Diffusion-type hydrogen meter. [liquid sodium or gaseous environments]

A system for measuring and controlling the concentration of hydrogen in liquid sodium and in gaseous environments is disclosed. The system comprises a reinforced hollow tube-like membrane which is positioned in the sodium or the gaseous environment such that the hydrogen diffuses through the membrane. Hydrogen diffusing through the membrane is removed by an ion pump to maintain a vacuum inside the membrane. The electrical current flowing through the ion pump is an indication of the hydrogen concentration. Alternatively, the hydrogen can be permitted to diffuse through the membrane until an equilibrium condition is established and a high pressure ionization gauge can be used to determine the hydrogen concentration. The membrane includes integral reinforcing sections permitting the membrane to be thin to achieve high sensitivity and withstand a high differential pressure. Valves are included which isolate the membrane from the sodium or gaseous environment so that the membrane can be easily changed.