It has been observed that in sodium-heated steam generators most of the hydrogen produced from water- or steam-side corrosion permeates into the secondary sodium. The amount of hydrogen that diffuses into the secondary side is extremely important from the standpoint of the design of the cold trap, hydrogen background levels, and tritium concentrations in the secondary system. We have compiled all the available data on H2 permeation from all operating sodium-heated steam generators. In addition, based on the available steam-side corrosion data, we have made tentative recommendations: Steady-state H2 flux:

1.Evaporator (Cr—1 Mo):
1.8 to 2.2 × 10−11 g H/cm2·s.
2.Superheater ( Cr—1 Mo):
1.2 to 1.7 × 10−11 g H/cm2 · s.
Initial H2 flux (up to 2000 h):
1.Evaporator and superheater ( Cr—1 Mo):
∼7 to 8 × 10−11 g H/cm2·s.