FIFTH CANADIAN CONFERENCE ON NONDESTRUCTIVE ... - IAEA

NEUTRON RADIOGRAPHY
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Neutron radiography has been used for many years for inspections of nuclear
fuel and control material, explosive components in aerospace, and high performance
turbine blades from jet engines to cite a few examples from the transportation
and energy fields [2,22,23]. It has also been recognized for some
time that neutron radiography would provide particular sensitivity to hidden
corrosion because the hydrogen-containing components in the corrosion products
would attenuate slow neutrons while most metals that might be in the radiation
path would be relatively transparent [24,25], Recent developments in
transportable neutron sources, coupled with improved neutron detectors (including
real-time methods [26]) have increased interest in neutron radiography.
Much of this new interest involves detection of corrosion in aircraft and space
structures. Neutron radiographie equipment now available includes a mobile,
accelerator-based system developed for the Army [27], An example of corrosion
detection in aluminum structures with this unit is shown for both film and
real-time detectors in Fig. 3.
Other systems soon to be available include higher neutron output acceleratorbased
systems for the Air Force and the Navy [28]. In addition, a large neutron-inspection
facility for aircraft maintenance is being planned at McClellan
Air Force Base; aircraft will be positioned in a special inspection hangar
for neutron radiography [29]. The inspection of aluminum honeycomb structure
will be particularly useful for detecting water and corrosion.
A novel application of real-time neutron radiography is the observation of
fluid movements inside metallic structures such as engines, pumps, etc. Studies
of lubrication and fuel movements in engines by a Rolls-Royce, Harwell and
Burmah-Castrol team [30-32] have excited interest in this technique for better
understanding of the movements of these fluids in operating systems. An example
of results from these studies is shown in Fig. 4.
DISCUSSION AND CONCLUSIONS
Several novel radiation test methods have been described along with inspection
applications in the transportation and energy industries. The techniques described
represent some highlights concerning novel radiation inspection advances
but the review was not meant to all-inclusive. Other developments such as
semiconductor array detectors, image enhancement, scattering methods and automated
inspection [1,2,5,12,33-35] have not been covered here; these also represent
significant advances in radiography.
Also not covered are advances in computerized axial tomography [36], There is
now much industrial interest in tomography as an inspection method for missiles,
engines, turbine blades, space hardware and other components and assemblies.
Tomography provides a cross-sectional view of the inspection object to
yield information about dimensions and discontinuities. An example of a tomographic
scan of a turbine blade to show wall thinning is given in Fig. 5.
This limited review has shown that many new radiation test techniques are