Abstract
Irradiation creep and irradiation stress relaxation data have been obtained for CW 316 SS, CW 316LN SS and SA 304L SS.  The measurements were performed on-line during irradiation.  This is the first time that irradiation stress relaxation measurements have been performed by this technique, and the accuracy of the measurements reported in this study are better than previously used methods.  The sample extension was observed to either decrease or increase when the reactor power, sample temperature, flux or stress changed   This behavior only occurred when the power, temperature, flux or stress exceeded a threshold value.  An initial shrinkage due to second phase precipitation/densification was observed for all of the materials tested.  The standard CW 316 SS data confirmed the relationship between irradiation creep and irradiation stress relaxation for light water reactor applications.  The irradiation creep of CW 316LN SS was a factor of 1.6 less than standard CW 316 SS.  This reduction may possibly be explained by the decreased stacking fault energy of 316LN SS relative to standard 316 SS.  The irradiation creep in thermal neutron spectrum reactors was observed to be very different than values measured in fast neutron spectrum reactors.  Therefore, fast reactor irradiation creep data are not recommended for application to light water reactors.

 

 
Dr. Foster’s Bio
Dr. Foster earned BS and PhD in Metallurgy/Materials from Drexel University and did his PhD thesis on liquid metal diffusion. He has been an engineer with the Westinghouse Electric Company for 39 years  in the Nuclear Breeders, R&D, and Commercial Nuclear Fuel Divisions. He has also contributed 55-60 technical papers and 13-14 US Patents to the field.

 

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