 — trench and log shelters, plus full Kearny Air Pump plans; MP-79 — construction drawings for homes without basements.

🧰 Stocking the shelter

FEMA says to have at least two weeks of water, food and supplies ready to carry to the shelter (H-20, p. 13; illustrated 1961 supply chart).

Item How much / what kind (FEMA H-20, pp. 29–31)
Water H-20's bare minimum is 1 quart per person per day just to drink; today FEMA advises storing 1 gallon per person per day. Kearny says store 15 gallons per person for two weeks (NWSS 1979, p. 71; storing water in lined bags and pits).
Food Canned or sealed, no cooking needed. Most adults do fine on half their usual amount — not children or pregnant women.
Toilet Bucket with a tight lid, liner bags, a second lidded can, bleach, toilet paper (hose-vented toilet-can; Bucket toilet).
Radio and light Battery radio, flashlight, spare batteries — the radio "may be your only link."
Medicines, babies Two weeks of regular medicines and a first-aid kit; formula or canned milk and diapers.
Tools Shovel, pick, saw, hammer, crowbar, broom, nails, wire (H-20, p. 18).

📚 Go deeper: FEMA H-20, Part 4 "Shelter Living" — supply lists, water, food and sanitation; Expedient Shelter Handbook Appendix C — emergency water storage, lights and sanitation; Shelter Management Handbook H-16 — running a shelter with a group.

⏳ How long to stay in

The 7-10 rule: every 7× increase in time after the blast cuts the radiation 10× (once the fallout has finished falling). (FEMA H-20, p. 8; see the seven-ten rule chart and the decay curve for the first two days)

Time after blast Radiation level (example)
1 hour 1,000 R/hr
7 hours 100 R/hr
2 days 10 R/hr
2 weeks 1 R/hr

Dose yardsticks — what a short-term whole-body dose does to a group of people (DCPA home-study course, p. 49; Acute radiation syndrome):

Dose received over a short time What to expect
50 R No visible effects
75–100 R Brief nausea the same day in about 1 in 10 people
200 R Up to half get some radiation sickness; 5–10% need care; deaths not expected
450 R Serious sickness in most; about half die within 2–4 weeks
600 R Serious sickness in all; nearly all die within 1–3 weeks

Sources set the line differently: the old civil-defense course says keep short-term doses under 100 R (DCPA, p. 50); today's EPA guideline for emergency workers is 5 rem, up to 25 rem only to save lives (EPA PAG Manual, p. 46). Treat 1 R of fallout as about 1 rem (rule of thumb). Lower is always better — the dose adds up.

📚 Go deeper: FEMA H-20 — the 7-10 rule and radiation sickness by dose; DCPA Introduction to Radiological Monitoring — dose effects and how to predict decay; EPA PAG Manual — official dose thresholds for sheltering, KI, food and water.

🧼 Cleaning yourself up (decontamination)

(CDC Decontamination; EPA Protective Action Q&A, p. 32; pictures: CDC step-by-step sheet, FEMA self-decontamination steps, Radioactive contamination)

📚 Go deeper: CDC Decontamination for Yourself and Others — the one-page picture guide; EPA Protective Action Q&A — self-decontamination, visitors, wounds, pets and service animals.

💊 Potassium iodide (KI)

FDA dose by age (one dose per day) (FDA 2001, p. 9):

Who Dose 130 mg tablets 65 mg tablets
Adults over 18 (including pregnant or breastfeeding) 130 mg 1 2
Ages 12–18 (130 mg if 154 lb or more) 65 mg ½ 1
Ages 3–12 65 mg ½ 1
1 month – 3 years 32 mg ¼ ½
Birth – 1 month 16 mg ⅛ ¼

Adults over 40 need it only for a very large expected exposure. To make liquid doses for small children from tablets, use the two FDA sheets in Nuclear-Radiation\Government-Guidance.

Making liquid KI for children — the two FDA sheets give the same recipe for one 130 mg tablet or two 65 mg tablets (FDA, one 130 mg tablet; FDA, two 65 mg tablets):

  1. Put the tablet(s) in a small bowl with 4 teaspoons of water. Soak 1 minute.
  2. Crush with the back of a spoon until there are no large pieces.
  3. Stir in 4 teaspoons of milk, chocolate milk, orange juice, cola, formula, raspberry syrup or water. You now have 8 teaspoons of KI liquid.
  4. Give once a day: 19 and older — 8 tsp; 13–18 years and 150 lb or more — 8 tsp; 13–18 under 150 lb — 4 tsp; 4–12 years — 4 tsp; over 1 month to 3 years — 2 tsp; birth to 1 month — 1 tsp.
  5. Keep leftover liquid in the refrigerator; throw it out after 7 days.

(The liquid sheet uses 150 lb for teens; the 2001 FDA guidance says 70 kg, about 154 lb. Either way a near-adult-size teen gets the adult dose.)

📚 Go deeper: FDA KI dosing guidance — the official dose table and timing; FDA liquid KI sheet — step by step for children; CDC How KI Works — what it does and doesn't do. Pictures: Potassium iodide.

🥫 Food and water

(EPA Protective Action Q&A, p. 29; FDA; Nuclear War Survival Skills Ch. 8)

Water sources, safest first (NWSS 1979, pp. 76–77): deep wells and covered tanks → covered shallow wells → deep lakes → shallow ponds → streams (worst after the first heavy rains) → roof runoff → melted snow. With the power off, a well can still be used with a homemade bail-can on a rope (bail-can drawing; Well).

Settling method (NWSS 1979, pp. 78–79):

  1. Fill a bucket three-quarters full of the doubtful water.
  2. Dig clay or clayey soil from at least 4 inches below the surface (fallout stays near the top).
  3. Stir in about 1 inch of dry clay for every 4 inches of water until it's all suspended.
  4. Let it settle at least 6 hours. The clay carries the fallout down.
  5. Dip or siphon off the clear water, then disinfect it.

(USDA says settle a day, then strain through cloth; for stock, stir up a pond's mud bottom and let it settle — PA-515, p. 8.)

Earth filter (NWSS 1979, pp. 77–78; cut-away drawing of the filter can):

  1. Punch about a dozen nail holes, from the bottom upward, within 2 inches of the center of the bottom of a 5-gallon can or bucket.
  2. Put in 1½ inches of washed pebbles, then one layer of towel or burlap cut a bit bigger than the can.
  3. Add 6–7 inches of crumbled soil with some clay in it, dug from 4+ inches deep, pressed down in layers. Not pure clay (too tight) or sand (too loose).
  4. Cover with one layer of towel held by a few stones. Set the can on sticks over a pan.
  5. Pour in (settled) water. Expect about 6 quarts an hour at first, 2 quarts an hour later. If it runs faster than a quart in 10 minutes, repack the soil. Replace the soil after about 50 quarts. Disinfect the filtered water.

Cut-away diagram of a bucket earth filter: nail holes in the bottom, 1.5 inches of pebbles, a towel, 6 to 7 inches of clayey soil, a towel held by stones, water poured on top, the bucket on sticks dripping into a pan The earth filter from the steps above, cut away: pebbles, cloth, 6–7 in of clayey soil, cloth and stones, set on sticks over a pan (a diagram drawn for this guide).

Disinfecting afterward: boil, or use plain unscented bleach — 8 drops of 6% bleach or 6 drops of 8.25% bleach per gallon, double if cloudy or very cold, wait 30 minutes (EPA Emergency Disinfection, pp. 1–2).

📚 Go deeper: Nuclear War Survival Skills 1979, Ch. 8 — water sources, bail-can, settling and earth filter; USDA PA-515 Fallout and Your Farm Food — cleaning home-grown food; FDA Accidental Radioactive Contamination of Food and Feeds — official food and milk limits.

🐄 Livestock and gardens

(USDA FB 2107, pp. 8–14, PA-516; Oregon ODOE, p. 2)

More from USDA FB 2107 (pp. 8–14):

Long-term garden choices: radioactive strontium (Strontium-90) acts like calcium. Liming acid soil cuts how much plants take up. Alfalfa, clover, soybeans and leafy greens take up more than grains, grasses, corn, potatoes and fruit — favor the latter on contaminated ground (FB 2107, p. 13).

📚 Go deeper: USDA FB 2107 Defense Against Radioactive Fallout on the Farm — livestock, feed, water, milk and crops; USDA Ag Handbook 234 — the science of fallout on soil, crops and animals; USDA Radiological Monitoring Handbook — checking pasture, water and livestock with a meter.

📟 Measuring radiation

What a KFM is made of (ORNL-5040, pp. 33, 39): an 8-ounce can (or a cut-down soup can), 2 square feet of aluminum foil, clean thread, clear plastic, doorbell wire. A drying agent goes in the bottom — gypsum from heated drywall, or silica gel, not calcium chloride or salt. Charge it by rubbing a plastic ruler on dry paper (the other way: charging with unrolled tape).

Using it (ORNL-5040, pp. 69–73):

  1. Charge it and read the gap between the two foil leaves on the paper scale.
  2. Hold it on a stick about 3 feet above the ground for a set time — 1 minute if you have no idea of the level — then read again. The table on the meter turns the drop into a dose rate.
  3. Dose = dose rate × time. At 1,200 R/hr, a 30-second dash outside is 10 R.
  4. Keep a daily dose record for every person, and use the meter indoors to find the lowest-dose spot in your shelter, then add shielding there.

Civil-defense instruments (DCPA course):

Instrument Range Use
CD V-715 (yellow) 0–500 R/hr Fallout levels outside and in the shelter (picture)
CD V-717 0–500 R/hr, 25-ft remote probe Read outside levels without leaving shelter (p. 109; picture)
CD V-700 0–50 mR/hr Low levels: food, water, people, training (p. 89; drawing)
CD V-742 Pocket dosimeter, reads to 200 R Your total dose; recharge with a CD V-750 (p. 83; the scale you read; Dosimeter)

If this goes wrong:

Problem What to do
KFM won't hold a charge The air is too damp. Above about 90% humidity it can't be charged — make and use the dry-bucket (ORNL-5040, pp. 65, 73; dry-bucket drawing). Check the drying agent.
Leaves leak charge fast Modern thread and floss may not insulate. Use 2-lb monofilament fishing line or 1/16-inch strips of dry-cleaner bag (ORNL-5040 preface, p. 1).
Old CD V meter reads nothing Check batteries and run its operational check before trusting it (DCPA, p. 116).

📚 Go deeper: KFM report ORNL-5040 — full build instructions, patterns and the dose table; DCPA home-study course — using CD V meters and dosimeters; CD V-715 manual — operating and maintaining the yellow meter. Pictures: Kearny fallout meter, civil-defense meters (CD V-715 and others), CD V-700.

🩺 If this goes wrong in the shelter

Problem What to do
Shelter is getting too hot Move air (a KAP or fan from outside air), strip to minimal clothes, drink freely and add salt to food (NWSS 1979, p. 62; only one opening? using a "divider" with a KAP).
Someone is vomiting Nausea and vomiting are the first signs of radiation sickness (H-20, pp. 10–11) — but stress and bad food cause them too. It isn't contagious. Keep them drinking small sips of the rehydration drink (Field care). (NWSS's "slightly salted water", about a teaspoon of salt per quart, is saltier than needed, especially for children — NWSS 1979, p. 114.) See the Medical guides.
Water is running low Drink as needed anyway. Plan a short trip when levels allow; use the settling and earth-filter methods above. Water stored soon after fallout gets safer with time as iodine decays (NWSS 1979, p. 79).
Someone must go out for medicine Only if life depends on it — EPA calls it a last resort after asking neighbors. Strip and wash on return (EPA Q&A, p. 43).
A nursing mother was outside If she has stored breast milk or formula, use it for now; if not, keep breastfeeding — feeding the baby comes first (EPA Q&A, p. 36).
The radio is silent Listen on a schedule to save batteries and try every band (rule of thumb). See the Radio guide.

📚 Go deeper: EPA Protective Action Q&A — pregnancy, breastfeeding, children, medicines; Nuclear War Survival Skills 1979 — shelter heat, water and salt, first aid; FEMA H-20 — radiation sickness signs.

📍 Our area

📚 Go deeper: Oregon ODOE Hanford pamphlet — Oregon's zones and farm steps; Nuclear War Survival Skills 1987 (OISM, Cave Junction) — trans-Pacific fallout and the corrected KFM patterns; FEMA Planning Guidance — emergency alert channels.

The 1987 edition of Nuclear War Survival Skills includes the author's personal view that small radiation doses are healthful; FEMA, EPA and CDC do not accept that. Follow the government guidance in this folder for dose decisions.

🖼️ Pictures & diagrams

Look before you try it. 🖼️ = drawings in the books on this drive; 📷 = photos in the offline Wikipedia.

The first minutes

Shelters, shielding and air

Supplies, decay and cleaning up

Water, food and the farm

Fallout meters

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