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Toble 18.3. Thermal Convection Loop Operation Through August 31, 1967
1255 Hastelloy N Hastelloy N + 2% Nba
1258 Type 304L Type 304L stainless
stainless steel steel
10 Hastelloy N None
12 Croloy 9Ma
13 Hastelloy h
14 Hastelloy N
15 Hastelloy N
Croloy 9Ma
Ti-modified
Hastelloy N
TI-modified
Hastelloy Nd
Ti-modified
Hastelloy Nd
16 Hastelloy N Ti-modified
‘Scheduled to start operation 9-30-67.
hr of exposure, and the rate of weight loss sub-
sequently declines with time. While several per-
turbations in the rates are obvious, in general,
the rate loss has remained constant at between 1
and 2 mils per year equivalent uniform attack.
This is many times the corrosion rate observed
for Hastelloy N under similar conditions.
Coolant Salts
Loops 10 and 12, both of which have ceased
operation, contained a fluoroborate salt which is
a candidate coolant salt because of its low cost
and low melting point. Loop 12, constructed of
Croloy 9M, plugged after 1440 hr circulation due
to mass-transfer and deposition of essentially
pure iron crystals in the coldest portion of the
loop. Similar crystals were found adhering to
specimens in the leg. A green dep
a variable compo n of 15 to 17% Fe, 11 to 14%
Cr, 2 to 4% B, 1.5% Mn, 10 to 15% Na, and 46% F
was noted in the drain pipe (Fig. 18.12). A best
SNommal analysis % Cr-1% Mo-Fe balance.
LiF-BeF 2-ZrF ,-UF,-ThF,
(70-23-5-1-1 mole 70)
LiF-BeF ,-ZrF,-UF,-ThF,
(70-23-5-1-1 mole 70)
NaF-KF-BF
(48-349 mole X)
NaF-KF-BF
(48-3-49 mole %)
LiF-BeF 2-UF4
(65.5-34-0.5 mole %)
LiF-ThF, (71-29 mole X)
NaF-BF3 (SO-SO mole %)
NaF-BF3 (SO-SO mole 7%)
~
dRemovable specimens.
1300 160 47,440
1250 180 36,160
1125
1125
1300
1250
1125
1125
eScheduled to start operation 9-15-67.
265 8,765b
100 (c)
300 (e)
300 (e)
Fig. 18.12. Plugging in Croloy 9M Loop 12 Containing
NaF-KF-BF3 (48-3-49 mole %) after 1440 hr at 1125OF.
AT= 260OF.