Nukalert.com has a really good website that gives good information about nuclear disasters. http://www.nukalert.com/ This is the company that sells nuclear alert key chains. What to do if a nuclear disaster is imminent, http://www.ki4u.com/guide.htm, discusses food supplies, water, shelter, and ways to survive safely. They have information about what to do if you don't have Potassium Iodide tablets. (What, I thought you were prepared?)
Because we are so far away from Japan there is a high likelihood that radiation that does reach here will be less dangerous due to natural atmospheric dispersion and natural decay over time before it arrives. Not that my telling you this will comfort you. You are kicking yourself for not preparing in advance for a nuclear reaction? If you don't have tablets you can still protect yourself! Apply on your skin (paint it on) either tincture of iodine or Betadine to get a similar protective effect. Do not drink this stuff! Start this procedure prior to exposure if at all possible. Doses are as follows: 1 1/2 teaspoons on the abdomen or forearm each day. For children or adults under 150 pounds use 1/2 to 1 teaspoon depending on weight. You can even use this on infants and young children under three years old. For them use 1/4 of a teaspoon. Don't use this if you are allergic to iodine!
Other than taking pills or wiping yourself with iodine or Betadine, what should you be doing to prepare? Easy! Pastures, livestock and crops quite possibly will be adversely affected for about a month or so. What does this mean to you? It means that our milk and vegetable supplies for the next month or two can become contaminated. Stock up now on fresh or frozen vegetables (or canned, dehydrated, or freeze dried) and milk, cheese, butter, and other dairy products. Fill all empty containers with water. It's almost spring. I know how many canning jars I have that are empty, waiting for the summer crops to be put up. They are all getting filled.
Two simple things to keep you safer and healthy: iodine rub and stocking up on veggies, dairy, and water.