Lock and lock all windows and doors. Go to the basement or to the center of the building. If possible, turn off fans, air conditioners, and forced air heating units that bring in air from outside. Enter the nearest building to avoid radiation.
The heavier and denser the materials (thick walls, concrete, or bricks) are between you and the rain particles, the better. If possible, enter a building or go home immediately. As soon as you can, go in and stay there. Stay away from doors, tall furniture, and windows, as they will likely break.
If the walls collapse, you'll have a chance to survive in a pocket in the rubble. The safety hazards of nuclear radiation can also be caused by natural or man-made disasters, such as earthquakes, tsunamis and tornadoes where nuclear power plants exist. There has been widespread debate about Russia's threat to use tactical nuclear weapons in its war against Ukraine. And after the collapse earlier this year of the Intermediate-Range Nuclear Forces treaty that limited weapons testing, the world could see more and more nuclear weapons tests.
In the United States, there are 99 nuclear reactors in 30 states, so Americans must be even more prepared for a nuclear disaster. Although the incident does not appear to have involved an active nuclear warhead, submarines armed with such weapons are a key component of Russia's nuclear deterrence strategy, just like in the United States. All of these are viable options to protect yourself if the nuclear event is not too large and is not a total exchange of nuclear weapons. Even if the chances of a nuclear attack are unlikely, being afraid of a nuclear disaster is not an irrational fear.