LSNReviews

From: Osvaldo Pensado [opensado@cnwra.swri.edu]Sent: Wednesday, October 12, 2005 6:57 PMTo: Roberto PabalanSubject: RE: TPA 5.0.1 corrosion and near-field environment model viewgraphsAttachments: TPA5Corrosion.ppt

Find attached ...

----- Original Message -----From: Bobby Pabalan [mailto:rpabalan@cnwra.swri.edu]Sent: Wednesday, October 12, 2005 5:03 PMTo: Osvaldo PensadoSubject: TPA 5.0.1 corrosion and near-field environment model viewgraphs

Osvaldo,

Could you please send me an electronic copy of theviewgraphs you presented to Center/NRC staff on TPA 5.0.1Updates regarding corrosion and near-field environment? I ampreparing my annual review viewgraphs and I need to haveslides on the status of ISI in the TPA code.

Thanks.

bobby

Properties Page

Return-path: <opensado@cnwra.swri.edu>Received: from DAKATH ([129.162.200.212])by rogain.cnwra.swri.edu (Sun ONE Messaging Server 6.0 (built Oct 29 2003))with ESMTP id <0109001WURR5MB20@rogain.cnwra.swri.edu> forrpabalan@cnwra.swri.edu; Wed, 12 Oct 2005 17:57:07 -0500 (CDT)

Date: Wed, 12 Oct 2005 17:56:37 -0500From: Osvaldo Pensado <opensado@cnwra.swri.edu>Subject: RE: TPA 5.0.1 corrosion and near-field environment model viewgraphsIn-reply-to:

<!-!UENERkVCMDkAAQACAAAAAAAAAAAAAAAAABgAAAAAAAAA3KD4jl3POxGCOQBgCJ BcRcKAAAAQAAAAzn LQxk4FwEyIN5znRG 1 P4QEAAAAA@cnwra.swri.ed u>To: rpabalan@cnwra.swri.eduReply-to: opensado@cnwra.swri.eduMessage-id: <002301 c5cf8O$337757f0$d4c8a281 @cnwra.swri.edu>Organization: CNWRAMIME-version: 1.0X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2800.1506X-Mailer: Microsoft Outlook, Build 10.0.6626Content-type: multipart/mixed;boundary="----=_NextPart_000_0024_01 C5CF56.4AA1 4FFO"

Importance: NormalX-Priority: 3 (Normal)X-MSMail-priority: NormalOriginal-recipient: rfc822;rpabalan@cnwra.swri.edu

TPA 5.0.1Corrosion and near-field environment models

Osvaldo Pensado

1

TPA 5.0.1 Updates

* Alloy 22 corrosion- Corrosion potential, Ecorr

- Repassivation potential, Ercrev

- Localized corrosion inhibitors

- Temperature dependence of the Alloy 22 corrosion rate

* Near-field environment- Logic to define chemistry as a function of time

- Distribution functions of brine chemistry

2

Motivation for Changes• -- - i -- - - - - - - - --

*TPA 5.0 overestimates0.8 p.Ecorr, temperature

dependence is incorrect

0.0 TPA 5... Localized corrosionX .frequency is greatly

overestimated in TPA 5.0-• pH 12S0.4 TPA 5.0.1 changes

a- aimed at deriving a more

0.2 Experimental defensible estimate ofthe probability of

. .. localized corrosion0 . . . . . . . . .

300 320 340 300 380Temperature[K]

3

Technical Approach

" Priority: define a defensible model to estimate thelocalized corrosion probability for the WP

• Model: localized corrosion activated if Ecorr > Ecrit,otherwise, general corrosion prevails (same approach asprevious TPA versions)

" Ecorr adjusted to resemble experimental trends (variationwith respect to pH and temperature)

* Ecorr Ecorr(122)

- 122 - Alloy 22 anodic dissolution current density

" Ecorr temperature dependence is partially due to thetemperature variation of 122

4

122(T)

TPA 5.0.1: 1 22 aexp a --- TPA 5.0 and previous: /22 = 10aRref

Oa "AA_ _1 l[C/m2/yr] Triangular(1.6e3, 3.2e3, 6.4e3)Eaa . OuterActivationEnergyPassiveCurrDens[J/mol] 4.47e4Ta ref RefTemperaturePassiveCurrDens[K] 368

/0a Triangular(5x 10-9 A/cm 2 , 10-8 A/cm 2 , 2.2x 10-8 A/cm 2 )Passive current density at 95°C

Corrosion rate at 95 'C - Triangular(50.6 nm/yr, 99.3 nm/yr, 200 nm/yr)50.6 nm/yr- 4 x 105yr99.3 nm/yr -2 x 105 yr200 nm/yr-* 105 yr

Longer WP failure times by general corrosion are computed in TPA 5.0.1because of the temperature decrease as a function of time

5

I122 (T)-4

EE

0C

(j)

0C-)o

_.J

-6

-8

-10

-12

-14

EE

0

0-jz

-7

-8-

-9-

-10-

-11-

-12-

Ea = 41.8 kJ mol-1

Mill-annealed Alloy 22

* 0.028 M NaCI I~1 *~-13 I I I 1 I

0.0026 0.0028 0.00301/T (1/K)

0 I0.0032

I

0.0034

0.0024 0.0026 0.0028 0.0030 0.0032 0.0034 0.0036lIT (l/K)

Figure 3-7. Activation Energy for Alloy 22 CorrosionRates in 0.028 M NaCI and 35-Percent MgCI 2

(7.5 M Choride) (Dunn, et al., 2003a)

Figure 3-9. Activation Energy for the PassiveCorrosion Rate for Mill-Annealed Alloy 22 in 0.028 MNaCI As a Function of Temperature. Corrosion Rates

Were Obtained from Multiple ElectrochemicalImpedance Spectra.

Passive And Localized Corrosion Of Alloy 22-modelingAnd Experiments; Dunn et al., March 2005Passive Dissolution of Container Materials -- Modelingand Experiments, Pensado et al., 2002

6

DOE Data

.30C)

20

1619WC Liquid14

12 ... .......

to ---- _________

8O~q~qid e0*C Vapor

90*C Vapocr

SA SD s -

SA SCW.SW O

-41

SC

.30

C0

20

C,

Source: DTN: SN0308T0506303.004. Source: DTN: SN0308T0506303.004.

NOTE: SAW = simulated acidified water; SCW = simulated concentrated water; SDW = simulated dilute water. NOTE: SAW = simulated acidified water: SCW = simulated concentrated water; SDW = simulated dilute water.

Figure M-6. Corrosion Rates for Alloy 22 Weight-Loss Coupons in Simulated Acidified Water, Simu Figure M-7. Corrosion Rates for Alloy 22 Creviced Coupons in Simulated Acidified Water, SimulatedConcentJated Water, and Simulated Dilute Water Concentrated Water, and Simulated Dilute Water

7

DOE Data

* CR(60 0C)- 5 nm/yr in average* Ea- 26 kJ/mol

* CR(95 0C) - 12 nm/yrT=95 0C

1.6x106 years WP lifetime if

8

Corrosion Potential

oE_ E fa T RVT [([ + ] nH p O 2 no "ef C ok (IZr Pef F Zrj6re F Tref Zr fref F M atm i° Co Ur

Eefa• OuterActivationEnergyReductionReactHighpH[J/mole] 40000.0OuterActivationEnergyReductionReactLowpH[J/mole] 40000.0

p3efr OuterChargeTransferCoefReductionReactHighpH 0.0248

OuterChargeTransferCoefReductionReactLowpH 0.01287

/ef OuterReferenceCurrReductionReactHighpH[C/(m2*yr)] 5.51 e9r

OuterReferenceCurrReduction ReactLowpH[C/(m2*yr)] 7.57e9

nH •OuterEffectiveReactionOrderHHighpH 0.01897

OuterEffectiveReactionOrderH LowpH 0.0256

All other non listed parameters are constant and not controlled by the user

/

9

Corrosion Potential

1000 -

800-

xw600 -

EE400 -8

LU

200-

0-

-200

TPA ukper boutnd95 *C [203 0F]

TPA most likely esti

TPA lower bound

tate

.... TPA upper bound

IPA rmost likely estimatp

TPA lower bound

Neutral to alkaline ranhge-"-,Acidic ranget I

1 3 5pH

7

e)F

9 11 13

4

TransitionLowHighpH = 6

10

Corrosion Potential

1000

850

700

; 550E

-400-

250-

100

-50

-2007.5

25 -C 77. -F]

TPA upper bound

TPA most likely estimate

...... TPAlowe-tound ..................

1000-

850-

700-

550-

400-

250-

100-

-50-

-200

40c [104 "Fj

.,TPA upper bound. .... °... .. ..... ....... ° .......

TPA most likely estimate

TPA lvowe bound... .. ...........................

8.5 9.5 10.5

(a)

11.5 12.5 7.5 85 9,5 10.5pH

(b)11,5 12.5

1000

850.

700.

550.

400.

250

100.

-50,

60 -C (140 "F]

TPA upper bound

TPA most likely estimale

....... TPA toweýr . ...........d

1000

850

700

>•550-E

400-

250

100

-50

12.5 -200 -7.5

80 -C [176 -F)

TPA upper bound

TPA most likely estimate

TPA lower bound

8.5 ... 5 10.5.700+ 8.5 9.5 105.

7.5 11.58.5 9.5 H 1 0.5pH

(C)8,5 9.5 PH10.5

pH

(d)11.5 12.5

11

Inhibitor Effect" Modeled as an increase in the repassivation potential:

Ercrev = f ([Cl ,T) + •AErcrevAE in~,1~E r[NO;]+rn [S0O4-] ~rn [CO•-]+[HC03]

A•Ercrev = min(r, r,,) Eo r - [N 31+r,,IO JrnC 3'][C 3

rn 0[C-] r, [CI-] rc [Ci-]

" r, OuterlnhibitingNitrateToCl = 0.1r OuterinhibitingCarbonateToCi ='0.2

r, OuterlnhibitingSulfateToCl = 0.5" Eo, OuterDeltaEcritlnh[mV] = 800.0* r, WeldlnhibitingNitrateToCl = 0.3* rc, WeldInhibitingCarbonateToCi = 0.2• rs, WeldlnhibitingSulfateToCl = 0.5* Eo, WeldDeltaEcritlnh[mV] = 800.0

12

Comments on TPA 5.01

* Improved technical bases to assess LC probability* Due to temperature dependence of passive corrosion

rate, WP failure by general corrosion will occur muchlater (millions of years?) than in previous TPA codeversions

13

NFENV Model

200

0

I.-

E0)

cocc

cca.0)

cc3:

11

8060

140

120100

80

60

4020

0

10 100ti it 0 tilTme, 6oo tTi'me, yr 10000

14

NFENV Model

* t :time at which- relative humidity > CriticalRelativeHumidityAqueousCorrosion (= 0.3)

* t11: time at which three conditions are fulfilled- Drift temperature < SeepageThresholdT[C]

* SeepageThresholdT[C] -triangular(100.0, 105.0, 120.0)- Drift seepage rate > 0- Drip shield must be failed (i.e., t11 > DS failure time)

* t11,: time at which three conditions are fulfilled- Relative humidity > RewettingHumidity[]

* RewettingHumidity[] - uniform(O.95, 0.98)- Drift seepage rate > 0- Drip shield must be failed (i.e., t111 > DS failure time)

" Environment II is displayed ONLY IF the drip shield fails before till.* Localized corrosion could only occur during Environment II

15

NFENV Model, Env I

* Due to abundance of nitrate in dust, it is assumed thatlocalized corrosion does not occur during Environment I

* Env I parameters arbitrarily selected to avoid localizedcorrosion of the WP- Environmentl_Fl[mol/L] = 1.0e-5

- Environmentl_Cl[mol/L] = 1.0- Environmentl_pH[] = 7

- Environmentl_N03[mol/L] = 1.0

- Environmentl_C03[mol/L] = 0.0

- Environmentl_S04[mol/L] = 0.0

- EnvironmentlWastepackage_DeltaECrit[VSHE] = 0.0

16

NFENV Model, Env II

* Multiple thermodynamic simulations of water evaporation performedusing Yucca Mountain saturated waters as initial condition

* Thermodynamic simulations were supplemented by the chemicaldivide concept

" From 156 initial Yucca Mountain waters, 8, 24, and 68 percentresulted in calcium chloride-, neutral-, and alkaline-type brines

* Numerical probability distribution functions (PDF) were derived foreach brine type, and combined according to the 8, 24, and 68percent proportions to derive global PDFs as well as correlationmatrices

* Approach documented in Passive And Localized Corrosion Of Alloy22- Modeling And Experiments; Dunn et al., March 2005

17

NFENV Model., Env II

0,9 (a) o0,9 (b)13 0 a8 )0.8

0.8 0.7 0

S0.6A 0.6

0.5 0.'00.4- A04

0 0 0.3 -

0.2 E 0

0.1 0 .1

0 0.5 6 7 8 9 10 11 12 3 S 7 9 1

pH [cq, momEnvironmentlipH Environmentl I_CI[mol/L]

1 1 • .. .

0.a (C)0.- (d)

S0.8 •• ~: 0-7 L 0.7

U 0.5

00.4- 00.4

03 0 0.3

0,2 -0.2

0.1 - 0.1

0 1 409 0.0000001 0U00001 0.001 0.1 10

[4O ;], molq. [CO 321+tHCO -j, moVL

EnvironmentliNO3 EnvironmentllC03-- -- 18

-C

E

00t

10

9

8

7

6

5

4

NFENV Model, Env Il

•. • •Correlateinputs(Environmentll pH[],Environmentll_C03[mol/L]) = 0.9

Correlateinputs(EnvironmentllCl[mol/L],EnvironmentlIpH[]) = -0.81";.-""'" " _p.H[])

6 7 8 9

pH

10 11

0E

c0

0

1.2

1

0.8

0.6

0.4

0.2

0

* *:- . **.. ". : *

• • . • .. .. .:.. .• . ."

• .• . .: . ",.• ;,,. . -:'..

" .* . ..... .. ,.

6 7 8 9 10 11

pH

19

NFENV Model, Env III

* Waters are diluted and not likely to induce localizedcorrosion

* Env III parameters arbitrarily selected to avoid localizedcorrosion of the WP- Environmentill_Fl[mol/L] = 4.08e-4

- Environmentll _Cl[mol/L] = 6.65e-3

- Environmentll _pH[] = 8.37e0

- Environmentlll_N03[mol/L] = 6.65e-3- Environmentill_C03[mol/L] = 2.1 le-3

- Environmentll _S04[mol/L] = 0.0- Environmentlll_WastepackageDeltaECrit[VSHE] = 0.0

20

TPA 5.0.1 ExampleRealization = 1

10.5

10

9.5

I- 90.

8.5

8

7.5

7

0.1

0.08

-a 0.06Erl-o 0.04Z

0.02

0

Env II

Env II1

Dry

10 100 1000 10000 100000. 1.x10aTime, yr

10 100 1000 10000 100000. 1.x10aTime, yr

7

6

5

E3-'3

2

1

010 100 1000 10000 100000. 1.x108

Time, yr

0.01

0.008

0

E 0.008C,,-00 0.004

0.002

010 100 1000

Time, yr10000 100000. 1.x1lP

21

Comments on TPA 5.01

The ally aged 9 Proof of concept simulations0.9 (Mathematica), indicate that0.8 26% and 3% of the realizations

1 0.7 will display localized corrosion0

W ? 0.6 on the weld area and mill-o Mill anneale annealed body, respectively, if

E I0DS protection is disregarded0a-E

0.2

-1500 -1000 -500 0 500 1000 1500E corr -E cnt, mV

22

NFENV in Mathematica

concsWP[realizj:=Module[{cM,time,i,EnvironmentlFl=l.0*^-5, EnvironmentlCll.0, EnvironmentlpH=7.0,EnvironmentlNO3=1.0,EnvironmentlCO3=0.0,EnvironmentlSO4=0.0,Environmentlll FI=4.08*A-4, Environment I ICI=6.65*A-3, Environment I IpH=8.37,EnvironmentIIINO3=6.65*A-3, EnvironmentlilC03=2.1 1*A-3,EnvironmentlllS04=0.0,CriticalRelativeHumidityAqueousCorrosion=0.3,critRH

(*realiz=realization number*)

time=Transpose[daCl][[1]];

critRH=CriticalRelativeHumidityAqueousCorrosion;

cM={};Do[

IffdaTRp[[i,realiz+l]]>SeepTemp[[realiz]] II daqHit[[i,realiz+l]]<= 0.0 II time[[i]]< dsFailTime[Irealiz]],(*No direct water contact case*)

lf[daRelHum[[i,realiz+l]]> critRH(*Deliquescence case*)AppendTo[cM,{time[[i]], EnvironmenuIc1,Environmentl pH, Environment] N03,EnvironmentIc03, EnvironmentIs04}],

(*Dry case*)

AppendTo[cM,{time[[i]],0.0,7.0,0.0,0.0,0.0}]

(*Direct water contact case*)

Iff daRelHum[[i,realiz+l]]> critRH && daRelHum[[i,realiz+l]]<relHumTran[[realiz]],(*dynamic evaporation*)

AppendTo[cM,{time[[i]],cl[[realiz]],pH[[realiz],no[[realiz]],co[[realiz]],so[[realiz]]}],

If[daRelHum[[i,realiz+l]]> relHumTran[[realiz]],(*diluted conditions*)

AppendTo[cM,{time[[i]],Environment] I ICIEnvironmentl I I pHEnvironmentl IIN03,Environmentl c C3,EnvironmentlIIS04}],(*Dry case*)

AppendTo[cM,{time[[i]],0.0,7.0,0.0,0.0,0.0}]

]

Ri,1 ength[time]}];

Return[cM]];

23