Nuclear detonation
Get inside, stay inside, stay tuned 12.
Ready.gov · Federal Emergency Management Agency · Centers for Disease Control and Prevention
Full guide →Be prepared before the alarm sounds.
What your government recommends, made for the people in your home and for your address: the water, the food, where to shelter, who to call. Plus an app that tells your family you are safe.
Includes Phaenyx SafeAn app for your phone: one tap tells your people you are safe and where you are. Works offline.See the app →00 · If an alert sounds now
The first minutes matter most.
What official agencies tell you to do, in their words, before anything else on this site.
Air-raid siren
Act immediately: go to the nearest designated shelter, a sturdy building or an underground space 15.
Cabinet Secretariat of Japan · Israel Home Front Command
Full guide →Chemical release
When told to shelter in place for a chemical release, go indoors, close and lock windows and doors, turn off fans, air conditioning and the furnace, and seal a room on the highest floor possible with few or no windows 1.
U.S. Centers for Disease Control and Prevention · Ready.gov · U.S. Environmental Protection Agency
Full guide →Water to store
Store at least one gallon (about 3.8 litres) of water per person per day, the US figure from Ready.gov and the CDC 12, for 3 days and, if possible, 2 weeks 2.
Ready.gov · Centers for Disease Control and Prevention · Government of Canada
Full guide →Get inside · stay inside · stay tuned
Get inside within 10 minutes.
Get inside, stay inside, stay tuned 12. After a detonation you will have 10 minutes or more to reach adequate shelter before fallout arrives 1. Go to a basement or the middle of a large brick or concrete building, away from windows and outer walls 12. Stay there at least 24 hours unless officials say otherwise or the building is on fire or unsafe 13.
01 · Your country in 30 seconds
Call. Listen. Go. Stock.
The four things your government wants you to know, for . Change the country at the top of the page.
Every line comes from an official source, checked and dated.
02 · The plan · $29 Free
Your government's list is free. We do the math for your home.
Tell us who lives with you and where. Get one plan with your quantities, your shelter, your numbers and what is still missing.
- Water and food counted for each person, pets included
- Iodine by age, and where to get tablets in your country
- A go-bag list, a warm room without fire, a shopping list sorted by store
- Every line marked official or added by Phaenyx, with its source
Launch offer: the full plan, all eight sections, and Phaenyx Safe are free for a limited time. Regular price $29.
Household planRue de Bourg 14, 1003 Lausanne · 2 adults, 1 teen, 1 child, 1 pet
4people
36 Lwater, 3 days
28person-days of food
4iodine group
SuppliesFirst minutesGo-bagIodine and healthHome and heatKnow-howStill to buyNumbers
Drinking water, 6 packs of 1.5 L36 L
Food for about one week28 person-days
Battery radio, DAB+ and FM1
Hygiene masks, 50 per person200
8 sectionsGo-bagIodine by personHeating without fireSafe app
Included with the plan
Phaenyx Safe. Tell your people you are safe.
An app that installs on your phone. When the network is shaky, one tap sends a message with the time and your position. Your plan, your family card and your numbers stay on the phone, readable with no signal.
- One tap, one message. Safe, at the meeting point, need a pick-up, someone is hurt. Sent from your own SMS or messaging app.
- Where am I, offline. GPS coordinates to read to the call-taker. No signal needed.
- Your plan in your pocket. Family card, medical card, numbers, shelter and go-bag checklist.
- Travel pack, free. Going abroad? Who to call and what the sirens mean in 62 countries, saved for offline.
No account, no tracking. Nothing is sent to Phaenyx. Install it while you still have a connection.
Get the plan and the app · free for a limited time Try the app preview
Good to know · the kitWhat a ready-made kit adds
One bag instead of thirty purchases, one expiry date to track. You can assemble the same from the list yourself.
Read the guide →Good to know · the shelterWhat a shelter module adds
Protection a room at home cannot give, and filtered ventilation. Know the official standards first.
Read the guide →03 · Guides
What are you preparing for?
Pick the situation. Each guide opens with a short answer and cites the agency behind every figure.
Power cut
Fridge, light, heat and cooking for the first 48 hours.
Siren, attack or chemical release
Where to go and what to do in the first minutes.
Radiation and iodine
Fallout, doses, and what actually protects you.
Water and food
How much to store, make it safe, and how long it keeps.
Cold, heat and fire
Keep one room warm without fire. Heatwaves and smoke.
Storm, flood or earthquake
Natural hazards at home and what to prepare.
Family, babies and pets
The people and animals who need their own list.
Kit, documents and first aid
What goes in the bag, and what to keep ready.
Guide · Radioactive fallout
The 7-10 rule.
Fallout from a nuclear detonation weakens fast. By the "7-10 rule", every sevenfold increase in time after the explosion cuts the dose rate tenfold: about one-tenth of the 1-hour level at 7 hours, one-hundredth at 49 hours (about 2 days) and one-thousandth at about 2 weeks 1. U.S. and Canadian agencies say to get inside and stay sheltered for at least 24 hours 345.
04 · Questions people ask
The first 24 hours, then the short answers.
Each answer is the opening of a verified guide. Follow the link for the full sources.
1Minute 0
The alert sounds. Go inside the nearest solid building.
210 minutes
About the time before fallout arrives. Basement, or the centre of the building.
324 hours
Stay in the most protective place unless officials say otherwise.
4Days
Stay tuned. Leave only on an all-clear or an evacuation order.
For a nuclear detonation, from Ready.gov (FEMA) and the CDC. Read the guide
How much water to store per person per day?
Store at least one gallon (about 3.8 litres) of water per person per day, the US figure from Ready.gov and the CDC 12, for 3 days and, if possible, 2 weeks 2.
Full guide →What to do if a nuclear explosion happens
Get inside, stay inside, stay tuned 12.
Full guide →What should you do when an air-raid or missile alert sounds?
Act immediately: go to the nearest designated shelter, a sturdy building or an underground space 15.
Full guide →How fast does nuclear fallout decay? The 7-10 rule
Fallout from a nuclear detonation weakens fast.
Full guide →What goes in a 72-hour emergency kit?
A 72-hour emergency kit holds drinking water, non-perishable food, a manual can opener, a flashlight, a battery or hand-crank radio, spare batteries, a first aid kit, personal medication, cash and copies of key documents.
Full guide →Potassium iodide (KI): when to take it and who needs it
Potassium iodide (KI) protects only the thyroid, and only against radioactive iodine 12.
Full guide →05 · Good to know
What a buried shelter module involves.
A standard shipping container collapses under the weight of soil. A module meant for burial has to be reinforced, coated and documented. Installation and permits stay with a local professional. This is information, Phaenyx does not sell one today.
Typical external size (20 ft)6.06 × 2.44 × 2.59 m
Occupants4 to 6 people
Soil coverper engineer's sheet
Ventilationcertified NBC filtration
Design life, buried10 to 15 years
Deliveryex-works (EXW) or port (FOB)
Installation and permitsby a local pro, paid by the buyer
Good to know
What a shelter module adds
Protection a room at home cannot give, and filtered ventilation for long stays. Know the official standards before you compare anything.
Information onlyRead the guide →06 · Our sources
We cite governments. Not forums.
Every recommendation on Phaenyx links to the official page that publishes it, with the date we checked it.
Bundesamt für wirtschaftliche Landesversorgung BWLSwitzerlandMyndigheten för civilt försvar (MCF)SwedenMinistry of the Interior / Suomi.fiFinlandBundesamt für Bevölkerungsschutz und Katastrophenhilfe (BBK)GermanyRząd Rzeczypospolitej Polskiej (publication 1/2025, ISBN 978-83-976775-0-0)PolandSecrétariat général de la défense et de la sécurité nationale (SGDSN)FranceCabinet Office (GOV.UK Prepare)United KingdomFEMA / Ready.govUnited StatesPublic Safety Canada (Canada.ca)Canada農林水産省 (MAFF)JapanHome Front Command (פיקוד העורף) / National Emergency Portal, hosted on gov.ilIsraelGet Ready (Queensland Reconstruction Authority), getready.gov.auAustralia