EDDY CURRENT MEASUREMENT OF ANNULAR GAP BETWEEN PRESSURE TUBE AND CALANDRIA TUBE IN INDIAN PRESSURISED HEAVY WATER REACTORS (PHWRs)
R. Taneja, S. K. Parulkar, Manjit Singh and G. Govindarajan Reactor Control Division, Bhabha Atomic Research Centre Trombay, Mumbai 400 085, India
Keywords: Advanced techniques in NDT; Eddy current gap measurement; inspection; coolant channel; condition monitoring
ABSTRACT
In PHWRs, the pressure tube is designed to be nominally concentric with the encircling calandria tube. A number of mechanisms may be hypothesised which will cause the pressure tube to become eccentric with respect to the calandria tube over the life of the reactor. If this becomes excessive, the hot pressure tube could make contact with cold calandria tube such a cold spot could act as potential location for initiating blister formation and premature failure of pressure tube. Hence it is important to periodically measure annular gap between pressure tube and calandria tube. Eddy current technique has been successfully developed for this purpose. The technique has been implemented in BARC Channel Inspection System (BARCIS) for in-service inspection of coolant channels of Indian PHWRs. More than 100 coolant channels have been inspected using this technique. The paper describes the technique and presents results of inspection.
Publication Source: Trends in NDE Science & Technology; Proceedings of the 14th World Conference on Non-Destructive Testing, New Delhi, 8-13 December 1996.Vol. 2, pages 377 - 380 Publisher:Ashgate Publishing Company
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