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8/17/2019 Ultrasonic Immersion System for Space Shuttle Components
http://slidepdf.com/reader/full/ultrasonic-immersion-system-for-space-shuttle-components 1/2
New equipment
raphite brick tests
Under a contract from Nuclear
Electric plc, supported by Scottish
Nuclear, graphite moderator
bricks and slices of bricks, typical
of those which are interlocked in
layers to construct the cores of
Advanced Gas-cooled Reactor
(AGR ) power stations, are being
subjected to an extensive series of
tests to provide more
comprehensive information on the
strength of the bricks. The results
of these tests will be used in
conjunction with sophisticated
finite element analysis
calculations to increase accuracy
in formulating the safety case for
core integrity.
The tests are being carried out at
the Risley Laboratory of AEA
Reactor Services and will examine
the effects of stresses within
bricks caused by external loads
and a sequence of stresses arising
from the complex shrinkage
behaviour of the graphite over the
operating lifetime of the reactor.
Radiation dose rates across the
cores are not uniform, and this
causes differential shrinkage and
distortion of the graphite
components. As a consequence
the bricks start by shrinking more
on the inside adjacent to the fuel
than on the outside. Later this is
reversed as the graphite on the
inside characteristically stops
shrinking and begins to expand.
Towards the end of the reactor
lifetime this process leads to a
build-up of internal stress at the
roots of the keyways by which
the bricks are interlocked. These
keyway roots are the most
stressed parts of the graphite core
bricks.
The core design mainly
compensates for the graphite
dimensional changes and the
necessary movements due to
temperature changes during
operation by having the individual
bricks loosely keyed together in
an arrangement which permits
expansion and contraction of the
whole core without affecting its
stability or integrity.
110
Graphite moderator bricks being measured as part of an assessment of the effects of stresses
Large-scale tests using full-scale
core bricks and brick slices of
thicknesses up to 250 mm will
push and pull the specimens in
order to determine the ability of
bricks to withstand external loads.
In other tests graphite slices are
being subjected to bending forces
designed to mimic the stresses
imposed on the keyways during
the lifetime of the reactor, to test
the resilience of the bricks to this
type of stressing.
As it is not practicable to replace
damaged graphite, AGR station
operation depends on maintaining
satisfactory integrity of the bricks
and their keyways. An extension
to the graphite core lifetime
would have enormous
implications for the economics of
nuclear power generation since
the stations have high capital
costs but low marginal fuel costs.
AEA Technology Ride y
Warrington Cheshire WA3 6A T
UK
Ultrasonic rail
inspection system
RMK’s Zenica rail fabrication
plant in Yugoslavia is the first
purchaser of the Micro Plus
ultrasonic inspection system from
Sonomatic. The plant
manufactures rail for Yugoslav
railways, and is gearing up to
export to other European
countries. To do this, the plant
will have to demonstrate its
quality control procedures and the
consequent quality of its product.
The Micro Plus system will
provide continuous,
full-volumetric inspection for
internal flaws, and will eventually
be able to handle five different rail
profiles, using the non-contact
immersion technique which has
proved successful for the
inspection of round and square
steel billet and bar.
The system was developed from
Sonomatic’s Midas ultrasonic
inspection and data acquisition
system, and is based around a
386 computer.
The Micro Plus is a multi-channel
inspection system with an array of
ultrasonic transducers which
examine the rail as it passes
through a water-injected stuffing
box at line speeds up to
1.5
m s-‘. The water acts as an
ultrasonic couplant, and
consequently the inspection
heads do not touch the surface of
the rail. This means that there is
no wear and the system is very
reliable.
The 32-channel system which
will be installed at Zenica will
N DT E International April 1991
8/17/2019 Ultrasonic Immersion System for Space Shuttle Components
http://slidepdf.com/reader/full/ultrasonic-immersion-system-for-space-shuttle-components 2/2
N e w e q u i p m e n t
incorpora te an au tomat ic pa in t
sprayer to mark the loca t ion o f
defects, use r-f r iend ly d isp lays and
audib le a larms. For each batch of
ra il inspected , a co lour -g raph ic
hard-copy inspect ion repor t w i l l
be generated as eviden ce of test ing.
Menu screens have been wr i t ten
in Serbo-Croa t fo r th is
appl icat ion, and heaters and
ant i f reeze for the immersion tank
wil l be able to keep the system
opera t iona l in Yugos lav w in te r
tempera tu res dow n to m inus 15 °C.
Sono rna t ic L td 20 R iv ing ton
Cour t H ardw ick Grange
Woo ls ton Wa rr ing ton WA 1 4RT
U K
U l t r a s o n i c i m m e r s i o n
s y s t e m f o r S p a c e
S h u t t l e c o m p o n e n t s
A computer ized u l t rason ic
immers ion system, inc lud ing a
2.1 x 1.2 x 1.2m tank, has been
de l ive red by Phys ica l Acoust ics
Corpora t ion to Marsha l l Space
Center in Hunts vi l le , Alabama. For
te s t in g co mp o s i t e co mp o n e n ts o f
the space shut t le , the Marshal l
System w i l l be ab le to loca te and
size structura l f laws, such as
de lamina t ions, c racks and vo ids.
The U l t raPAC I I w i l l be used to
inspect parts of the space shut t le
in te r tank door and o ther
associated f l ight hardware.
Po s i t io n e d b e tw e e n t h e o xyg e n
and hyd rogen tanks o f the Shu t t le ,
the in te r tank door p rov ides access
to e lect ron ics , a t tach ing shu t t le
struts and fuel l ines, and is where
the tanks feed the three main
eng ines on the Shut t le .
As w e l l as the tank, the un i t
includes mo tor ized X, Y, Z axes
and tu rn tab le , a long w i th
th rough- t ransmiss ion adapte r and
squ i r te r -bubb le r t ransducer
assembly. Pump, f i l ters and
cont ro ls tha t can accommodate
either the squir ter assembly or fu l l
immers ion tank, comple te the
system hardware. Ma ter ia ls w hic h
cannot be immersed in water,
UltraPAC I I u l t rasonic imme rsion test ing system, for test ing Space Shutt le comp one nts
such as g raph i te w i th a foam
back ing , a re tes ted w i th the
squ i r te r assembly ; f la t, m id -s ized
panels can be tested in the
customized tank.
The U l t raPAC I I system so f tware
incorpora tes a 386 SX computer
w i th VGA graph ics . For smoother
scann ing and improved inspect ion
accuracy, a new four -axes motor
contro l ler card has been designed.
System features include A, B,
C-scan , f law de tect ion and
t ransducer characte r iza t ion
so f tware .
Phys ica l Aco ust ics Corpora t ion
P.O. Box 3135 Pr ince ton NJ
08543 - 3135 USA
N o n c o n t a c t
m e a s u r i n g s y s t e m s
Elect ro -op t ica l inspect ion system
specia l ists, C. E. Joha nsso n, have
in t roduced the i r Q-SEE
non- con ta ct m easur ing systems to
rep lace the ex is t ing Vid icom
range. Q-SEE machines use
s imi la r op t ica l systems and
Non-c on tac t o p t ica l gaug ing sys tem w i th comp ute r con t ro l , f rom C. E. Johansson
N DT E In te rna t iona l Apr i l 1 991 111