Structural Integrity Assessment of the Hardface Coatings Used in Indian FBRs

Hardface coatings are widely used in the components of sodium-cooled fast reactor to avoid self-welding and galling. After thorough study, colomonoy-5 is selected as hardface coating material in Indian fast breeder reactor. Even though extensive studies were done on the various metallurgical aspects of the hardface coatings, studies on the stress distribution and load-carrying capability of the hardface coatings are non-existent in the open literature. Further, no rules are available for integrity assessment of hardface coatings in nuclear codes or in national standards or in professional bodies. Hence, authors have drawn out few guidelines for evaluating the hardface-coated components for in-reactor applications. These guidelines were used to qualify a critical component for reactor operation. Another challenging aspect of the present analysis is the contact geometry, which makes it difficult to use the finite element analysis techniques for stress analysis. With design innovation, the induced stresses were reduced by nearly 70%. The significance of the current work is that it provides basic guidance for integrity assessment of hardface coatings.