I would love to tell you I am expert on Nuclear, Biological & Chemical Warfare... but I am not. What I am is a grunt (infantry man) who got do some training with the NBC guys or as we also called them "No Body Cares" well at least your skin is burning or melting off or you are dying of radiation poisoning. So here is what I learned hanging with the NBC crew...
1. Radiation from a power plant is more dangerous then a bomb, why because the material in a power plant is intended to last for a longer time and so yes can poison an area for hundreds of years with radiation.
2. Radiation from a Nuclear Bomb is faster deteriorating due to the sudden release of energy as compared to the slow degradation of say a Nuclear Power Plant's control Rod. This means that you can wait out a disaster from a nuclear weapon but not from a nuclear power plant.
3. You need iodine. Iodine is used to treat cuts and such but liquid iodine can be taken by a 2 table spoon dose with a liter or quart of clean water. Iodine Water Filtration Tablets can be used with a 1-quart of water in a standard GI issued canteen. And of course their is Iodine Solution you can buy online for radiation poisoning. The latter is your best bet.
A gas mask is also good to have...
Now I will explain the construction of the bomb shelter.
What you will need is cinder blocks, mortar, concrete, 4x4 Wooden posts, ply wood sheets and 5 Steel external doors without peep holes.
You need a twelve foot by eight food living area. This can accommodate four people quite well. Ideally you might only need to be here for two weeks to a month. So keep in mind the space is going to be limited and well you need to maximize the room you have. This means bunk beds, storing supplies under beds or stacked into boxes.
So you need for 4 adults (assuming teenage children as adults) 4 gallons of water for 2 weeks (14 days) equals 56 gallons of water. Add some board games, playing cards etc. You will also need gas masks, hazmat suits and other items. Once you have about four feet of wall built you need to add 1 and 1/2 inch pipe as an air vent, this vent needs to be built with an "S" curve as shown and allows for a flow catch to catch heavier partials of debris in the air open end on the outside should face down, this prevents falling partials of debris from entering the air flow pipe as well. The hole cut into the wall is patched with mortar and concrete poured into the cinder blocks to strengthen the walls.
This provides some protection. After the walls have reached the desired height a roof can be fashion with the plywood sheets about 1/2 to 1 inch thing. Concrete is then mixed and spread over the plywood in layers of 2 to three inches at a time. They may need to be reinforced with 4x4 support columns to bear the weight until the concrete dries & you need 24 to 28 inches of concrete over head to provide protection.
A Faraday cage should be used to protect any electronics key electronics should include but not be limited to an emergency radio, a handheld CB radio, any night vision devices and any power inverters and charge controllers for solar kits. Needless to say food should be rationed, as well as water. Major targets for a nuclear war will be are military bases, especially naval bases where nuclear submarines are based carrying Inter Centennial Ballistic Missiles (ICBMs), large industrial centers, large population centers and any major airports. So you want to be away from them as best you can.
Once the bombs go off, hopefully you have gotten some warning and can get you and your loved one's into the Bomb Shelter, DO NOT got out of the Shelter in the first 48 hours. Remember the 7/10 rule radioactive fall out breaks down at a rate of ten every factor of seven increase in time. Meaning that after seven minutes a unit of radiation breaks down to 1/10th, after seven hours breaks down to 1/100th, after seven days breaks down to 1/1000th and so on exponentially.
So 2 weeks is a safe minimum; so you need to stock up on food and can get instructions on how to build your own Hazmat Suit from Poorman's Guide to Prepping & you can find free resources on Nuclear Protection here. Building such a shelter in one's basement or an old cave or mine, only adds Nuclear defense protection & adds concealment of prepper OPSEC.
Now allow me to explain the need for so many doors. The doors provide for an airlock system to reduce contamination to the shelter chamber. Leaving the shelter one would move to the first airlock, which doubles as washroom. Once here one enters the suit room, closing the airlock door and puts their hazmat suit (whether commercial or home made) as specified by its proper design. One exits the suit room, entering the scrub room and then the outer airlock, closing each door behind one's self. One then scavenges for supplies and does whatever one wishes to do outside...
Upon returning one uses warm soapy water and washes off beginning with one's hands up to the elbows, then one's head and down to the feet. Once one does this preliminary washing down, one enters the Airlock and locks the door behind one's self. If there is a lot of debris being blown around one can avoid this step until inside the Airlock. One moves to the scrub room using a new clean bucket of warm soapy water to wash off again as before using a scrub brush this time. Once in the suit room, one exits the Hazmat suit and enters the internal airlock. Here one washes off their skin and hair directly and consumes potassium iodine to prevent any radiation sickness.
I must stress this, one should not exit the Bomb Shelter before the first 48 to 72 hours and remain their a possibility of 14 to 30 days. So with all this talking of nuclear war from Russia and China, now is the time for people to start thinking of dealing with that threat and perhaps even pulling our resources to get things done.