Long half-life (thousands of years) products are usually not too worrisome because they are not very radioactive. That's the reason why they are long half-life.

Long half-life (thousands of years) products are usually not too worrisome because they are not very radioactive. That's the reason why they are long half-life. Short half-life (days) products are very radioactive and dangerous, but because they are quickly depleted, they are manageable. The worst are medium half-life (decades) products. Short enough to be dangerously radioactive, and long enough to be a long term problem. These are the ones that make Chernobyl inhospitable.