I located this publication. It appears to be from the Department of Homeland Security. It has a rather impressive name. However, it includes a lot of information about radiation that can be released from reactors. It details precautions that people can take and probable effects of the radiation.

NUCLEAR GENERATING STATION PLUME AND POST-PLUME EXERCISES AND INCIDENTS
LIBRARY OF PRESS RELEASES

Here’s an excerpt –

There are two important concepts that help in understanding radiation: exposure and contamination. Both can occur when radioactive materials are released in a power plant emergency.
Exposure: Radioactive materials give off a form of energy that travels in waves or particles. This energy is similar to an x-ray, and can penetrate the body. This exposure ends when the radioactive material is no longer present, for example, after the noble gases disperse. Some of the radioactive material deposited on the ground may also contribute to external exposure. You may hear this referred to as “groundshine.”
Contamination: Contamination occurs when radioactive materials (dusts) are deposited on or in an object or person. External contamination occurs when radioactive material or dust comes into contact with a person’s skin hair or clothing.
People who are externally contaminated can become internally contaminated if radioactive materials get into their bodies. This could happen if people swallow or breathe in radioactive materials. Some types of radioactive materials stay in the body and are deposited in different body organs. Other types are eliminated from the body in blood, sweat, urine, and feces.
Limiting skin contamination: Both external and internal contamination can cause exposure to radioactive materials. Removing contaminated clothing and washing off the radioactive materials will minimize exposure from external contamination.
If you think you have been contaminated, you should:
•
Remove the outer layer of your clothing.
•
Place the clothing in a plastic bag.
•
Wash all of the exposed parts of your body, as you would normally, with soap and warm water. There is no need to scrub.
Do not eat, drink or smoke until you have removed contamination as described above.

This material was written for a small release of radiation, a plume, from an American nuclear power plant. It may not be totally relevant to radiation arriving from a meltdown. However, based on my reading in the area, I believe the information to be useful. Certainly, if you read the full report, you can decide for yourself if it is on point. I think it is.

James Pilant