Did the trinity atom bomb have nuclear radiation because today you can visit the site but people told me that atom bombs radiate sites for millions of years so how come it is safe to visit it and go?

Answer 1

Yes, the first atomic bomb, detonated at the Trinity site on July 16, 1945, released a significant amount of radiation and radioactivity contamination. Ground zero at the Trinity site today is still radioactive and you will receive about twice the average daily exposure during a one hour visit to the site. While it is true that isotopes such as U-235, U-238, and Pu-239 are radioactive for billions of years, they're not the isotopes that you need to worry about. U-238 has a half life of one billion years. It is typically accepted that after 10 half lives, all of the radioactive material has decayed. A half life is the time necessary for half of the material to decay, by giving off radiation, into another isotope. This new isotope may be stable and therefore not give off any more radiation or it may be unstable (radioactive) and decay into yet another isotope. This will continue until a stable isotope results. Consider two different materials, one with a half life of one year and the other with a half life of one billion years. In one year, half of the material with the one year half life will have given off radiation. However, in that same year, only 1/100000000th of the material with the one billion year half life will have given off radiation. The longer the half life, the "less" radioactive a material is. In the over 60 years since the first atomic bomb was exploded, most of the dangerous short lived (short half life) material has already decayed into stable isotopes. This, combined with the removal of some of the top soil, has resulted in a radiation level that is only a little above the natural background level.