The private papers of what scientist had to be decontaminated for two years in the 1990's before being put on file at the national library in paris? 577 points

The answer is Marie Skłodowska Curie (AKA Marie Curie). She lived her life awash in ionizing radiation. She would be carrying bottles of the radium and polonium in the pocket of her coat and put them in her desk drawer. 
So even after a century, her papers are still radioactive. Since the most general isotope of radium, which is radium-226, has a half life of 1,601 years.