With no explanation, label text_A→text_B with either "not_related" or "related".
text_A: One Direction released their album Four in Europe and Asia.
text_B: Tritium -LRB- -LSB- ˈtrɪtiəm -RSB- or -LSB- ˈtrɪʃiəm -RSB- symbol or , also known as hydrogen-3 -RRB- is a radioactive isotope of hydrogen .. radioactive. radioactivity. isotope of hydrogen. isotopes of hydrogen. The nucleus of tritium -LRB- sometimes called a triton -RRB- contains one proton and two neutrons , whereas the nucleus of protium -LRB- by far the most abundant hydrogen isotope -RRB- contains one proton and no neutrons .. nucleus. atomic nucleus. proton. proton. protium. hydrogen-1. Naturally occurring tritium is extremely rare on Earth , where trace amounts are formed by the interaction of the atmosphere with cosmic rays .. trace. trace radioisotope. It can be produced by irradiating lithium metal or lithium bearing ceramic pebbles in a nuclear reactor .. lithium. lithium. nuclear reactor. nuclear reactor. Tritium is used as a radioactive tracer , in radioluminescent light sources for watches and instruments , and , along with deuterium , as a fuel for nuclear fusion reactions with applications in energy generation and weapons .. radioactive. radioactivity. radioactive tracer. radioactive tracer. radioluminescent. radioluminescence. deuterium. deuterium. The name of this isotope is derived from the Greek word τριτος -LRB- tritos -RRB- meaning `` third '' .
not_related.