A teenager, or teen, is a young person whose age falls within the range from 13â19. They are called teenagers because their age number ends with teen.Someone aged 18 or 19 is also considered a young adult. Usage by ordinary people varies, and also varies in different societies.Most societies traditionally had a formal ceremony to mark the change from childhood to adulthood.n the United Kingdom (UK); teenagers and non-teens are mixed in secondary school. Teenagers attending secondary school (high school in the US) generally graduate at the age of 17 or 18.
Which nuclides are fissile? In general, most actinide isotopes with an odd neutron number are fissile. Most nuclear fuels have an odd atomic mass number (N = the total number of protons and neutrons), and an even atomic number (Z = the number of protons). This implies an odd number of neutrons.
Since the energy per fission from Pu-239 and U-235 is about the same, the theoretical fuel value of fissile Pu is $5600 per gram. Reactor grade Pu also contains non-fissile isotopes, reducing its value to about $4400 per gram..