ORNL-2106 - the Molten Salt Energy Technologies Web Site

ANP PROJECT PROGRESS REPORT
It was also found that the silicon content had
dropped to about one-third its normal value (5%)
in the depleted area. Evidence of the time de-
pendence of the amount of depletion is presented
in Fig. 3.2.4. None of the buttons tested showed
attack to a depth of more than 0.5 mil.
Hardness measurements on the interior of the
Fig. 3.2.3. Typical Crack Found in an lnconel
Joint Brazed with the 70% Ni-13% Ge-11% CrdX
Si Brazing Alloy After Exposure for 500 hr to NaK
at 15006F in an lnconel Thermal-Convection Loop.
Etched with 10% oxalic acid. 1OOX. Reduced 29%.
144
Sample
button exposed to NaK for 350 hr gave a value of
716 DPH, while measurements at the edge gave
a value of 145 DPH, as shown in Fig. 3.2.5. The
buttons tested in the fuel mixture gave similar
hardness traverse results. Chemical analysis of
the fuel mizture from the 500-hr test and of the
NaK used in the 100-hr test showed significant
concentrations of boron.
NIOBIUM IN STATIC SODIUM
D. H. Jansen
Specimens of niobium were tested in static
sodium at l5OOoF for a period of lo00 hr to de-
termine the suitability of liquid sodium as a pro-
tective environment for niobium during high-
temperature mechanical property tests. The tests
were designed to show whether the niobium would
be corroded by the sodium and whether the hard-
ness of the niobium would be appreciably altered
through the pickup of oxygen from the sodium.
The specimens were contained in type 304 stain-
less steel and lnconel capsules, and the variables
such as the volume of the bath, the container size,
and’ the area of the specimen were adjusted to
obtain a surface-area-to-volume ratio that would
be as close as possible to that found in creep-test
equipment. Cold traps were utilized on the bottom
of each capsule to reduce the amount of oxygen
in the sodium bath. The niobium specimen tested
in the type 304 stainless steel capsule showed
more evidence of surface roughening than did the
specimen tested in the lnconel capsule, Fig. 3.2.6,
and the thickness loss was also more than that
of the specimen tested in the lnconel capsule,
Table 3.2.3. A thin, brittle layer, approximately
TABLE 3.23. RESULTS OF TESTS OF NIOBIUM IN STATIC SODIUM
Exposue time: 1000 hr
Temperature of sodium: 1500°F
Hardness Thickness Loss
Impurity Analysis of Somple (ppm)
(VHN) (mils) H2 02 N2 I C
As-rece ived material 130.5 2.4 40 125 300
Specimen tested in type 304 135.0 3.0 3.8 84 250 370
stainless steel tube
Specimen tested in Inconel 116.4 1.8 3.4 90 92 1180
tube
L4