Nuclear proliferation Alliance of Nuclear Weapons and Nuclear Power", tritium is not classified as a "special nuclear material" but rather as a by-product. It is seen as an important litmus test on the seriousness of the United States' intention to nuclear disarm. This radioactive super-heavy hydrogen isotope is used to boost the efficiency of fissile materials in nuclear weapons. The United States resumed tritium production in 2003 for the first time in 15 years. This could indicate that there is a potential nuclear arm stockpile replacement since the isotope naturally decays. In May 1995, NPT parties reaffirmed their commitment to a Fissile
Isotope left in the periodic table, whereas beta decay emission produced an element one place to the right. Soddy recognized that emission of an alpha particle followed by two beta particles led to the formation of an element chemically identical to the initial element but with a mass four units lighter and with different radioactive properties. Soddy proposed that several types of atoms (differing in radioactive properties) could occupy the same place in the table. For example, the alpha-decay of uranium-235 forms thorium-231, whereas the beta decay of actinium-230 forms thorium-230. The term "isotope", Greek for "at the same place", was