Molten-Salt Reactor Program Semiannual Progress Report, January 31, 1964 Page: 70
xvi, 166 p. : ill. ; 28 cm.View a full description of this report.
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70
lattice are being tested to make reasonably certain what level of tenacious-
ly held oxygen can be expected in the MSRE graphite moderator.
Lattice Constants
Precursory measurements of lattice constants have been made on samples
from two bars of the MSRE graphite, grade CGB. X-ray diffraction indicated
these to be 2.464 A for ao and 6.746 A for co. The patterns indicated a
well-graphitized material with a small amount of amorphous material. The
lattice constants of the nonporous impregnating phase were found to be
2.466 A for ao and 6.740 A for co. There were also indications that there
is some turbostatic structure present in this nonporous impregnating phase;
that is, there is an orderly arrangement of atoms in the layer planes, but
the planes have irregular azimuthal angles relative to each other. The
diffraction patterns for both the bulk graphite and the nonporous impreg-
nating phase were obtained on uncrushed material in order to minimize me-
chanical deformation of the lattice constants.
Reliable measurements of the lattice constants for the other micro-
scopically visible structural phase, the cellular-like impregnating phase,
have not been obtained because it has not been possible to get enough pure
sample of this material. Additional work will be necessary before typical
lattice constants can be assigned for the MSRE graphite.
Structural Integrity of Retainer Ring and Lattice Bars
The bars for the MSRE retainer ring and lattice bars were selected
and/or fabricated to have high structural integrity. A spare bar for the
retainer ring and six spare bars for the lattice bars have been received.
These were radiographed since they should be representative of the material
used.
The spare bar for the retainer ring was unmachined and was nominally
2-1/4 in. square and 57 in. long. It was a good bar except for two very
tight cracks, 1-3/4 and 5-1/4 in. long.
The lattice bars were fabricated with higher permeability than the
core bars in order to secure more structural integrity. The six spare
lattice bars had been machined to 1- by 1-5/8-in. cross sections and were
57 in. long. Three bars had no radiographically visible cracks, and three
bars had tight cracks. One bar had a 7/8-in.-long crack; another bar had
two cracks (3/8 and 2 in. long); and the other cracked bar had three cracks
(5/8, 3/4, and 1-1/8 in. long). There were slight density variations in
the bars. The radiographs of all six spare lattice bars had small low-
density spots in them that are probably voids partially or completely
filled with impregnants.
The overall radiographic examination of the spare bars indicates that
structurally perfect bars for the MSRE retainer ring and lattice bars were
not fabricated, but this goal was approached closely.
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Oak Ridge National Laboratory. Molten-Salt Reactor Program Semiannual Progress Report, January 31, 1964, report, July 1964; Oak Ridge, Tennessee. (https://digital.library.unt.edu/ark:/67531/metadc100344/m1/88/: accessed April 19, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.