ORNL-1771 - Oak Ridge National Laboratory

ANP QUARTERLY PROGRESS REPORT
oxide remaining on the metal surfaces. The rig
is then washed with butyl alcohol, which reacts
with the NaK and leoves the surfaces clean and
ready to be filled with sodium.
The sodium is metered out into a tube that has
first been cleaned with NaK, sealed with Swagelok
fittings, and provided with a helium valve. A
micrometallic filter sealed into the line remov~ts
any oxides of sodium that may be formed when the
connection to the test rig is made. Once the con-
nection is made, the apparatus is evacuated and
the sodium is melted and forced into the chamber
by helium pressure through the valve; a combi-
nation of high surface tension and back pressure
made filling the chamber sonlewhat more difficult
without this procedure. For the bench tests, in
which sticks of sodium were used, the filled
chamber was heated while a vacuum was pulled
on the system, and a rise in pressure was noted
at about 525”F, presumably from dissociation of
sodium hydride. It remains to be seen whether
such a procedure is necessary to ensure the purity
of the sodium now available, The dry-box work
is completed by cutting the outer fill tube, re-
moving the inner (contaminated) tube, and crimping
and welding both the fill and exhaust tubes.
The entire assembly is welded into a stainless
steel water jacket furnished with Kovar seols and
a capillary tube through which helium flows
throughout the test. A probe beneath the weight
cuts off the current to the furnace at a prede-
termined deflection of the lever arm and indicates
the time required for a given degree of deformation.
A gravity “ti It” indicator aids in plumbing the
specimen in the exposure can. A base plate with
a conical cup furnishes a well for the sodium in
case of rupture during operation. A suitable safety
system is being developed,
Approval by the L-ITR Experiment Review Com-
mittee is being withheld until additional tests are
made on the compatibility of sodium with the
various component materials it might contact if
a rupture occurred at the test temperature. Several
tests aimed at a qualitative determination of the
speed of reaction and the heat generated by such
reactions should be completed within a short time.
After an irradiation period of from two to six
weeks in hole HB-3 of the LITR and a suitable
decay period, the specimen is to be sectioned by
the remote metallography group and examined for
stress-corrosion effects.
144
Bench tests on the specimen tube alone are
under way with the outside surface in air. The
inside of the tubes contains either air, helium, or
NaF-%rF,-UF, (50-46-4 mole %). An atmosphere
chamber has been built for testing four specimens
simultaneously in vacuum or any desired atmos-
phere. One 200-hr test has been completed on
barren NaF-ZrF,-LJF, (50-46-4 mole %) at 1500” F
and about 1500 psi. No stress dependence of
corrosion was found; another specimen was tested
for 400 hr but has not yet been examined. A
melting and overturning technique for removing
fluoride fuel from the section that is to be ex-
amined metallographically has been successful;
this will greatly simplify handling of irradiated
capsules.
The MTR tensile creep rig is undergoing final
testing and is scheduled for irradiation tests on
lnconel in October.
REMOTE METALLOGRAPHY
M. J. Feldmon W. Parsley
A. E. Richt
R. N. Ramsey
Solid State Division
Work was continued on the examination of the
solid-type fuel sandwiches of interest to the Pratt
& Whitney Aircraft Division. In addition to the
two experiments mentioned previouslyI6 six other
specimens have been examined. The results on
three of them (capsules 1-4, 1-6, 1-7) have been
publi~hed.~ A report covering the other three
capsules (1-5, 1-8, 1-9) is being prepared. Ex-
amination of the eight capsules processed to date
has indicoted greater resistance to cracking and
core-clad separation upon bending of the stainless-
steel-matrix samples than upon bending of the
iron-rnatrix samples, better resistance to cracking
upon bending of the large UO, particle size core
than upon bending of the smaller particle size
core, and a greater increase in hardness upon
irradiation of the small particle size core than
upon irradiation of the larger particle size core.
Work on solid-type fuel elements for the GE-ANP
group has continued. Examinations of two ni-
. .. . . . . . .
6A. E. Richt, E. Srhwortz, and M. J. Feldman, Solid
State Dzw. Semiann. Prog. Rep. Feb. 28, 1954, ORNL-
1677, p 9.
’M. J. Feldman et al.. Metalloerabhic AnaIvsis ol
Pratt and Whztney Capsules 1-4, r-6: and 1-7,’ ORNL
CF-54-5-41 (May 5, 1954).