Some Aspects of Materials Development for Sodium-Heated Steam Generators

A development program was undertaken to support the materials selection for steam generator piping and intermediate heat exchangers that are to be used in liquid-metal fast breeder reactors. Four major topics have been reviewed, and the results obtained as well as the direction of future tests have been described. These topics are carbon transport in sodium, the effect of carbon loss/gain on materials in the reactor intermediate heat transport system (IHTS), corrosion fatigue, and aqueous corrosion. Thus far, the results on hand support the initial assumptions made in specifying the use of Cr—1 Mo as the construction material for the evaporator and superheater and Type 316 piping of the IHTS. The future direction of the experimental programs is to verify further the materials choice and also to obtain information that will be essential during the plant installation and operation and the reliability of the components.