ML19029A864

04/24/1979 Legal Correspondence Non-Proprietary Version of Exxon Nuclear Company'S Report on Fuel Storage Racks Corrosion Program

ML19029A864
Person / Time
Site:	Salem
Issue date:	04/24/1979
From:	Wetterhahn M Conner, Moore & Corber, Public Service Electric & Gas Co
To:	Kornblith L, John Lamb, Milhollin G Atomic Safety and Licensing Board Panel
References
Download: ML19029A864 (23)

Text

RELATED CO~ONDENCJ?

LAW OFFICES CoNNER.MooRE & CoRBER 1747 PENNSYLVANIA AVENUE, N. W.

TROY :e. CONNER, JR. WASHINGTON,D.C. 20006 ARCH A. MOORE, JR~

ROBBB.T J. COB.BER MA.RXJ.WETTERELA.:e:N April 24, 1979

~/iif(r1 DONALD J. BALSLE:Y, JR.

ROBERT K. RAJ:>BB (.ao.a) a::i::i-::i:100 B:E:lTH H. ELL:lS 6KOT AlHll:ZTTZD :llC' D.C.

CAB:Lll: ADDRESS: ATOMLAW Gary L. Milhollin, Esq. Mr. Lester Kornblith, Jr.

Chairman, Atomic Safety Member, Atomic Safety and and Licensing Board Licensing Board Panel 1815 Jefferson Street U.S. Nuclear Regulatory Madison,. Wisconsin 53711 Commission Washington, D.C. 20555 Dr. James c. Lamb, III Member, Atomic Sa'fety. and Licensing Board Panel 313 Woodhaven Road Chapel Hill, N.C. 27514 In the Matter of Public Service Electric and Gas Company, et al.

(Salem Nuclear Generating Station, Unit 1)

Docket No. 50-272 Gentlemen:

In otder to minimize or eliminate the need for an in camera session with regard to the Exxon Nuclear Company'S proprietary report, Fuel Storage Racks Corrosion Program, XN-NS-TP-009, I am transmitting herewith a non-proprietary version of that document* to the Board and parties.

Wetterhahn Counsel for the Licensee cc: Chairman, Atomic Safety and Licensing Appeal Board Panel Chairman, Atomic Safety and Licensing Board Panel Barry Smith, Esq.

Richard Hluchan, Esq.

Richard Fryling, Jr., Esq.

Keith Onsdorff, Esq.

Sandra T. Ayres, Esq.

Mr. Alfred c. Coleman, Jr.

Mrs. Eleanor G. Coleman Carl Valore, Jr., Esq.

Off ice of the Secretary June D. MacArtor, Esq.

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.NUCLEAR FUEL STORAGE RACKS CORROSION PROGRAM, BORAL STAINLESS STEEL (NON-PROPRIETARY VERSION)

MARCH 1979 GR-005

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'NUCLEAR IMPORTANT NOTICE REGARDING CONTENTS AND USE OF THIS DOCUMEN~

1. Exxon Nuclear Company's warranties and representatives concerning* the subject matter of this document are those set forth in the Agreement between Exxon Nuclear Company, Inc. and the Customer pursuant to which this document is issued. Accordingly, except as otherwise expressly provided in such Agreement, neither Exxon Nuclear Company, Inc. nor any person acting on its behalf makes any warranty or re-presentation, expressed or implied, ~ith respect to the .

accuracy, completeness, or usefulness of the information contained in this document, or that the use of any information, apparatus, method or process disclosed any liabilities with respect to the use of, pr for damages resulting ffom the use of any information, apparatus, method or process disclosed in this document.

2. The information contained herein is for the sole use of Customer.

XN-NS'"'.TP-009 VALIDATING SIGNATURES VALIDATING SIGNATURES:

Revision No. and Date Rev a (11-10-78) Rev. 0 (3/14/79)

Revised Sections Proprietary All Revised Pages Vers*ion Non-Proprietary Version Prepared By

~;~

Project M~nager

-?.:?~----

Date 11/1.0 h1 Concur.red By t}~

Mgr. Mechanical Engr.

• Date I/ /1tJ I 7 r:

~~,,,,.,.,,.._-/.--

Mgr. Licensing/

Compliance Date 11/1~ _/?!

Approved By gj-1~-1----=~

Mgr. Storage Engr.

Services Date

EX[ON

,NUCLEAR

e. e XN-NS- TP-009/NP TABLE OF CONTENTS ABSTRACT i

1.0 INTRODUCTION

1-1 2.0 TEST PROGRAM DESCRIPTION 2-1

2. 1 Specimen Description 2-1 2.2 Environment Description 2-2 2.3 Initial Measurements 2.-3 3.0

SUMMARY

3-1 4.0 RESULTS 4-1

4. l

• Internal Environment of Edge-Sealed and Storage Cell Specimens 4-1 4.2 Visual Appearance 4-2 4.3 Weight Gain 4-3 4.4 Pitting 4-5 4.5 Meta 11 ography 4-6

4. 5. 1 Surface Corrosion Films 4-6 4.5.2 Edge Attack 4-7 4.5.3 Bulges. 4-7 LIST OF REFERENCES

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,NUCLEAR ABSTRACT Exxon* Nuclear Company, Inc. has conducted a Boral*-Stainless Steel Corrosion Program during the past 18 months to establish additional performance information for use of Baral plates in spent fuel stor-age applications~ The program consisted of a detailed_review of related literature, an evaluation of test programs conducted by others, and additional corrosion tests performed at Exxon Nuclear facilities.

The objective of the Exxon Nuclear test program was to obtain corrosion data for Boral-304 stainless steel test*specimens in simulated PWR fuel pool environments so that reliable predictions could be made of what physical.changes would occur in a defective, i.e., unsealed spent fuel storage cell after a 40-year exposure.

The Exxon Nuclear.tests indicate that storage cells, containing a leak simulating hole, will sustain aluminum corrosion at a rate which can be expected to consume of the aluminum in the Baral core after a 40-year exposure.

Should Baral plates be exposed to a typical PWR pool environment, the material is subjected to pitting, edge attack, and internal gas pressuri-zation; but no effect on criticality safety is expected over the lifetime of storage cells due to dislodgement of s4c particles.

• The Baral test samples discussed in this report are a neutron absorbing, shielding material manufactured by the Brooks and Perkins Company. The Baral specimens are a composite material consisting of boron carbide evenly dispersed within a matrix of aluminum and clad with aluminum.

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1.0 INTRODUCTION

Prior to designing*racks utilizing stainless steel clad Baral plates in PWR pool environments,_ Exxon Nuclear initiated, (during 1976 and early 1977), a rev*iew of applicable material corrosion 1iterature and conducted analys.es of test results performed by others.

Exxon Nuclear's review of the r~lated literature*, and performance of.

Baral *tn similar environments, indicated that there should be no adverse effect on nuclear safety analyses of storage racks in a PWR pool environment. To provide further assurance of satisfactory material performance, Exxon Nuclear initiated a test program in February, 1977 to evaluate Baral clad in stainless steel 304 specimens in environ-ments simulating utilization in Exxon Nuclear PWR storage rack applications.

• Li~t 6f appropriate mat~rial contained in Reference section of this report.

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,NUCLEAR 2.0 TEST PROGRAM DESCRIPTION

• 2. 1 SPECIMEN DESCRIPTION Exxon Nuclear's test program placed emphasis on investigation of Bo.ral utilized in conditions typical of expected storage cells and PWR pool water environments. Consequently, storage cell component sections were fabricated which resembled the larger, ful*l-size storage cells. Specifically, these reduced-size storage cell specimens consisted of inner and outer stainless *steel 304 shrouds int~ which four (4) Baral plates were inserted. The complete assembly was sealed welded, resulting _in 611 high x 611 wi*de test specimens. Each completed cell specimen was made to simulate a leaking condition by drill~

. ing 1/16-inch holes as described in Appendix A.

In order to separately observe and measure various corrosion and material properties during the test, additional test specimens were utilized. These additional specimens consisted of 211 x 2" coupons made as follows:

1) Open-edge Baral/stainless steel composite; *

2) Sealed-edge Baral/stainless steel composites with a leak simulating hole; and,

3) Unencapsulated Baral coupons.

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,NUCLEAR 2.2 ENVIRONMENT DESCRIPTION Insulated nine (9) gallon polyethylene tanks, with fitted covers, were used for the plain Baral and open-edged'Boral-stainless specimens. Thirty (30) gallon tanks of the same construction were used for the closed-edge tests. Each tank was fitted with a stainless immersion heater and stirring mixer, which were affixed through openings in th~ tank covers.

A stainless steel screen was used to hold the specimens off the bottom of the tanks and *permit circulation of the environ-ment on all sides. In order to isolate the plain Baral speci-mens from the stainless steel screen, a ped~stal was fashfoned from phenolic plastic. The open-edged composite samples, a 2 x 2 Baral piece sandwiched. between two 2 x 2 stainless 11 11 11 11

• steel pieces, were held together with four (4) Met-clip springs~ one along each edge. These were placed on the stain-less screens so that the clips held the specimens in a hori-zontal posttion over the* screen.

The initial environment in each tank was deionized water with a pH of 5.ss*and a conductivity of 0.75 µ mho/cm. Boric.acid (H 3so 3) and lithium hydroxide (LiOH H20) additions were made to produce the following:

Environment A) Deionized water plus 13.3 g/1 Boric Acid (resulting in 2'300 ppm Boron at 150°F).

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,NUCLEAR Environment B) Deionized water, 13.3 g/l Boric Acid, 0.0121 g/l lithium hydroxide Environment C) Deion.ized water_ plus 0.0121 g/l lithium hydroxide

.The specimens, were immersed in each environment on July l, 1977. The initial temperature and pH of each ~nvironment were measured as follows:*

Environment _El!_ Tempera tu re, °F l 5.20 . 146. 4 2 5.53 147 .'2 3 9. 15 153.4 The.temperature and pH were. measured daily. The temperature showed some fluctuations and variacs were installed in order to gain better temperature control. The pH in the borated solutions, 1 and 2, remained constant but in the alkaline tank, C, it dropped into the 7 range within.* days. *In order to keep the solution pH in the alkaline range, addi-tional additions of lithium hydroxide were made.

2.3 INITIAL MEASUREMENTS

. Appendix A of this report contains descriptions of all Baral and stainless steel specimens utilized for the test program.

The initial measurements and cleaning programs are also pro-vided in Appendix A.

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,NUCLEAR 3.0

SUMMARY

No corrosion, pitting, nor stress-corrosion cracking was observed on any of the stainless steel coupons, or storage cell specimens used in this study. The austeniti.c stainless steel can be expected to withstand exposure-to borated fuel pool environments for the pro-

. jected forty-year life of spent fuel racks. Similarly, without a leak path through the stainless steel liners, the interior Baral plates would not be s*ubject to degradation as a result of aqueous corrosion. In the situation of a leak path through the stainless liner~ which permits the interior space to fill with the pool environ-ments, the *.results of the 2 month; 6 month, and 12 month exposure studies,

. show that Bo~al is subject to general corrosion, pitting and edge attac~,

and clad deformation due to internal gas pressurization. To various degrees, the severity of each of these corrosion effects depends on the particular environment chemistry and the specific geometry of the exposed materials. Based on comparisons between the four (4) specimen types and the three (3) environments -used in this study, the following summary can be drawn concetning the corrosion resistance of Baral and its suitabili~y for use when exposed in stainless lined storage cells 'to borated environments.

The general corrosion rate, as determined by weight gain measurements, When all the storage cell specimen data are examined on a semi-log plot, the amount of aluminum consumed in conversion to oxide after a 40-year exposure,. is: percent for the low pH and percent for the higher pH environments.

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'NUCLEAR The weight gains were lowest for the storage cell specimens in each of the three (3) environments, followed in general by the plain, open-edged, and edge-sealed specimens. The weight gains, measured for the plain and open-edged specimens, wer~ nearly identical to each other in the three (3) environments. This similarly indicates that galvanic coupling between the stainless steel in the open-edged specimens does not accelerate general corrosion in the Baral.

In all ihree (3) environments, the edge-sealed specimens showed the greatest weight gain.

Similar considerations apply to edge attack of the Baral. However, the depth of edge attack did*not increase. significantly betw~en the 3-2 GR-005

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.NUCLEAR 6 and 12 month exposure. The deepest edge penetration, 0.028 was 11 measured on the open-edged specimen in the low pH environment. No measurable edge attack was* observ:d in the vicinity of the leak simulating hole in 'the Baral plates of the storage cell specimens.

Gas generation, due to corrosion of the aluminum in Baral, has been observed in the edge-sealed specimens and the storage cell specimens.

This gas has been observed to bubble from the upper hoJe in each of the storage cells. In several of the specimens removed after 12 months, bulges were observed between the aluminum cladding and the B4C aluminum core.

. The occasional unhanded layers of the Baral matrix occurred randomly and were observed in concentrated areas of very small B4C particles*

• (i.e., ~150 mesh) .. It has been determined that the Baral specimens provided by Brooks and Perkins for the ENC corrosion test program con-tained a much higher concentration of small B4c particles than utilized for production Baral plates~ Accordingly, it is possible that the small bulges observed on the sealed specimens*may not occur in finished plates where improved s4c and aluminum bonding result with larger B4C particles.

The occasional lack of bonding between B4c and aluminum particles also allows a small amount of water to enter the inner portions of the bulged.

specimens. Normally, water does hot penetrate into well-bonded Baral plates and no internal corrosion can occur.

The small bulges have not been reported or observed in prior related corrosion test programs. They appear to be a self-limiting phenomenon, 3-3

cJX.UN NUCLEAR e.

where the gaseous corrosion product both causes the bulge and dis-places the water causing.the corrosion. An inspection of both the aluminum cladding and inner Baral matrix demonstrates that no clad pitting or deterioration __of the inner face of cladding and Baral material occurred near the bulged areas. Consequently should random small bulges occur, any dislodgement of B4c particles will be of no significance on neutron shielding or attenuation properties.

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. . NUCLEAR 4.0 RESULTS On June JO, 1978, after a nominal 12-month exposure, the remaining three (3) plain Baral and three open-edged

• Boral-stainl~ss composite specimens, were removed from

• the three (3) heated tanks. On August 10, 1978~ the edge-sealed, and storage cell specimens, were removed from their environments. These twelve (12) samples were subjected to visual, metallographic, weight ~ain, and pit depth measurement analyses.

This section of the report places emphasis on the de-tailed results obtained from the storage cell specimens.

Appendix B presents additional test results for other specimens and contains most referenced tables and figures.

for information presented in this section. Table 4. l provides specimen identification numbers and exact lengths of exposure for each of the twelve (12) specimens eval-uated during the final period.

4.1 Internal Environment Of Edge-Sealed And Storage Cell Specimens The pH of the solution, within the edge-sealed and storage cell specimens, was measured using indicator paper for the former, and a Beckmann pH meter for the latter. Approximately 2.5 grams of solution ~as contained in the edge-sealed speci-mens and 39 grams in 'the cell specimens.

In Table 4.2 is a summary of the interior pH of the edge-sealed and cell specimens for the 2-, 6-, and 12-month exposures.

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'NUCLEAR For th~ high pH lithium environment, the interior pH consistently shows a decrease in pH *toward a neutral value for all e~posure times. A similar trend toward a more neu~ral pH is exhibited for the acidic environments for exposures up to 6-months. Af~er 12-months, the interior pH is the same as the bulk solution or, slightly more acidic.

4.2 Visual Appearance The storage cell specimens were disassembled and cut open to separate the Baral plates from the stainless. liners.

A visual examination of each Baral piece was conducted using a low power stereo-microscope. The f'ollowing observations were noted:

Storage Cell Specimen #3 (S.C.S.-3}

Surfaces were generally metallic in col.oration. Extra corrosion products, and some pitting, were seen on the faces and along the edges where the leak simulating holes were drilled through the stainless liners.

Storage Cell Specimen #6 (S.C.S.-6}

Specimens are darker than SCS-3. Pitting is much less.

Rust existed along edges where holes were drilled.

Bulges were observed in the dimple area of plate S.C.S.-6(1),

on both the outside and.inside.

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,NUCLEAR Storage Cell Specimen #9 (S.C.S.-9)

Specimens were white: in coloration with rust colored deposits*along the e~dges*\~here holes were drilled. s4c stringers were evide_.nt, but no pitting. Plate S.C.S.-9(4)*

had a 1-1/4 11 pure aluminum strip on one short edge.

4.3 Weight Gain After the visual analysis, the appropriate Baral plate specimens were weighed; oven-dried, and reweighed in order to determine the amount of absorbed moisture in the c6re and the change ;in weight due to exterinr and ~nte rior corrosion. The specimens were dried in- stages in an air-circulating oven for two (2) hours at 150, 200, 250°F, and for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> at *300°F. The original weight, the weight prior to oven-drying, and the dried weight for each specimen, ts listed in Table 4.~

A.summary of the moisture absorbed weight percentages, for the 2-month, 6-month, and 12-month exposures, is given in Table 4.4. The overall average for all specimens, environments, and exposures, was This corresponds to a minimum average porosity level in the Baral core of approximately The absorbed moisture decreased

. between 2-months and 6-months and increased between 6-months and one year. This may be the result of an initial decrease in porosity as corrosion products were generated in the core followed by a porosity increase as additional corrosion enlarged the pores. The greatest moisture absorption occurred in the open-edged specimens in the A environment .. This specimen also showed the greatest number of pits and would, therefore, contain the greatest amount of material capable 4-3

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NucLEAR of absorbing moisture. The least moisture, on the average, was in the storage cell Baral plates, which may be due to their larger size and lower edge to volume ratio.

In TabJe 4.Sr the corrosion weight gain percentages are summarized for an the* specimens tested in the program.

The values, in brackets, have been corrected to account for the fact that certain* of the 611 x 411 Baral plates in the cell specimens* contain a strip of solid aluminum along one edge. Since this strip did not contain the normal porous core structure, it could contribute weight gain only by external surface corrosion. To make valid comparisons, using these specimens, their weight was re-duced by a factor corresponding to the reduced core volume. Under the assumption that the weight gain per-centages are an indication of the extent of uniform corrosion in these specim~ns, the results presented in Table 4.5 show that the corrosion rates have decreased with increased exposure time. The results are.plotted for each specimen type as a function of environment in Figures 4.4 through 4.6.

The weight gains are largest for the edge-sealed specimens in each environment. Similarly, they are the smallest for the storage cell specimens. In between, with very similar results, are the plain and open-edged specimens. The similar weight gains, ex~erienced by these two (2) specimen types, show that the general corrosion is not accelerated due to coupling with stainless steel.

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,.NUCLEAR When the weight gain values for the storage cell speci-mens are considered on a semi-logarithmic scale, the relationship appears to be amenable to extrapolation, as shown i~ Figures 4.7 through 4.9. From these figures, the extrapolated weight gain percentage and the calculated percent of aluminum consumed after 40 years exposure, are:

4.4 Pitting To evaluate the* extent of pitting in the 12-month exposure specimens, the corrosion products were cleaned from the surfaces of*a ~ortion of one of the*fou~ (4) plates from each cell specimen. A summary of the pitting frequency and pit depth, for the 6-month and .12-month exposures, is given in Table 4.6. The ~it diameter for the 12-month specimens is also given in the table.

'Table 4.6 shows that the pitting characteristics after 12-months were very similar to those after 6-months.

Those specimens and environment combinations which did not pit or showed little. pitting tendency after 6-months, showed no or few p*its .after 12-months, however, those with significant pits after 6-months had a large number of pits after 12-months. Increased pitting was observed in the plain specimens in the A environment and in the edge-sealed specimens in the A and B environments. The other specimens showed nearly the same number of pits after 12-months as after 6-months.

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.NUCLEAR The pit depth, however, increased with the extended 12-month exposure. In some cases where pits had not pene-trated the aluminum clad in 6-months, they had done so after 12 months.

4.5 Metallography Sections of Baral from each specimen were mounted and metallographically polished in order to observe the thickness of surface oxidation films, the depth of edge attack, the undercutting around drilled holes, and the nature of surface bulges~ Sections were made along an edge for the plain and open-edged specimens, and through the drilled hole in the Baral for the edge-~ealed and storage cell specimens. In addition, sections through bulges in the specimens were made to characterize these structures.* _The specimens were back-filled with epoxy under-vacuum conditions to impregnate surface porosity, then rough poli~hed on silicon carbide papers and final polished on diamond using automatic vibratory equipment.

4. 5. l Surface Corrosion Films The surface corrosion films on several of the specimens

'were thick enough to measure using a filar eye piece at a magnification of The film thickness, as measured for these specimens, is listed in Table 4.7. The thickness for the C environment specimens was thickest, being a maximum of for the plain specimen. Where the bulge in this specimen caused the surface layer to break apart, the corrosion films were much thicker. Appendix B contains photographs showing the surface film in one area away from a bulge and, for comparison, on a bulge.

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.4. 5. 2 Edge Attack Ta~le 4.7 also shows the depth of corrosive attack at the Baral coupon edges in the plain and open-edged specimens.

The attack was greatest in the A environment and was somewhat greater in the open-edged specimen than in the plain specimen. Only one specimen of the six (6) edge~

sealed ~nd storage cell types showed accelerated corrosion around the partially drilled leak simulating hole.* This was the edge-sealed specimen in* the C environment. The*

similarity. in edge attack between the p1a in and open-edged specimens again indicates a lack of corrosion acceleration due to galvanic coupling of the Baral to stainless steel.

4.5.3 Bulges Several bulges were observed on the 12-month exposure specimens. Similar bulges were not observed on specimens exposed for 2- or 6-months. Table 4.8 lists the number of bulges observed on each specimen. Photographs demonstrating bulged areas are shown on Figures 4.2 and 4.3.

The bulges are separations between the aluminum clad and the B4C-aluminum matrix. They appear to result from gas pressure caused by internal corrosion. The corrosion of aluminum would generate hydrogen gas following the reaction

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,NUCLEAR Such gas generation has been observed in the edge-sealed and storage cel.l specimens. To generate a bulge would  ;

require.sealing of the edges.with corrosion products to enabl~ the internal gas pressure to increase suffici~ntly

• to expand the ten mil aluminum cladding. The edge-sealed specimens each had four (4) bulges. These specimens also showed the largest corrosion weight gains which could result in the sealing of edges in these specimens.

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,NUCLEAR e XN-NS- TP-009/NP REFERENCES (1) Corrosion Data Survey Fifth Edition, NACE 1974, P. 34.

(2) A Guide to Corrosio*n. Resistance, J. P. Polar, Climax Molybdenum Co., P. 54.

(3) Corrosion and Corrosion Product Release in Neutral Feedwater, E. G: Brush and W. L. Pearl, Corr. y. 28, No. 4, April 1972, Pp. 129-136.

(4) Stress Corrosion Cracking Problems and Research in Energy Systems Proceedings.

ERDA Meeting 2/24/75. ERDA 76-98, Edited by L. C. Janniello (5) Corrosion Resistance of Metals and Alloys, F. L. LaQue and H. R. Copson, Chapter 5, Corrosion Testing, P. 136. (1963) Reinhold Publishing Corp.

(6) Fundamental Aspects of Stress-Corrosion Crackin[, NACE 1969, ~tress-Corrosion Cracking of Iron-Nickel-Chromium Alloys, R. M. Latanision, R. W. Staehle,

p. 214. . .

(7) Corrosion and Corrosidn Control - Herbert H. Uhlig, John Wiley & Sons, New York 197ls P. 309 ..

(8) "Aqueous Corr. of Aluminum Part I Behaviour of 1100 Alloy 11 J. E. Draley and W. E. Ruther, Corr. 12 441t 1956.

(9) Reactor Technology - Selected Reviews 1964 USAEC Aluminum Alloys, J. E. Draley and W. E. Ruther, P. 215.

(10) "Resistance to Corrosion and Stress Corrosion," vi. \*I. Binqer, E. H. Hollings\'torth and 0. 0. Sprowls, in Aluminum Vol. 1, ASM, Ohio, 1967.

(11) Atlas of Electrochemical Equilibria in Aqueous ~olutions, Marcel Pourbaix

~ergamon Press, New York (1966).

(12) Aqueous Corrosion of Aluminum Part I Behavior of 1100 Alloy, J. E. Draley and W. E. Ruther, Corr. 12 441t 1956.

(13) 1 0bservations on the Mechanisms and Kinetics of Aqueous Aluminum Corrosion, 11 V. H. Troutner, Corr. 13 595 (1957)

(14) A Survey of Materials and Corrosion in Dry Cooling Applications, A. B. Johnson,Jr.

D. P.* Pratt and G. E. Zima, BNWL-1958, UC-12 1976.

(15) Private Communicati,on between R. McGoey and* B. C. Fryer.

(16) Dynamic Corrosion St.udies for the High Flux Isotope Reactor, J. L. English and J. C. Griess, ORNL-TM-1030 1966, Oak Ridge National Laboratory.

(17) Galvanic Corrosion of Al Alloys I Effect of Dissimilar Metal, F. Mansfeld, D. H. Hcn9stenbcr~ and J". V. Kenkel Co.rr. Vol. 30, No. 10, .Oct. 1974, P. 343.

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