History of the metric system levels of the krypton 86 atom as the new standard for the metre. The standard metre artefact was retired. In 1960, Giorgi's proposals were adopted as the basis of the "Système International d'Unités" (International System of Units), the SI. This initial definition of the SI included six base units, the metre, kilogram, second, ampere, degree Kelvin and candela, and sixteen coherent derived units. The evolution of the SI after its publication in 1960 has seen the addition of a seventh base unit, the "mole", and six more derived units, the "pascal" for pressure, the "gray", "sievert" and "becquerel" for radiation,
Radioactivity Fixatives Radioactivity Fixatives Radioactivity or radionuclide fixatives are specialized polymer coatings used to “fix” radioactive isotopes or radioactive material to surfaces. These fixatives, also known as permanent coatings in the radioactive contamination control field, have been used for many decades in facilities processing radioactive material to control radioactive contamination. There has been increased interest in these fixatives or coatings recently due to the growing concern of contamination from a radioactivity dispersal device (RDD also known as a dirty bomb) and because radioactivity fixatives in use today lose the ability to contain the radioactivity to the surface during a fire. Radioactivity fixatives