Nuclear Plant Journal, March-April 2015 NuclearPlantJournal.com
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The Time of Flight Diffraction
(TOFD) technique is used for the
testing of weld roots and for the sizing
of volumetric or planar discontinuities
which have to be analyzed. Parallel and
non-parallel scanning of the tested area is
performed if the geometry of the tested
part makes it possible. Probe angles and
probe separation are chosen so that the
tested volume is covered with enough
sensitivity.
The phased array technique is used
mainly for the testing of austenitic piping
welds.
Eddy current testing
The reactor pressure vessel’s inner
and outer surfaces are tested by surface
multi-coil probes, which detect flaws
in both orientations, parallel with and
perpendicular to the probe movement.
Studs, nuts and threaded holes
in the reactor flange are tested using
surface probes designed to detect flaws
perpendicular to the tested part’s long
axis.
Bobbin coil probes are used for the
testing of steam generator heat exchang-
ing tubes, while the steam generator tube
sheet is tested by a cross-probe of the
X-point type and rotating probes.
Visual testing
Remote visual inspection is done by
color and B/W CCD TV cameras. The
cameras can be equipped with different
lenses. Remotely-controlled external
lights help maintain the best possible
conditions for the visual inspection. A
camera accessory generating laser dots
of a known distance is used to measure
the dimensions of displayed objects. The
position of the manipulator, the date, time
and operator comments can be mixed
with the TV picture and displayed on the
TV monitor. The entire visual inspection
or the inspection of selected parts is
recorded on a digital video recorder.
Testing Systems
ŠKODA JS uses several manipulators
for the testing, some provided by the
NPPs, some designed and produced or
adapted by the company.
Reactor pressure vessels have so far
been tested from the inner surface by a
system consisting of a SKODA Internal
(SKIN) manipulator (inspection system
for VVER 440 and VVER 1000 reactors
from internal surface), the 48-channel UT
instrument Microplus 2, the eddy current
instrument MS5800 and a color CCD TV
camera, TV CC 510TL. The camera has a
lens with a horizontal viewing angle of 5°
- 49° and can operate in a light intensity
of only 1.5 lux.
The testing from the outer surface in
Dukovany is done by a system consisting
of an upgraded manipulator USK-213, the
16-channel UT instrument Microplus 2,
the ET instrument MS-5800 and a color
CCD TV camera, the SONY XC-999.
The camera has a lens with horizontal
view angle 59° and can operate in a light
intensity of only 4.5 lux.
The system for the testing from the
outer surface in Temelín is composed of
an upgraded manipulator SK-187, the
16-channel UT instrument Microplus 2,
the ET instrument MS-5800 and a SONY
XC-999 TV camera.
Reactor internals at Temelín are
inspected by the Televizní Kontrola
Reaktorovýchcástí (TEKOR)manipulator
equipped with a radiation tolerant TV
camera with remote control and lighting
head with remotely controllable halogen
lights. The camera lens is interchangeable;
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