ORNL-CF-59-8-133.txt

 

'DATE:

suBJECT: Molten Salt-Graphite Compatibility Test.

e By o

Distribution

- chemical composition of "impervious™ graphite rods

. ppnm respectivelyl._ :

WASTER
| EXTERNAL TRANSMITTAL
S aiaZiD.

 

   
  

 

OAK RIDGE NATIONAL LABORATORY
Ope;uted by N
UNION CARBIDE NUCLEAR COMPANY
Division of Union Carbide Corporation

uee

Post Office Box X
Ock Ridge, Tennessee

T .
-

I

by - P
Ll

CENTRAL FILES NUMBER
HhO-8-_Lz7
. COPY NO. 7/

  

 

 

August 31, 1959

Results of Physical and Chemical Measurements

R. J. Sheil, R. B. Evans, and G. M. Watson

ABSTRACT
The observed changes in dimensions, weight, and

in contact for a year with flowing liquid LiF-BeF,-
UF, (62~37~1 mole %) in a pump loop at 1300°F are
listed. On the average the change in diameter was
less than 0.02%, and the change in weight was less
than 0.03%. Chemical analyses of machine cuttings
from the graphite rods show average uranium and
beryllium concentrations of approximately 20 and 100

'NOTICE

This document éontqin_s information of a preliminary nature
and was prepared primarily for internal use at the Oak Ridge
National Laboratory. It is subject to revision or correction
and therefore does not represent a final report. The information
is not to be abstracted, reprinted or otherwise given public
" dissemination without the approval of the ORNL patent branch,
Legal and Information Control Department. o

 

wE
a

 

 MOLTEN SALT~-GRAPHITE COMPATIBILITY TEST
RESULTS OF PHYSICAL AND CHEMICAL MEASUREMENTS

In a graphite moderated-molten salt reactor, certain
advantages are possible if the graphlte is in direct contact
with the circulating fluid. The feasibility of such a design,
which depends to a large extent on the compatibility of the
graphite-fused salt system, was tested by inserting 56 samples
of an impervious graphite contained by INOR=8 in a flowing

stream of LiF~BeF,-~UF, (62-37-1 mole %) for a period of one -
year at 1300°F.

The_experimental assembly consisted_of’a pump loop
constructed and operated by the Metallurgy Division and the
Experimental Engineering section of the Reactor Projects
Division as described elsewhere,l

 

Graphite Loop - Initial Preparations

Two sets of graphite specimens were obtained from the
National Carbon Company. All rods were 11" long and either
1/2" or 3/16™ in diameter. After calipering and weighing,
the rods were packaged in an INOR-8 box as shown in Figures 1
and 2. Each of the larger was fitted with four spacing rings
to permit the desired flow characteristics and to provide
samples for carburization and metallographic examination.

Upon welding the cover plate in place, the assembly was

swaged in the loop and the graphite degassed under. vacuum for

24 hours-at 1100°F., It was then repressured with argon before
being contacted with salt. During operation, a total presspre
of 13 psig was maintained on the graphite; 3 psig the contri-
bution of the helium cover blanket and the remaining due to
the head developed by the pump-rate of 1.1 gal/min., VWhen the
test was completed, the salt was drained from the loop and

‘sampled for optical_micrqscopy,_X~ray and wet chemical analyses.

 

1. J. LJ Crowley, ‘MSR Quar. Prog.-Rep.* Jannary 31 1958
0RNL~Z474

732 @ &

 
 

 

 

 

Fig.1.

 

UNCLASSIFIED
PHOTO 30631

 
. UNCLASSIFIED
ORNL-LR-DWG 44088A

& &L

 

 

 

Fig. 2. Numbering Scheme for Positioning Graphite Rods.

 
 

The box containing the graphite was opened by grinding
off the- top of the container in the Y«l2 Beryllium Shop.
Figure 3 is a photograph of the opened vessel after exposure
to molten fluorides for one year at 1300°F.

Post Test Examinations

A. Salt Condition. =~ The chemical analysis, given in
Table I shows the chromium content of the salt increased from
135 ppm to 550 ppm. Petrographic and X-ray analyses did not
reveal any oxidation products or dissolved carbon.

 

B. Graphite Condition

 

1. Chemical Analyses Data. Machined increments
of graphite specimens were submitted for chemical analysis.
Successive cuttings, 1/32™ in depth were taken from two of
the larger diameter rods until center portions of less than
3/16™ diameter were left. These portions and "as received™
impervious graphite "blanks™ were then ground to =100 mesh
in a mortar and pestle (thoroughly scoured with Ottawa Sand
according to the recommendations of the Analytical Chemistry
Division after ‘each grinding). All graphite samples were
submitted for an analysis of the uranium and beryllitm con-
centrations. Two machine cuttings, 1/32" in depth, were taken
from four additional rods. These results are given in .
Table IX with the beryllium and concentrations graphed as a
function of penetration depth in Figure 4. Only a very slight
migration of salt to the center of the graphite is noted.

2. Physical Changes in Graphite. Macroscopically,

there was no change in the rods. None of the samples were -

- broken or distorted and except for the bottom layer of rods
- that was covered with solidified melt, the salt did not adhere

- to the graphite. The weight and dimensional changes observed
af ter they had been contacted with circulating fluorides are
listed in Table III. The dimensional changes for the 13-~1/2"
diameter rods corresponded to an average loss of less than
0.5 mil in diameter which approximates the probable error of
the measurements. . Otherwise, there was no evidence of erosion.
Weight losses, which ranged from negligible to 0.05% and |
averaged 0.02% could be attributed to desorption of residual
gases from the graphite. No statistically significant differ=- -
ences were noted in the 13-1/2" diameter rods as compared with
‘the 8-3/16" diameter rods for whichnweight data were available.

Based on the 1oss in weight of the test samples and the

chemical analyses of the machine cuttings, it appears that only
minute quantltles of salt permeated the graphite.

723 ¥ 5

 

 
 

 

 

 

UNCLASSIFIED
PHOTO Y30339

 

 

 
 

 

 

 

 

 

 

-7 -
Table I
. Chemical Analyses of Fuel*
. | Wt. % o Theoretical*#* ___rou
| ~_Be U/Be _U/Be Fe Cr_Ni
Charge 4.87 8.37  0.582 0.767 235 135 5
After
- operating , | |
1 year 4.97 9.77 0.509 330 555 25
¥  G. J. Nessle, Persona1 Cofimunication.'
** Calculated for LiF-BeF,-UF; (62-37-1 mole %).

22y

 
 

 

Pi

‘Table II

Analyses of Machine Cuttings from Graphite Rods

| Rod Cutting . PPM Theoret:i.cal1 Actual
. No. _No. T Be U/Be _U/Be
8 1 30 125 0.573 0.240
v 2 9 175 0.051
* 10 <1 -
11 1 22 125 0.176
2 10 110 0.091
14 1 24 75 0.320
. 2 28 105 0.267
23 1 17 125 0.136
-2 <1l 60 0.017
* 5 < 1 -
18 * 8 <1 -
1 50 170 0.294
2 15 130 0.115
3 15 125 0.120
4 12 100 0.120
5 10 65 0.154
- é 13 105 0.124
7 <1l 50 0.020
8 13 - 140 0.093
’ 9 . 5 165 0.030
10 <l < 1 1.000
11 6 105 0.057
12% <1l <1 o _
- Center 100 125 . 800,”
31 % 5 <1 -
. o 1 20 165 0.121
| 2 18 140 0.129
° 3 24 120 0.199
4 20 - 85 0.235
- - 20 75 0.267
i 6 20 8¢ - 0.250
T 17 55 0.310
8 <1l 80 0.013
9 <1 - 95 6.011-.
10 <1 <1 - 1.000
11 <1 90 0.011
Center 70. 170 0.411
* <1 <1 -

 

*'Samples machined from as received™ material. |
1. Based on chemical analysis at original salt batch, nominally

LiF-BeF, ~UF; (62-37-1 mole %fl

73? v
“

- Impervious Graphite‘Rods (0.5" diameter)

‘Before Exposure

 

 

Impervious Graphite Rods (3/16" diameter

9.1095
9.4826
9.0329
9.3176
8.7251

Weight Dia.
- _(gms) - (in.)
Lost
"Lost
68.0556  0.498
68.0571 0,498
68.5709 0.502
68,4152  0.500
68.7779  0.499
67.7389 0.496
68,2650 0.498
Lost |
68.5801 0.500
67.9828  0.497
68.2956 0.499
68.6806 p.501
67.8522 0.499
67.9389  0.499

9.0932

- 9,5142
9.0149

¥

 

- Table III

Weight
(gms)

68.0397

68,0438
68.5572

68.4096

68.7639
67.7205
68.2517

68.5793
67.9703
68.2911

' 68.6666

67.8352
67.9169

9.1082

- 9,1228

9.4810

After Exposure

(in.)

ao496
0.497
0.501
0.500
0.500

0.497

0.500
0.496

0.500

0.501
0.498
0.498

9&9352'~'

9.3126

. 8.7372
90930
9&5998.

9.0104

Net
Change

(gms)

-650158 i

=-0.0133

. =0,0137

~0.0056
~0.0140

- =0,0133

~0.0008
-0.0125
-0.0045
-0,0174
~0,0220

"""Oo 9913
-0.0012
~0.0016

+0.0021

-Ga. 9059
+0.0121
~0,0002

-0.0044
=0.0045

Percent
Change

-0,.02
-0.02
~0.01
~0.02 .
-0.03
-0'02

. 0.00
- ~0.03
~0.01
=0 .02
- ~0.03
=~ . 04

-0.01
-0.01
-0.02
+0.02
-0.05

40,14

0.00
-0.05

 
£ €2

o7

URANIUM, BERYLLIUM CONCENTRATION (ppm)

200 |

160

80

—40

UNCLASSIFIED

 

?..

ROD 18

 

 

ROD 3¢

ORNL-LR—-DWG—44131A

A

 

«—BERYLLIUM

1.

 

 

120 |—

BERYLLIUM

 

 

 

¥
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40|

 

 

 

 

 

 

 

URANIUM

.Z/'\l—o-o\.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

WAL W

a; 8 12 16 4 8 12

/52 /32 /32 /2 O /32 732 /32
. DEPTH (in.)

Fig.4. Penetration of an Impervious Graphite by ‘LiF-B_e FZ-UF4 .

16,
4/32

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19.

21.
ZZ.
23.
24,

25.

26,

27.

28.
29.

30.
31.

- 32,

33.

34,

M. Weinberg
- A. Swartout
. E. Boyd

'A. Charpie
,.H, Jordanmn

. B. Briggs

G. MacPherson

C. Lind

L. Culler
R. Grimes

. H, Taylor
. L. Boch
, G. Bohlman

A. Bredig

, R. Bruce
., P. Fraas

D. Manly
F. McDuffie
Jd. Miller

"F. Baes

J. Barton

. Blander

F. qunkenship
E. Browning
Cantor

R. Cuneo

, B. Evans

- Insley

. V. Jones |
. W, Keilholtz
. J«. Kelly

Langer
L. Marshall

 

- 11 =

GRNL Y~12 Technical Library

 

Distribution —
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36. G. J. Nessle
.37. R. F. Newton
. 38. L. G. Overholser
390.-Wp Tg Rainey
40. J. H. Shaffer
41. M. D. Silverman
42. B. A. Soldano
43. R. A. Strehlow .
44- "R« E. Thoma
45, G. M. Watson
- 46, L. G. Alexander
47. K. B. Brown
- 48. G. I. Cathers
49, J. H. DeVan
50, L. M. Doney
51. J. S. Drury
52;' D. Eq Fergus'on
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55, H. W. Hoffman
56. B. W. Kinyon
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58. . W, B. McDonald
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62. P. H. Emmett (Consultant)
63. D. G. Hill (Consultant)
64=-68. Central Research Library
' 69-89. Laboratory Records Department
'~ 90. laboratory.Records, ORNL R. C.
‘91, Reactor Experimental Eng. Library
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