The lifetime of a deuteron in the ground state of HD molecule has been calculated as 10^47 years. Obviously, at zero pressure and temperature it is slightly shorter, because hydrogen is solid at these conditions - but not much shorter, because in solid hydrogen at zero pressure the other neighbours are much further than the moleculemate. Radioactive decays start to become relevant and measurable from the lifetime of 10^20 years - spontaneous fission, double beta, alpha activity like Bi-209 are in that range. For comparison, protium lifetime in red dwarfs is around 10^13 years. What is the density and pressure of hydrogen, at zero temperature, where deuteron lifetime is 10^20 years?