ML20084V210
| ML20084V210 | |
| Person / Time | |
|---|---|
| Site: | Braidwood  |
| Issue date: | 06/09/1995 |
| From: | WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP. |
| To: | |
| Shared Package | |
| ML20084V204 | List: |
| References | |
| SG-95-06-005, SG-95-6-5, NUDOCS 9506130450 | |
| Download: ML20084V210 (47) | |
Text
1 JUN 09 '95 04:49PM IEST PURCH SERVIECE WALTZ MILLS P.2/40
~i l
SG 95-06-005.
I
{
BRAIDWOOD UNIT 1 1995 INTERIM PLUGGING CRITERIA 90 DAY REPORT JUNE 1995 4 k
t j
l l
1 I
WESTINGHOUSE EIECTRIC CORPORATION l' ENERGY SYSTEMS BUSINESS UNIT NUCLEAR SERVICES DIVISION P.O. BOX 355 PITTSBURGH, PENNSYLVANIA 15230 l
i rw w.nw.mu,roura .insun I i
l ph CK P
JLN 9 '95 15:50 412 7225119 PAGE.002 i
.JUN 09 '95 04849PM IEST PURCH SERVIECE WALTZ MILLS P.3/40 I
i I
BRAIDWOOD UNIT 1 '
1995 INTERIM PLUGGING CRITERIA 90 DAY REPORT JUNE 1995 .
'l t
TABLE OF CONTENTS 1.0 Introduction 2.0 Summary and Conclusions 3.0 MOC-5 Inspection Results and Voltage Growth Rates 3.1 MOC-5 Inspection Results 3.2 Voltage Growth Rates 3.3 NDE Uncertainties 4.0 Data Base Applied for IPC Correlations >
5.0 SLB Analysis Methods -
6.0 Bobbin Voltage Distributions Probability Of Detection (POD) 6.1 6.2 Calculation of Voltage Distributions 6.3 Projected BOC-5 to MOC 5 Voltage Distributions 6.4 Comparison of Actual and Projected MOC-5 Voltage Distributions 6.5 Projected EOC-5 Voltage Distributions 7.0 Tube Leak Rate and Burst Probabilities 7.1 Leak Rate and Tube Burst Probability for EOC-5A 7.2 Leak Rate and Tube Burst Probability for EOC-5B 8.0 References 3.peweswa w rne e s. ten am 2 !
JUN 9 '95 15:50 412 7225119 PAGE.003
, JUN 09 '95 04:49PM WEST PURCH SERVIECE WALTZ MILLS P.4/40 BRAIDWOOD UNIT 1 1995 INTERIM PLUGGING CRITERIA 90 DAY REPORT
1.0 INTRODUCTION
This report provides the Braidwood Unit 1 steam generator tube Eddy Current Test (ECT) inspection results together with Steam Line Break (SLB) leak rate and tube burst probability analysis results, in support of the implementation of a 1.0 volt Interim Plugging Criteria (IPC) at Middle Of Cycle 5 (MOC-5) according to NRC guidelines. Comparisons of the actual MOC-5 voltage distributions as well as leak rates and tube burst probabilities (POB) calculated witb these distributions (based on MOC-5 ECT data) are made with the corresponding projections for MOC-5 (based on the previous cycle 4 data). Also provided are projections of ECT tube voltage distributions, leak rates and burst probabilities for the completion of Cycle 5 operation (MOC-5 to EOC-5)*. The methodology used in these evaluations is in accordance with previously published Westinghouse reports (References 8.1, 8.2).
The application of the Interim Plugging Criteria (IPC) at Braidwood Unit 1 involves 100% Eddy Current Test (ECT) of the tube bundle and plugging of >1.0 volt indications which are confirmed by Rotating Pancake Coil (RPC). Plugging of >2.7 volt bobbin indications is performed regardless of any RPC inspection. Along with this field activity, an analysis is performed to predict the tube leakage rate and burst probability for a postulated SLB accident during the remainder of Cycle 5. Since tube degradation increases with time during operation, it is most likely that the maximum estimate for tube leak rate and burst probability would occur at the end of a cycle; the analysis does not take into account unexpected events that could alter this probability.
2.0
SUMMARY
AND CONCLUSIONS SLB leak rate and tube burst probability analyses were performed for the actual EOC-5A ECT bobbin voltage distributions and are conservative (lower) relative to corresponding projections for EOC-5A calculated with a Probability of Detection (POD) of 0.6 by approximately an order of magnitude. SG O was found to be the limiting SG at actual EOC-5A voltage distributions.
i l
- For clarity, BOC-5 to MOC-5 will be referred to as cycle 5A (from BOC. 5A to EOC-5A) and J MOC-5 to EOC-5 as cycle SB (from BOC-5B to EOC 5B). 1
.wxwsswoowy rey A= e. aos is oo 3 JLN 9 '95 15:51 412 7225119 PAGE.004 l l
1
, ,. JUN 69 '95 04. E 1 WEST PURCH SERVIECE NALTZ MILLS P.5/40 4
i For the actual EOC-5A bobbin voltage distribution, the SLB leak rate is calculated to be 0.32 gpm and the burst probability is 3.04 E-03 for SG C; these values are below I the corresponding projections for SG C assuming a voltage frequency based on the '
NRC SER endorsed probability of detection (POD) of 0.6. Also, these values are much lower than the allowable SLB leakage limit of 9.1 gpm and the NRC reporting guideline of 10 for the tube burst probability. The prediction expected SG D to be more limiting than SG C at EOC-5A because of significantly higher voltage indications at EOC-4, although SG C had a larger number oflow voltage indications.
The projections for SG D yield SLB leakage and tube burst probability that are close to a factor of 10 higher than obtained for the actuallimiting SG C. This supports the conservatism of the IPC methodology of applying the limiting SG as the basis for IPC analyses.
Comparisons of the EOC-5A projections with the actual distribution for SG G show that a POD of 0.6 overestimates the actual distribution above 0.9 volts although <
slightly underestimating the maximum voltage (4.9 volts versus actual 5.2 volts). The '
projections for SG D are excessively conservative in predicting the higher voltage (above 1.6 volts for SG D and about 2.8 volts for SG C) tail of the distribution due to applying the POD = 0.6 to EOC-4 indications above about 2 to 3 volts. These results show the value of applying a voltage dependent POD.
A total of 3935 indications were found in the EOC-5A inspection of which 1125 were RPC inspected (including all indications above 1.0 volt) and 874 were confirmed as flaws by the RPC inspection. The RPC confirmed indications included 836 above 1.0 .
volt. SG C had 1526 bobbin indications, of which 431 were above 1.0 volt and 339 :
of these were confirmed by RPC inspection. No unexpected inspection results were found at the TSP intersections, such as circumferential indications, indications extending outside the TSP or PWSCC at dented TSP intersections.
3.0 MOC-5 INSPECTION RESULTS AND VOLTAGE GROWTH RATES 3.1 MOC-5 INSPECTION RESULTS In accordance with the IPC guidance provided by the NRC draft generic letter, the Middle Of Cycle 5 inspection of the Braidwood Unit I steam generators (SG) consisted of a complete,100% Eddy Current Test (ECT) bobbin probe full length examination of all TSP intersections in the tube bundles of the four SGs. A 0.610 l inch diameter probe was used for all hot and cold leg TSPs where IPC was applied.
Subsequently, Rotating Pancake Coil (RPC) examination was performed for all '
bobbin indications with amplitudes > 1.0 volt. RPC confirmed indications > 1.0 bobbin volt were plugged. In addition, an augmented RPC inspection was performed consistent with the NRC requirements.
.w.wnwou.7 ra.a .t un a a 4 JUN 9 '95 15:51 412 7225119 PAGE.005
, ,o JLN 09 '95 04:59PM WEST PURCH SERVIECE WALTZ MILLS P.6/40 The augmented RPC inspection included dented TSP intersections with dont voltages
> 2.5 volts, 40 artifact signals and 20 indications with bobbin voltages < 1.0 volt.
There were no RPC flaw indications reported in the augmented inspection.
There was no evidence of any unexpected eddy current results at MOC-5. There were no RPC circumferential indications at the TSPs, no indications extending outside the TSPs, no RPC indications with potential PWSCC phase angles, no flaw indications at danted TSP intersections at any dent voltage and no flaw indications were found in the augmented RPC inspection. All RPC responses were consistent with that expected for ODSCC at TSP intersections.
A summary of ECT indication statistics for all four steam generators is shown on Table 3-1, which tabulates the number of field bobbin indications, the number of these field bobbin indications that were RPC inspected, the number of RPC confirmed indications, and the number of plugged indications. The indications that remain active for the cycle 5B operation is the difference between the observed and the plugged. Overall, the combined data for all four steam generators of Braidwood Unit I shows that:
- Out of a total of 3935 indications identified during the inspection, a total of 2725 indications were returned to service for cycle 5B.
- Of the 3935 indications, a total of 1125 were RPC inspected. l Of the 1125 RPC inspected, a total of 874 were RPC confirmed.
A total of 1210 indications were removed from service. The RPC confirmed but not removed from service indications have bobbiu amplitudes of $;1.0 volt.
Review of Table 31 indicates that steam generator C has more and L . her BOC 5B indications (a quantity of 1034, with 79 indications >1.0 volt) than 3G A, B or D, thereby it potentially willbe the limiting SG at EOC 5B. Figure 3-1 shows the actual bobbin voltage distribution determined from the EOC-5A ECT inspection; Figure 8 2 shows the population distribution of those EOC-5A indications which were plugged and taken out of service; Figure 3-3 shows the indications which are being returned to service for cycle 5B. ,
The distribution of EOC 5A indications as a function of support plate elevation, summarized in Table 3 2 and shown on Figure 3-4, shows the predisposition of ODSCC to occur in the first few hot leg TSPs (3827 of 3935 indications occurred in the first four TSPs), although the mechanism did extend to higher TSPs, including a few in the cold leg. This distribution indicates the predominant temperature dependence of ODSCC at Braidwood Unit 1, similar to that observed at other plants.
a;\ apt \eso86%ece90 day Tnday .hane 9,1993 at 00 5 JLN 9 '95 15:51 412 7225119 PAGE.006
, y JUN 09 '95 04:50PM W_ST PURCH SERVIECE WALTZ MILLS P.7/40 Of the 3935 total indications represented by Table 3-2, nine IPC indications were reported in coldleg TSPs. All nine indications were < 1.0 volt. Two of the affected tubes were plugged, because of hot leg IPC indications in those two tubes.
3.2 VOLTAGE GROWTH RATES For project:.on of cycle 5B operation, voltage growth rates are developed from the March 1995 inspection data and a reevaluation of the same indications from the previous (1994) inspection ECT signals. The previous cycle 4 growth rate and indication distributions at BOC-5A are used to develop the EOC-5A predictions, but cycle 5A growth rates, found to be slightly more conservative than cycle 4 values, are used to develop the EOC-5B predicticas. Of the 3935 bobbin indications found in the 1995 inspection, the growth for cycle 5A could be calculated for 3884 indications since a reliable value for 1994 bobbin voltage could not be obtained for the others.
Growth statistics for the Braidwood Unit I steam generators, shown on Table 3 3, provide a comparison of the last three operating periods (1991 - 1992,1992 - 1994 and 1994 - 1995). Table 3 3 indicates that the growth rate per EFPY decreased from cycle 3 to cycle 4 and increased from cycle 4 to cycle 5A.
Table 3-3 compares the average voltage growth rates for Cycles 3,4 and 5A, with cycle SA growth exceeding that of cycle 4. The trend of the growth data summarized on Table 3 3 is not conclusive. Cycle 4 indicates a reduced growth rate (from 89% to 47% per EFPY), compared to Cycle 3, with the implication that chemistry enhancements have been effective in reducing the growth of ODSCO indications at
- he TSP intersections. During the protracted 1994-1995 operating period of cycle 5A, the average growth changed from 47% to 72%, on a comparable EFPY basis.
Average growth rates in each SG for cycle 5A (1994 - 1995) are shown in Table 3-4 The average growth rates vary between 49% and 86% per EFPY, between SGs, with an overall average of 72% per EFPY. The average growth for indications > 0.75 volt is 64% per EFPY and for indications < 0.75 volt is 75% per EFPY, SG C has the the !
highest average voltage at BOC-5A whereas SG A has the largest average voltage growth during cycle 5A. Table 3-5 shows the cumulative probability distribution i function of each SG during cycles 4 and 5A, on an EFPY basis for relative comparison; these growth rates were used for.the midcycle predictions in the return-to. power evaluation. The guidance of the NRC draft generic letter recommends that the more conservative growth distribution from the last two cycles be used for projecting EOC distributions. For conservatism consistent with the NRC guidance, a worst case hybrid growth distribution is defined on Table 3 5, which envelopes the actual EOC 5A distribution with the simultaneous limitations of SO A (highest average growth) and of SG C (highest growth increment of 5.7 volts during cycle 5A).
i r w es w rner u.s.sessism G JUN 9 '95 15:52 412 7225119 PAGE.007
l,- 9 .JUN 09 #95 04:51PM WEST PURCH SERVIECE WALTZ MILLS-P.8/40 i:
- i. .
This hybrid growth was imposed 'on all four steam generators, to provide a conservative basis for predicting EOC-5B performance. Tabh 3-6 shows distributien >
- functions that were used for the 90 Day evaluation. Table 3-7 lists the Ir/ gest growth rates, in descending order, that were developed during cycle 5A; it ie noted !
that all of these bobbin calls were RPC confirmed. ,
3.3 NDE UNCERTAINTIES The NDE uncertainties applied for the cycle 5 vo tage projections in this report are {
the same as those previously reported in the Braidwood Unit 1 IPC report of !
Reference 8.1. The probe wear uncertainty has a standard deviation of 7.0 % about a mean of zero and has a cutoff at 15 % based on implementation of the probe wear t standard. The analyst variability uncertainty has a standard deviation of 10.3% !
about a mean of zero with no cutoff. These NDE uncertainty distributions are :
included in the Monte Carlo analyses used to project the EOC 5 voltage distributions. !
l l
l I
r sNyeWet3%e90 day Tnder Jue 9.1993 1890 7 JUN 9 '95 15:52 412 7225119 PAGE.000
c s:
L4 g 4' E
o Table 31 '@
d un Braktwood Unit 1 - Steams Generneer IPC 8' '
G Susannary of Inspecties and Plagging During EOC-5A g
Semene Somerator D CemeinedDets
-y {
sesers on wester A Steesn Genosseer a Stose GomesseerC 3
Des opC 80ungensten puPC APC m Ned esense stPC RPC tenusmus Masemus pec 3EPC tedutuw Mauestate RFC OfC euemens Fussense fuPC teemamme suessamme out emessemns inspeans Csemed Phgese ensumums nuessume cuenrad Pheged h W comeusse Phepos buensamms asynceed Capdhaus pegged tusumamme husmansd Camemums utsams 01 0 0 0 0 0 0 0 0 6 0 0 0 0 0 C e 0 0 0 0 02 4 0 e 0 1 0 0 0 3 0 e 1 2 4 0 9 to 0 0 1 e to e 0 31 0 0 e 21 1 0 3 108 3 0 10 03 de 1 4 t i 0.4 SS 4 e 11 es 2 S 1 93 3 1 90 _ SF 2 1 $ 2W 11 2 27 4 11 52 4 1 4 162 2 1 te m & 2 0 4 90 13 5 43 03 tta 1 4 2 14 51 4 2 2 See 1 0 to 115 2 1 15 482 11 5 46 -
06 198 138 0 23 48 9 1 6 173 3 1 25 115 1 1 14 4M e 3 87 9.F 1 es 113 4 1 23 43 e 3 182 1 9 1e 10F_ _20 1 12 445 12 11 SF g, es 103 5 3 19 37 4 0 e 106~ 2 e 16 88 9 12 382 11 3 47 P1 90 81 2 1 S 33 3 3 1 ~i2F 2 0 16 at 6 4 14 300
=
12 9 at h
8.1 7. F. t. t. . O tee m 7. . 49 4e 2. t.
40~ Se IF 17 8 9 S1 91 S3 67 48 48 37 30 208 20s 157 194 .__
12 _ 64 64 32 5 5 58 58 47 47 M 34 as 2s 139 139 111 112 -
1.3 38 38 31 19 ft 1.4 25 26 22 23 0 9 S
4 2
0 2
46 34 45 as 38 at 40 32 it se 19 to 15 ta 95 s6 OS se 90 to p3 96 W
71 h
24 24 20 22 S g
1.5 ~
1.6 is 18 18 19 2 2 1 6 26 25 21 21 13 it s
is s
17 s
87 s
83 3s 83 3s
_. 57 30 SF 3 -
t.F 12 12 e 10 a e 4 4 13 13 12 4 . se 10 2 2 2 2 IS it 14 14 5 6 6 6 36 39 at 31 1.9 10 to to 7 7 7 7 2 2 2 2 te se F 4 e 9 9 9 28 30 28 3 1.0 4 4 4 0 0 4 8 2F 27 22 22 70~ 10 to a e 3 3 2 2 8 4 2 2 2 to to 10 19 2.1 4 4 4 4 0 0 0 0 4 4 4 __ 2 4 4 4 4 1 1 4 9 4 4 3 _3 3 2 2 2 _2 et et 10 m 2.2 0 3 3 i 3 1 1 9 7 7 7 7 2.3 3 3 3 3 0 0_ _e _3 1 ,
4 4 4 4 0 0 0 0 2 2 2 2 1 1 1 1 7 7 7 7 2.4 3 3 3 a 1 1 1 . . . .
e N
__ 2 .
27 2
3 2
3 - 3 2 2 3
0 0
e e
0 0 3 3 3 I 1 1
1 1 1 7 7 7 7 0 0 0 0 4 4 4 9 1 1 1 S S S S 1 1 1 1 4 2A__ 1 3 3 3 3 N 2.9 1 1 1 8 9 0 0 0 1 1 1 1 1 1 1 1 2 2 2 2 S S S S h
32 3.3 2 1 1 2
1 2 2 1
0 1
0 1 1 0
1 9
1 1
1 1
1 1 1 0 0 0 0 3 3 3- 3 2 2 g u 2 2 2 2 . 0 0 '8 0 .
0 O
0 e
D e
0 0
1 1
1 1
2 1
2
. 1 1-3.0 9 e 0 0 0 37 e 4 0 0 0 0 0 0 t i 1 1 0 9 0 0 t i 1 1 4.1 1 1 1 1 0 0 0 0 9 0 0 0 e 8 9 0 t 1 i 1 52 e e e e 0 e e 0 1- 1 1 1 e o e O t t 1 t reest 10es 31s See 374 413 ses so et is2s ses See est est 257 aos ses sees 1125 e7e ce 303 78 79 45 46 439 431 330 352 Set att tot 100 1000 iteS O3e MD 'y m1Y 298 ISS ats
.g F$ Yh
. _ . . . _ . . . . . . . _ . . . ~ . , . . . __m.. _ _ _ . . . , . , _ . _ _ . _ . , _ _ _ . _ .
.- ,, JLF1 09 '95 04351Pt1 NEST PURCH SERVIECE WALTZ MILLS P.10/40 4
j] ! ! ! ! ! !! ! !!
.a )l ! ! ! !! !!!!!
! ! ! E. ! ! !
J ll ! ! !
ll ! ! s a s . - - - -
I O
ji ! ! ! ! ! ! ! - - -
ll ! ! ! ! !!! - - -
j ll !! !!!!! - - -
, ,i . . . . . _ . . . . .
Q.5 w1 !!!!!! - - - -
e U
l1
{3 W
1 ll ! ! !!!! - - - -
g es j gjj H ~ li g ll
=
!!!!e! - - - -
I I E 8 C
.g' I g
.g. 11 I..i.t. ! !
1 i ll !. !. a. i.s-j l ~
5 5E 5 i 3. , - - . . . . .
I, j
jl !!! ! ! ! ! ! !!
__ ll ! ! ! ! ! ! ! ! ! !
" }
g ll ! ! ! ! ! ! 5 ! ! ! I ;
l { i
,lI y$? s e n e - e n l I l
i i sli m ar i s s i a s s! g 8
- u 9
AN 9 '95 15:53 412 7225119 PAGE.010
U t u' E.
e 8
8" -
8
$ Table 3-3 d Brakhrood Unit 1 Februsty 1995 EOC - 5A -@
Average Voltage Growth g CoWreof All Steem GeneratorData 3 i
Number of Average BOC Average DV Growth / Cycle Cycle EFPY Average DV Growth 1EFPY
% Growth per Cycle
% Growth per EFPY
]
g Indications Voltage Cycle SA 3/94 to 2f95 EY Entre Voltage Range 3884' , 0.56 0.28 0.714 ._ 0.40 _ _ _ _ 51, ,_ ,, _ _ ,_72 A 75 3085' O.46 0.25 0.35 54 .
V BOC < .75 " _ _
64 V> =.75 -- 799" ~ 0.92 0.42 0.59 46 3
5 Cycle 4 9#92-3t94 F
e 2854 0.48 0.26 1.147 0.23 54 47 Entire Voltage Range 2289 0.41 0.29 0.25 71 62 V BOC < .75 365 0.92 0.13 0.11 14 12 ;
V>=.75 Cycle 3 4791 to Sf92 h 89 0.62 0.82 0.55 100 y Entre Vottage Range 167 0.65 1.12_ .
0.58 151 135 V BOC < .75 145 0.43 N 0.42 0.38 46 41 C V> .75 22 0.92 e
- includes only those indications for which 1994 to 1995 growth was calcula1cd.
m 7
l Q
o i
GROWTH MLWisese 3.JE'Nug6273 PW i
l
E %
Tatde 34 BreldwoodUrdt1 PotmeeryitM S
$ Average Vetlege Growth for Cycle 5A g p l Newntper of Average ROC Average AV Cycle Average AV % Stewth % Geomen g IrH$lcotterts Vehage GeowebfCycle EFPY CrowstSFPY per Cycle por EPPY g i
s Compeelte of All Steam Generefore g 0.28 0.40 51 1 72 Entire Vete0e RenGe 3684 0.54 0.714 _ _
0.25 R35 54 75 l VBOC$:p,,,_ , , _,,,_ _3085 0.46 ,_
0.42 0 50 46 64 l V> =.75 799 0.92 l pl Steese Generater A h 0.32 0.714 0.45 61 88 h EntWe Vollege ReeGe 1030 0.52 0.43 0.29 0.41 67 _ 94 849 h
[V BOC < .75 _
0.45 0.84 de 88 V>=.75 190 0.93
~ r1 Stessa Generator B 3 0.55 0.19 0.714 0.27 35 de h
_Erwe Voltage Range 410 1 0.46 0.17 0.24 38 53 V COC < .75 332 0.28 6.30 29 41
-V>=
~ TS-~ 77 0.98 l Steam Generator C S 0.30 48 05
" 1514 0.54 0.27 0.714 Eattre Ww Renee_ 0.32 48 85 N 1141 0.40 0.23 V BOC < .75 -
46 65 3Y3 0.91 0.42 0.50 h V>E75--~
s Stearn Genevatar D e.30 0.714 0.42 56 79 Enties Vallege R s 921 0.54 0.46 0.27 0.38 58 8I V SOC < .75 763 0.00 0 44 OA2 50 70 158 h V>=.75 -
m o
e tsargyseg atvirteens 3 ettegge M M4
P.13/40
,, --,.. JUN 09 '95 04:52PM WEST PURCH SERVIECE WALTZ MILLS l
l ! ! !!!!i! !!l!!!!!!!,!! !!! ! ! !! ! !!! !!! !!! !! ! ! ! ! ! ! ! ! I
] g ,g_ i u 2 1 ,s
.l.i.4 . . . - . . - . . . -- . . . . . - - . . . .
I..;j.iee i .l.i.i.p ;
l ! !!ftl1l! ! !'!l!!!'!!!!
I!' !!! ! !!! ! !'!!! !! !! !!! ! ! ! ! ! !
I ist-
}g . sI s.na . . .. . . . . . . . - . . . . . . . . . -- . . . . . i
..{iin f*! l ! ! ! !! ! !!! ! ! ! !!! ! ! ! ! !! ! !! ! !!! ! !!! ! !! !!!! !
1 l ! ! ! ! ! ! ! ! ! ! ! ! ! ! !! !!!!!! ! !! ! ! !!!!
is{
g
.11 l
-l.:lia$ I e:Isi'zlisl..ta gj
- :si.
- .ill I= ! i l !
g t ia! l i
!! !5!" *H H k ! ! ! ! ! ! !! ! !! ! ! !! ! ! ! ! ! ! ! ! !! ! !
! ,li j
l
';I! u l I !!! !!!! !ji!! !! !!!!!!!!!!!!!!i!!!!!!!! !! !!!
"15 I !=E A j }g .. . . n sn . . . u . s . . . . . . - - - -- -- . . . . . . . . . ..
i
!*i I !!!! !
!!f!!! !!! ! ! !! ! ! ! !!
l a l !,
i
! !!i!!! ! !! !i!!!* ! ! !! !!! ! ! ! ! !!! ! !!!! ! !
[s{ _
}g - - t6 . . . .! = . . . -. - . . . . . . .. . . . . . . . ,
[
l s
!I !!! !! ! ! ! I Ea! l n
}
I! ! !! ! !! !! ! ! ! !!!! ! ! ! ! ! ! !! ! ! !'! I l ! !'!i!! ! !!!!!!l!!
isi- gi g ii ss!i'l:lst q
- a . z. ! ir ess a z : 3 . . . . . .. . . -- - . -. . . - - - . .
) g i ? I g gg ((gt B b
[s{ { fi l ii lfifE!!!!E((jgilff9
.iirii i - Eft t l
fil{g if gt I
8 t
.a s' 1 1 sl l I ff5 I"lt'l*!.;.:!:;;"**:l*":!. S:**: : : :1, ?: !." ) }
i..... ,
- r:::\ :h.*: .
8 f
! i i
12 JUN 9 '95 15:53 412 7225119 PAGE.013
, , JUN 09 '95 04:52PM IEST PURCH SERVIECE 14ALTZ MILLS P.14/40 Table 3 - G Braidwood Unit 1 Signal Growth Distibutions Aseumed for Limiting Case Projections CYCLE 4 CYCLE 5A Steein Generator A Steam Generator D Hybr6d $/G Delta Volts No. of No.Of No. of CPDF Bin m Obs Obs
-0.3 5 0.007 0 0.000 0 04 6 0.016 5 0.007 0 4.3 14 0.037 18 0.034 0
-02 26 0.075 32 0,08i a 0.004
-0.1 48 0.146 49 0.152 9 0.013 00 62 0.237 83 0.274 $4 0.064
- 0. 8 64 0.331 86 0.400 146 0.243 0 462 11$ 0.568 226 0.461 02 89 0.3 63 0.J54 86 0.094 172 0426 0.4 60 0.643 38 0.779 11 0.733 33 0.696 40 0.837 74 0.404 0.5 06 29 0.734 20 0867 52 0.854 0.7 30 0.778 24 0.902 38 0.890 0s 26 0.816 13 0.928 26 0.915 0.9 21 0.547 to 0.936 27 0.941 19 0 875 11 0.952 13 0.954 1.0 1.4 14 0 896 4 0.958 13 0.966 1$ 0.918 6 0 966 6 0.972 1.2 1.3 10 0 932 3 0.971 5 0.977 1.4 6 0.941 3 0.975 5 0.982 6 0.950 3 0.980 2 0.984 IJ 1.f. 2 0.953 0 0.980 4 0.988 3 0.957 2 0.982 1 0.955 1.7 0 962 0 0.982 3 0.991
- i .8 3 1.9 3 0.966 0 0.982 1 0.992 l 0.968 0.984 1 0.993 20 1 4 0.974 0 0.984 0 0.993 2.1 0.975 2 0.987 2 0.995 2.2 1 0.979 0 0.9ai 0 0.995 2.J 3 0 0.979 0 0.957 1 0 996 14
~ LS 2 0.982 0 0.987 1 0.997 16 1 0.964 2 0.990 0 0.997 0.985 0 0.990 1 0.998 2.7 1 0.987 0 0.990 0 0 998 2.8 1 0.988 0 0.990 0 0.998 2.9 1 2 0 991 1 C #91 1 0.999 3.1 0 0.991 0 993 0 0.999 33 1 3 0.996 0 0.993 0 0.999 3.5 3.7 0 0.996 1 0 994 0 0.999 0.996 C.996 0 0.999 39 0 1 0.996 0 0.996 1 1.000 4.2 0 4.3 0 0.996 1 0 997 47 1 0.991 0 0.997 _
0.999 0 0 997 5.1 1 6.7 1 1.000 0 0.997 8.1 1 0 999 98 1 1.000 680 683 1040 Total Onowa rRXLw7able )+44mi u PM 13 JIJ4 9 '95 15:54 412 7225119 PAGE.014 i
.1
f >, JUN 09 #95- 04:53PM WEST PURCH SERVIECE WALTZ MILLS P.15/40 j d
Tobis 3 -1 Braidwood Unit 1 February 1995 l Sansmanry of Largest Voltage Growth Rates for BOC-5A to EOC-5A l l
l RPC I'94 )
Swam GenereOr Bobbin Data '
BobblD Row Col Elevadon EOC.5A 50C5A Grow $ Cornmed can 73 3M S.13 1.01 4.12 Y 00f C '5 4A aw a g3 q .pg 3.0E Y ODI A 3 0 10$ SM 34s OM 2 79 Y ocu C
A 45 S4 SH 3.20 083 2A5 Y 00t 'l I
10 94 GH 3.39 (LW 2.46 Y 0 01 A
l EH 3.34 0 09 1A6 Y ODI
' A 44 GD 78 3H 3.22 SAS 2 34 Y Otp C 27 13 8 3M 3.93 12 22 Y 0 01 D I D di $4 SH 3 30 0.88 2E Y ODI GH 3 17 OWF 130 Y ODI C 31 73 5H 3 12 ON 2.17 Y ODI A 12 19 28 SM 3,13 0.97 2 18 Y OCW B 28 72 3H 2 52 0.38 2.18 Y NDO A 41
- EH 3 17 1.12 2 06 Y 0 01 D 35 82
- 13 4 3M 2.81 0.79 1 02 Y 800 D
C 21 74 SH 2 72 0 74 1,98 s V 0 01 [
GH 2 57 0.99 148 Y OD6 A i 103 78 3M 2 46 OAS 1 08 Y 0 04 ;
0 16 '
111 TH I E3 0.91 1 92 Y 0 06 C 1 7H 2 72 0A4 1 08 Y ODI C 13 20 3H ifE SAO 1.00 Y ODI A 23 9 I 104 eM 2.81 0.70 1A1 Y OCH C 27 I 2 00 1A0 1A0 Y ODI D 28 Si GH 9 3H 2 to CAS 1.79 Y ode C 2D 40 as 7M 2 ES CA7 1.75 Y sco A I SH 10? O 29 1.78 Y ISD A 25 OS 44 15 GH 2 00. 1 03 1.77 Y ODI f A f 3M 13e 0 79 1 77 Y ODI C 17 37 AM 2 77 1.01 1,78 Y 0 01 C 33 et 6 3H 2J6 0.85 1,71 Y 00 C it 3H 2 59 0 00 129 Y ODI ;
D 22 39 '
100 DM 2.38 0.70 1 $$ Y 0 01 A e
'Y i 8 92 3M 2 87 1.Ge 144 0Q1 C f 13 77 $$1 13S 6.70 1.83 .Y 0 01 __
D 3H 130 0 79 1.eD Y ODI C 22 42 12 3H .22 0.79 1A0 Y ODI C 22 4 es eH 2.as One 1.58 Y 00 l C
3H 2 00 0 82 9.87 Y 94 0 [
D 18 88 A to es sH 1 32 o 77 1H Y NDD f i
71 eM 2 GB 1.18 1 58 Y 0 01 A 38 SH ,22 0.88 1.83 Y led A 33 91 3H 2A9 1 37 1 52 Y 0 01 A 3 79 2.s1 1.11 - 1 50 Y_ 0 01 ;
C 30 as 3M 90 3H 2 11 OAS 1 49 Y NOD A 10 3H 2.27 0 00 147 Y ODI C 11 108 2.19 0.77 1.42 Y ODI 75
~C 32 3M 2.30 0 00 1,41 Y 0 01 l A 9 71 SH 1.30 Y ODI !
A 3 100 SH 2 30 1.30 75 EM 2 15 035 1.30 Y ODI f A 21 81 3H 1 ed 0 25 1m Y NOD D 46 E 101 SH 2 14 0 77 1.37 Y teD l 5 15 SM 1.8e 051 1.37 Y 86D A 21 43 ed 3M i st O ss 1 37 Y ODI i A 40 i
14 onowma.cMm m o w I l +
i i !
M 9 '95 15:54 412 7225119 PAGE.015 t 1
1 - _ _.
s a y.
m E 8
8 -
- F1gere 3-1 8 l; 9 Braidwood Ush-1 February 1995 EOC-SA T
Measured Bobbin Vokage Distributions 2l v1 200 -
(9 180 m
ggj . . _ _ . _ . _ _ . . . . _ .
MWA _ _ _ _
140 R'
G s SIG B _
4 120 --- -- - - - J - - - - -
ostoc $
- 3 ,oo _ g
- m
= RED g ---- -
g NO g $ -
to 60 d l -.
h g G
E a :1 20 -
. ll 1 I l 6 a m . ..._... . _.. _ _
l m
a a aiaiisisiawai=iniaica Bobbis Cell Voltage g!
8 eeis 71VWFeeure 3-1881tWe9 208 Paa 1 _ _ _ _ _ _ _
5-y .
E y e E d Figure 3-2 81 Braidwood Unk-1 February 1995 EOC-5A -
g 9 Bebbin Voltage Distribution for Plugged Tubes T 2, so h
70 --- -
G '.
@1 9
ea -
.sm y l3 so .--
.--I
.- - - a s/o a _ . . . _ _ . . . _
h y
- os/o c g C 40 -
N a S/G D 3
E 2 5
. g 30 . 1- -
z 20 _
id 1
=
N 10 - - - -
5 n ..
II i
I lini,kbifLlulL.IL__anoa l B.bbia coit voltage y B i~
l PPCRESLT.XLWFigu's 343246 kit PM
- - _ _ _ _ _ - - = _ _ _ _ _ _ _ _ - - - _ _ _ . _ - . _ _ _ _ _
g i
8 Figure 3-3 0 9
Braidweed Unk-1 February 1995 U
Bobbin CoR Voltage Distribution for Tubes Returned to Service for Cycle 5B 2 180 -
160
- = - - _ . __ .
go _.. ._._ _ __ _
- 3 . . . . . _ . . . _ __
h 5 S/G B g goo E
30 as/c o g 60 -
7 N A F i n i n ,- , ,_
f i .
o ' "i a:
i 2
i
- : : : aa: : : : : : aa ,
3
- Ifebbie CoilVoltage y e
- ... ~ . m u m
5 E
e 8 -
8' G.. Figure M g M Braidweed Ush- 1 February IMS G EOC- SA ODSCC Amiel Distributions h 5
1000 --
900
~~i -___.___ _ . . . _ . _ g
' q yon _ . . _ _ . _ _ . B S/G A M g
W S/G B fog _
____ _. _ ___ __ h. ,
N m
D S/G C *
- F
- = - - -
O 500 -
s S/G D
- ~---
400 -
s Z -
! 300 - -
~ - -- -
200 h
5 ggg .
m1 _ _ . _ . _ _
g _
p.
. I , L ,_.I. p.m _, - q_ _ . 9_ _. . . ; . . .. . 3_
N
__p_ _ _ .
I k k k N k k h ,
. sebbia vokage T G e EMstRPlet EIWeathCC SilP teSA ORTW995414494
- . - - . . . ~ - _ - . . . . _ - .
c , JLN 09 '95 04:53PM WEST PURCH SERVIECE WALTZ MILLS P.20/40 4.0 DATA BASE APPLIED FOR IPC CORRELATIONS l
The database used for the IPC correlations that are applied in the analyses of this j report are consistent with the Braidwood 1 SER for Cycle 5 and the Byron-1 SER !
(with the addition of the Braidwood 1 and Byron-11995 pulled tube results) and is documented in Reference 8.2. Model boiler specimen 5981 is excluded from the i database based on application of EPRI data exclusion criterion for very high voltage :
indications and concurrence by the NRC. Braidwood-1 and Byron 1 pulled tube 1 indications R16C42, TSP 5 (0.28 volt) and R2007, TSP 7 (0.38 volt), respectively,
, are excluded from the correlation based on EPRI data exclusion criterion 2a accepted by the NRC. Criterion 2a excludes indications with burst pressures high on the voltage correlation if the maximum crack depth is 5 60% and there are 6 2 '
remaining uncorroded ligaments. Plant S pulled tube indication R28041 is included l
in the leak rate correlation at a SLB leak rate of 2496 liters /hr consistent with NRC recommendations. Accordingly, this databaso is in compliance with NRC guidelines !
for application ofleak rate vs voltage correlations and for removal of data outliers in the 3/4 inch tubing burst and leak rate correlations and is referred to as the NRC database, in contrast with the EPRI database which excludes several outlier data points.
5.0 SLB ANALYSIS METHODS Monte Carlo analyses are used to calculate projected voltage dlstributions and to calculate the SLB leak rates and tube burst probabilities for both actual and projected voltage distributions. The Monte Carlo analyses account for parameter uncertainty and the methodology complies with with the Braidwood Unit 1 SER and is described in Reference 8.1 and is also documented in the Westinghouse generic methods report of Reference 8.2.
Monte Carlo analyses include POD adjustments, voltage growth and NDE uncertainties in the projected analyses while only NDE uncertainties are included in the tube leak and burst analyses for the actual voltage distribution. Based on the 3/4" diameter tubing database, the NRC requirement that the p value obtained from the regression analysis be less than or equal to 5% to apply the SLB leak rate versus voltage correlation is satisfied and the correlation is applied for the leak rate analyses of this report.
Two sets of calculations were performed for this outage evaluation the first set for the Return-to Power (RTP) cvaluation in March 1995 and the second set for this 90 Day evaluation. The 90 Day report calculations are based on up-dated tube leak rate !
and burst probabilities which incorporate new data from Byron /Braidwocd but do not l l
.s.,e%*w .., ru.r u um n+o 19 i
n J
j JUN 9 '95 15:55 412 7225119 PAGE.020
., ,.1 JUN 09 '95 04:54PM lEST PURCH SERVIECE 14ALTZ MILLS P.21/40 i I
effect the methodology that has been documented by Westinghouse and approved by the NRC. ;
6.0 BOBBIN VOLTAGE DISTRIBUTIONS 6.1 PROBABILITY OF DETECTION (POD)
The number of indications assumed in the analysis to predict tube leak rate and burst probability is obtained by adjusting the number of indications measured, to ,
account for measurement uncertainty and birth of new indications over the projection !
period. This is accomplished by using a Probability of Detection (POD) factor. The calculation of projected bobbin voltage frequency distribution is based on a net total number ofindications returned to service, defined as:
N.r. ars = N,/ POD N,,,,a + N,,,io,,,,
where Nro,ars = Number of bobbin indications being returned to service for the !
next cycle Ni = Number of bobbin indications (in tubes in service) identified after the previous cycle POD = Probability of Detection l N,,,,,, = Number of N, which are repaired (plugged) after the last cycle '
Na.,3,,,,, = Wmber of N iwhich are deplugged after the last cycle and are returned to service in accordance with IPC applicability.
The draft NRC generic letter (Reference 8.3) requires the application of a POD = 0.6 to define the BOC distribution for the EOC voltage projections, unless an alternate POD is approved by the NRC. A POD = 1.0 represents the ideal situation where all indications are detected; a voltage-dependent POD may provide a more accurate )
i prediction of voltage distributions consistent with APC/IPC experience. There are no deplugged tubes returned to service at BOC 5B.
I 6.2 CALCUIATION OF VOLTAGE DISTRIBUTIONS The overall growth rates for the previous two operating periods, represented by the ;
cumulative probability distribution functions on Figure 6-1, confirm the discussion I in Section 3.2 that the 1994-1995 operation (cycle 5A) growth rates exceed those of the 1992-1994 cycle 4. For these two operating periods, SG A rates exceed those of i the other three SG, as indicated by Figures 6 2 and 6-3.
.wwnwn.or rne, s... e, an en 20 JUN 9 '95 15:55 412 7225119 PAGE.021
JLN E;9 '95 04:54Pt1 WEST PURCH SERVIECE WALTZ f1 ILLS P.22/40 To conservatively predict the IPC voltage distribution at EOC-5A, the SG A growth rate was applied to the BOC-5A tube indication conditions in SGs A, B,and C. The the SG D growth rate was applied to the BOC-5A tube conditions in SG D.
To conservatively predict the IPC voltage distribution at EOC-5B, the growth projections are based on rates determined for a hybrid steam generator, defined in Section 3.2, with growth characteristics which envelope the growth data developed from the EOC-5A ECT inspections. This hybrid growth rate will be used in the prediction calculations for cycle 5B. In Table 3-1, SG C is tentatively identified as the limiting SG with 431 indications > 1.0 volt at EOC 5A, of which 352 have been plugged and 79 returned to service for cycle 5B operation.
The operating periods used in the voltage projection calculations are:
Cycle 4 - - 418.94 EFPD.
Cycle 5A -
Cycle 5B -
6.3 PROJECTED BOC-5A TO EOC 5A VOLTAGE DISTRIBUTIONS The methodology used in the projection of bobbin voltage frequency predictions is described in Reference 8.2 and is essentially the same as that used in Reference 8.1 for the cycle 5 predictions of 1994. Analyses were performed to determine projected EOC-5A bobbin voltage distributions, based on the BOC-5A cond.itions summarized in Table 6-1 and the 1992 - 1994 (cycle 4) cumulative distributions summarized in Table 3-6. The actual EOC-5A bobbin voltage distributions and the corresponding EOC-5A projections are summarized on Table 61 and are also shown on Figures 6-4 for the individual steam generators.
6.4 COMPARISON OF ACTUAL AND PROJECTED EOC 5A VOLTAGES A review of Table 61 and Figure 6-4 provides a ccmparison of the actual EOC-5A bobbin indications with the corresponding predictions based on a constant POD of 0.6.
These data indicate the following trends; a) The POD = 0.6 tends to over predict the tube defect population and is predominantly conservative.
b) A voltage-based POD might provide a more accurate prediction for IPC/APC performance.
. s.pe= Sos ,en.a.y swe., a . n. sens is as 21 JLN 9 *95 15:56 412 7225119 PAGF.022
-JUN 09.'95 04 55PM WST PLRCH SERVIECE WALTZ MILLS P.23/40 r
6.5 PROJECTED EOC 5B VOLTAGE DISTRIBUTIONS Using the methodology previously described in this report, analyses were performed to predict the performance of the Braidwood Unit I steam generators at EOC-5B, in a manner similar to that used for EOC 5A. The IPC voltage distribution projected from BOC-5B to EOC-5B is summarized on Table 6-2 for POD = 0.6. As anticipated, i the limiting steam generator is SG C with 2051 indications predicted for POD = 0.6 - l These results are shown graphically on Figures 6-5. l l
I I
J l
l I
i l
l I
j i
rNaptW95None90.dar Fdesy June 9.1995 14:00 t2 l
i i
JLN 9 '95 15:56 412 7225119 PAGE.023 ;
6 : JLN 09 ?95 04255PM IEST PURCH SERVIECE IMLTZ MILLS .P.24/40 Table 6- 1 (Pass I of 2)
Braidwood Unit 1 February 1996 Comeperison of Prmueted and Actual F,0C 5A Voltage Statistics Seeen Generseer A SteepGenerster B BOC $A EOC.5A BOC 4 BOC-5A 80C.5A EOC 4 twea- Anal risese- Ammel p0o a eco a =< me new .m ase 8 me asa, ness me as m en new me me me w m Its en m m w w w w _
0 8 4 SA $ 46 0 ei 1 0 1.7 0.99 4 46 4 5 o L3 3.5D I 0.2 6 0 40.0 se 24 e 3:s i34s is SJ e e si i 27.7s see *
- Ce 4 s ist.i e s5 e6 . 58 i 33.2s s ses 3 76 so its e o 71.7 44.za s 8.s 92 6:
-- e4 92 e i45J e2w us es e so.e s t.75 136 27 6 45.0 49.84 46 0.7 68 4 107.3 94.99 It3 25 2 39.7 4516 43 09 45 2 73 0 08.21 8 T1.0 83.M 183 25 0 3L) 41;8 37 0.9 St 47 3 76 40 51 3 0 5.0 'N i 33 1 44 4 6 4 6.0 ;LSD 19 34 33 23.7 64,21 TD II 19 7 #1.46 54 4 4 6.8 at03 17
~ I.2 2$ 22 16.7 41.06 35 2 e 3J .lJe il IJ DS 23 2 2J I4.30 9 4 14 9.3 32 30 25 1 4.4 5 24 0 0 0 8 47 I.S ,8 10 EJ 21 52 2 2 IJ 6.37 2 f .6 9 9 6.0 30.46 il la 0 e a 4.88 6 4.7 13 83 87 86.74 le 2 2 IJ 3 76 2 a.s a 5 53 13 FT 7 0 0 0 3 33 2 a.9 7 7 4.7 11.47 le 0 0 0 ._ 3J6 3 2 6 6 4.0 9.73 4 2 2.3 2.20 0
- 2. 4 5 3 33 8.34 4 4 0 0 4 I 95 4 2,2 4 8 53 7.47 2.0 6.09 3 0 0 0 17] O 23 3 3 0
S,82 4 0 0 0 1.51 2A I a 0.7 4 4 27 4.28 0 1 0 1.7 IJ6 0 2.5 0 3.$$ 2 0 e 9 4.36 26 2 2 IJ 0 0 97 0 0.7 2.94 3 0 0 2.7 I )
4 ._
00 1 47 I I i 0.7 . 8 74
~- 2J 0 0 0 4 0 TJT 0 2.9 0 0 00 2.14 1 0
e S 6 4 CA4 3 3 3 2.0 4.ts 0 0 0 6 33 0 3 3 26 1 00 0 j 3.1 e.ge I 0.0 8.75 0 e s 32 0 0 8 l
1.3 1.00 2 D 0 0 ejts SJ 3 2 0 .e9 0 S S 9 25
'- 3.4 0 0 l IJ JS il D 8 0 4J6 S.S 2 2
.24 0 9 ll 9 6.25 36 e 8 0.7 0 0 0 1.11 0 1 0.7 ._ OJ4 3 .7 I 0.7 8.01 0 8 0 0 eJ3 l 38 I i 0 0 ir e a EI 3.9 0 e c 0.92 0.34 0 0 0 9 0 4 2 2 13 0 0 0 0 4L 0 0 0 0.77 1 _
0.7D 0 5 9 0
' 4.2 a 3 07 s.66 1 1 0.7 0 43 0 0 0 5
44 0 0 0 D.63 4 63 0
4.S 0 0 0 0.58 0.7
- 46 0 0 0 _
5 4.7 0 0 0 OJ3 8 30 4.8 0 0 0 0.44 4.9 0 0 D o 35 e s 0.7 0.79 5
5I O O O 0 25 0 0 0 0.20 S.2 53 0 0 0 0 15 0.7 0 36 8 8 34 0 0 0 0.70 s.3 8 4 0.7 0 59 0 0 0 DJ6 __
947.7 9e6.71 196$ 272 30 433J 433.ti 413 TOTAL 706 229 35834 296 26 17 MJ 187.92 7t
> l .0 V 194 199 134.3
>2.7V 18 18 12 26.44 & J 3 2 SJO 4_
23 PMEDCO68P Ew VOL7 57 An$7CS 47/95 e la PM JLN 9 '95 15:56 412 7225119 PAGE.024
- s , b- jJUN 09 f95 04:55PM WEST PURCH SERVIECE &#t TZ MILLS . P.25/40 Table 6 - 1 (Page 2 of 2 )
Braidwood Unit i February 1995 Comparhon of Predicted and Acesal EOC-SA Voltage Statistics Steen Generseer C SeesenCesareser D EOC.4 90C.sA EOC-3A BOC.4 30C.3A s0C sA Mukana Ashst feudlemset Asissi Oman Phas et> t poo.s ein e Ita s Flumme P0b4 MD4 Ns. W Wege 4s Wte say W as al ein d 64 es flh W hk W IIk W he to td ha tut but his ' tut et t 0 at om W 9 6 0 tu e 43 7 9 48 7 3 55 3 3 1 4.5 1 35 I 93 9, 9 $$ $ 18 98 il 21 e fe ? 2LM 11 es IJd a R7 517r 33 sy I ly? ) es M ey --
T ew je in se is2 m . me is se a 46 14 6 !. IT 163 62 en 197 6 ,71) 11 5 #15 i 47 143 i ,.57 (Mes IT) #5 (2 43 5 lp 4 aps i el il7 -its e 477.3B 483 5 4 112 ta .sp ar7 GT T2 le 441 ) 44A GS 44 35 4 GZJ '888.f7 ~ 86 8 6e 7 99 7 143 34 aff-' M e 55 7 80.15 Os ee di Il M7 113 55 fed ~ el 4 );0 GL31 M ,
1 71 39 I2.7 59 99 96 _. 85 7 I:.9 43 16 46
.J 16 3) 43 0 1k39 _ le 44 3 ill) 3835 N 4 23 17 e4 7 Ss N 45 9 B 44 16.39 i9 - ~ ~
.S S 7 6.3 di M 3e 4 S 56 14 95 at 16 7 4 37 31.14 25 4 5 17 4e te 40 s.7 3 7 20 23 25 a3 6 6 ._4 5.33 3
- ' 45 J ) 10 11.56 15 .7_ 2 35 L32 3 49 3 J 20 43 0 le 4 4 11 f 25 9 2 3 3 3 !6 91 8 3 9 to e le 8 -
]
~.t t t I li7 5 57 4 0 0 0 1N t j l,3 3 3 .J TM 4 4 4 17. _ __ ; 12 l l 3 e e e 4 69 5 4 e1 ,,36
. . . ., ou a .. 4 . .
. 1
.., . . ., au , . e- 4 .
.6 0 0 0 3W 3 I t e1 ,as .
11 6 8 J_ WD
_3 9 il 5 l b.W i is t i e7 4 1 47 q3 l
~
19 4 15 6 . 57 4.E 1 0, Il 81: a n
3 32 4 39 su , [b 4 T *I*T'
_0_
e1
.e e ts 2~-
s'1 23 - e.us 6 s i et 4 15 e se sa e e 6 e _e s9 6
' R$ es e 0 0 0 OJD 9 36 ofJ 8 0 e e its e 37 E4 4 1 e ai c es
- a 4 53 _e o e ~~e- eJe 20 #4 6 4 e ?P 6.M 4 +N 6 4 4 47 DN dI a ss 0 6 9 e e.4 43 0.02 0 0_ e e c..A 4J 0 e a a ai ae se a y e 5 5 c.M 43 e a e e e an d6 a a e s y sn d.7 . _ R7 8 9 9 9 9 13 45 4 4 e o e o *1 ;
d5 0.2 5 0 e e Ils s --e e e e em Il 9 6 _I e7 a.32 52 8 0 e e en
'~
1J _'[ ~
9 9 9 -- 9 17 74 9 4 5 e 13 55 5 0 g B.3 3 6 0 0 0 9 If i i
7 . . . .n 5 0 0 e als
- s. , o . -e e is e e o e e is o e en W
en e
- o e
-e o e
.oi, . .
6., i i e7 .
.e. . . . .1 .
45 6 5 75 (O T g pg totar. im ses syne uwo ism ew i4s min mus ni
. i.e v us., siest wa an u i.s { su ni in iw 3.i ouv i j i .o n.u . n i, u iu, .
24 w =%,se.,ces .:
JUN 9 '95 15:57 412 7225119 PAGE.025
, ,-. JUN 09 '95 04:55PM WEST PURCH SERVIECE WALTZ MILLS P.26/40 Table 6 - 2 BerAwood Unit-1 February 1996 Voltapp Distdbution Projection for EOC 58 Steam Generator A Steam Generator B SteamGeneret0r C SteamGenerator O E % 58 EM DOC-58 BOC 50 BOC-5B BOC-5B PREDICTION PREDICTION PREDICTION PREDICTION oves vans Pol > 5 POD =.8 Poba.0 Set POO=.0 Wo. of No. at No. W Na d ha of Naet No. Of No. of innamhms inmuukms hansakms inemanana inda:obens becamene Inshcaelens Indicadans 0 0 0 0.01 0 0.01 01 0 0 01 0.s5 3 1 2 06 0.2 4 16 0 8.18 31 11DS __. 21 7.93 03 40 18 51 _i 16 23 26 93 44.00 47 31.4 0,4 as 47.44 44.35 152 90 08 as e6 05 118 49.7 48 __
62 61.98 168 153M 119 101.19 06 its 126 82 1H et 70.32 173 '4 A5 115 125.88 0.7 150 7_1 48 70.4a 142 222.59 107 144 01 09 113 181'47 67.7 itt __237 41 86 143 53 00 103 _ 1'.38 2 43 37 E2 47 1?? 229 16 W 138.07 1 51 ,, 140.28 121.13 33 53 it_ 100 197 46 11 70 ___ 114 17 19 41 79 91 186 91 46 98.54 12 $4 49 22 31.71 86 119.48 34 72,30 1.3 30 04 73 17 11 73 67 48 9121 it 63.37 14 25 62 44 0 17 46 39 49.28 15 30 46 1.5 24 39.8e 12.a2 25 52 04 18 23 33 Ty it 30.43 5 2 0 54 13 30 67 8 21.98 17 12 23.36 6 7 25 18 29.95 5 15.08 1.s 10 14.05 2 0 to 22 96 9 11.37 1.9 7 14 17 2 424 6 17.75 9 9.25 2 10 11 36 ,
4 13.57 2 7 34 2.1 4 9.2 3 S 25 l 0 2 45 4 1029 R 5.47 ;
2.2 4 7.30 1 18 3 7.78 1 4 26 ;
2.3 3 6 87 !
0 127 2 6 95 1 3.1e 24 4 4 64 l
0 09 0 4.05 0 2 38 2.5 0 3.es 0.64 3 3 73 1 1.85 2.6 2 2 96 0 ce6 3 3,1 1 1.40 27 3 2 30 0 0 0.34 4 2.83 1 1 22 2.0 1 0 1 16 0 0 79 1 0 1 1.02
_ ?. 9 0 0 0 1.44 0 0.89 3 0 1.32 1.11 0 0 0 1.5 0 0.7s 2.1 0 0 0 1 1.2 2 0 3.2 1 0 06 1 0 1 0.95 0 0.38 3.3 2 0.87 _'
06 0 0 0.77 0 0.52 3.4 2 0.72
~
0.7 0 a52 0 0 48
$.6 0 0 0 05 1 0 0 0s
[ Se 0.3 1 0.4 0 3.7 0 0.4%
~
0 83 0 1 3.8 ~ 0 0 71 0.7 l 0 0 3.9 0 0 0 4 0 0 ___
0 0 03 41 1 07 0 4.3 0.3 0
4.5 0.7 53 03 u
413 821 78 1525 2048.07 931 1357.98 TQTAL 1065 139904 430 664 35 241 gas 30 j
>10V 268 !bOR 14 111 214 56 t i3 e time a s es 27v s 50 is i 25 uu u m e w woc m io ce,,
JUN 9 '95 15:57 412 7225119 PAGE.026
5 e
e Figurt 6- 1 d m - Braidwood Unit- I 3 Cumulative Probaldtity Distributions for Voltage Growth on EFPY Basis g
Cossposite of' AN Four Stenen Generators 1
-wo-o-o-o-o-c g 0.9 g
0.8 -
- - - Q n
o.7 -- - ~ ~ - - -
R
-+-Cycle 4 ( 1992 to 1994 )
-- -- =
h n
0.6 - -
3 N 0.5
-o-Cycle SA ( 1994 to 1995 ) 5
.j o.4 1
A g e.3 - - - -
" U d - - - - - -- - - - -
g o.2 -----
e 0.1 0 bd . ; ; ; ; ; . : : . . . .
e e o n e e = -
- e o T , n o n y e a o n ,
A A 5 5 d d & & $ d 6 6 6 A A A d j j 6 6 Vokase Growth hs
@ b
.-.. m.c .
~. .- . -. - -. _ . . - .
L4 E _
E e
8
$ Figure 6 - 2 m Braidweed Unit -1 Cycle 4 ( 1992 to 1994 )
- "; Cumuletive Probability Distribtnions for Voltage Gmwth on EFFY Basis
- - ^ ^ ^ ^ - ;;;_;;;; ;; ; ; ;; ; "
= .. -- = x_ - .. .
1.0 ,
--t
- - - - ~ - - - - - - - - -
0.9 -
1 0.5 -
9
-+- S/G A . . . _ g
-l o g . . _....-. _ _ .
R 8
u.
g 0.6 - ---
-o- SIG B fn s --- // -*- S/G C 3 t! 0.5- -
4e.- S/G D 0.4-
^
h0.3- -
N
-a v f-0.2-t t e
' O.1 -
l . . . . . . .
l 0.0 -
. . . . . . v.
- N o *. 9 M o N
- 9 M 9 N
t N v. 9 M n n n m m m n
- v. N o.
o o o o o - - - - - n- n m 9 9 Voltage Crowth
$ 8
&^
e $
8 8 -
Figure 6- 3 d
@ Braidweed Unit - 1 Cycle 5A (1994 to 1995)
$ g Cumislative Probability Distributions for Voltage Growth as EFFY Basis
~ - - - - - - Z!!!C00 0 0 0 ;
i g
1.0
~=
0.9- - -
^
~~
- ~ - - - - - - -
0.8 -
-- - - - U R
0.1 -
^ h
--- n 0.6 - 2
- -o-- S/G B p
0.5- w g - - - -
-*- S/G C
., 0.4 .
-*-- S/G D A 0.3 -
N
~
0.2
/
3 0.1 -
0.0 .. x e
.l ce O l l l l vl l l l l l l l al l al l al l al l dl l ld l ld l l l lci l N e se O A
N v W ee O N 9 @
ci ee -
5 T
5
& T 6 6 6 6 c;i 4 ,6 hs Voltage Growe e
t m t 6 .
m 9 3m'4# 0 6
6 e ;
c2g436 cs7c - .
S ,
6 o*EI 3' g .mE*! 25=E ,.2E{* . g h 5. aE g.
I i E * $ .> :<*.g 5 S:
T23 g!ggm 8 > ' 3, , e& O S P G :
S
_8 9 d
W 1 m F
' .' * . l' s
t.
!-l'
_8 ,il j i a
n m
s e
. :l,I i[I
_8 i. ' , ' ! 1 m
m O*kn2 t
- ij' i! !
~ 8 "
u
' l
- r z
3 .
6 m
- EE fl, n
8 -
' i s
l#t '
8 ' ' i ,l l ,' l I'l-.
P -
I m-
Z
%i 4
2 2
S I
8'-l 1 T
6 =
_ = e -
s m
_ u h
m a
_k8:5 kb P
>b> > b h ->' i t < , rr m' iI i r r ir :>F . , "
1 w' .
- ~ " " : - " ,
"."7 '.~'1
. - - ' ~ ~ : - " " ; ~ ~ " ' . ~
. "7 g ." "5 7 3 9 u
3 1 1 3 "5 7 9 1 3 5 7 9 1
1 2
3 2
5 2 2 9
2 3 3 3 3 3 1
4 4 4 5 5 8 d 0 0 0 0 0 1 1 1 1 0
0 01-[=g a 3
e e
0 E w O e l,3 e g,s y
,l !fIIllll !llll1l ( ' I ; ' ' , ' I
4 G
E m
,d
- Figure 6 - 4B Braidwood Unit - 1
}
Comparisen of Measured and Predicted EOC-SA Voltage Distributions $
G Stemas Generator- B - POD = 0.6 70 iw 60 ----
, 2
' 1 50 -
w m
I R e -
OPredicted - - - - - -
r
,Q 40 m
F N
- 3 Li> O '
.} -
o :- e Measured - - - - - - p
,3 30 -
w E
=
E 20 - - - - - - -
l
,m b .
( 10 Dl - - - - - - -
C e
0 : : : : ; ': ; l: ': : : : I: : I: lU ;E ;U :U :n :n n :n ; ;_ ;_ ; a;_ ;_ ;_ ;_ ;_ ;_ :n ;- ,_
S d d d d $ d d d d $
d 6 6 6 $ $ S S d l
!R
- a Bot,s. c . v . a.e .
e
~ A o
PREOCOMPX1NFio E49eeS6405 PM l
l - . .. -. .-- - _ . . - _
i E
e 1
Figure 6 -4C g Braidweed Unit- 1 -
d Ui Comparison of Measured and Predicted EOC-SA Voltage Distributions Steam Generator - C - POD = 0.6 g
- 200 150 -- - - - - - - - - - - - - - - - - - - - - - - - - - --- - - - - - - - - - - - - - - - - - - - -
h' w
160 - - - - - -
m
[40 - - - - - - - - - - - - - - - ----
- M 120- - - - -- -
,Q OPredicted y 5 a N
M 100 - -
i5 o
5 I shked g 3 80 a - - - - - -
o E
60 - - - - -
S N
y 40 - - - - - - -
- n. ,
Dl g 20 - - - - - - - - - - - - - -'
O - :1: , ' , , ; ; . : : : : : I; ; ; , : I: :b:E:E:M:N:": ':~; :- :-: -:- :- :- :-:- : - :- : :- :-- :
- m => s . - n e s . - c> c e.- m - n e c . - ~
m 6 6 6 6 6 s a a a s a w w w a ci w cs es ci 4 e iti Bobbin CoilVoltage -
M s .
.I
_nm .- <m
I f
n N r i
6 .
W
,g-;sge'4C i
0 6 ,. 6 S WE542E Cmx ,
6 i oo5wmf $Ega{ "E EE&
s . tm ca> hrj .. C.g= G S:
S m EB Og.2*'%
- D I 3gu3* $ O P
E :
s S 2
d W
1 3
S e ! iI I . 1 d
n f
2 3
H i . .' a l.
A s I n , 3 3
i o 3 t
a c - - l a ' g. g ~ a. l1 l t
i d lL I
n r 2
f o - W r -
s EIEg
. I S e ,l ! jj E b IT m S u
N
, l ! i i' I it -! ! , .h i' ! , ,l , j, aI iI P
T
- 2 m'
- -m
/.
2 2
, l .
S I
T Q
6
-yhrpl6! ii "":~hr:
- i - - : _ ' : * - - : - ~ - : - - ~
I1kr ;r rr - ' : :
- - ~ : : - ' : : - : - :
F ' : ' . : - : trr 4
^ 4 7 0 3 6 9 2 5 3 1 4 7 '
3 6 9 2- 5 8 1 0 0 1 1 1 1 2 2 1 3 3 3
- 4 4 4 5 5 5 6 6 d
0 d 0
3 f$ a < I"3
- E E
0 /
E P E O 3l.s 3 llllt!Ill !ll, ( l' i\l , . l l , ; .i ; : filI fj, !li1
4 4
e 5-Figure 6- SA g Braldwood Unit - i ,
Voltage Distribution Prediction for EOC-5B $
l g g Steam Generator- A - POD = 0.6 g 180 v, 1
N 160 -
140 120- -
s 3 1 .
O Assumed BOC-5B
-3 Distribution p--
g 100 - _ _ _ _ _
.".! u Predicted EOC-5B d
= o Distribution "
r
- 6 80 3
h, 1 E '
e l
- 60 - - - - - .- -- - - -
h to 40 - - - - - - - - -
a f8 l 8
w 20 - ' l 0- ;1; ; . ; ; ; ; ; ; ; ; ; , ; ; ". : ; ; ; ;5;M: ':'";*: : : : -:-;^-;" : -; -: -: -- r : -;
- n n e . - n e s . - n n w a - n e s .- e 6 6 6 6 6 e e e a e a a a a a a n n n 4 4 g
m Bobbin Coll Voltage -
e -W W h1 Q
pnecccMP mms.ammes ame Pad
.O
.G^
l e Figues 6- SB 0
8 Braidwood Unit- 1 Vokage Distribution Prediction for EOC-5B $
g Stenut Generator - B - POD = 0.6 80 $'
3 A"
70 - -
g so - ---
- O Assumed BOC-5B i
~
k
- ~ ~ ' -" - ~~-
j So - Distribution
.E 3
4 49 _ _ _ _
-I m a Predicted EOC-5B Distribution y
g 2-
~
w b l o g
! 30-lc
=- - - - - -
8 -
s 20 -- - - - -
- G id E
y io . _. - _ _ _ _ _ _
G o -: : : : :! : : : : : : : : : : : :n 5:G: B;a . . _ _ _ _;n :_.
aa :=a:aea 2: : : : : : =aaaaaaanaa n senten con vettage y k
9 e
- s
--m ~
E -%
e S.
- Figure 6-SC si e
8 Braidwood Unit- 1 g Voltage Distribution Prediction for EOC-5B Steam Generator- C - POD = 0.6 g' 250 m 3
b H
200 - ---
I f
I i l
I l-D Assumed BOC-5B Distnwtion f
m a
E 150 - - - -- - - -- -
8
.E aPredicted EOC-5B y' i Distribution A
$ )
.X 3
E to g 300 _ - - _ _
, a '
- E
~ \- '
y 50 h
i e 0 :': : , . , : ll: : : : : : : : : : :": : : ;J; 8; 8 '*;"P:- ; : -: : :- ; - : -:
- n a n a e e m n a - n m n a - n a n n d 6 6 6 6 & & & & S d d d d d d d $ d 50 m Bobbia CoilVettage .'
N a,
--- - m -
l
l 4
E -
e $
e
. FQun6-SD @
u Braidwood Unit - 1 ,
Voltage Distribution Prediction for EOC-5B $
g Steam Generator-D - POD = 0.6 g 160 m l40 - - - - - ~ - - - -
l 120 - -- -- -- - -- --- - -
O Assumed BOC-5B i;;
3 I" - - - - -
Distributton R 3
h a
m Prediced EOC-5B -j go _ _ _ _ _
4 Distribution -
r z
3 40 - - - - - -
f0 Y
$ 20 -- - -
0 : ;: : : : :i : : : : : : : <: : : I: 1:J:8:2: :- - : :--: -: : -:
= = , = = = = = = = m m = m = = = , ;
k sobum coli voli se ?
. m M. g
- - _ _ . - - _ - . . _ _ - _ _ _ _ . _ _ _ - _ _ _ _ _ - - _ _ - - _ - _ _ - _ - _ _ _ _ _ - _ _ _ _ . - .- - . - - - - - - . . .. ..,. -_ _ _~ . - . _ , _ _ - - _ _ . _ _ _ _ - - _ .
Jtfi 09 '95 04:57PM WEST PURCH SERVIECE WALYZ MILLS P.38/40 7.0 TUBE LEAK RATE AND TUBE BURST PROBABILITIES 7.1 LEAK RATE AND TUBE BURST PROBABILITY FOR EOC-5A Using the methodology previously described in this report, analyses were performed to calculate EOC 5A SLB leak rate and tube burst probabilities for the actual and predicted bobbin voltage distribution previously presented in this report. The results of Monte Carlo calculations performed for the predicted and the actual voltage distributions, based on the growth distributions of Table 3-6 and the indication population of Table 6-1, are summarized on Table 71. Comparison of the EOC-5A actuals with the corresponding predictions indicates that:
a) SG D was predicted to be the most limiting steam generator for EOC-5A, with the lughest tube leak and POB numbers.
b) SG C was determined to have the highest tube leak and POB numbers based on actual ECT bobbin measurements for EOC-5A.
c) The leak and POB predictions (based on projected indication population) for all four SGs are conservative compared to actualleak and POB values (based on ECT bobbin measurements for EOC-5A). The projections for SG D are conservative by approximately an order of ulagnitude.
d) A voltage based POD may conservatively predict tube leak and POB, possibly with greater accuracy than POD = 0.6.
7.2 LEAK RATE AND TUBE BURST PROBABILITY FOR EOC-5B Calculations have been conducted to predict the performance of the limiting steam generator in Braidwood Unit 1 at EOC-5B conditions. The methodology used in these predictions is the sarne as previously described for EOC-5A. Results of the EOC-5B predictions are summarized on Table 71. With POD = 0.6, the projected EOC-5B SLB leak rate for S/G C is calculated as 0.48 gpm and the EOC 5B SLB tube burst probability is calculated as 4.94 E-03. The performance of the individual steam generators, shown on Table 71, indicates that the limiting steam generator for Cycle 5B of Braidwood Unit 1 is expected to be SG C.
e \spescce95 we90 Aar Tnday June 9. IDH n to 37 J134 9 '95 15:59 412 7225119 PAGE.038
q
,_ ,, JUN 09 '95 04:58PM WEST PLRCH SERVIECE WALTZ MILLS P.39/40
.' )
l Table 7 - 1 Braidwood Unit 1 1995 Midcycle 5 Outage Summary of Calculations of Tube Leak Rate and Burst Probability Based on Predicted and Actual Bobbin Voltage - look Simulations I SLB Steam POD No. cf Mar. Burst Probability Generator Indic- Volts Leak Rate athe 1 Tube- 2 Tubes epm EOC-5A PROJECTIONS A 0.6 948. 8.9 1.52 E-02 2.39 E-04 1.44 l
I B 0.6 433. 4.8 1.69 E-03 None 0.21 C 0.6 1597. 4.9 3.45 E 03 None 0.44 D 0.6 1012. 10.9 3.08 E-02 5.96 E-04 2.81 EOC-5A ACTUAL __
A 1.0 1065. 4.3* 2.02 E-03 4.75 E-05 0.22 B 1.0 413. 3.4 3.26 E 04 None 0.03 C 1.0 1526 5.5 3.04 E 03 None 0.32 D 1.0 931. 3.8 1.07 E-03 4.75 E-05 0.12 EOC-5B PREDICTED A 0.6 1401. 4.5 2.92 E-03 4.75 E-05 0.33 B 0.6 627. 3.7 7.81 E-04 None 0.08 C 0.6 2051. 5.6 4.94 E 03 4.20 E-05 0.48 D 0.6 1269. 4.1 1.97 E 03 4.20 E-05 0.22
- Voltages include NDE uncertainties from Monte Carlo analyses and exceed mewured voltages.
l 1
aw.cww sea, rar.w.e. an am 38 l JLN 9 '95 15:59 412 7225119 PAGE.039
,, , JLN 09 '95 04:59PM WEST PURCH SERVIECE WALTZ MILLS P.40/40
8.0 REFERENCES
8.1 WCAP 14047,"Braidwood Unit 1 Technical Support for Cycle 5 Steam Generator Interim Plugging Criteria", Westinghouse Nuclear Service Division.
8.2 WCAP-14277, "SLB Leak Rate and Tube Burst Probability Analysis Methods for ODSCC at TSP Intersections", Westinghouse Nuclear Services Division, Jan.1995.
8.3 Draft NRC Generic Letter 94 XX, " Voltage Based Repair Criteria for the Repair of Westinghouse Steam Generator Tubes Affected by Outside Diameter Stross Corrosion Cracking", USNRC Office of Nuclear Reactor Regulation, August 1994.
i
.ww..w>u.,- ra., u.. .. a.. i. .. 39
.4 1 4
Attachment B Review of Programs Implemented to Reduce SG Tube Degradation Per a commitment from a letter from NLA (Denise M. Saccomando) to the NRC on November 23,1994, Comed is required to assess the indication voltage growth rates by reviewing the effectiveness of the various programs which were put in place or were already in place to mitigate degradation. The various programs which were put in place or were already in place to mitigate degradation include:
Following the EPRI Secondary Chemistry Guidelines Maintaining Condensate Dissolved Oxygen below 3 ppb Reduce iron transport to the SG by use of ethanolamine (ETA)
Implement a Secondary Boric Acid Program Evaluate IIideout Return information Continue to follow the Molar Ratio Control Program Installation of a Reverse Osmosis unit in the Make-up Demineralizer (MUD) system Eddy Current the Main Condenser Maintain elevated hydrazine concentration in the FW system Review the need to chemically clean the SG's Evaluate the use of other amines to reduce iron transport Evaluate the use of other chemicals to improve iron transport out of the SG A list of these programs was provided to the NRC in a letter from K. L. Kofron on May 2, 1994. This assessment is required to be performed following tlw AIM 05 outage and within 90 days following the startup from AIM 05. Voltage growth rate data is available ,
I from Braidwood Unit 1 Cycle 4 and the first part of Cycle 5. Data is also available for the IC SG at two periods of Cycle 4 due to an eddy current inspection being performed in the l middle of the cycle due to a primary to seconoacy leak in October 1993. l 1
On March 31,1994, personnel from the station Chemistry Department, Corporate Chemistry Support organization, the Corporate SG and RPV Projects, and SEC met to perform this assessment. The following is a summary of our findings.
EPRI Secondary Chemistry Guidelines The EPRI guidelines, as incorporated into procedure BwCP PD-4, Braidwood Station Secondary Water Chemistry Surveillance Program, were followed. There are some differences between the EPRI Guidelines and BwCP PD-4. The chemistry programs for Cycle 4 and 5 were no appreciably different, therefore, the issue could not have contributed to the increase in SG tube indication voltage growth rate.
l I
r;.
Cand*=* Dinealved Oxvnen ,
For the most part, Condensate Dissolved Oxygen (CD_ Dis. 02) is maintained below 3 ppb. Cycle 5 had occasions of high CD Dis. 02 (in the range of 200 ppb) due to the periodic operation of the 1 A CD Pump which had a seal leak following AIR 04. Every time the 1 A CD Pump would be run, the CD Dis. O2 would increase to approximately ,
200 ppb. The Dis. O2 would return to normal when the 1 A CD Pump was shut down. -
Due to this problem, the 1 A CD Pump was not normally run.' The pump was repaired in [
cycle 5. In addition to this, entries were made into the Condenser waterboxes during -
Cycle 4 and 5 to search and repair Condenser tube leaks. CD Dis. O2 always elevates when a waterbox is taken off-line. System Engineering has reviewed this problem and has :
determined that it is due to Steam Jet Air Ejector (SJAE) drawing gases from the :
waterbox with the highest pressure i.e. the waterbox which is off-line. Therefore, the :
condenser is not removing the non-condensable gases from the waterboxes that are in l service causing the CD Dis. O2 to elevate. During Cycle 4, modest elevations in CD Dis. !
02 were noted. In Cycle 5, Action Level 2 for CD Dis. O2 (>30 ppb) was typically ;
entered whenever a waterbox was taken off-line. The difference between taking a ,
waterbox off-line during Cycle 4 and Cycle 5 is attributed to differences in the amount of j air inleakage during these cycles. During Cycle 4, there was moderate air inleakage (<10 <
SCFM). During Cycle 5, there was high air inleakage (>15 SCFM). It should be noted ;
that after the repair of the Turbine Rupture Discs during a forced outage of Cycle 5 in !
May 1995 (after AIM 05), the air inleakage after unit startup was reduced to <10 SCFM. ;
When a waterbox was taken off-line following this outage with the reduce air inleakage, !
Action Level 2 for CD Dis. O2 was not entered. The conclusion drawn from this i information was to try to maintain the air inleakage below 10 SCFM so that the station is ;
are prepared to take a waterbox off-line without entering Action Level 2. System Engineering is investigating a modification to isolate the SJAE from drawing gases from a waterbox which is off-line.
Another potential problem with CD Dis. O2 is the performance of the AF Full Flow test.
During this test, typically performed just prior to going into a refueling outage, cold, air saturated water (6 to 8 ppm Dis. 02) from the Condensate Storage Tank (CST) is injected into the SG's from the AF Pump for a short time. System Engineering has an open item to review the requirement to perform this test to see if the frequency of the test can be reduced. Some plants (Commanche Peak and Shearon Harris) have installed a nitrogen sparge on their CST's which also functions as a nitrogen blanket. These two features combine to reduce the CST Dis. O2 concentration. Even if the frequency of this surveillance is reduced, cold, air saturated water from the CST is injected into the SG by the AF Pumps during a Reactor trip. The amount of oxygen ingress during s Reactor trip can only be reduced if the Dis. O2 concentration in the CST is reduced, or the frequency of Reactor trips is reduced.
Figure I suggests there may be a link between Condensate Dissolved Oxygen and SG tube voltage growth rate. There is insufficient data to draw a strong conclusion, but reducmg i
i
- . + . - - . . -. . -.
,+...,
.4 the time CD Dis. O2 is in an action level and reducing the concentration of CD Dis. O2 [
while in the action level could be re=W until further information is available.
i Reduce Iron Transpon l t
, Iron transpon has been reduced by the use of ETA. ETA was staned in Cycle 4. The ' j Cycle 5 FW iron concentration is less than the FW iron concentration in Cycle 4 (pre and !
post ETA implementation). Byron is testing the use of a different amine,3-methoxypropylamine (MPA). Data from Byron should be available by the middle of 1995.
The group decided to continue with the use of ETA and review the data from Byron once it is available. With the reduction in FW iron transpon and increase in SG voltage growth '
rate, it is believed that iron transport did not contribute to the increased voltage growth i rate.
i i
Implementation of a Secondary Boric Acid Pronram The Secondary Bodc Acid Program began at the startup from the AlR04 outage. The program consists of a low power Boric Acid soak along with maintaining a residual boric acid concentration at high power. No reduction of the initiation of new cracks in the SG tubing was noted. No reduction in the voltage growth rate of existing cracks in the SG tubing was noted. A high concentration boric acid soak at low power (200 ppm at <15%
power) was performed during the startup from the AIM 05 outage. A low concentration ,
soak at low power (50 ppm at <30% power) was performed during a stanup from a )
forced outage after AIM 05. A review of the Boric Acid program with input from l Westinghouse is planned The group decided to continue the Secondary Boric Acid ;
Program through Cycle 5 including the performance oflow power boric acid soaks A 1 review of the results from the AIROS eddy current inspection will be performed to I' determine if the program should be continued for Cycle 6.
Hideout Rdutn Review of the hideout return data from Cycle 5 shows that the sodium to chloride molar ratio is above 1 and that there appears to be more sodium return from shutdowns that occurred after the implementation of the Secondary Boric Acid Program as compared to the amount of sodium that returned prior to the programs implementation. A Secondary Boric Acid program is believed to impact the sodium hideout. There was no Boric Acid hideout return. The hideout return sodium to chloride molar ratio was higher than past ~
shutdowns. Since the implementation of the Molar Ratio program, the crevice pH, based on the hideout return data and calculated from the EPRI MULTEQ program, has been reduced to what is believed an acceptable range. With no boric acid hideout return, boric acid did not contribute to the reduction in crevice pH. Even if there had been boric acid hideout return, it would not play a major role in reducing SG crevice pH.
i
_ _ _ . . . ~ , , . -
Molar Ratio Program The group decided that the molar ratio program has had a positive effect on the SG crMee pH although this effect has not reduce the SG tube degradation. Since the program has negligible costs, the group decided to continue the program. The molar ratio program and its effects on SG degradation was reviewed by an independent contractor (Dominion Engineering, Inc.) as part of an EPRI study. The preliminary conclusion is that Molar Ratio Control (MRC)"per the MRC guidelines, in conjunction with ALARA impurity control, high hydrazine, and boric acid, appears to be worth trying, but cannot be relied upon to stop IGA / SCC." Comparing the average cycle molar ratio to the average SG tube voltage growth per EFPY (see Figure 2) no correlation could be drawn between the molar ratio and the SG tube indication voltage growth rate.
Questions have been raised in the past concerning the effects of chloride on SG tubing. At the low concentration of chloride used for the Molar Ratio Program, there is negligible effect of chloride on the SG tubing.
Installation of a Reverse Osmosis Unit in the MUD System The installation of the Reverse Osmosis Unit in the MUD system (November 1992) was evaluated to be successful in improving the operation and performance of the MUD system although its effect in mitigating the degradation of the SG tubing is believed to be negligible. The group decided to continue the operation of the Reverse Osmosis unit due to it improving the operation and performance of the MUD system and due to its cost benefits for the MUD system.
Condenser Eddy Current Program Two waterboxes (IC and ID) were eddy current tested during AIR 03. One waterbox (I A) along with 15% of the fourth waterbox (IB) was eddy currented tested during AIR 04. The remainder of the fourth waterbox will be eddy current tested during the AIROS outage. Several hundred tubes have been plugged as a result of the eddy current program, but Condenser tube leaks have occurred in tubes that were eddy current tested The recent Condenser tube leaks have mainly been from tubes on the outside row of the tube bundle and have occurred in the Winter months. It is believe that the cold CW in the Winter months is causing wear of the Condenser tubes due to steam impingement. Some outside row tubes have been preventatively plugged. More outside row tubes are planned to be preventatively plugged prior to the AIROS outage. Eddy current testing of the IB waterbox and preventative plugging of outside row tubes in all waterboxes will reduce the leakage from these tubes. This reduction in leakage is consistent with the industry recommended ALARA chemistry program.
- .s, e-4 h8-Waia Elevated Hydrada Co "3mdan in the FW Svetam Elevated iryd.idr.e (>100 ppb in FW) has been maintained in Cycie 4 and 5. There was no pade==hla changes in the elevated hydrazine program between Cycle 4 and 5, therefore, it is not believed that elevated hydrazine contributed to the increase in voltage growth rates from Cycle 4 to 5. The group decided to continue elevated hydrazine operation due to its potential to reduce SG tube degradation and its effort in reducing erosion / corrosion of the CD system Review the Naad to Chamie=lly Claan the SG's With the decision to replace the SG's in AIR 07 (1998), there is little opportunity for SG -
chemical cleaning to be beneficial Braidwood will review the SG eddy current results from Byron's mid-cycle outage (BIP02) to complete the review of the benefits of SG chamical cleaning.
Evaluate the Use of Other Amines to Reduce Iron Transoort As mentioned above, the use of MPA at Byron is being reviewed for Braidwood. ;
Presently, MPA is the only other amine under evaluation. The performance SG soaks with dimethylamine (DMA) is also being evaluated. Since the use of amines other than ETA was not incorporated in Cycle 4 or 5, they could not have contributed to the increase in voltage growth rate. ;
Evaluate the 'Use of Other Chertdcals to Imorove Iron Transoort Out of the SG l Discussions are in progress with chemical manufactures to develop a polymer that will disperse iron to improve removal by the SG blowdown system. The contract for testing the should be issued soon. Testing of the polymer in a Comed SG is planned for later this year. Since the use of polymers was not incorporated in Cycle 4 or 5, they could not have contributed to the increase in voltage growth rate. l I
In addition to the above listed issues for discussion, two other issues were discussed as possible future programs.
~
SG Blowdown Flow Reduction The group decided they wanted to review what the effect ofreducing SG Blowdown flow would have on the hideout molar ratio. Reducing SG Blowdown flow will lengthen the life of the SG Blowdown resin and, therefore, reduce the sodium ingress or improve the sodium removal efficiency. At the same time, the concentration of the anions, excluding the effects of the Molar Ratio Control Program, should increase in the SG. Periods of reduced SG blowdown flow have occurred in the past. The reduction in flow did not increase the impurities in the SG appreciably during periods oflow chemical ingress.
i
i
- . A .l y
Dwing periods of higher amounts orchemicat ingress, some elevation ofimpurities was observed. These elevations are typically less than 2 ppb, therefore not jeopardizing any I actionlevels j Secondary Lav-up I i
Lay up practices of the secondary systems (CD, FW) in the past has only been to drain the !
systems and leave the drains open. The systems have not been dried with air or inerted I with nitrogen Due to this, the systems can contain a high moisture atmosphere This l leads to elevated corrosion of the systems. The group felt that better lay-up practices
{
should be irnplemented. The group agreed to start with the lay-up of the Main Condenser. l Debumidifiers are being evaluated for use during AIROS. The use of dehumidifiers at l other plants has proven to be beneficial in r-Indag the iron transport dur*mg unit startup. ,
Iron transport during unit startup is believed to be a major contributor to the total iron l transport to the SG's. ;
I Conclusion j This celate the review of the effectiveness of the various programs which were put in place or were already in place to mitigate degradation. No strong conclusions could be '
identified that relate secondary chamig operation to changes in SG indication voltage growth rates although the following goals were set: .
i
- 1. Reduce the occurrence, duration, and the concentration above Condensate '
Dissolved Oxygen action level;
- 2. Ensure the IB waterbox is eddy current tested and the necessary outside row !
tubes in all waterboxes are preventatively plugged; :
- 3. Evaluate the effect of reduced SG Blowdown flow in an attempt to alter the '!
chemical environment in the SG's; and i
- 4. Evaluate the use of dehumidifiers in the Main Condenser during AIROS. j u
The secondary chemistry program is evaluated following each refuel outage as required by l BwCP PD-4. A review of these programs is included in this evaluation. !
l i
'I i
I i
Figura 1 ,
Braidwood 1 CD Dis. O2 Action Level Hours /EFPY i
vs. Voltage Growth /EFPY CD Dis. 02 ppb-Hours /EFPY O 2000 4000 6000 8000 10000 12000 14000 16000 0.5 . . . . 0.5 e AL Hours /EFPY a pp Hours /EFPY 0.4 Cycle Sa -with Boric Acid e A - 0.4 k
in 2
I 0.3 - 0.3 e
o e
[0 Cycle 4 ae
> 0.2 Cycle da (1C SG only) e a - 0'2 E
k O.1 A e Cycle 4b (1C SG only) - 0.1 0 . . . . . . 0 0 50 100 150 200 250 300 350 400 450 500 CD Dis. 02 Action Level Hours /EFPY
. .. ~
Figura 2 o Braidwood 1 Molar Ratio vs. Voltage Growth /EFPY 0.6 Cycle 3 - Pre Molar Ratio ,
Control and Pre IPC 0.5
- u.
- Cycle Sa - with Boric Acid 0 .4 1
e o
& 0.3 -
E E
- Cycle 4 h 0.2 . Cycle 4a (1C SG only) so 0.1 -
+ Cycie 4b (1C SG only) 0 , . .
0.000 0.500 1.000 1.500 2.000 2.500 Average Cycle Molar Ratio l
l l
. _ _ - - _ _ _ _ - _ _ _ _ _ _ _ _ _ - _ - _ . . .