ML13323B207

Attachment 10: CHLE-018, Rev. 2, Results of Bench Tests to Assess Corrosion of Aluminum in STP Containment Conditions.

ML13323B207
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Site:	South Texas
Issue date:	09/16/2013
From:	Mitchell L Southern Nuclear Operating Co
To:	Office of Nuclear Reactor Regulation
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ML13323A673	List: ML13323B187 ML13323B191 ML13323B194 ML13323B196 ML13323B198 ML13323B199 ML13323B200 ML13323B201 ML13323B202 ML13323B204 ML13323B207 ML13323B208 ML13323B209 NOC-AE-13003040, Attachment 1: CHLE-005, Rev. 1, Determination of the Initial Pool Chemistry for the Chle Test.
References
GSI-191, NOC-AE13003040, STI 33762096, TAC MF2400, TAC MF2401 CHLE-018, Rev 2
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NOC-AE-1 3003040Attachment 10CHLE-018:

Results of Bench Tests to Assess Corrosion of Aluminum inSTP Containment Conditions PROJECT DOCUMENTATION COVER PAGEDocument No.: CHLE-018 Revision:

2 Page 1 of 45Title: Results of Bench Tests to Assess Corrosion of Aluminum in STP Containment Conditions Project:

Corrosion/Head Loss Experiment (CHLE) Program Date: 8/16/2013 Client: South Texas Project Nuclear Operating CompanySummary/Purpose of Analysis or Calculation:

The Corrosion/Head Loss Experiment (CHLE) program has been designed to obtain realistic materialrelease and product formation results for use in Containment Accident Stochastic Analysis (CASA).Values for the CHLE test parameters were derived from South Texas Project (STP) conditions for aspectrum of Loss of Coolant Accident (LOCA) scenarios.

The objective of this bench test series was to evaluate the corrosion of aluminum under conditions typicalof a LOCA at STP, including the effect of pH and temperature in the presence of boric acid and trisodium phosphate (TSP). Tests were also conducted with additional silicon in solution at a concentration similarto that which was observed in earlier 30-day LOCA experiments to evaluate whether small amounts ofsilicon would contribute to aluminum passivation, and with pH adjustment using sodium hydroxide insteadof TSP to evaluate whether phosphate would contribute to aluminum passivation.

Tests of leaching ofaluminum,

silicon, and calcium from fiberglass were also conducted.

The results were compared toregression equations from WCAP 16530-NP.

The series consisted of six 24-hour bench tests asdescribed in this document.

The rate of corrosion of aluminum increased as temperature and pH increased.

TSP inhibited thecorrosion of aluminum but a low concentration of silicon did not. Aluminum and calcium leaching fromfiberglass in the presence of TSP were lower than predicted by the WCAP 16530-NP regression equation(generated without TSP). Silicon leaching from fiberglass in the presence of TSP showed strongerdependence on pH and temperature than predicted by the WCAP 16530-NP.

Role Name Signature DatePrepared by: Lana Mitchell

<signed electronically>

7/18/2013 UNM review: Kerry Howe <signed electronically>

9/9/2013STP review: Ernie Kee <signed electronically>

8/28/2013 UIUC review: Zahra Mohaghegh

<signed electronically>

9/9/20139/20/2013 Revision Date Description 0 7/18/2013 Original draft1 8/15/2013 Revised to address internal review2 9/16/2013 Revised to address technical team review_ _ _ [I _ I _ _ _ _ _ _ _ _ _ _ _

Title: Results of Bench Tests to Assess Corrosion of Aluminum in STP Containment Conditions Contents1.0 Introduction and Objectives

.............................................................................................................

52.0 M ethods and M aterials

..............................................................................................................

52.1 Experim ental Apparatus and Equipm ent ................................................................................

82.2 Coupon Preparation

.............................................................................................................

82.3 Tem perature

.................................................................................................................................

82.4 Solution pH Control ..............................................................................................................

82.4.1 pH 7.2 stock solution

...........................................................................................................

82.4.2 pH 6.0 and pH 7.7 solutions

.....................................................................................................

92.5 Step-by-Step Procedure for Bench Testing ...........................................................................

102.6 Post Test ......................................................................................................................................

112.6.1 Post-Corrosion Cleaning

........................................................................................................

112.6.2 Calculation of Corrosion and Release Rates ........................................................................

113.0 Results .............................................................................................................................................

133.1 Effect of pH and Temperature on the Corrosion of Aluminum in Boric Acid/TSP Solution

........

133.2 Corrosion of Aluminum in the Presence of Silicon in Boric Acid/TSP Solution

......................

193.3 Corrosion of Alum inum in a Solution of Boric Acid and NaOH ..............................................

243.4 Effect of pH and Tem perature on the Leaching of Fiberglass

...............................................

303.4.1 Alum inum ...........................................................................................................................

313.4.2 Calcium ...............................................................................................................................

333.4.3 Silicon .................................................................................................................................

353.4.4 Conclusion

..........................................................................................................................

363.5 Leaching of Fiberglass in the Presence of Soluble Alum inum ..............................................

363.5.1 Alum inum ............................................................................................................................

373.5.2 Calcium ................................................................................................................................

393.5.3 Silicon ..................................................................................................................................

413.5.4 Conclusion

..........................................................................................................................

434.0 Sum m ary and Conclusions

..........................................................................................................

445.0 References

......................................................................................................................................

45Document No: CHLE-018, Rev 2 Page 2 of 45 Title: Results of Bench Tests to Assess Corrosion of Aluminum in STP Containment Conditions List of FiguresFigure 1: Bench test bath on shaker table ................................................................................................

6Figure 2: 1-L Nalgene bottle w ith solution

..............................................................................................

6Figu re 3 : T itratio n setu p ................................................................................................................................

9Figure 4: Using measured weight of aluminum coupon to determine corrosion

.................................

12Figure 5: Exam ple of corrosion score of 1 of alum inum ........................................................................

14Figure 6: Exam ples of corrosion score of 2 of alum inum ......................................................................

14Figure 7: Exam ples of corrosion score of 3 of alum inum ......................................................................

14Figure 8: Exam ples of corrosion score of 4 of alum inum ......................................................................

14Figure 9: Effect of pH and temperature on corrosion rate of aluminum in solution

.............................

16Figure 10: Effect of pH and temperature on release of aluminum in solution

.....................................

17Figure 11: Aluminum concentration vs. pH and temperature on the AI(OH)3 solubility curve .............

18Figure 12: Effect of pH and temperature on corrosion rate of aluminum in solution with added silicon.

21Figure 13: Effect of pH and temperature on release of aluminum in boric acid/TSP solution with addedsilico n ..........................................................................................................................................................

2 2Figure 14: Aluminum concentration in STP solution with or without added silicon .............................

23Figure 15: Effect of pH and temperature on corrosion rate of aluminum in boric acid/NaOH solution

.... 26Figure 16: Effect of pH and temperature on release of aluminum in boric acid/NaOH solution

..........

28Figure 17: Release rates of aluminum in boric acid/TSP and boric acid/NaOH solutions

.....................

30Figure 18: Aluminum concentration in boric acid/TSP solution with fiberglass

.....................................

32Figure 19: Concentration of calcium in solution with fiberglass

..........................................................

33Figure 20: Concentration of silicon in solution with fiberglass

.............................................................

35Figure 21: Concentration of aluminum in solution with fiberglass and AI(NO3)3 ..................

................. 38Figure 22: Concentration of calcium in solution with fiberglass and Aluminum nitrate .......................

40Figure 23: Calcium release from fiberglass vs. fiberglass with Aluminum nitrate .................................

41Figure 24: Concentration of silicon in solution with fiberglass and Aluminum nitrate .........................

42Figure 25: Silicon release from fiberglass vs. fiberglass with Aluminum nitrate ...................................

43Document No: CHLE-018, Rev2Page 3 of 45 Title: Results of Bench Tests to Assess Corrosion of Aluminum in STP Containment Conditions List of TablesTable 1: Alum inum alloy 3003 com position

...........................................................................................

5Table 2: Series of six benchtop tests .......................................................................................................

6Table 3: Cleaning solution for alum inum ................................................................................................

11Table 4: Initial and final pH values during aluminum-only corrosion tests ............................................

13Table 5: Corrosion scores of alum inum coupons ..................................................................................

14Table 6: Average aluminum mass lost post-test and post-cleaning

.....................................................

15Table 7: Release of aluminum concentration in boric acid/TSP solution

..............................................

16Table 8: Corrosion rate results for alum inum .........................................................................................

19Table 9: Target and final pH values during tests of aluminum in boric acid/TSP solution with 4.5 mg/L ofa d d e d silico n ...............................................................................................................................................

1 9Table 10: Average aluminum mass lost in boric acid/TSP solution with 4.5 mg/L of added silicon ...........

20Table 11: Test results for aluminum measurements in the presence of 4.5 mg/L of added silicon in boricacid /T S P so lutio n ........................................................................................................................................

2 2Table 12: Silicon concentration verification

...........................................................................................

23Table 13: Corrosion rate results for aluminum in the presence of added silicon ..................................

24Table 14: Initial and final pH values during aluminum in boric acid/NaOH corrosion tests ..................

25Table 15: Average aluminum mass lost post-test and post-cleaning in boric acid/NaOH solution

..... 25Table 16: Aluminum concentration in boric acid/NaOH solution

...........................................................

27Table 17: Corrosion rate results for aluminum in boric acid/NaOH solution

.......................................

28Table 18: Corrosion rates for aluminum in boric acid/TSP and boric acid/NaOH solutions

...................

29Table 19: Release rates for aluminum in boric acid/TSP and boric acid/NaOH solutions

......................

30Table 20: Temperature and pH test conditions for leaching from fiberglass in boric acid/TSP solution...

31Table 21: Resulting concentrations of aluminum in boric acid/TSP solution

.......................................

32Table 22: Release rate results for aluminum from fiberglass

..................................................................

33Table 23: Concentration results of calcium in solution containing fiberglass

.......................................

34Table 24: Release rate results for calcium from fiberglass

....................................................................

34Table 25: Concentration results of silicon in solution containing fiberglass

.........................................

35Table 26: Release rate results for silicon from fiberglass

......................................................................

36Table 27: Temperature and pH conditions for leaching of fiberglass with added aluminum

................

37Table 28: Concentration of aluminum in solution with fiberglass and Aluminum nitrate ....................

38Table 29: Aluminum concentration corrected for added aluminum

.....................................................

39Table 30: Concentration of calcium in solution with fiberglass and Aluminum nitrate ........................

40Table 31: Release rate results for calcium from fiberglass with Aluminum nitrate ..............................

41Table 32: Concentration of silicon in solution with fiberglass and Aluminum nitrate ..........................

42Table 33: Release rate results for silicon from fiberglass with Aluminum nitrate ................................

43aluminum nitrateDocument No: CHLE-018, Rev 2Page 4 of 45 Title: Results of Bench Tests to Assess Corrosion of Aluminum in STP Containment Conditions 1.0 Introduction and Objectives The Corrosion/Head Loss Experiment (CHLE) program was designed to obtain realistic material releaseand product formation results for use in Containment Accident Stochastic Analysis (CASA). Values for theCHLE test parameters were derived from South Texas Project (STP) conditions for a spectrum of Loss ofCoolant Accident (LOCA) scenarios.

These conditions were tested in three ways: 30-day tank tests, benchtests, and short-term tank tests. This report describes the results of bench tests of aluminum corrosion and release of materials from fiberglass.

The objectives of this bench test series were to create conditions that promoted the generation ofchemical products from corrosion sources (i.e., aluminum coupons and fiberglass) as a function oftemperature and pH. The tests evaluated the corrosion of aluminum in a solution of boric acid andtrisodium phosphate (TSP), with or without added dissolved silicon.

Another test evaluated the effectsof temperature and pH on the corrosion of aluminum in a boric acid and sodium hydroxide (NaOH) mix.The bench test was also used to evaluate chemical release products from fiberglass (Nukon) and theresponse of fiberglass to the presence of added soluble aluminum concentrations in the form ofAI(NO3)3-9H20. The chemical release products of interest were aluminum,

calcium, and silicon.

Theseries consisted of six sets of 24-hour bench tests, as described in this document.

These tests were conducted from November 9, 2012 to February 14, 2013 with the following characteristics:

1. Six sets of benchtop tests in a water batch on a oscillatory table at temperatures of 35, 60, and85°C, with the table rotation set at 75 rpm to create turbulent fluid conditions.

2. Aluminum

coupons, 1" by 1" by 16 gauge, ASTM B-209, were the source of aluminum corrosion

material, with 100% of the surface area submerged in a 1-L bottle filled with 500 mL of STPsolution.

3. Fiberglass (Nukon) massed at approximately 5.0 grams.4. Material exposure to baseline chemicals of boric acid and TSP for a pH of 7.2, with additions ofhydrochloric acid (HCI) or sodium hydroxide to reach desired pH of 6.0 and 7.7, at time zero.2.0 Methods and Materials A bench-scale bath (Figure 1) was constructed and insulated to fit atop a shaker table while athermoregulator provided and maintained heat through the bath via copper pipes and water heattransfer.

The shaker bath apparatus provided a non-quiescent condition and maintained the desiredtest temperature.

The results in this report were collected during a series of six benchtop tests (Table 2),each lasting 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> at one of the three temperatures (35, 60, and 85°C) and 3 pH values (6.0, 7.2, or7.7 boric acid/TSP solutions).

A single aluminum coupon (Figure 2) or a 5.0 gram sample of fiberglass was suspended by nylon string in a 1-L bottle with 500 mL solution.

Aluminum alloy 3003 was used inthese tests. The composition table for alloy 3003 is listed below with a weight percentage in Table 1.Table 1: Aluminum alloy 3003 composition Alloy Si Fe Cu Mn Zn Al3003 0.6% 0.7% 0.05-0.20%

1.0-1.5%

0.10% remainder Document No: CHLE-018, Rev 2Page 5 of 45 Title: Results of Bench Tests to Assess Corrosion of Aluminum in STP Containment Conditions Figure 2: 1-L Nalgene bottle with solutionand aluminum coupon.Figure 1: Bench test bath on shaker table.Table 2: Series of six benchtop tests.fl~tp nftpct Nnu~mh~rQ

~fl12 9A-hnairtpct

~t R'~CMaterial

-Boric acidb/TSPC

solution, pH6.0 7.2 7.7Aluminum only 3 + blank 3 + blank 3 + blankAluminum

+ 4.5 mg/L Si 3 + blank 3 + blank 3 + blankFiberglass 3 3 + blank 3Fiberglass

+ 0.3 mg/L AI(NO3)3f e 3aDate of test: November 14, 2012. 24-hour test at 60°CMaterial

-Boric acid b/TSPc solution, pH6.0 7.2 7.7Aluminum only 3 + blank 3 + blankAluminum

+ 4.5 mg/L Si 3 + blank 3 + blankFiberglass 3 3 + blank 3Fiberglass

+ 0.3 mg/L Al(N03)3 f 3Date of test: December 5, 2012. 24-hour test at 35°CaMaterial Boric acidb /TSPc solution, pH6.0 7.2 7.7Aluminum only 3 + blank 3 + blank 3 + blankAluminum

+ 4.5 mg/L Si 3 + blank 3 + blank 3 + blankFiberglass 3Fiberglass

+ 0.3 mg/L AI(NO3)3f 317Document No: CHLE-018, Rev 2Page 6 of 45 Title: Results of Bench Tests to Assess Corrosion of Aluminum in STP Containment Conditions aDate of test: January 16, 2013. 24-hour test at 35°CCbMaterial Boric acid , pH6.0 7.2 7.7Al, in NaOH 3 + blank 3 + blank 3 + blankFiberglass

+ 0.3 mg/L AI(NO3)3f / TSPc 3 + blank 3 + blankaDate of test: January 28, 2013. 24-hour test at 60°CbMaterial Boric acid , pH6.0 7.2 7.7Al, in NaOH 3 + blank 3 + blank 3 + blankFiberglass

+ 0.3 mg/L AI(NO3)3f / TSPc 3 + blank 3 + blankDate of test: Feburary 14, 2013. 24-hour test at 85°CabMaterial Boric acid , pH6.0 7.2 7.7Al, in NaOH 3 + blank 3 + blank 3 + blankdFiberglass

+ 0.3 mg/L AI(NO3)3f / TSP 3 + blank 3 + blanka Temperature was maintained

+/-3°C.b Boron was added as H3B03.C Trisodium phosphate (TSP) = (Na3PO4.12H20)4-NaOH.d Trisodium phosphate (TSP) = Na3PO4.12H20.e Gray cells indicate conditions that were not part of the test matrix.f Al was added as AI(NO3)3.9H20.Prior to testing, the filled bottles were placed inside the preheated bath, capped, and allowed to cometo the desired temperature, usually overnight.

Pre-heating the solution prior to introducing thealuminum coupon or fiberglass was done so that material exposure to the correct temperature wasfrom time zero. The shaker baths were maintained at 5°C above required temperature prior to testingto accommodate the temperature loss when removing bottles to add coupons or fiberglass.

During thetest, the temperature setting on the thermoregulators was set at 3°C above the required temperature.

Calibration testing done before the start of test showed a -3°C reading between the thermoregulator and bath and sample temperatures.

Samples were run in triplicate, and a blank sample for each solutionpH condition was tested. The blank was used to measure the pH change that occurred over the testperiod without materials present.During testing, bottles were capped to prevent evaporation.

After the immersion time was complete, each aluminum coupon and fiberglass was removed for observation and the weight was recorded.

Fiberglass was discarded, and aluminum coupons were weighed,

cleaned, and weighed again. Foraluminum

coupons, the difference in mass between the start of test and after cleaning includes thealuminum (both soluble and insoluble) released into solution and assimilated into the scale layer.When testing analyte release from aluminum

coupons, a filtered 125-mL sample was collected fromeach bottle and aluminum,

calcium, and silicon concentrations were measured by inductively coupledplasma optical emission spectrometry (ICP-OES) analysis at Hall Environmental Analysis Laboratory (HallDocument No: CHLE-018, Rev 2Page 7 of 45 Title: Results of Bench Tests to Assess Corrosion of Aluminum in STP Containment Conditions Environmental, an independent certified laboratory).

The filter used was an Inlet Pall Corporation 0.45-Ipm Aquaprep filter.2.1 Experimental Apparatus and Equipment

• VWR Advanced Digital Shaker* TECHNE TU-20D Temp unit thermoregulator

• OHAUS AR1140 Scale, readability:

0.0001 g* ThermoOrion model 720A+ pH meter* Nano-pure water* 1000-mL volumetric flask* 1000-mL Nalgene polypropylene bottles" 125-mL bottles, acidified with 0.40 mL of nitric acid* Inlet Pall Corporation 0.45-pm AquaprepTM filter* 50-mL syringe" Graduated cylinder" FirelineTM0.008" diameter braided nylon thread2.2 Coupon Preparation The aluminum coupons (ASTM B-209) were 1" x 1" x 0.0787".

Each coupon had a 1/16" hole drilled in itfor stringing.

The following coupon preparation was in accordance with ASTM 3G31-72.* The coupons were rinsed with de-ionized (DI) water and then with a suitable solvent such asacetone.

Rinsing removed residual boric acid/TSP solution from the surface, which wouldadd to the weight if allowed to dry on the surface.

Scrubbing with abrasive powder mighthave damaged the surface of the specimen.

• The coupon was allowed to air dry. Towel drying might have introduced an error throughcontamination of the specimens with grease or lint.* The coupon was weighed, and its dimensions were recorded to determine the initial massand total surface area.2.3 Temperature The test was conducted at 85°C (185TF),

60°C (140°F),

and 35°C (957F). These temperatures wereselected to span the range of temperatures in the CHLE tests and were not representativeof a specificLOCA scenario.

The high temperature is close to the CHLE equipment limits. Temperature in the shakerbath was maintained by a TECHNE TU-20D Temp unit thermoregulator and measured with athermometer.

2.4 Solution pH Control2.4.1 pH 7.2 stock solutionA stock solution of boric acid/TSP was made by mixing 250.0 mM boric acid with 2.16 mM(Na3PO4.12H20)4.NaOH (TSP, molecular weight of 1560 g/mol) in the desired amount of DI water andDocument No: CHLE-018, Rev 2Page 8 of 45 Title: Results of Bench Tests to Assess Corrosion of Aluminum in STP Containment Conditions then allowing it to fully dissolve to produce to the pH 7.2 solution.

The masses of boric acid and TSPwere calculated independently by the following equation:

M = C * (FW)

• V(1)M = Mass of the stock chemicals (g)C = Molar concentration (mol/L) of boric acid or TSPFW = Formula weight for boric acid (61.83 g/mol) or TSP (1560 g/mol)V = the volume of solution being prepared (L)2.4.2 pH 6.0 and pH 7.7 solutions A stock solution of pH 7.2 can be brought to pH 6.0 by adding a qualitative 1/10 dilution of 12.1 Mhydrochloric acid (HCI). In the same manner, a stock solution can be brought to pH 7.7 by addingstandardized 12.0 M sodium hydroxide (NaOH). These solutions were actually made by mixing 275.5mM boric acid with 1.64 mM TSP for pH 6.0, or 231.4 mM boric acid and 2.16 mM TSP for pH 7.7, andfully dissolving in the desired amount of DI water. A precise 1.0-L aliquot was then taken. A generaltitration setup was constructed with a ring stand to hold a vertical

burette, a 1.O-L Erlenmeyer flask witha stir bar in it, and a stir plate. A calibrated pH meter was used.Figure 3: Titration setupTo prepare the pH 6.0 solution, the titration apparatus (see Figure 3) was assembled and the burettewas rinsed (conditioned) with the dilute HCI solution that was used for the titration.

The burette wasthen filled, and the initial volume was read and recorded to two decimal places. The pH probe wasplaced into the 1.0-L Erlenmeyer flask with the 1-L aliquot of the stock solution, the stir bar was thenplaced on the stir plate with the ring stand and burette, and an initial pH reading was taken. Thetitration was conducted at room temperature.

Titrant was slowly added to the boric acid/TSP solutionuntil a pH of 6.0 was reached, and the final volume on the burette was recorded.

The 1-L aliquot wasDocument No: CHLE-018, Rev2 Page 9of45Document No: CHLE-018, Rev 2Page 9 of 45 Title: Results of Bench Tests to Assess Corrosion of Aluminum in STP Containment Conditions returned to the bulk stock solution.

The volume of HCI needed to adjust the full volume of the solutionto the required pH was calculated by Equation 2.VHCI = (Vfinal-Vinit)

X CDHCI X(VT.to-L) (2)CsHc1 1VHC= Total volume of stock 12.1 M HCI needed (L)Vfinal = Volume of solution in burette after titration was complete (L)V= Volume of solution in burette before titration started (L)CDHCI = Concentration of the dilute HCI (M)CSHC1 = Concentration of the stock HCI (M)VTot = Volume of solution being created (L)To prepare the pH 7.7 solution, this same procedure was followed except that NaOH was titratedinstead of HCI.After the added HCI or NaOH had been mixed thoroughly into the solution, a pH reading was taken. Ifthe pH was not correct, a second titration was performed by following the same procedure outlinedabove.The DI water was measured with a graduated

cylinder, so the absolute error of the volumemeasurement had to be taken into account in determining the potential error of the solutionconcentration.

If the graduated cylinder was used more than once (e.g., a 2,000-mL graduated cylinderused 10 times to make 20.0 L of solution),

the accuracy must be accounted for. The new error for thetotal measurement can be calculated as follows:Totalerror=

/[n* (+/- Instrument error2)] (3)n = number of times instrument is used.Instrument error = error value indicated on the graduated cylinder.

2.5 Step-by-Step Procedure for Bench Testing1. Measure and record:a) For coupons, measure the initial mass and dimensions of aluminum coupons.

A surfacearea of 13 cm2 is targeted.

b) Forfiberglass, measure and record the mass of fiberglass.

A repeated mass of 5.0 g ofrectangular piece of cut fiberglass is sought.2. Prepare bulk solutions of boric acid/TSP of pH 6.0, 7.2, and 7.7.3. Measure and record the actual pH of the solutions.

4. Heat 500 mL of prepared test solution in 1-L Nalgene bottles to desired temperature of 35, 60,or 85"C, and maintain the temperature for the remainder of the test.5. Insert a coupon or fiberglass by hanging with nylon string so that coupon or fiberglass issuspended at the midpoint of the solution depth and is completely submerged.

6. Set shaker bath to a speed of 75 oscillations per minute. This speed allows flow across thecoupon and fiberglass without its bumping the inside of the bottle.Document No: CHLE-018, Rev 2Page 10 of 45 Title: Results of Bench Tests to Assess Corrosion of Aluminum in STP Containment Conditions

7. After 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />s:a) For coupons, remove, rinse with DI, and allow to air dry and cool to room temperature.

Note formation of precipitate in the bottle or on the surface of the coupon.b) For fiberglass, note any formation of precipitate on fiberglass or in the bottle, anddiscard fiberglass.

8. Measure and record the final pH of the solution.

Shake the bottle of solution, and pour 125-mLsamples for testing of metal precipitates by ICP-OES.

Metals of interest are aluminum, calcium,and silicon.

Filter all solutions having fiberglass.

Use Inlet Pall Corporation AquaprepTM, 0.45-pImfilters.2.6 Post Test2.6.1 Post-Corrosion CleaningAfter a test was completed, coupons were removed from solution and set aside to air dry. Dry couponswere weighed and recorded, and then cleaned one-by-one in the proper cleaning solution.

The ASTMGl-03 "Aluminum and Aluminum Alloys" cleaning procedure was followed to determine corrosion ofaluminum coupons.

The cleaning solution used is given in Table 3, and the cleaning procedure follows.Table 3: Cleaning solution for aluminum.

Cleaning solution Time and temperature Note50 mL of phosphoric acid (H3PO4) 5 to 10 min 90*C to Boiling If corrosion product film20 g of chromium trioxide (CrO0) remains, rinse and then followReagent water to make 1,000 mL with nitric acid procedure.

Remove any visibly remaining Nitric acid (HNO3) 1 to 5 min 20 to 25°C y y gdeposits.

In hood vent:o Place the cleaning solution on a hot plate and allow it to reach at least 90°C but not more than100°C.o Place the coupon in the hot solution for 5 to 10 minutes (suspend coupon with a string for ease).o Rinse with DI and allow to air dry. Clip off any string.o Weigh and record.o If corrosion product film remains, place the coupon in nitric acid for 1 to 5 minutes.o Rinse with DI water, allow to air dry, weigh, and record.2.6.2 Calculation of Corrosion and Release RatesWhen aluminum metal corrodes, the aluminum can be released into solution or it can form a scale layeron the material itself. Once in solution, the corroded aluminum can remain in solution, precipitate andbe separated from solution by sedimentation or filtration, or adhere on other surfaces in the system.The concentration of material remaining in solution, whether in soluble or precipitate form, wasobtained by ICP-OES measurements.

The corroded mass is the sum of the aluminum released intoDocument No: CHLE-018, Rev 2Page 11 of 45 Title: Results of Bench Tests to Assess Corrosion of Aluminum in STP Containment Conditions solution and the mass assimilated into the scale layer on the corroded material itself, as shown in Figure4 and defined by Equation 4.Alcorroded

=Alreleased

+Alscale (4)Alcorroded

= mass difference of aluminum coupon before test and after cleaning:

A -C.Alreleaed

= mass of aluminum that leaves the coupon and enters the solution during the test, measuredby ICP-OES.Alcaie = mass of aluminum that adheres to the coupon as a scale layer.Al Aluminum corrosion AlA I Alscale B CPre-test Post-test Finalweight weight weightAlreleased Removed scaleFigure 4: Using measured weight of aluminum coupon to determine corrosion.

The mass of the coupons were measured three times. First, the initial mass of the coupon wasmeasured and recorded.

After immersion in the solution for the test period, the coupons were removed,rinsed, and allowed to air dry, and the new mass was recorded.

A decrease in mass represented arelease of aluminum and/or original scale (aluminum hydroxide layer formed from being in normalenvironmental air) into solution.

The release may contain soluble and insoluble aluminum (precipitate),

which cannot be differentiated by ICP-OES, and new scale. New scale may also form on the surface ofthe aluminum and add weight to the coupon. To include the mass of corroded aluminum that wasincorporated into the scale layer on the material itself required measuring the mass of the aluminumcoupon at the end of testing after cleaning.

Corrosion rates were calculated using the initial and final (post-cleaning) mass of the aluminumcoupons.

This result can be compared to ICP-OES results.

The dimensions of the coupons and the time ofexperiment were also in this calculation.

MCR = m- (5)A, *tCR = corrosion rate (g/(m2.min)M = total mass lost (g)A, = surface area (m2)t = time of immersion in test solution (min)Document No: CHLE-018, Rev2 Page 12 of45Document No: CHLE-018, Rev 2Page 12 of 45 Title: Results of Bench Tests to Assess Corrosion of Aluminum in STP Containment Conditions If there is some loss of mass due to corrosion, then this value, M, may be positive.

If a significant scalelayer forms, then M may be negative.

The surface area was calculated using the dimensions of thealuminum coupons.3.0 Results3.1 Effect of pH and Temperature on the Corrosion of Aluminum in BoricAcid/TSP SolutionAs described in Section 2.6.2, corrosion processes were evaluated by determining the corrosion rateusing weight loss measurements and by determining the release rate by measuring the concentration ofmetals in solution.

The target temperature and pH were verified during testing.

The temperature wasmeasured in the blank sample at start of the test, at a random time in the middle of the test, and at theend of test and was consistently found to be within +/-1°C of the target temperature.

The pH wasmeasured in the blank sample and in one of the triplicate samples at the beginning and end of the test.At the beginning of the test, the pH was consistently found to be within +/-0.05 of the target pH. The pHvalues measured at the end of the test are reported in Table 4. In general, the pH increased during thecorrosion immersion period. The pH was typically 0 to 0.2 higher than the target value at the end of theimmersion period.Table 4: Initial and final pH values during aluminum-only corrosion tests.Boric acid/TSP solutionpHTemperature Target Actual initial Final Change6.0 6.0 6.13 +0.13350C 7.2 7.2 7.38 +0.187.7 7.7 7.81 +0.116.0 5.99 6.03 +0.0460°C 7.2 b b b7.7 7.7 7.69-7.73

-0.01 to +0.036.0 6.0 a __85°C 7.2 7.2 ....7.7 7.7 ....a Final pH was not measured.

b A test at pH 7.2 and 60°C was not completed.

After immersion time was complete, the aluminum coupons were removed to air dry and then beweighed and photographed.

Each coupon was visually examined for any change and for formation ofscale on its surface.

The solution was examined for any precipitate formation therein or on the bottomof the bottle. No visible precipitates were seen in the bottles.

The degree of corrosion and scaleformation was rated on a scale of 1 to 4, where 1 indicated no change and 4 indicated a blackened surface with no shine, as shown in Figure 5 through Figure 8 and described in Table 5. For tests at 35TC,Document No: CHLE-018, Rev 2Page 13 of 45 Title: Results of Bench Tests to Assess Corrosion of Aluminum in STP Containment Conditions aluminum coupons seemed unchanged (score of 1); at 60°C and pH of 6.0, the coupons were stillunchanged except for a few pit marks on one of three coupons tested at that pH and temperature; at pH7.7, the coupons were darker at edges (score of 3) and no longer shiny. At 85°C and pH 7.2, the couponswere black and no longer shiny (score of 4).Figure 5: Example of corrosion score of 1 ofaluminum.

Figure 6: Examples of corrosion score of 2 of aluminum.

Figure 7: Examples of corrosion score of 3 of Figure 8: Examples of corrosion score of 4 of aluminum.

aluminum.

Table 5 describes for corrosion score, the appearance of the metal coupons upon completion of testing.The duration for soaking in the acid solution for cleaning of the coupons varied from 0 to 10 minutes,depending on the visual appearance of the coupons at the end of the immersion time and onobservation of removal of the scale layer during the cleaning operation.

General times for the durationof soaking in the acid solution for each of the degrees of corrosion are listed in Table 5. Coupons wereremoved as soon as they appeared clean, to prevent further reaction.

Time for cleaning was determined by visual inspection and never to exceed a total of 10 minutes.

The coupons were immediately rinsedwith DI water to stop acid solution from reacting with the aluminum.

Table 5: Corrosion scores of aluminum coupons.Corrosion General corrosion Color Luster Cleaning timescore appearance 1 No apparent corrosion light grey metallic 0-2 minutes2 Low corrosion grey mostly metallic

/ some 2-5 minutesdullness3 Moderate corrosion dark grey loss of metallic

/ very dull 5-8 minutes4 High corrosion black very dull / ash-like 8-10 minutesWeight loss measurements for corrosion at 35 and 60°C are shown in Table 6. Results from the tests at85°C are not shown because of coupon handling errors during the final weight measurements.

AsDocument No: CHLE-018, Rev 2Page 14 of 45 Title: Results of Bench Tests to Assess Corrosion of Aluminum in STP Containment Conditions expected from previous corrosion

studies, the corrosion rate increased as the pH increased and as thetemperature increased, as shown in Figure 9. At 35TC, the corrosion rate increased by a factor of 2.6 asthe pH increased from 6.0 to pH 7.7, whereas at 60TC, the corrosion rate increased by a factor of 7.3 forthe same pH increase.

Table 6: Average aluminum mass lost post-test and post-cleaning.

Aluminum in boric acid/TSP35°C solutionpH = 6.0 pH = 7.2 pH = 7.7A, Avg. starting mass of coupon (g) 2.4175 2.4941 2.3997B, Avg. post-test mass of coupon (g) 2.4172 2.4939 2.3990C, Avg. post-cleaning mass of coupon (g) 2.4170 2.4934 2.3984Alre.leaed(g)=

A -B (g) 0.0003 0.0002 0.0007Aleae(g)=

B -C (g) 0.0002 0.0005 0.0006Alcorrosjon(g)=

A -C (g) 0.0005 0.0007 0.0013Aluminum in boric acid/TSP60°C solutionpH = 6.0 pH =7.2 pH = 7.7A, Avg. starting mass of coupon (g) 2.4663 2.4393B, Avg. post-test mass of coupon (g) 2.4662 -- 2.4356C, Avg. post-cleaning mass of coupon (g) 2.4656 -- 2.4342Alreleased(g)=

A -B (g) 0.0001 -- 0.0037Alsfaie(g)=

B -C (g) 0.0006 -- 0.0014Alcorrosion(g)=

A -C (g) 0.0007 -- 0.0051__a A test for pH 7.2 at 60TC was not completed.

Document No: CHLE-018, Rev 2Page 15 of 45 Title: Results of Bench Tests to Assess Corrosion of Aluminum in STP Containment Conditions 3.002.50'E 2.00E mpH6a1.504a pH 7.2C 0 pH 7.7o* 1.0000o°0.500.0035*C 60*CFigure 9: Effect of pH and temperature on corrosion rate of aluminum in solution.

The increase in aluminum concentration in solution resulting from release into solution followed thesame trend as did the weight loss, with respect to pH and temperature.

The concentration of aluminumin solution in each test is shown in Table 7 and Figure 10. The lowest concentrations of aluminumoccurred for the tests at pH 6.0 and were below the reporting limit of 0.2 mg/L for the tests at all threetemperatures.

The highest concentration of aluminum (29.33 mg/L) was measured for the highesttemperature and pH tested. The reported concentrations are the average of three replicate tests. Therelative standard deviation (RSD) of the three measurements was generally 10% or less.Table 7: Release of aluminum concentration in boric acid/TSP solution.

350CpH 6.0 7.2 7.7Avg. concentration, mg/L 0.11 0.55 1.63Standard deviation 0.010 0.012 0.058% RSD 9.09 2.09 3.5360°CpH 6.0 7.2 7.7Avg. concentration, mg/L 0.10 _a 8.47Standard deviation 0.020 -- 1.153% RSD 20.90 -1.8085"CpH 6.0 7.2 7.7Avg. concentration, mg/L 0.17 14.12 29.33Standard deviation 0.006 0.168 0.577Document No: CHLE-018, Rev 2Page 16 of 45 Title: Results of Bench Tests to Assess Corrosion of Aluminum in STP Containment Conditions I% RSD1 3.3311.19 1.97 1-A test at pH 7.2 and 60°C was not completed.

3530E~25M.20 MAI only, pH 6.0a Al only, pH 7.21 AI only, pH 7.7ES1035°C 60°C 85°CFigure 10: Effect of pH and temperature on release of aluminum in solution.

To evaluate whether the aluminum concentration had reached the saturation concentration, themeasured concentrations in solution were compared to the saturation concentration of aluminum inequilibrium with amorphous aluminum hydroxide.

The solubility curves shown in Figure 11 werecalculated as a function of temperature and pH using Visual MINTEQ for aluminum hydroxide (identified as an expected precipitation product in previous testing [1]). The solubility calculations demonstrate that aluminum in solution will reach minimum solubility in a pH range of 5.7 to 6.8 for temperatures from 85*C to 35T. The corrosion of aluminum increases as pH and temperature increase due toincreased

kinetics, but Figure 11 demonstrates that the solubility of amorphous aluminum hydroxide follows the same trend when the pH is above 7. For each test, the aluminum concentration measured insolution was less than the saturation concentration of aluminum at that pH and temperature, indicating that the measured concentration was not limited by the formation of a precipitate in the solution.

Document No: CHLE-018, Rev 2 Page 17 of45Document No: CHLE-018, Rev 2Page 17 of 45 Title: Results of Bench Tests to Assess Corrosion of Aluminum in STP Containment Conditions 100E0 104.E 1E0.105.0 5.5 6.0 6.5 7.0 7.5 8.0pH-AI(OH)3 solubility at T = 35C -AI(OH)3 solubility at T = 60C -AI(H)3 solubility at T = 85°C0 Benchtest at 35°C

• Benchtest at 60°C Benchtest at 85°CFigure 11: Aluminum concentration vs. pH and temperature on the AI(OH)3 solubility curve.The corrosion rate determined by weight loss measurements can be compared to the release ratedetermined by solution concentrations and to the rate of release calculated from WCAP 16530-NPEquation 6.2. These comparisons are shown in Table 8. For all tests that can be compared, the rate ofrelease into solution was less than the measured corrosion rate. This result is expected becausecorrosion brings about release of ions into solution and formation of a scale layer. Since only a portionof the corroded aluminum is released into solution, the release rate is expected to be less than thecorrosion rate. The ratio of release to corrosion appears to increase as the pH increases.

At pH 6.0, thealuminum release rate is at most 10% of the corrosion rate. At pH = 7.2, the release rate is 40% of thecorrosion rate; and at pH = 7.7, the release rate ranged from 60% to over 80% of the corrosion rate.In these tests, the measured release rates were generally less than the corresponding release ratedetermined from Equation 6.2 in WCAP-16530-NP.

At the lowest pH, the measured release rate wasdramatically lower than the calculated rate, ranging from 4 to 140 times lower than the calculated rate.At pH = 7.2, the measured and calculated rates were closer to each other, with the measured ratesbetween 1.5 and 2.5 times lower than the calculated rates. At the highest pH, the measured ratesranged from slightly above to slightly below the calculated rates. The results may indicate that theWCAP-16530-NP equation is less accurate at low pH values or with TSP in solution.

At this pH, therelease rate is very low (close to the detection limit) so relative differences between calculated andmeasured rates may appear more significant, but both the WCAP-16530-NP equation and themeasurements indicate low release rates. Some variability is common in corrosion studies because ofthe difficulties in measuring small changes in weight and the impact that scale formation and cleaningcan have on weight loss measurements.

Document No: CHLE-018, Rev 2 Page 18 of45Document No: CHLE-018, Rev 2Page 18 of 45 Title: Results of Bench Tests to Assess Corrosion of Aluminum in STP Containment Conditions Table 8: Corrosion rate results for aluminum.

Aluminum in boric Release rate by solutionacid/TSP solution Corrosion by weight loss measurement (ICP-OES)

Calculated aMass lost Corrosion rate Aluminum conc. Release rate release rateTemp. Final pH (g) mg/(m2-min) (mg/L) mg/(m2.min) mg/(m2.min)6.13 0.0005 0.248 0.11 0.027 0.10535oC 7.38 0.0007 0.347 0.55 0.136 0.2047.81 0.0013 0.645 1.63 0.404 0.2776.03 0.0007 0.347 0.10 0.025 0.898b6 0 oC 7 .2 0 ... .. .. .1 .5 07.70 0.0051 2.53 8.47 2.10 2.036.00 N/Ac N/A 0.17 0.042 5.5385oC 7.20 N/A N/A 14.12 3.50 8.557.70 N/A N/A 29.33 7.27 11.2abCN/ACalculated using WCAP-16530-NP Equation 6-2.A test at pH 7.2 and 60°C was not completed.

Weight loss measurements are not available because of errors in coupon handling during thefinal weight measurements.

3.2 Corrosion of Aluminum in the Presence of Silicon in Boric Acid/TSPSolutionThe corrosion processes for aluminum in the presence of silicon were also evaluated, by determining thecorrosion rate using weight loss measurements and by determining the release rate by measuring theconcentration of metals in solution.

The target temperatures and pH were verified during testing in thesame way as aluminum in boric and TSP solution (Section 3.1) with no added silicon.

The temperature atstart of test, mid-test, and end of test were consistently found to be within +/-1*C. At the beginning of thetest, pH was found to be within +/-0.05 of the target pH. The pH values measured at end of test arereported in Table 9. The pH was typically 0.2 to 0.5 pH units higher than the target value at the end ofthe immersion period.Table 9: Target and final pH values during tests of aluminum in boric acid/TSP solution with 4.5 mg/L of added silicon.pHTemperature Target Final Difference 6.0 6.47 +0.4735°C 7.2 7.47 +0.277.7 7.87 +0.176.0 6.49 +0.49a60°C 7.2 a7.7 7.81 +0.11Document No: CHLE-018, Rev 2Page 19 of 45 Title: Results of Bench Tests to Assess Corrosion of Aluminum in STP Containment Conditions 85°C6.0 ....7.2 ....7 "77 ...I '-- I-- A test at pH 7.2 and 60°C was not completed.

After immersion time was complete, the aluminum coupons were removed to air dry, to then beweighed and photographed.

Each coupon was visually examined for any change and for formation ofscale on its surface.

The solution was examined for any precipitate formation within or on the bottom ofthe bottle. However, no visible precipitates were seen in the bottles.

The degree of corrosion and scaleformation was rated on the same scale of i to 4 as was used in the tests without added silicon.

For testsat 35TC, aluminum coupons again seemed unchanged (score of 1); at 60°C and pH of 6.0, the couponswere less shiny, slightly darkened especially at edges, and coupons had some pitting (score of 3); at pH7.7, the coupons were darker (score of 3 to 4); and at 85C and pH 7.7, the coupons were black and nolonger shiny (score of 4).Weight loss measurements for corrosion at 35 and 60°C are shown in Table 10. Results from the tests at85°C are not shown because of coupon handling errors during the final weight measurements.

Asexpected from previous corrosion

studies, the corrosion rate increased as the pH increased and as thetemperature increased, as shown in Figure 12. At 35TC, the corrosion rate increased by 2.4 times as thepH increased from 6.0 to pH 7.7 (similar to the corrosion rate increase of 2.6 times for aluminum insolution without added silicon),

whereas at 60TC, the corrosion rate increased 9.5 times (for aluminumin solution without added silicon, the increase was 7.3 times) for the same pH increase.

Table 10: Average aluminum mass lost in boric acid/TSP solution with 4.5 mg/L of added silicon.35"C pH=6.0 pH=7.2 pH=7.7A, Avg. starting mass of coupon (g) 2.4018 2.4062 2.4415B, Avg. post-test mass of coupon (g) 2.4017 2.4060 2.4406C, Avg. post-cleaning mass of coupon (g) 2.4013 2.4057 2.4403Alreleased(g)

= A -B (g) 0.0001 0.0002 0.0009Als,.,e(g)

= B -C (g) 0.0004 0.0003 0.0003Alcorrosion(g)

A -C (g) 0.0005 0.0005 0.001260°C pH=6.0 pH=7.2 pH=7.7A, Avg. starting mass of coupon (g) 2.5048 a 2.4940B, Avg. post-test mass of coupon (g) 2.5054 -- 2.4908C, Avg. post-cleaning mass of coupon (g) 2.5042 -- 2.4883Alreleased(g)

A -B (g) -0.0006 -- 0.0032Alscaie(g)=

B -C (g) 0.0012 -- 0.0025Alcorrosion(g)=

A -C (g) 0.0006 -- 0.0057__. A test at pH 7.2 and 60°C was not completed.

Document No: CHLE-018, Rev 2Page 20 of 45 Title: Results of Bench Tests to Assess Corrosion of Aluminum in STP Containment Conditions 3.503.00,i 2.50EEv2.00 M pH 6.0.S=pH 7.2M1.5015 M pH 7.7.00.500.0035°C 60°CFigure 12: Effect of pH and temperature on corrosion rate of aluminum in solution with added silicon.The increase in aluminum concentration in solution resulting from release into solution followed thesame trends with respect to pH and temperature as did weight loss. The concentration of aluminum insolution in each test is shown in Table 11 and Figure 13. The lowest concentrations of aluminumoccurred for the tests at pH 6.0 and were below the reporting limit of 0.2 mg/L at 350C. The highestconcentration of aluminum (33.33 mg/L) was measured at the highest temperature and pH tested. Thereported concentrations are the average of three replicate tests. The relative standard deviation (RSD)of the three measurements was 7% or less, except for the 601C test at pH 6.0, which had a relatively high RSD (19%).Document No: CHLE-018, Rev 2Page 21 of 45 Title: Results of Bench Tests to Assess Corrosion of Aluminum in STP Containment Conditions Table 11: Test results for aluminum measurements in the presence of 4.5 mg/L of added silicon in boric add/TSP solution.

350CpH 6.0 7.2 7.7Avg. concentration, mg/L 0.15 0.76 2.07Standard deviation 0.012 0.012 0.058% RSD 7.53 1.53 2.79600CpH 6.0 7.2 7.7Avg. concentration, mg/L 0.32 -- 8.27Standard deviation 0.060 -- 0.115% RSD 18.64 -- 1.40850CpH 6.0 7.2 7.7Avg. concentration, mg/L 0.62 18.12 33.33Standard deviation 0.021 0.487 2.082% RSD 3.34 2.69 6.24--a A test for pH 7.2 at 60°C was not completed.

4035E 3030= 25ma pH 6.020 pH 7.28E 15 mpH 7.7.CE~ 105035°C 60°C 85°CFigure 13: Effect of pH and temperature on release of aluminum in boric add/TSP solution with added silicon.When comparing aluminum release in solution with and without added silicon, as shown in Figure 14,the concentration resulting from release from the corrosion with added silicon was higher in 7 of the 8comparable experiments.

However, at pH 7.7 at 60'C, the measurements are almost equal (within 3%),due to silicon's not being added to solution as intended.

When comparing concentration differences (among concentrations above reporting limits of 0.20 mg/L), aluminum release in solutions with addedsilicon were slightly higher, ranging from 12 to 27% additional aluminum.

Based on weight lossmeasurements,

however, the rates of aluminum corrosion were similar with and without silicon inDocument No: CHLE-018, Rev 2Page 22 of 45 Title: Results of Bench Tests to Assess Corrosion of Aluminum in STP Containment Conditions solution (Tables 5 and 9). The WCAP 16785 report reflects passivation with the addition of 50 mg/L ofsilicon [2].403530,- Al only, pH 6.025 Al only + Si, pH 6.0a'20 a Al only, pH 7.2o 0 Al only + Si, pH 7.2E 15MAI only, pH 7.7.CE 10 U Al only + Si, pH 7.75035°C 60°C 85°CFigure 14: Aluminum concentration in STP solution with or without added silicon.As a check, measured concentrations of silicon were compared to the amount of dissolved silicon (4.50mg/L) added to solution at the start of the test. The measured concentrations of silicon are listed inTable 12. At 60°C and pH 7.7, the check confirmed that silicon had not been added to solution.

Otherwise, the concentration of silicon was +/-0.34 mg/L of the intended 4.50 mg/L of silicon.Table 12: Silicon concentration verification.

Temperature pH Avg. concentration of Si, mg/L Difference, mg/L6.0 4.60 +0.1035°C 7.2 4.53 +0.037.7 4.50 +0.006.0 4.20 -0.30a60°C 7.2b7.7 0.00 -4.506.0 4.50 +0.0085°C 7.2 4.16 -0.347.7 4.47 -0.03a A test for pH 7.2 at 60°C was not completed.

b Indicates silicon was not added to solution.

Document No: CHLE-018, Rev 2Page 23 of 45 Title: Results of Bench Tests to Assess Corrosion of Aluminum in STP Containment Conditions The corrosion rate determined by weight loss measurements were compared to the release ratedetermined by solution concentrations and to the rate of release calculated from WCAP 16530-NPEquation 6.2. These comparisons are shown in Table 13. For all tests that can be compared, the rate ofrelease into solution was again less than the measured corrosion rate. Again, this result is expectedbecause corrosion brought about both release of ions into solution and formation of a scale layer (seeSection 2.6). The ratio of release to corrosion appears to increase as the pH increases.

At pH 6.0, thealuminum release rate ranged from 15% to 27% of the corrosion rate; at pH 7.2, the release rate was76% of the corrosion rate; and at pH 7.7, the release rate ranged from 72% to over 85% of the corrosion rate.In these tests, the measured release rates were also generally less than the corresponding release ratedetermined from Equation 6.2 in WCAP-16530-NP.

This time, the measured release rate ranged from 3to almost 40 times lower than the calculated rate at the lowest pH. Otherwise, measured release rateswere 1 to 2 times lower than the calculated rate. The differences in measured release rate andcalculated release rates are less dramatic in solution with added silicon but still indicate that the WCAPequation overestimates release.Table 13: Corrosion rate results for aluminum in the presence of added silicon.Release rate by solutionCorrosion by weight loss measurement (ICP-OES)

Calculated Temp. Final pH Mass lost Corrosion rate Aluminum Release rate release rate(g) mg/(m2-min) conc. (mg/L) mg/(m2-min) mg/(m2.min)6.47 0.0005 0.248 0.150 0.037 0.12235'C 7.47 0.0005 0.248 0.760 0.188 0.2177.87 0.0012 0.595 2.070 0.513 0.2896.49 0.0006 0.298 0.320 0.079 1.06b60°C 7.20 -- -- -- -- 1.507.81 d 0.0057 2.83 8.27 2.05 2.186.00 N/Ac N/A 0.620 0.154 5.5385°C 7.20 N/A N/A 18.120 4.49 8.557.70 N/A N/A 33.330 8.27 11.2a Calculated using WCAP-16530-NP Equation 6-2.b-- A test at pH 7.2 and 60°C was not completed.

N/A Weight loss measurements are not available because of errors in coupon handling during thefinal weight measurements.

d Silicon was inadvertently not added to solution for this experimental condition.

3.3 Corrosion of Aluminum in a Solution of Boric Acid and NaOHIn this series of tests, the solution contained sodium hydroxide (NaOH) instead of TSP. The testprocedures were otherwise the same. The corrosion processes were evaluated by determining thecorrosion rate using weight loss measurements and by determining the release rate by measuring theconcentration of metals in solution.

The target temperature and pH were verified during testing.

TheDocument No: CHLE-018, Rev 2Page 24 of 45 Title: Results of Bench Tests to Assess Corrosion of Aluminum in STP Containment Conditions temperature was measured in the blank sample at start of test, a random time in the middle of the test,and at the end of a test and was consistently found to be within +/- 1VC of the target temperature.

The pHwas measured in the blank sample and one of the triplicate samples at the beginning and end of thetest. At the beginning of the test, the pH was consistently found to be within +/-0.05 of the target pH,except for the test series at 85°C. The pH values measured at the end of the test are reported in Table14. The pH remained mostly unchanged during the corrosion immersion period. An increase of 0.5 in pHwas measured at the lowest temperature and lowest pH, and a decrease of 0.2 in pH was measured atthe highest temperature and highest pH tested.Table 14: Initial and final pH values during aluminum in boric acid/NaOH corrosion tests.pHTemp. Target Actual Initial Final Difference 6.0 6.0 6.47 +0.4735°C 7.2 7.2 7.47 +0.277.7 7.7 7.87 +0.176.0 5.99 -6.0 6.03 0+.0360°C 7.2 7.25 7.2 0.007.7 7.7 7.69 -0.016.0 5.75 5.98 -0.0285°C 7.2 6.96 7.02 -0.187.7 7.44 7.5 -0.2After immersion time was complete, the aluminum coupons were removed to air dry to be weighed andphotographed.

Each coupon was visually examined for any change and for formation of scale on itssurface.

The solution was examined for any precipitate formation within or on the bottom of the bottle.No precipitates were visible in the bottles.

At 85°C and pH 6.0, the aluminum coupons appeared grayand lacked luster (corrosion/scale score of 2); at pH 7.2 and 7.7 the coupons were black and had noluster (corrosion/scale score of 4). For all other temperatures and pH ranges tested, the couponsshowed no visible change (corrosion/scale score of 1).Weight loss measurements for corrosion at 35, 60, and 85°C are shown in Table 15. Again, the corrosion rate increased as the pH increased and as the temperature increased, as shown in Figure 15. When thepH was 7.7, At 35°C, the corrosion rate increased by a factor of 6.4 as the pH increased from 6.0 to pH7.7; at 60°C, the corrosion rate increased by a factor of 7.6 for the same pH increase; and at 85°C thecorrosion rate further increased by a factor of 11.4 for the same pH increase.

Table 15: Average aluminum mass lost post-test and post-cleaning in boric acid/NaOH solution.

35°C pH = 6.0 pH = 7.2 pH = 7.7A, Avg. starting mass of coupon (g) 2.6610 2.6917 2.7191B, Avg. post-test mass of coupon (g) 2.6610 2.6903 2.7158C, Avg. post-cleaning mass of coupon (g) 2.6603 2.6894 2.7146Document No: CHLE-O 18, Rev 2 Page 25 of 45Document No: CHLE-018, Rev 2Page 25 of 45 Title: Results of Bench Tests to Assess Corrosion of Aluminum in STP Containment Conditions Alr.i.j.d(g)

= A -B (g)0.00010.00140.0033

= B -C (g) 0.0006 0.0009 0.0012AlI.a..(g)

= A -C (g) 0.0007 0.0023 0.0045600C pH = 6.0 pH = 7.2 pH = 7.7A, Avg. starting mass of coupon (g) 2.7597 2.8300 2.6807B, Avg. post-test mass of coupon (g) 2.7576 2.8252 2.6671C, Avg. post-cleaning mass of coupon (g) 2.7574 2.8209 2.6632

= A -B (g) 0.0021 0.0048 0.0136Al=,,(g)

= B -C (g) 0.0002 0.0043 0.0039Alco,,ojo(g)

= A -C (g) 0.0023 0.0091 0.0175856C pH = 6.0 pH = 7.2 pH = 7.7A, Avg. starting mass of coupon (g) 2.7124 2.7950 2.8245B, Avg. post-test mass of coupon (g) 2.7109 2.7810 2.7865C, Avg. post-cleaning mass of coupon (g) 2.7076 2.7716 2.7696Alreesjd(g)

= A -B (g) 0.0014 0.0140 0.0380Aljce(g)

= B -C (g) 0.0033 0.0094 0.0170AlIoroo(g)

= A -C (g) 0.0048 0.0234 0.0549302520EE N pH 6.015s pH 7.20

• pH 7.71010050 T35*C 60*C 85*CFigure 15: Effect of pH and temperature on corrosion rate of aluminum in boric add/NaOH solution.

The increase in aluminum concentration in solution resulting from release from the corrosion followedthe same trends with respect to pH and temperature as the weight loss. The concentration of aluminumDocument No: CHLE-018, Rev 2Page 26 of 45 Title: Results of Bench Tests to Assess Corrosion of Aluminum in STP Containment Conditions in solution in each test is shown in Table 16 and Figure 16. The lowest concentrations of aluminum (0.21mg/L) occurred for the tests at the lowest temperature and pH, and were at the reporting limit of 0.2mg/L. The highest concentration of aluminum (65.33 mg/L) was measured for the highest temperature and pH tested. The solution was examined for any precipitate formation within or on the bottom of thebottle; no precipitates were visible in the bottle. The reported concentrations are the average of threereplicate tests. The relative standard deviation (RSD) of the three measurements was generally 5% orless.Table 16: Aluminum concentration in boric acid/NaOH solution.

350CpH 6.0 7.2 7.7Avg. concentration, mg/L 0.21 3.00 7.00Standard deviation 0.01 0.361 0.265% RSD 4.76 12.02 3.7860°CpH 6.0 7.2 7.7Avg. concentration, mg/L 0.74 14.33 33.33Standard deviation 0.025 0.577 1.155% RSD 3.42 4.03 3.46850CpH 6.0 7.2 7.7Avg. concentration, mg/L 2.80 30.67 65.33Standard deviation 0.100 1.155 8.386% RSD 3.57 3.77 12.84Document No: CHLE-018, Rev 2 Page 27 of 45Document No: CHLE-018, Rev 2Page 27 of 45 Title: Results of Bench Tests to Assess Corrosion of Aluminum in STP Containment Conditions 807060EUN pH6S40C 4 pH 7.2E 30 S pH 7.7.E3E 20100~35*C 60*C 85*CFigure 16: Effect of pH and temperature on release of aluminum in boric add/NaOH solution.

The corrosion rate determined by weight loss measurements can be compared to the release ratedetermined by solution concentrations and to the rate of release calculated from WCAP 16530-NPEquation 6.2. These comparisons are shown in Table 17. As in previous test series, the rate of releaseinto solution was less than the measured corrosion rate for all tests (except at 60°C and pH = 7.7, whenthe release rate was slightly higher than the measured corrosion rate).In these nine tests, five of the measured release rates were higher than the corresponding release ratedetermined from Equation 6.2 in WCAP-16530-NP, and four were lower. The measured release ratesranged from 1.6 to 7 times higher than the calculated release rate. At low pH, measured release rateswere lower than the calculated release rate and ranged from one-tenth to one-half the calculated release rate.Table 17: Corrosion rate results for aluminum in boric acid/NaOH solution.

Release rate by solutionCorrosion by weight loss measurement (ICP-OES)

Calculated Mass lost Corrosion rate Aluminum Release rate: release rate(g) mg/(m2.min) conc. (mg/L) mg/(m2.min) mg/(m2.min)6.00 0.0007 0.332 0.21 0.052 0.10035°C 7.17 0.0023 1.06 3.00 0.744 0.1787.68 0.0045 2.07 7.00 1.74 0.2516.03 0.0023 1.06 0.74 0.184 0.898600C 7.20 0.0091 4.21 14.33 3.55 1.507.69 0.0175 8.10 33.33 8.27 2.0185°C 5.98 0.0048 2.22 2.80 0.694 5.50Document No: CHLE-018, Rev 2Page 28 of 45 Title: Results of Bench Tests to Assess Corrosion of Aluminum in STP Containment Conditions 7.02 0.0234 10.8 30.67 7.61 7.867.50 0.0549 25.4 65.33 16.2 9.98Calculated using WCAP-16530-NP Equation 6-2.Measured corrosion rates in solution of boric acid and NaOH were generally three times those insolution of boric acid and TSP buffer (Table 18). The corrosion rate difference was lower at 35°C and pH6.0, 1.3 times lower. Release rates were also higher in solution of boric acid and NaOH compared tosolution of boric acid and TSP buffer (Figure 17 and Table 19). The release rates ranged from 2 to above16 times higher than in solution with TSP buffer. The release rate difference was also lower at 35°C andpH 6.0, with measured concentrations near or below minimum reporting limits.Table 18: Corrosion rates for aluminum in boric acid/TSP and boric acid/NaOH solutions.

Corrosion rate Ratio ofTemp. pH mg/(m2.min) corrosion ratesTSP NaOH (NaOH/TSP) 6.00 0.248 0.332 1.3435°C 7.20 0.347 1.06 3.077.70 0.645 2.07 3.216.00 0.347 1.06 3.0760°C 7.20 -- 4.21 --7.70 2.53 8.10 3.206.00 -- 2.22 --85°C 7.20 -- 10.8 --7.70 -- 25.4 --Document No: CHLE-018, Rev 2 Page 29 of 45Document No: CHLE-018, Rev 2Page 29 of 45 Title: Results of Bench Tests to Assess Corrosion of Aluminum in STP Containment Conditions 3025E20 TSP PH 6.0E NaOH pH 6.0E a TSP pH 7.2a NaOH pH 7.2usM 10

• TSP pH 7.7GD U NaOH pH 7.7035*C 60*C 85*CFigure 17: Release rates of aluminum in boric add/TSP and boric acid/NaOH solutions.

Table 19: Release rates for aluminum in boric acid/TSP and boric acid/NaOH solutions.

Release rate Ratio ofTemp. Target mg/(m2.min) releasepH ratesTSP NaOH (NaOH/TSP) 6.00 0.027 0.052 1.9135°C 7.20 0.136 0.744 5.457.70 0.404 1.74 4.296.00 0.025 0.184 7.4060°C 7.20 -- 3.55 --7.70 2.10 8.27 3.946.00 0.042 0.694 16.4785°C 7.20 3.502 7.61 2.177.70 7.274 16.2 2.233.4 Effect of pH and Temperature on the Leaching of Fiberglass Release rates for aluminum,

calcium, and silicon from fiberglass (Nukon) were determined by measuring the concentration of metals in solution by ICP-OES.

The target temperature and pH were verified duringtesting by measuring temperature in the blank sample at start of test, a random time in the middle ofthe test, and at the end of the test and was consistently found to be within +/-10C. The pH was measuredin the blank sample and in one of the triplicate samples at the beginning and end of the test. At thebeginning of the test, the pH was consistently found to be within +/-0.02 of the target pH. The pH valuesDocument No: CHLE-018, Rev 2Page 30 of 45 Title: Results of Bench Tests to Assess Corrosion of Aluminum in STP Containment Conditions measured at the end of the test are reported in Table 20. During the corrosion immersion period, theincrease in pH beyond the target value ranged from 0.14 to almost 0.40.Table 20: Temperature and pH test conditions for leaching from fiberglass in boric acid/TSP solution.

Temperature pHTarget Actual initial Final Difference 6.0 + 0.02 6.14 0.1435TC 7.2 + 0.02 7.41 0.217.7 + 0.02 7.84 0.146.0 + 0.02 6.26 0.2660°C 7.2 + 0.02 7.57 0.377.7 + 0.02 7.89 0.196.0 + 0.02 -- --85TC 7.2 + 0.02 -- --7.7 + 0.02 ....-- Failed to measure ending pH.After immersion time was complete, the fiberglass was removed and was visually examined for anychange and for precipitate formation on the fibers. The solution was also examined for any precipitate formation within or on the bottom of the bottle. No precipitates were visible in the bottles, but thefiberglass lost some of its yellow color and the solution took on a yellow color. Fibers were also seen tobe floating or settling on the bottom of the bottle, prompting the collection of all samples by filtering solution through 0.45- jm AquaprepTM filters into a 125-mL sample bottle.3.4.1 AluminumAt temperatures of 35 and 60°C, aluminum concentration in solution increased as pH and temperature increased, with the highest concentration of aluminum (0.07 mg/L) at pH 7.2 or 7.8 in combination withtemperature 60°C (Figure 18, Table 21). The lowest concentrations of aluminum occurred for tests at85TC, but the measured concentrations of aluminum for all three temperatures and across the pH rangetested were below the reporting limit of 0.2 mg/L (concentrations that a commercial laboratory wouldnormally report as being below the detection limit (BDL) because they would not meet the laboratory's QA standards).

The reported concentrations are the average of three replicate tests. The RSD was highbecause of the concentrations' being below the reporting limit.Document No: CHLE-018, Rev 2Page 31 of 45 Title: Results of Bench Tests to Assess Corrosion of Aluminum in STP Containment Conditions 0.100.080 mpH 6.0pH 7.20.04S004

• pH 7.7E"C 0.020.0035°C 60°C 85°CFigure 18: Aluminum concentration in boric acid/TSP solution with fiberglass.

Table 21: Resulting concentrations of aluminum in boric add/TSP solution with fiberglass.

35°CpH 6.0 7.2 7.7Avg. concentration, mg/L 0.02 0.02 0.03Standard deviation 0.001 0.003 0.007% RSD 8.84 13.48 22.4460°CpH 6.0 7.2 7.7Avg. concentration, mg/L 0.00* 0.07 0.07Standard deviation 0 0.010 0.006% RSD 0 14.63 8.4485°CpH 6.0 7.2 7.7Avg. concentration, mg/L 0.005 0.00* 0.00*Standard deviation 0.009 0 0% RSD 173.21 0 0* Less than minimum detection limit of 0.0109 mg/LThe release rate can be determined by solution concentrations and can be compared to the release rateand concentrations calculated from WCAP 16530-NP Equation 6-4. These comparisons are shown inTable 22.. The concentration of aluminum in solution was consistently lower than the predicted WCAPconcentration.

In these tests, the measured concentration was below reporting limits (0.2 mg/L) andshows there is virtually no release of aluminum in solution.

The results of these tests demonstrate thatthe WCAP equation is a conservative prediction of the amount of aluminum that may be released intoDocument No: CHLE-018, Rev 2Page 32 of 45 Title: Results of Bench Tests to Assess Corrosion of Aluminum in STP Containment Conditions solution under STP conditions, and that fiberglass dissolution will not be a significant source ofaluminum under these conditions.

The lower release of aluminum may be related to passivation by thephosphate in solution.

Table 22: Release rate results for aluminum from fiberglass Measured Al Calculateda Temp ('C) pH Time (min) Fiberglass (kg) conc. (mg/L) conc. (mg/L)35 6.14 1440 0.005 0.02 0.0735 7.41 1440 0.005 0.02 0.1135 7.84 1440 0.005 0.03 0.1360 6.26 1440 0.005 0.00 0.3260 7.57 1440 0.005 0.07 0.4960 7.89 1440 0.005 0.07 0.5585 6.0 1440 0.005 0.01 0.6885 7.2 1440 0.005 0.00 1.0185 7.7 1440 0.005 0.00 1.18a WCAP 16530 NP, Equation 6-4 using rate constants for E-glass from Table 6.2-3 using 1-hour increments.

3.4.2 CalciumAnother analyte of interest from leaching of fiberglass was calcium.

Calcium release increased as pHincreased at 35 and 60°C as shown in Figure 19 and Table 22. At those temperatures, concentrations were below 7 mg/L. The highest concentration of calcium (15 mg/L) was measured at the highesttemperature and lowest pH tested. At higher pH, the concentration of calcium in solution was againbelow 7 mg/L.1614E12ECo104-a pH 7.2C0 6*NpH 7.7E20 =a35°C60°C85°CFigure 19: Concentration of calcium in solution with fiberglass.

Document No: CHLE-018, Rev 2Page 33 of 45 Title: Results of Bench Tests to Assess Corrosion of Aluminum in STP Containment Conditions Table 23: Concentration results of calcium in solution containing fiberglass.

35°CpH 6.0 7.2 7.7Avg. concentration, mg/L 0.84 1.02 1.47Standard deviation 0.050 0.076 0.058% RSD 6.02 7.51 3.9460°CpH 6.0 7.2 7.7Avg. concentration, mg/L 2.07 5.23 6.50Standard deviation 0.208 0.551 0.200% RSD 10.07 10.52 3.0885TCpH 6.0 7.2 7.7Avg. concentration, mg/L 15.00 4.50 3.13Standard deviation 0.000 0.100 0.208% RSD 0.00 2.22 6.64The measured concentrations in solution were compared to the WCAP predicted concentrations; thesecomparisons are shown in Table 24. With one exception (pH = 6,T = 85°C), the measured concentrations of calcium in solution were lower than the corresponding WCAP concentrations.

The calculated concentrations ranged from 1.4 to 6.3 times greater than the measured concentrations.

The lowermeasured concentrations may have been due to interactions with phosphate that reduced the releaseof calcium in these tests compared to the WCAP experiments, which were conducted without TSPpresent.

The results indicate that the WCAP equation is a conservative prediction of the amount ofcalcium that would be present due to the dissolution of fiberglass following a LOCA. The results areconsistent with the 30-day LBLOCA test, but the MBLOCA test resulted in a calcium concentration thatwas somewhat higher than the predicted concentration.

Table 24: Release rate results for calcium from fiberglass.

aMeasured Ca Calculated Temp ('C) pH Time (min) Fiberglass (kg) conc. (mg/L) conc. (mg/L)35 6.14 1440 0.005 0.84 5.2435 7.41 1440 0.005 1.02 6.4035 7.84 1440 0.005 1.47 6.8560 6.26 1440 0.005 2.07 6.9660 7.57 1440 0.005 5.23 8.5560 7.89 1440 0.005 6.50 8.9985 6.0 1440 0.005 15.0 8.38Document No: CHLE-018, Rev 2Page 34 of 45 Title: Results of Bench Tests to Assess Corrosion of Aluminum in STP Containment Conditions 85 7.2 1440 0.005 4.50 10.185 7.7 1440 0.005 3.13 10.9a WCAP 16530 NP, Equation 6-4 using rate constants for E-glass from Table 6.2-3, using 1-hour increments.

3.4.3 SiliconSilicon release as concentrations in solution were also measured in these tests. Silicon has beenobserved to passivate the corrosion of aluminum when in solution at concentrations over 50 mg/L [2].Silicon release increased as temperature and pH increased (Figure 20 and Table 25). The lowestconcentration (0.98 mg/L) was measured at the lowest temperature and pH tested. The highestconcentration of silicon (170 mg/L) was measured at the highest temperature and pH tested. Thereported concentrations are the average of three replicate tests. The RSD of the three measurements was generally 6% or less.180160140E 120.0M 100 0 pH 6.0Ct80 a pH 7.2o 0 pH 7.7= 600S4020035°C 60°C 85°CFigure 20: Concentration of silicon in solution with fiberglass.

Table 25: Concentration results of silicon in solution containing fiberglass.

35°CpH 6.0 7.2 7.7Avg. concentration, mg/L 0.98 4.60 8.63Standard deviation 0.015 0.265 0.289% RSD 1.55 5.75 3.34600CpH 6.0 7.2 7.7Avg. concentration, mg/L 6.40 30.33 43.00Standard deviation 0.400 2.082 1.000% RSD 6.25 6.86 2.3385°CDocument No: CHLE-018, Rev 2 Page 35 of 45Document No: CHILE-018, Rev 2Page 35 of 45 Title: Results of Bench Tests to Assess Corrosion of Aluminum in STP Containment Conditions pH 6.0 7.2 7.7Avg. concentration, mg/L 81.00 143.33 170.00Standard deviation 4.583 5.774 0.000% RSD 5.66 4.03 0.00The measured concentrations in solution were compared to the WCAP predicted concentrations, asshown in Table 26. In these tests, the measured concentrations of silicon in solution were sometimes lower and sometimes higher than the corresponding WCAP concentrations.

At lower temperature (35°C) and at 600C and pH = 6, the measured concentration was lower. At higher temperature and pHconditions, the measured concentration was higher than the predictions.

Table 26: Release rate results for silicon from fiberglass.

aMeasured Si Calculated Temp (°C) pH Time (min) Fiberglass (kg) conc. (mg/L) conc. (mg/L)35 6.14 1440 0.005 0.98 8.1635 7.41 1440 0.005 4.60 11.535 7.84 1440 0.005 8.63 12.860 6.26 1440 0.005 6.40 21.360 7.57 1440 0.005 30.33 29.360 7.89 1440 0.005 43.00 31.685 6.0 1440 0.005 81.00 41.785 7.2 1440 0.005 143.33 55.885 7.7 1440 0.005 170.00 62.5a WCAP 16530 NP, Equation 6-4 using rate constants for E-glass from Table 6.2-3, using 1-hour time increments.

3.4.4 Conclusion

Aluminum release from fiberglass appeared to be zero, in contrast to other analytes tested. Even at85°C, aluminum release was undetectable.

Across all temperatures and pH tested, aluminum was foundin only trace amounts.

Calcium concentration peaked at pH 6.0 at high temperature (85°C); calciumotherwise measured below 7 mg/L. Silicon made up the highest concentration of analyte release infiberglass.

3.5 Leaching of Fiberglass in the Presence of Soluble AluminumThe purpose of this test was to determine the effects of soluble aluminum on the dissolution offiberglass.

It utilized 0.3 mg/L aluminum nitrate for the soluble aluminum (an aluminum concentration of 0.038 mg/L). Release rate for aluminum,

calcium, and silicon from fiberglass (Nukon) was determined by measuring the concentration of metals in solution by ICP-OES.

The target temperature and pH wereverified during testing by measuring temperature in the blank sample at start of test, a random time inthe middle of the test, and at the end of the test and was consistently found to be within +/-1°C. The pHwas measured in the blank sample and one of the triplicate samples at the beginning and end of thetest. At the beginning of the test, the pH was found to be within +/-0.02 of the target pH except at 85°C.The pH values measured at the end of the test are reported in Table 27. During the immersion period,the pH increased in the range of -0.02 to almost 0.56 pH units from the target value. Analyte releaseDocument No: CHLE-018, Rev 2Page 36 of 45 Title: Results of Bench Tests to Assess Corrosion of Aluminum in STP Containment Conditions from fiberglass was compared with analyte release from fiberglass with added aluminum nitrate at thesame conditions.

Table 27: Temperature and pH conditions for leaching of fiberglass with added aluminum.

Fiberglass in boric acid/TSP solution

+ 0.3 mg/L AlTemperature pHTarget Actual Ending Difference 6.0 6.0 6.13 0.1335°C 7.2 7.2 7.56-7.68 0.36 to 0.487.7 7.7 7.68 -0.026.0 6.0 6.10 0.1060°C 7.2 7.2 7.28 0.087.7 7.7 7.67 -0.036.0 5.78* 6.34 0.5685°C 7.2 -- a-- --7.7 7.48* 7.69 0.21* Actual pH levels were lower than the intended pH for 24-hour tests done at 85TC. A different TSPwas used (Na3PO4.12H20) and had a molecular weight of 380.-Final pH was not measured.

When immersion time was complete, the fiberglass was removed and was visually examined as inSection 4.4. No precipitates were visible in the bottles, the solution took on a yellow color, and thefiberglass lost some of its yellow color. Fibers were also seen to be floating in or settling on the bottomof the bottle, prompting the collection of all samples by filtering solution through 0.45-Itm AquaprepTM filters into a 125-mL sample bottle.3.5.1 AluminumDocument No: CHLE-018, Rev 2Page 37 of 45 Title: Results of Bench Tests to Assess Corrosion of Aluminum in STP Containment Conditions Most of the measured concentrations of aluminum for all three temperatures and pH values testedwere below the reporting limit of 0.2 mg/L. A high concentration (2.33 mg/L) was measured at pH 6.0and 60°C and is outside the general trend (Figure 21 and Table 28). Lab notes do not reveal anythingunusual, but an excess amount of aluminum nitrate might have been added to solution, or thelaboratory reported the results incorrectly.

The reported concentrations are the average of threereplicate tests. The RSD was generally below 12%.0.20E 0.1520E a Al in fiberglass

+ AI(NO3)3, pH 7.2UE 0.0 MAI in fiberglass

+ AI(NO3)3, pH 7.74-" 0.10 eAl in fiberglass

+ AI(NO3)3, pH 6.00.0035°C 60°C 85°CNote: The aluminum concentration at 60°C and pH 6.0 is not depicted on the graph as it made itdifficult to see the trends of the other data points.Figure 21: Concentration of aluminum in solution with fiberglass and AI(NO3)3.Table 28: Concentration of aluminum in solution with fiberglass and Aluminum nitrate.35°CpH 6.0 7.2 7.7Avg. concentration, mg/L 0.15 0.13 0.11Standard deviation 0.006 0.006 0.08% RSD 3.94 4.33 5.4160°CpH 6.0 7.2 7.7Avg. concentration, mg/L 2.33 0.11 0.08Standard deviation 0.321 0.006 0.007% RSD 13.78 5.41 8.50850CpH 6.0 7.2 7.7Avg. concentration, mg/L 0.08 0.02 0.03Standard deviation 0.002 0.032 0.004% RSD 1.98 173.211 12.86Document No: CHLE-018, Rev 2Page 38 of 45 Title: Results of Bench Tests to Assess Corrosion of Aluminum in STP Containment Conditions The resulting concentrations were corrected by subtracting 0.038 mg/L aluminum concentration (Table29). Concentrations of aluminum in solution measure higher than those measured in solution withoutadded aluminum at temperatures of 35 and 60°C and across the pH values tested. However, themeasured concentrations remained below reporting limits (except at pH = 6.0 at 60°C). Due to possibleerrors in reporting and in test method, these concentrations are considered equal to those measured insolution without added aluminum.

Table 29: Aluminum concentration corrected for added aluminum.

35°CpH 1 6.0 7.2 7.7Corrected Al concentration, mg/L 0.11 0.10 0.07600CpH 6.0 7.2 7.7Corrected Al concentration, mg/L 2.30 0.07 0.0485°CpH 6.0 7.2 7.7Corrected Al concentration, mg/L 0.04 0.00 0.00The release rate was again determined by solution concentrations and compared to the release rate andconcentrations calculated from WCAP 16530-NP Equation 6-4. The concentration of aluminum in solutionwas higher than the predicted WCAP concentration at 35°C. However, the measured concentrations arebelow reporting limits (0.2 mg/L) and show there is virtually no release of aluminum in solution.

Whilethe WCAP prediction overstates concentration, the calculated WCAP concentrations also indicated lowconcentrations.

3.5.2 CalciumCalcium release increased as pH increased at 35 and 60°C as shown in Figure 22 and Table 29. Thecombination of 85°C and pH 6.0 yielded the highest concentration of calcium (13 mg/L), but all othercombinations of temperature and pH yielded a concentration of calcium below 5 mg/L. This follows thesame behavior as calcium release from fiberglass without added aluminum, except that concentrations are lower (1 to 2 times) in solution with added aluminum, as seen in Figure 23. Aluminum in solutionreduced the concentration of calcium leached from fiberglass.

Although the measured concentrations insolution are lower, they are still higher than the corresponding WCAP concentrations, ranging from 4 toover 32 times greater than predicted.

Document No: CHLE-018, Rev 2 Page 39 of 45Document No: CHLE-018, Rev 2Page 39 of 45 Title: Results of Bench Tests to Assess Corrosion of Aluminum in STP Containment Conditions 16.0014.0012.00C2 10.000 pH 6.08.00u o pH 7.2o 6.00 MpH 7.7E4.002.000.0035*C 60*C 85*CFigure 22: Concentration of calcium in solution with fiberglass and Aluminum nitrate.Table 30: Concentration of calcium in solution with fiberglass and Aluminum nitrate.350CpH 6.0 7.2 7.7Avg. concentration, mg/L 0.80 0.66 0.75Standard deviation 0.046 0.026 0.071% RSD 5.73 4.01 9.5060°CpH 6.0 7.2 7.7Avg. concentration, mg/L 1.40 3.83 3.97Standard deviation 0.100 0.513 0.058% RSD 7.14 13.39 1.46850CpH 6.0 7.2 7.7Avg. concentration, mg/L 13.00 4.50 3.23Standard deviation 1.000 0.200 0.252% RSD 7.69 4.44 7.78Document No: CHLE-018, Rev 2Page 40 of 45I Title: Results of Bench Tests to Assess Corrosion of Aluminum in STP Containment Conditions 1816ý7 1412E g2 __Ca in fiberglass, pH 6.0.o s Ca in fiberglass

+ AI(NO3)3, pH 6.010a Ca in fiberglass, pH 7.205o N Ca in fiberglass

+ AI(NO3)3, pH 7.20E 6 0 Ca in fiberglass, pH 7.7U U Ca in fiberglass

+ AI(NO3)3, pH 7.7q4.20+-35*C 60*C 85*CFigure 23: Calcium release from fiberglass vs. fiberglass with Aluminum nitrate.The measured concentrations of calcium in solution were compared to the WCAP predicted concentrations, as shown in Table 31. With one exception, the measured concentrations of calcium insolution were lower than the corresponding WCAP concentrations.

The comparison to the WCAPcalculations were generally similar to the comparison without added aluminum.

Table 31: Release rate results for calcium from fiberglass with Aluminum nitrate.Measured Ca Calculated Temp (°C) pH Time (min) Fiberglass (kg) conc. (mg/L) conc.a (mg/L)35 6.00 1440 0.005 0.80 5.1435 7.20 1440 0.005 0.66 6.2035 7.70 1440 0.005 0.75 6.7160 6.00 1440 0.005 1.40 6.6960 7.20 1440 0.005 3.83 8.0860 7.70 1440 0.005 3.97 8.7485 5.78 1440 0.005 13.0 8.1185 7.20 1440 0.005 4.50 10.185 7.48 1440 0.005 3.23 10.6a WCAP 16530 NP, Equation 6-4 using rate constants for E-glass from Table 6.2-3, using 1-hour time increments.

3.5.3 SiliconSilicon release increased as temperature and pH increased (Figure 24 and Table 32). The lowestconcentration (0.49 mg/L) was measured at the lowest temperature and pH tested. The highestDocument No: CHLE-018, Rev 2Page 41 of 45 Title: Results of Bench Tests to Assess Corrosion of Aluminum in STP Containment Conditions concentration (150 mg/L) was measured at the highest temperature and pH tested. The reportedconcentrations are the average of three replicate tests. The RSD of the three measurements wasgenerally 7% or less.1601407 120r 100n pH 6.08080 a pH 7.2U860

• pH 7.70u*--4020035°C 60°C 85°CFigure 24: Concentration of silicon in solution with fiberglass and Aluminum nitrate.Table 32: Concentration of silicon in solution with fiberglass and Aluminum nitrate.35°CpH 6.0 7.2 7.7Avg. concentration, mg/L 0.49 1.23 1.47Standard deviation 0.087 0.058 0.058% RSD 17.71 4.68 3.9460"CpH 6.0 7.2 7.7Avg. concentration, mg/L 1.57 20.67 22.00Standard deviation 0.058 1.528 0.000% RSD 3.69 7.39 0.00850CpH 6.0 7.2 7.7Avg. concentration, mg/I 54.00 143.33 150.00Standard deviation 1.732 5.774 0.000% RSD 3.21 4.03 0.00As mentioned previously, silicates are major release products of fiberglass.

Silicon release increases astemperature and pH increase.

Silicon release decreases at lower pH and temperatures when Aluminumnitrate was added; although at 85C, releases were more similar to that of fiberglass without addedaluminum, as shown in Figure 25.Document No: CHLE-018, Rev 2Page 42 of 45 Title: Results of Bench Tests to Assess Corrosion of Aluminum in STP Containment Conditions 1801607 140120 Si in fiberglass, pH 6.0e-12.0 W Si in fiberglass

+ AI(NO3)3, pH 6.0100N Si in fiberglass, pH 7.280 E Si in fiberglass

+ AI(NO3)3, pH 7.20C 60. Si in fiberglass, pH 7.70S400 Si in fiberglass

+ AI(NO3)3, pH 7.734020035*C 60tC 85*CFigure 25: Silicon release from fiberglass vs. fiberglass with Aluminum nitrate.The measured concentrations of silicon in solution were compared to the WCAP predicted concentrations, as shown in Table 33. In these tests, the comparison between the measuredconcentrations of silicon and the corresponding WCAP concentrations was similar to the results withoutadded aluminum.

Table 33: Release rate results for silicon from fiberglass with Aluminum nitrate.aMeasured Si Calculated concTemp (°C) pH Time (min) Fiberglass (kg) conc. (mg/L) (mg/L)35 6.00 1440 0.005 0.49 7.8635 7.20 1440 0.005 1.23 10.935 7.70 1440 0.005 1.47 12.460 6.00 1440 0.005 1.57 20.060 7.20 1440 0.005 20.67 26.860 7.70 1440 0.005 22.00 30.385 5.78 1440 0.005 54.00 39.785 7.20 1440 0.005 143.33 55.885 7.48 1440 0.005 150.00 59.7a WCAP 16530 NP, Equation 6-4 using rate constants for E-glass from Table 6.2-3, using 1-hour time increments.

3.5.4 Conclusion

For all three analytes (aluminum,

calcium, and silicon) tested, leaching of fiberglass with addedAluminum nitrate follows the same trend as leaching from fiberglass without that added compound.

Foraluminum, concentration remains below the reporting limit of 0.20 mg/L. The measured calcium andDocument No: CHLE-018, Rev 2 Page 43 of 45Document No: CHLE-018, Rev 2Page 43 of 45 Title: Results of Bench Tests to Assess Corrosion of Aluminum in STP Containment Conditions silicon concentrations decreased when soluble aluminum is added at all temperature and pH valuestested.4.0 Summary and Conclusions The following summary and conclusions can be drawn from these bench scale tests.1. The rate of corrosion of aluminum increased as temperature and pH increased.

These trends areconsistent with the trends that have been observed in previous literature.

2. The experimental results show that the measured concentrations in solution were lower thanthe saturation concentration, indicating that the measured release results were not limited bysaturation considerations.

3. The corrosion rates of aluminum coupons measured by weight loss measurements (whichinclude a procedure to remove scale from the coupon surface after the immersion time wascomplete) were consistently greater than the release rates measured using the concentrations of aluminum in solution.

A corrosion rate higher than the release rate is consistent with theconcept that a portion of the corrosion products remains on the surface as a scale layer insteadof being released into solution.

4. When TSP was present, the aluminum release rate was generally lower than predicted byWCAP-16530-NP Equation 6.2. This result was particularly notable at pH = 6, where measuredrelease rates in this study were very low compared to the WCAP predictions.

5. When pH was controlled by NaOH instead of TSP, the corrosion rate was substantially higher(typically 3 to 4 time higher) than when TSP was present.

Release rates were also consistently higher when TSP was not present, often more than 3 times higher. Although natural variability exists in data from corrosion

studies, the release rates when NaOH was used for pH controlwere on average comparable to the rates predicted by WCAP-16530-NP Equation 6.2. Theseresults are evidence that a component in TSP (most likely phosphate) effectively reduces therate of corrosion of aluminum, and that the WCAP-16530-NP Equation 6.2 are conservative forpredicting the rate of aluminum corrosion when TSP is present.6. When 4.5 mg/L of silicon was present, the release rate in a boric acid/TSP solution was slightlyhigher than when silicon was not present.

The corrosion rates were similar with and withoutadded silicon.

This result is not consistent with previous testing indicated that silicon may havean inhibitory effect on aluminum corrosion.

However, these tests were conducted underdifferent conditions than previous testing.

In WCAP 16785, added silicon was in the form ofsodium silicate with pH of 8.0 in high concentrations

(_> 50 mg/L) compared to 4.5 mg/L in thesetests, and used sodium hydroxide (NaOH) to achieve desired pH compared to TSP in these tests.It is possible that the concentration of silicon was too low to have an inhibitory effect in thesetests or that the effect of silicon on aluminum corrosion is not the same when TSP is present aswhen it is not present.7. At 35 TC, there was very little change in the visual appearance of the coupons at the end of thetest. As the pH and temperature increased, the surface became darker and less shiny. At 85 TC,the coupons were dull and grey at pH = 6 and dull and black at pH = 7.2 and 7.7.Document No: CHLE-018, Rev 2Page 44 of 45 Title: Results of Bench Tests to Assess Corrosion of Aluminum in STP Containment Conditions

8. The pH generally increased during the corrosion tests with aluminum coupons.

The end of testpH was often 0 to 0.2 pH units higher than the initial pH, although in a few cases it was as muchas 0.5 pH units higher. The variability in pH at the end of the test may have led to variability inmaking comparisons to the WCAP release rates.9. The aluminum concentration was very low (below the reporting limit) in tests for leaching fromNukon fiberglass.

The results are consistent with the predictions of the WCAP release equations that Nukon is not a major contributor to the Al in solution during a LOCA. This result was trueregardless of whether additional Al was added to solution at the beginning of the test.10. The calcium concentration in tests for leaching from Nukon fiberglass was generally lower in thisstudy than predicted by WCAP-16530-NP Equation 6.4. The presence of TSP in solution mayhave contributed to a reduction of the leaching from fiberglass, since the WCAP equation wasdeveloped from experiments that did not include TSP.11. The silicon concentration in tests for leaching from Nukon fiberglass in this study was lower thanpredicted by WCAP-16530-NP Equation 6.4 at low temperature and pH and higher thanpredicted at high temperature and pH. Silicon release ranged from just below 1.5 mg/L at 35°Cto over 140 mg/L at 85°C. In general, the results predict a stronger dependence on temperature and pH in the presence of TSP than predicted by the WCAP equation, which was developed without the presence of TSP.5.0 References

1. Lane, A.E. et al., Evaluation of Post-Accident Chemical Effects in Containment Sump Fluids toSupport GSI-191, 2006, Westinghouse Electric Company:

Pittsburgh, PA.2. Reid, R.D., K.R. Crytzer, and A.E. Lane, Evaluation of Additional Inputs to the WCAP-16530-NP Chemical Model (WCAP-16785-NP),

2007, Westinghouse Electric Company:

Pittsburgh, PA.Document No: CHLE-018, Rev 2Page 45 of 45