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Fret Replica Inspection Laser Scanner (FRILS)

Precision profilometry of pressure tube flaw replicas in a portable package.

Detailed knowledge of flaw geometry is crucial when conducting the stress analysis of flaws found in the thin-walled zirconium alloy pressure tubes of CANDU reactors. 

While ultrasonic fret replica inspection provides much of the required data, measurement of the sharpness or root radius at the bottom of the flaw, requires a replica of the flaw to be taken and subsequently measured. 

Immediately upon removal from the reactor, the Fret Replica Inspection Laser Scanner (FRILS) has the capability to provide an accurate profile of the flaw replica. This facilitates rapid analysis and engineering decisions during critical outage situations. 

The FRILS system has a depth resolution of < 1 micrometer and a traceable depth accuracy to better than 50 micrometers. The FRILS system is also capable of measuring root radius of < 40 micrometers. 


  • Narrow (20 micrometers) laser stripe, CCD camera with zoom optics
  • Portable hardware
  • Depth resolution to <1 micrometer at high magnification (presently 50 micrometers traceable accuracy)
  • Can measure root radius to < 40 micrometers
  • Portable data files, may be analyzed on most typical desktop computers
  • Measurement on rubber replicas – no hard cast required
  • Several hundred surface profiles per fret if desired (up to 3000 profiles per scan)
  • The width of each surface profile is 1 to 5 mm, and a scan is up to 50 mm long
  • Colour graphics highlight deepest/sharpest locations in fret
  • Automatic reporting of fret location, depth, width, length, volume