Abstract

Eddy current testing method has been standardized for monitoring the Garter Springs which are used in coolant channel assemblies of Pressurized Heavy Water Reactors (PHWRs). The standard bobbin type probe is used for monitoring the Garter Springs to detect only the location but does not monitor the tilt orientation of the Garter Springs. The modified bobbin probe coil with tilted angular winding has been developed in the laboratory for monitoring the location as well as tilt orientation (if Garter Springs.

There are 306 nos. of coolant channel assemblies in 235 MWe PHWF. Each coolant channel assembly consists of two tubes, i.e. pressure tube (Zr-2.5 Nb) and calandria tube (Zr-2). High temperature (575°K) and high pressure (1500 psi) coolant is flowing through the pressure tube which contains the oxide fuel. Surrounding the pressure tube, there is low pressure cool heavy water moderator which is thermally separated from the pressure tube. There are four Carter Springs in the annular gap between coolant tube and calandria tube to maintain gap. Besides other measurement. the Garter Spring position is measured during periodic inservice inspection of coolant channels for any shift from their design location.

This paper describes the details of coil design, criteria for interpretation of Eddy Current signals from Garter Springs which are used for measuring the position and tilt of garter springs in PHWR.

Keywords: Eddy Current Testing

Source: Conference Proceedings of the 4th International Conference of the Slovenian Society for Nondestructive Testing, 24 - 25 April 1997, Ljubljana, Slovenia.
Pages:193 - 204

Publisher:
Slovenian Society for Nondestructive Testing, Faculty of Mechanical Engineering, Askerceva 6, SLO 1000 Ljubljana, Slovenia. Tel +386 61 177 12 03, Fax +386 61 218 567, Email: janez.grum@fs.uni-lj.si.