Diagnostics of direct CT - PT contact of the coolant channels of PHWRs Original Research Article

It has now been realised that the garter springs which maintain the gap between the pressure tube (PT) and calandria tube (CT) of a PHWR can get displaced significantly from their deign position in many channels. It has also been recognised that the large unsupported span of the PT restricts the life of the channel due to premature contact of the PT with the CT making it susceptible to delayed hydrogen cracking. This paper reports the details of a non-intrusive diagnostic technique based on vibration measurement for detecting the contacting channels.