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From: Osvaldo Pensado [[email protected]]Sent: Wednesday, October 12, 2005 6:57 PMTo: Roberto PabalanSubject: RE: TPA 5.0.1 corrosion and near-field environment model viewgraphsAttachments: TPA5Corrosion.ppt
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----- Original Message -----From: Bobby Pabalan [mailto:[email protected]]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
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Date: Wed, 12 Oct 2005 17:56:37 -0500From: Osvaldo Pensado <[email protected]>Subject: RE: TPA 5.0.1 corrosion and near-field environment model viewgraphsIn-reply-to:
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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