FIFTH CANADIAN CONFERENCE ON NONDESTRUCTIVE ... - IAEA

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Though CIGARette was based on CIGAR, it differed in a number of ways (see
Table A). First, if CIGAR is automated (ie) computer controlled, CIGARette is
mechanized (ie) operator controlled. The operators run the CIGARette console
directly and watch and control the NDE instrumentation. Consequently CIGARette
scans a lot slower than CIGAR. The CIGAR drive is much larger, more powerful
and automatically aligns and connects to the channel being inspected whereas
the CIGARette drive is smaller and is clamped to the end-fitting by two
operators (Figure 6). The two drive rods are the same for both systems, but
are loaded by hand for CIGARette. Both CIGAR and CIGARette use CIGAR heads,
closure plugs and drive rods, with only minor modifications.
CIGAR records ultrasonic data on 1A channel tape and plays back directly
through a computer for quasi-on line print outs. In contrast, CIGARette
records data on a similar recorder for later playback, and operators are
required to make assessments of the data in situ. CIGARette play back is
supplementary. Also, the CRT screen of the ultrasonic flaw detector was
videotaped during CIGARette inspections to assist in post test assessment.
CIGAR has a slip-ring unit that allows the inspection head to rotate
continuously. CIGARette does not, so it has to scan back and forth with a
maximum rotation of A00°. CIGARette is operated from an AECL-designed
console/5/,(Figure 7) which can be operated manually or be made to perform a
continuous scan pattern with rotational and axial steps of preset size and
velocity.
3.1 CIGARette NDE Inspections
When CIGARette was developed, the CIGAR inspection head did not contain a
garter spring spacer location system. The head was modified by installing an
eddy current coil for this purpose in place of the CIGAR Sag Module.
Subsequently, the CIGAR head was changed to contain both these systems. The
CIGARette head includes all but the Sag Module. Once the head was in channel
with both drive rods and end connector in place, the CIGARette inspection
typically took the following sequence:
1) An axial pass (with ultrasonic probes at 6 o'clock or bottom dead centre)
to locate the garter spring spacers using the eddy current probe;
2) If one or both of the two garter springs was found to be out of position,
ultrasonic inspections were performed on the longest span. If the two
garter springs were in their design locations (or could not be found),
ultrasonic inspections were performed on the middle of the outlet span
(Figure 8). Typically a number of locations along the PT were inspected
if reflectors were found.
3) Eddy current gap measurements were performed along the length of the PT.
A) Ultrasonic gauging of the wall thickness was performed, along nominally
the same path as the gap measurements, to provide correction information
for the gap measurement.
This sequence is illustrated in Table 5. Ultrasonic volumetric inspections
were performed over an arc of only 45 degrees around bottom dead centre, using
a 2mm axial step. The scans were performed over a limited length of pressure