ORNL-TM-1907.txt

 

 

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OAK RIDGE NATIONAL LABORATORY
operated by

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

UNION CARBIDE CORPORATION m
NUCLEAR DIVISION
for the
U.S. ATOMIC ENERGY COMMISSION
LDCI":HEE[.;I :-ua*.-.r_u ENERGY flESE_AH:HIUB_Hnm_gs- o RN L - T M B ] 907
[IIERARER YO
1 .|'.“| “ |.‘|| |‘ il ‘I‘ | |H COPY NO. - =
3 445k 0513418 2 paTE - July 21, 1967

CORROSION OF THE VOLATILITY PILOT PLANT INOR-8
DISSOLVER AFTER SEVEN COLD DISSOLUTION RUNS

E. C. Moncrief
A. P. Litman

ABSTRACT

The Volatility Pilot Plant dissolver vessel, based on ultrasonic thickness measurements,
seems to be sustaining low corrosion losses.

Wall thickness changes were measured for the Volatility Pilot Plant INOR-8 dissolver

a fter 204 hours of exposure to anhydrous HF and equimolar NaF-LiF fused salt contain-
ing 22-52 mole per cent ZrF at 495-655°C while Zircaloy-2 dummy fuel elements
were being dissolved. Measurements were taken using the "Vidigage, " an ultrasonic
thickness measuring device, first after an ammonium oxalate solution wash to dis-
solve residual salt, and later after an HNO3-AI(NO3)5 rinse to remove any metallic
deposits that might have formed.

For the dissolver, maximum wall thickness losses were nofed in the vapor region where
a maximum loss of 11 mils was found. This loss corresponds to 0.054 mils/hour, based
on HF exposure time, or 17.0 mils/month, based on molten salt residence time. Lower
losses occurred in the vapor-salt interface region, and still less in the salt region of
the vessel. Bulk metal losses due to the use of the oxalate and nitric acid-aluminum
nitrate solutions were considered negligible. OAK RIDGE NATIONAL LABORATORY
CENTRAL RESEARCH LIBRARY
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NOTICE This document contains informatian of o preliminary nature
and wos 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.
 

 

 

LEGAL NOTICE

This report was prepared as on account of Government sponsored work. MNeither the United States,

nor the Commission, nor any person acting on behalf of the Commission:

A. Makes ony warranty or representation, expressed or implied, with respect to the accuracy,
completeness, or usefulness of the information contained in this report, or that the use of
any information, apparotus, method, or process disclosed in this repert may not infringe
privately ownad rights; or

B. Assumes any liobilities with respect to the use of, ar for domoges resulting from the use of
any information, apparatus, methed, or process disclosed in this repert.

As used in the obove, "person octing on behalf of the Commission" includes any employee or

contractor of the Commission, or employee of such contractor, to the extent that such employee

or contractor of the Commission, or employee of such contractor prepores, disseminotes, or
provides occess to, ony informotion pursuant to his employment or contract with the Commissien,
or his employment with such contractaor.

 

 

 
\.\".

The Volatility Pilot Plant has.curréntiy completed a series of seven

cold dissolution runs using Zircaloy-2 dummy fuel elements according to

the head-end procedure of the fused salt Volatility Process.

- .These runs
were designed to evaluate the HF dissolution step of the Volatility Proc-
€sS. - N

A necessary part of that evaluation was the determination of the

corrosion losses occurring on INOR-8, the material of construction for
the dissolvef vessel

Table I summarizes the corrosion rate losses
nominal composition of INOR-8 is Ni: 71 wt %, Cr:

and Mo: 16 wt %.

runs and indicates that equimolar NaF-LiF fused salt containing 22-52

"The

7wt %, Fe: 5wt b, -
Table II details the process conditions for the seven

mole per cent Zth.waa used at temperatures of 495-655°C along with 1160 kg

of anhydrous HF to dissolve eight dummy fuel elements

schematic of the hydrofluorination operation.

'Figure 1 shows a

Wall thickness measurements were made prior to the development runs

and twice after run T-7 using an ultrasonic thickness measuring device,
the "Vidigage."

The first measurement after run T-7 followed a Wl hr

wash with boiling 0.35 M ammonium oxalate solution; and the second measure-

ment followed a 10 hr rinse with boiling 5 wt % HNO

v 3-5 wt % AL(NO
oxalate wash served to remove residual fused salt while the HNO

solver walls during fuel element dissolution.

. Th
3)(3 ©

)., ~AL{NO

| 3" 3)

rinse dissolved any metallic deposits which might have formed on the dis-

3

. Figures 2, 3, and 4 present
the data obtained and show that measurements were made at 90

_ ° intervals .
around the circumference of the dissolver at three inch height increment

The present operating orientation of the dissolver vessel is also indicated

Although a restricted number of readings were taken on the top

cylindrical section of the dissolver because of thé presence of insulation,

sufficient data were collected to indicate that the vessel had lost an

average of 9.3 mils on the inside diameter of that section (see Fig. 2)

1g. I. Cathers, "Fluoride Volatility Process for High Alloy Fuels,”
ORNL-CF-57-4-95, Presented at Symposium on Chemlcal Proce551ng, Brussels,
Belgium, May 20-25, 1957

 

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3

- This loss cbrresponds to 0.045 mils/hr, based on HF exposure time. The

top section was exposed only to the process vapors except for occasional
salt splash. However, for comparative purposes, an average rate loss
figure of 14.4 mils/month, based on molten salt residence time was also
calculated, The maximum wall thickness loss in the vapor region of the
dissolver, 1l mils, did not deviate greatly from the average quoted.

The conical section of the hydrofluorination vessel was exposed to -

" both process vapors and fluoride salts during the runs described. In

run T-7 the salt level was in the conical section; in all other runs salt
contact was from splash. The average wall thickness loss found for this

section was 4.2 mils, less than the 1% accuracy of the "Vidigage" instru-
ment, although a maximum of 10 mils loss was noted at one point (see

Fig. 3). Maximum rate losses were 0.0M9 mils/hr, based on HF exposure

4time or 15.4 mils/month, based on molten salt residence time,

The bottom section of the dissolver consists of five cylinders of

5-1/2 inches inside diameter and varying length joined by circumferential

welds'to form a right cylinder 9 feet in height. Thickness measurements
of this section did not disclose significant bulk metal loss (see Fig. 4).

However, two areas in the west quadrant did register unusual hlgh and low

- thickness changes. These 1rregular1t1es may be due to inaccuracies in the

' base~line data collected on the dissolver vessel. Excludlng the high and

low data -mentioned, a maximum loss of 6 mils was found for the bottom
section,

Comparison of the thickness Jata before and after the nitric acid-
aluminum nitrate rinse (Figs. 2, 3, and 4) ihdicated that negligible
changes occurred outside the accuracy of the "Vidigage" instrument.

The Volatility Pilot Plant dissolver vessel, based on ultrasonic

thickness measurements, seems to be sustaining low corrosion losses.

ECM:1j - o o
e

Table I. Summary of Corrosion Rate Losses on Volatility Pilot Plant
INOR-8 Hydrofluorinator after Seven Runs

 

 

Corrosion Rate

 

 

 

 

S . a ‘e b
Region ' Mils/hr . _ Mils/mo
Dissolver - Average Maximum - Average: Maximum

- Top - 0.0k45 0.05k 14,4 17.0
Cone ' 0.021 . 0.0k49 - 6.5 15.4

 

"Bottom . . 0.003 . 0.05h 1 17.0

®Based on HF exposure time of 204 hr.

bBased on molten salt residence time of 465 hr.

E .

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S - a.-, - » 3\
“ Table II. Summary of Zircaloy-2 Dissolution Runs in the Volatility Pilot Plant
‘ - . : | Zircaloy-2 HF
F?;ziésélfiagfgfgfgiéo?’ Saltogemp" HF Dissolution  Utilization
: b, Rate; Time, Rate, (Over-all

Run No. Initial Final . Max Min (g/min) (hr) (mg/cm®-min) Average)
T-1 h2.8-21.7-35,5 30.9-17.3-51.8 560 520 104 38.0 - 0.60 : 15.0'

- T2 38.3-30.1-31.6 30.2-26.8-42.9 530 525 Lo 41.5 " 0.l9 23.4
T-3 38.8-38.8-22.4 31.4-25.9-42.7 625 550 90 2.7 | 1.01 23.2
T-4 -37.3-37.3-25;3 29.3-27.3-&3.3 630 1495 90 22.5 1.01. 22.3
T-5 37.5-37.5-25.0  27.h-27.Lh-L5.2%% 625 530 ° 90 27.2 0.85 18.4
T-6 37.5-37.5-25.0 30.7-30.7-38.5%% 650 500 150% 25.7 0.87 ©11.3
T-7+ 36.9-36.9-26.3 25,.3-25.3-49.4%% 655 523 135  23.0 0.97 27.8

 

¥HF rate 118 g/min (avg) first 8.5 hr; 160 g/min thereafter.

. + - b | a )
Two elements dissolved during run

- #%Theoretical value (analyses of final salt not available to date).
—= : UNCLASSIFIED
o : ' . ' " ORNL-LR-Dwg. 53572

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

FV-1500 " 1 ,— FV-8501 Slug Carrler-Charger
Barren Salt - - '
Trons{er
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A HCV-1000-2 /Ccr:\:rct;er
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HF Cooler .
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3 ._ 1. Dissolver
Freeze
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FV-2005
HF Condenser
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\—'/ | FV-1006 —
- . HF Accumu- - ©8alt to FV-100

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

' FV-1009 . lator . and waste
Coustlc Neutralizer s
' - b ' _ HF D '
Q FV-4200 .

FV-1207

Milton Ro -HF Vapor Generator

Remote Head Y’ump

Fig. . Schematic Diagram of Hydrofluorinafion Operation.

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ORNL-LR-DWG. 54469

A .
(North) UNCLASSIFIED

 

1. Total HF time, 204 hr

2. BReadings taken on 1ineibeneath letters
every three inches. -

3. Dissolver cleaned with boiling 0.35 M
ammonium oxalate solution for 41 hr;
boiling 5 wt % HNO3 5 wt % AL{NO )
.for 10 hr.

 

 

 

{ (South)

Insulatiofl

 

    
 
 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

¢
< 3
4 on 1]
§<F2h-in. dia op Readings in Mils
~t 17
¢ Section (Accuracy ~t 1% of Material Thickness)
\ ~ (Normal - ~ Change in Wall Thickness
N 3/8 in. T After Oxalot After HNO3-AL(NO2)-
. Thick) er Vxa:gLe HV3-A3I3. 1 Averege
" f . A B | C D A B C D '} Change
4 . I =10 # 11 * -10 * ~10 * ~10.3
o 8 . :
- S§§\ -8 10 -8 -9 - 8.8
g -8 -11 -8 1 =10 .~ 9.3
\O | _ :
3 | 20| l-9 -11 | -5 - 8.8
_ |
st tE e *% ' L + 2 Fa _ -
H ' ek ¥ ** +1 + 1 -
o » o
h‘ fi LD ¥ H5 7 ¥ o + 2 -
Lo | -
— Over-all Average - 9.3
5.1/2 | |
dig'z; ¥B and D readings obstructed by FV-1000 heaters
¥*0riginal readings not available.
[ ]

 

 

Vessel Material INOR-B:) Ni 71 wt %, Cr T wt %,
Fe 5 wt 9%, Mo 16 wt %.

Normal salt interface: - 75-110 in. from bottom
. of FV-1000.
FV-1000 VPP Dissolver '

 

 Fig. 2. Summary of VPP Dissolver Corrosion Measurements (Top Section).

 
8 ‘ ORNL-LR-DWG+ 544770
' UNCLASSTEIED

 

Total HF time, 204 hr.

2. Reading taken on line beneath letters
every three inches.

3. Dissolver cleaned with boiling 0.35 M
ammonium oxalate solution for 41 hr;
boiling 5 wt % HNO.-5 wt % jAl(No3)3

 

 

 

- for 10 hr. 3

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_ Readings in Mils
{ - " (Accuracy ~t 1% of Material Thickness)
. -
] . Eg ' B ‘Change in Wall Thickness
20 in“dia—4«$: After Oxalate fAfter HNO3-A1(N03)3 Average
\ Al AT B C|D A B C D | Change
) ; - _ .
0 * 1 .6 | * +1 ¥ | b * -2.3
- -2 -3 -3 -2 -2.5
b S5 ] -k -1 -3 -3.3
& § 7
# A I -9 -6 -4 1. -4 -5.8
v f i oy 41t [
5 / - -6 |8 Joi |- -5.0
\0 - AT b -10 oL -8 -6.5
| ffi ! TR | - -2 | -8 -
- Cone : _ » : ‘
_ Section . Over-all Average -L.2
" (Nominal % . . : , 7
o2 | 1/2 in. B and D‘readingg obotrucped by FV-1000 hgaters.
S - Thick) Vessel muterial INOR-8: Ni Tl wt %, Cr T wt %,
,,Ei o Mo ;6 wt %, Fe 5wt b. . E
— ' '
" . ' . Normal salt interface: 75-110 in. from bottom
-] 5-1/2 : . ~ of FV-1000. - .
: inc v ; . - A n
dia -,
. T L ]

 

 

FV-1000. VPP Diszolver

 

Fig. 3. Summary of VPP Dissolver Corrosion Measurements (Cone Section).

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-9~ DNCLASSIFIED _ ~  ORNL-LR-DYG. 54471
1. Total HF time, 204 hr. ' .

2. Readings taken on line beneath letters
- every three -inches.

3., Dissolver cleaned with boilihg 0.35 M
ammonium oxalate solution for 41 hr; boiling

 

5 wt %lHHO3-5'wt % Al(N03)3 for 10 hr.

 

Readings in Mlls _
(Accuracy ~+ 1% of Materisl Thickness)

 

Change in Wall Thickness

 

 

After Oxalate After HNO3-A1(NO3) 4 Average

 

 

 

 

  

JReadings
jevery 3
~iinches

 
 

 

 

 

 

)

 

 

| U Botthm Section

(Nominal /% in. Thick)

 

FV-1000 VPP Dissolver

" Fig. 4.

   

 

'A_ B C 1D A B C D | Change
- | - - |- =2t =37 =Lkp -l
~3 | -3] 6] -3 [ -3] 3] -5 -2

 

 

 

 

 

 

 

 

 

: -3:>
3| -2} b2} b} -3) b} 51 -3.h
=2 | b b3 b -5) =30 5| -3 3.6
A1 | -k -2l a2} 5] Wb L} a2 ~3.0

01 «31 ~«2] -k § 0] =3{ +Ly O -l.k
31 +1 =31 =31 =3 +1] =3 Ol 41| ~l.1
il +3 4} L} -l +1 | ~3| 1] +1 +0.6
4] 0| 41| ~L| © O] O] <1} =1 =0.3
#L | 41| =1| -k ol +2] +1| -1 =0.1
0 O ~3{ -2 [ 41| +1| +1| =2 -0.5
41 | +2 “3 =1 0 +1 0 -2 «0.3
0 Of «1] O -1 O +L| =2 0.4
0 +1 ! -2 o 1| -1} o} -2 -0.6

0 | 42| -2| -1 O 41| 41] =1} O
+1 0| -1 O ! 41| +2]| +1{ 41 +0.6
+1. 0} ~2| © +1| +2 0 0 +0.3

0 +1, O -k +1] +2| +#1] -1 0
O | =6 =1| -2 | -1| -6 +41] +1| -1.8
41 | . =T] ~1| -2} +1| -8 o +1 -1.8
+2 -1l +1 0 +2 -7 +1 +1 -1,k
+1 |7 0| «3| =2 1 42| +1 1| 41 -0.1
+2- 0 o} -4 41| 0 0 0 -0.1

42 +10| -1]| «3- 0| 49| =1 0 +2.0
+1. +10| +1{ -2 0| +1q 4+ 0 +2.6
+2 | +10] -1| -1 +1| 8 0] +1 +2.5
+1 +3 ] 4| =3 +2] +2] -2 0] =-0.1
+2 41| -3} -2 +1 o} =L} =1] -0.h
+1 +1 | -2 -k 0 0] =~L| =1 -0.8
w2 | 2| b -2 +2] 0] -2| -0 -0.3
+2 +1 ~-51 -3 +1| .+2 -2 0 ~0.5
-1 -2 | «1l] -2 +1] O] <l| -2 -1.0
| w2 w2 -2 -2 of o 0 -1.5
-1 -21 ki b o <l -1} -2 -1.9
-2 =51 «5]| =5 +2| -0| <2 0. -2.1

Over-all Averaga. = <0.7

 

 

 

Vessel Material INOR-8: Ni TL'wt 9, Cr T wi %,
Fe 5wt %, Mo 16 wt %. T

.. Normal selt interface: 75-110 in. from botfom
- of FV-1000., - S :

Sumnary of VPP Dissolver Corrosion Measurements (Bottom Section).

L
-

 
~

210-

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