This is glowing deuterium in an IEC reactor. Although this is a picture of a reactor, the glow is due to the ionization of deuterium, not radioactivity.
Question: Is Deuterium Radioactive?
is one of the three isotopes of hydrogen. Each deuterium atom contains one proton and one neutron. The most common isotope of hydrogen is protium, which has one proton and no neutrons. The 'extra' neutron makes each atom of deuterium heavier than an atom of protium, so deuterium is also known as heavy hydrogen.