The maximum dimensions for your carry-on bag are: Length - 24 (61cm) including wheels and handles ; Width - 17 (43cm) Height - 10 (25cm) For additional carry-on items beyond the one-bag limit, each piece will incur a fee. Refer to the checked baggage page for more information.
Tritium (3H) is the most stable radioisotope of hydrogen. That is, of all radioactive isotopes of hydrogen, tritium is the least radioactive. It has a proton and 2 neutrons in its nucleus. Tritium decays through beta minus decay and changes to helium-3. It has a half-life of 12.32 years.
The half-life for the spontaneous fission of 238U, for example, is 1016 years, or about two million times longer than the age of our planet! We don't have to wait, however, for slow spontaneous fission reactions to occur.