ORNL-1771 - Oak Ridge National Laboratory

Fig. 6.17. As-Received Hastelloy B (u) and Hot-
Leg Surface of Hastelloy B Loop (b) After Circu-
lating NaF-krF4-UF, (50-46-4 mole %) for 1080 hr
at 15OOcF. Etched with H,Cr04 -1- HCI. 250X.
Reduced 36%.
Chemical analysis results now available for the
Hastelloy B loop previously operated4 for 500 hr
confirm the low attack rate found metallographical Sy,
since neither the nickel nos the molybdenum content
in the fluoride mixture increased.
LITHIUM IN TYPE 316 STAINLESS STEEL
E. E. Hoffman
C. R. Brooks
Metallurgy Division
W. H. Cook
C. F. Leitten
Tests have recently been completed on three
type 3 16 stainless steel the rma I-convect ion IOOPS
- - _.. . . ~ __ .- ~ ~
G. M. Adomson, .4NP @~27. PTOg. Rep. June 20, 19j4,
ORNL-1729, p 77.
PERIOD ENDING SEPTEMBER 70, 7954
in which lithium was circulated. These loops were
constructed of 0.840-in.-OD, 0.147-in.-wal I pipe.
The hot and cold legs were 15 in. in length, and
the 15-in. connecting legs were inclined at an
angle of 20 deg. The welding and loading opera-
tions on these loops were performed in a dry box
in a purified helium atm~sphere.~ At no time during
these tests was there any indication of plug fotma-
tion. The operating conditions are given in Table
6.9. Macroscopic examination revealed no dif-
ferences between hot- and cold-leg surfaces in
loops 1 and 2. Only loop 1 has been examined
completely; loops 2 and 3 hwe been sectioned
and have been examined macroscopically. Loop 2
was very similar in appearance to loop 1, with no
crystal deposition. Loop 3, however, revealed
mass-transfer crystals attached to the cold-zone
walls. These crystals did not plug the loop or
noticeably affect the circulation. The crystal
deposition was heaviest on the major radius of the
exposed loop-bend wall in the cold zone. This
loop has not yet been examined metollographically.
TABLE 6.9. OPERATING CONDITIONS FOR TYPE 316
STAINLESS STEEL THERMAL-CONVECTION LOOPS
Loop
No.
WHICH CIRCULATED LITHIUM FOR 1000 hr
. .... ..__. .
Hot-Zone Cold-Zone Temperature
Temperature Temperature Differential
(OF) (OF) (OF)
1 1490 1220 270
2 1472 1355 117
3 1301 1094 207
Loop 1, which was operated at the highest temper-
ature and with the highest temperature differential,
had no mass-transfer crystals in the cold zone, and
the maximum attack in the hot zone was 1 to 2
mils (Fig. 6.18). Chemical analyses of the lithium
and the amounts of crystals recovered are presented
in Table 6.10. At present it is not understood why
so little mass transfer occurred in loops 1 and 2,
since in a11 three loops the same procedures and
testing techniques were used and all were filled
from the same batch of lithium. Some as yet un-
discovered factor seems to have an effect on the
rate of mass transfer.
T-Er-Hoffman et al., Met. DIU. Serrizmn. Prog. Rep.
4Jr. 10, 1954, ORNL-1727, p 37.
99