Uranium emits a very small amount of radiation, its half life is 4.5 billion years. Its acute chemical toxicity is way more threatening. Same with plutonium.

Now fission products from a nuclear explosion are entirely different. Strontium 90, for example has a half life of 29 years, so it's ~150 million times more radioactive than uranium, and it's right under calcium in the periodic table, so it will happily deposit itself in your bones and cook you from the inside.