Assessment of Delayed Hydride Cracking at volumetric flaws formed due to bearing pad fretting


Pressurized Heavy water reactor is a horizontal channel type reactor where fuel bundles are inside pressure tubes (PT) and supported at bearing pad locations. Bearing pad (BP) fretting results in formation of volumetric flaws at PT inner surface which may lead to delayed hydride cracking (DHC). In this paper, safety assessment of pressure tube was carried out against DHC initiation at volumetric flaws using CSA N285.8 procedures. Bounding envelop was developed for threshold bulk Heq and volumetric flaw depth for DHC initiation. Several flaw root radius (r) were assumed to arrive at bounding flaw sizes and threshold bulk Heq in the PT. Peak stress was calculated considering hydride ratcheting condition at flaw tip considering sustained hot condition. Four locations, rolled joint inlet/ outlet and PT main body inlet/outlet were selected to assess DHC initiation for volumetric flaws. Residual tensile stress was considered for the assessment at rolled joint location

Countries: India

Article metrics loading...

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error