Prediction of Denting and Associated Inconel 600 Tube Cracking on the Primary Side in PWR Steam Generators

摘要

In order to predict denting in PWR steam generators with any degree of confidence, it is necessary to have at least a minimum qualitative and quantitative understanding of the factors involved in the rapid linear growth of Fe sub 3 O sub 4 on carbon steel. Up to the present, such knowledge has been incomplete, both from the standpoint of the corrosion mechanisms and of the actual environmental conditions leading to denting in the field. This is emphasized by the fact that a lengthy exploration was made at this Symposium of possible factors that may account for the absence of denting in secondary systems of Japanese PWR units, while denting occurred in several units in the U.S.A. operating under apparently similar conditions. Of course, many reactions that may be involved in the rapid oxide growth that causes the problem have been suggested and a good deal of experimental evidence has come to light, as is discussed in this paper. This paper presents some ideas on factors that are involved or that have to be clarified in order to predict denting and its secondary effects. It also describes briefly the development of a probe that is underway at Brookhaven National Laboratory (BNL) for the early detection of localized corrosive conditions in secondary systems of nuclear power plants. (ERA citation 04:042888)