As a part of this system, eddy current transducers namely Concentricity Detection Probe (CDP) and Garter Spring Detection Probe (GSDP), along with respective signal processor units have been designed and developed. These transducers are required to detect garter spring spacers and eccentricity between Pressure Tube (PT) and Calandria Tube (CT) of the channel respectively under hostile operating conditions of intense radioactive fields and wet conditions. The signal processing units of these transducers are based on OP-AMPS.

In a recent campaign of garter spring repositioning using INGRES at MAPS-2 the performance of CDP and GSDP transducer system was evaluated under actual operating conditions for INGRES. Based on initial trials improvements were made to make these devices more robust and trouble free for field application.

The data collected provides valuable information relating to temperature sensitivity of these transducers and their stability under radiation environment. The data obtained from these devices also provides some additional useful information relating to dimensional changes in the coolant channel. These aspects are discussed in the paper.