FIFTH CANADIAN CONFERENCE ON NONDESTRUCTIVE ... - IAEA

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5) an eddy current probe to locate the position of garter spring spacers.
These transducers are operated from instruments in the remote control location
using up to 100 metres of cable.
The NDE transducers are mounted in a CIGAR inspection head (Figure 4), which
consists of two centering modules, a universal joint connector, plus eddy
current, sag measurement and ultrasonic modules. The heads are modular so
inspection systems can he readily interchanged. The limiting factor at the
present time is the number of miniature coaxial cables and connectors that
can be inserted down the drive rods, namely fifteen. A radiation resistant
in-channel multiplexer is under development that will allow more transducers
to share the 15 available cables.
2.4 Control and Data Handling
CIGAR inspections are controlled by a DEC PDP11 minicomputer at the remote
console, using a series of preprogrammed scanning patterns. For example, the
operator might perform 1) a high speed helical ultrasonic inspection using a
3mm axial step (100 minutes for the whole channel); 2) sag measurements,
performed axially (15 minutes), 3) eddy current and ultrasonic wall thickness
measurements for gap (15 minutes), 4) garter spring location if required (15
minutes), 5) detailed ultrasonic inspection of a selected area (say 20-50
minutes), for a total inspection time of about 3 hours per channel. The order
is flexible, depending on the operator.
CIGAR generates a vast amount of data, more than an operator can absorb while
watching the various screens and displays, so some method of recording and
displaying the data is necessary. Much of the data is recorded by a 14 channel
magnetic tape recorder in analog form (Figure 5). This device records the
axial and circumferential positions from the console, 2 channels (X and Y)
from the eddy current instrument, eight channels of data from the flaw
detection ultrasonic instrument (two channels each from four probes), plus a
voice channel. These can he played back through a second computer to give, for
example, isometric displays of the ultrasonic flaw detection data. The
ultrasonic gauging data and sag data are recorded on digital cassette. Also,
the ultrasonic flaw detection system triggers alarms to notify the operator
when signals above threshold are observed, and these are printed out on the
alarm print module, along with the axial position.
3. CIGARette
When Pickering unit 2 pressure tube G16 burst on August 1, 1983, due to
'hydride blister' related cracking, CIGAR was not ready for operation. A mini-
CIGAR, quickly nicknamed CIGARette, was improvised using many CIGAR components
and basic inspection system concepts, and was under test in about a month. A
small friction drive mechanism was designed and built by AECL Sheridan Park
using standard components for speedy delivery/5/.