ML20116J077
| ML20116J077 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 07/31/1996 |
| From: | WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP. |
| To: | |
| Shared Package | |
| ML20116J073 | List: |
| References | |
| SG-96-07-009, SG-96-07-009-R01, SG-96-7-9, SG-96-7-9-R1, NUDOCS 9608130033 | |
| Download: ML20116J077 (64) | |
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WESTINGHOUSE PROPRIETARY CLASS 3 SG-96-07-009 Revision 1 BEAVER VALLEY UNIT 1 1996 ALTERNATE REPAIR CRITERIA 90 DAY REPORT July 1996 0
Westinghouse Electric Corporation Energy Systems Business Unit Nuclear Services Division P.O. Box 158 Madison, Pennsylvania 15663-0158 9608130033 960802 PDR ADOCK 05000334 R
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s SG-96-07-00 Revision 1 l
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l BEAVER VALLEY UNIT 1 l
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l 1996 ALTERNATE REPAIR CRITERIA 90 DAY REPORT i
l JULY 1996 1
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6 BEAVER VALLEY UNIT 1 i
199G ALTERNATE REPAIR CRITERIA 90 DAY REPORT TABLE OF CONTENTS Pare No.
l 1.0 Introduction 1-1 l
2.0 Summary and Conclusions 2-1 3.0 EOC-11 Inspection Results and Voltage Growth Rates 3-1 3.1 EOC-11 Inspection Results 3-1 3.2 Voltage Growth Rates 3-3 3.3 Probability of Prior Cycle Detection (POPCD) 3-4 l
3.4 Assessment of RPC Confirmation Rates 3-6 l
3.5 NDE Uncertainties 3-7 4.0 Data Base Applied for ARC Correlations 4-1 5.0 SLB Analysis Methods 5-1 j
6.0 Bobbin Voltage Distributions 6-1 l
l 6.1 Probability of Detection (POD) 6-1 l
6.2 Cycle Operating Time 6-1 i
6.3 Calculation of Voltage Distributions 6-2 6.4 Predicted EOC-12 Voltage Distributions 6-3 l
6.5 Comparison of Predicted and Actual EOC-11 Voltage Distributions 6-3 7.0 Tube Leak Rate and Burst Probabilities 7-1 l
7.1 Calculation of Leak Rate and Tube Burst Probabilities 7-1 7.2 Predicted and Actual Tube Leak Rate and Probability of Burst for EOC-11 7-1 7.3 Projected Leak Rate and Tube Burst Probability for EOC-12 7-2 i
l 8.0 Comparison of Probability of Prior Cycle Detection for 15 Inspections, l
8 plants with EPRI PGD 8-1 l
9.0 References 9-1 b
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4 BEAVER VALLEY UNIT 1 l
1996 ALTERNATE REPAIR CRITERIA 90 DAY REPORT
1.0 INTRODUCTION
This report provides the Beaver Valley Unit I steam generator tube support plate (TSP) bobbin voltage distribution summary, together with postulated Steam Line Break (SLB) leak rate and tube burst probability analysis results, in support of the implementation of a 2.0 volt Alternate Repair Criteria (ARC) for Cycle 12 as outlined in the NRC Generic Letter, Reference 9.1. Information required by the NRC Safety l
Evaluation Report (SER) is included in this report. Also provided are projections of bobbin voltage distributions, leak rates and burst probabilities for Cycle 12 operation.
The methodology used in these evaluations is consistent with the NRC SER, Reference 9.3, Westinghouse generic methodology described in Reference 9.3, as well as the methodology reported in the prior ARC reports for Beaver Valley Unit-1 (References 9.2 and 9.4).
The results of the End of Cycle 11 (EOC-11) inspection are provided in Section 3. The I
actual EOC-11 voltage distributions as well as leak rates and tube burst probabilities calculated for those distributions are compared with the projections for EOC-11 conditions using the EOC-10 data. During this inspection, plugs were removed from previously repaired tubes, the tubes were reinspected, and those with indications satisfying the 2 volt repair limits were returned to service. The indication population returned to service from deplugged tubes are included in the Cycle 12 analyses. Leak rates and burst probabilities for the projected EOC-12 voltage distributions are reported in Section 7 and compared with allowable limits. The predicted steam l
generator (SG) tube leak rate and probability of burst during a postulated steam line break (SLB) at EOC-12 meet the regulatory requirements outliaed in the NRC SER.
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i 2.0
SUMMARY
AND CONCLUSIONS I
SLB leak rate and tube burst probability analyses were performed for the actual EOC-11 bobbin voltage distributions and for projected EOC-12 distributions. SG B l
with the largest indication detected (3.35 volts) was found to be the limiting SG at EOC-11, although SG A was projected to be the limiting SG and it also has the highest l
number of indications detected during the EOC-11 inspection.
However, the differences in the results for those two SGs are small, with SLB leak rates based on the measured EOC-11 voltages being the same for the two SGs (1.50 gpm), while SG B yielded a slightly higher tube burst probability (6.48 x 10 5 vs. 6.07 x 10 5 for SG A) since it had one more tube burst than SG A in the 250,000 simulation Monte Carlo l
analysis performed for each SG. The corresponding results for SG C are well below those shown above for SGs A and B. SG B is also predicted to be limiting at EOC-12, with the highest number ofindications, bobbin voltage amplitude, and leak rate and tube burst probability for postulated SLB conditions. EOC-12 SLB leak rate projected for SG B is equal to the SER acceptance limit of 4.50 gpm, however, alternate calculations with some of the conservatism in the present licensing database and method removed show much higher margins in the EOC-12 leak rates. The tube burst i
probability at EOC-12 is low, varying between 1.02 E-04 and 1.76 E-04 among the three SGs.
These calculations show that ARC application at EOC-11 (actual l
distribution) and at EOC-12 (predicted for POD = 0.6) will satisfy NRC criteria for allowable leakage and burst probability.
i A total of 1936 bobbin indications was reported for tubes in service during the Cycle 11 inspection. 242 of the 1936 bobbin indications were above 1.0 volt, and only three indications exceeded the 2.0 volt repair limit. 77 bobbin indications were RPC inspected, including the three indications above 2 volts, of which 43 were confirmed.
83 indications were repaired for tubes in service during Cycle 11, of which only two were repaired because of exceeding the 2 volt repair criteria. Accordingly,1853 of the 1936 indications were returned to service for Cycle 12.
l SG A with 849 indications (in the tubes in service during Cycle 11) had the highest l
number ofindications at EOC-11. 96 of the 849 indications were reported as above 1.0 l
volt and only two indications had a voltage above 2 volts. 32 indications were RPC inspected and 21 were confirmed. 29 of the 849 indications were removed from service due to tube repairs, but only one of those was repaired because of exceeding the 2 volt repair limit for outside diameter stress corrosion cracking (ODSCC) at tube support plates (TSP).
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During the outage, tubes previously plugged in accordance with prior repair criteria were deplugged, inspected and either returned to service in accordance with the 2 volt ARC criteria or replugged. Accordingly,508 such indications (258 of them with a bobbin voltage above 1.0 V) were returned to service, for a total of 2361 indications l
returned to service for Cycle 12 operation in accordance with ARC criteria. The largest number ofindications added from tube deplugging are in SG C (252), and the reason for this being a large number of tubes were already deplugged and returned to service from SGs A and B, but none from SG C, during the EOC-10 inspection.
Using the NRC mandated POD value of 0.6 to calculate the performance of the limiting SG during the next Beaver Valley Unit 1 operating cycle, the SLB tube leak rate is projected to be 4.5 gpm for SG B and the corresponding tube burst probability is 4
projected to be 1.76 x 10 at EOC-12. These results meet the Beaver Valley Unit 1 l
ARC requirement for allowable tube leakage (4.5 gpm) and the NRC guideline for tube
)
l burst probability (1 x 10'8); accordingly Cycle 12 operation of Beaver Valley Unit 1 is l
considered to be in compliance with the requirements of the NRC SER of Reference 9.3.
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l It is anticipated that a revision to the approved industry database (Reference 9.6) will be sent to the NRC in mid August,1996. Contained in this revision will be a j
discussion and justiHcation for excluding the French datapoints when determining correlations for 7/8" diameter SG tubes.
With the French data removed, the requirement for applying the SLB leak rate versus bobbin voltage correlation can be met. Therefore, the correlation can be used in leak rate calculations. The SLB tube leak rate at EOC-12 for SG B, the limiting SG, is projected to be 4.5 gpm using the currently approved database which does not result in a voltage dependent leak rate correlation. However, upon NRC acceptance, Duquesne Lights' intention is to use the l
updated database which excludes the French data. The SLB tube leak rate at EOC-12, l
utilizing the updated database which supports a voltage dependent correlation, for SG l
B is projected to be 0.52 gpm.
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3.0 EOC-11 INSPECTION RESULTS AND VOLTAGE GROWTH RATES I
3.1 EOC-11 INSPECTION RESULTS l
In accordance with the ARC guidance provided by the NRC generic letter (Reference 9.1),' the end of Cycle 11 (EOC-11) inspection of the Beaver Valley Unit 1 steam generators (SG) consisted of a complete 100% bobbin probe fulllength examination of i
all TSP intersections in the tube bundles of all three SGs. Rotating Pancake coil (RPC) examination was performed for all bobbin indications with amplitudes greater than 2 volts. The NRC ARC criteria in the recent SER for Beaver Valley Unit-1 (Reference 9.3) require that RPC confirmed indications above 2.0 volts bobbin amplitude and that all bobbin indications above 5.6 volts shall be plugged. Only three indications i
exceeded the 2 volts in the current inspection, and two of them were confirmed by RPC and plugged. Tubes previously plugged in accordance with prior repair criteria for ODSCC at TSPs were deplugged during this outage, inspected and either returned to service in accordance with the 2 volt repair criteria or replugged.
i A summary of eddy current test (ECT) indication distributions for all steam generators l
is shown on Table 3-1. For those tubes that were in service for Cycle 11, Table 3-1 i
provides the number of field bobbin indications, the number of these field bobbin indications that were RPC inspected, the number of RPC confirmed indications, the number ofindications in plugged tubes, the number of Cycle 11 in-service indications that remain active for Cycle 12, the indications recovered from deplugged tubes which were returned to service for Cycle 12, and the subsequent totalindication population being returned to service (RTS) for the beginning of Cycle 12 (BOC-12). Overall, the combined data for the Beaver Valley Unit 1 steam generators show that:
e Out of a total of 1936 indications which were in-service during Cycle 11 and were identified during the EOC-11 inspection, 83 were removed from service, of which only two indications did not meet the 2 volt repair criteria (and the remaining were plugged for causes other than ODSCC at TSP intersections), leaving 1853 which were returned to service for Cycle 12. The largest indication was found in SG B and it had a bobbin amplitude of 3.35 volts.
o Of the 1936 indications, a total of 77 were RPC inspected, with 22 of the 77 above 1 volt.
e Of the 77 RPC inspected, a total of 43 were RPC confirmed.
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e Additionally,508 indications from deplugged tubes were recovered and returned to service, for a total of 2361 indications returned to service for Cycle 12 operation in accordance with ARC criteria.
- The largest number ofindications added from tube deplugging are in SG C (252),
i and the reason for this being a large number of tubes were already deplugged and returned to service from SGs A and B, but none from SG C, during the EOC-10 inspection.
A review ofTable 3-1 indicates that SG A has more total as well as higher amplitude BOC-12 indications ( 953, with 160 indications above 1.0 volt) than either of the other l
two SGs, thereby being the likely limiting SG at EOC-12.
Figure 3-1 shows the actual bobbin voltage distribution for tubes that were in service during Cycle 11, as determined from the EOC-11 ECT inspection, and SG A has a higher number ofindications than the other two SGs. However, the largest bobbin indication found in the EOC 11 inspection (3.35 volts) was in SG B (shown in the 3.4 volt bin). Figure 3-2 shows the distribution of the EOC-11 bobbin indications which were plugged and taken out of service and Figure 3-3 shows the bobbin voltage distribution ofindications in service during Cycle 11 RTS for BOC-12.
During the outage, tubes previously plugged in accordance with prior repair criteria for ODSCC at TSPs were deplugged, inspected and either returned to service in accordance with the 2 volt criteria or replugged; a summary ofindications in those tubes is presented on Table 3-2. Accordingly,508 such indications (with 258 above 1.0 volt and two above 2 volts bobbin amplitude) from all three SGs were returned to service for Cycle 12 in accordance with the 2 volt repair criteria. Figure 3-4 shows the bobbin voltage distribution for the deplugged indications which were returned to service for Cycle 12. The total number ofindications in deplugged tubes returned to service for SG C is almost equal to the combined total of such indications for the i
remaining two SGs because a large number of tubes were already deplugged and returned to service in SGs A and B during the EOC-lo inspection (but none from SG j
C). Figure 3-5 shows the voltage distribution for allindications (those continuing from Cycle 11 service and those deplugged at EOC-11) which were RTS for Cycle 12.
The distribution of EOC-11 indications as a function of support plate elevation, summarized in Table 3-3 and illustrated on Figure 3-6, shows the predisposition of i
ODSCC to occur in the first few hot leg TSPs (1723 of the 1936 indications occurred in i
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the first two hot leg TSPs), although the mechanism does extend to higher TSPs.
l There were no bobbin indications reported in the cold leg. This distribution shows the i
predominant temperature dependence of ODSCC at Beaver Valley Unit 1, similar to l
that observed at other plants.
l 3.2 VOLTAGE GROWTH RATES The bobbin voltage growth rates for the Beaver Valley Unit-1 steam generators, shown l
on Table 3-4, provide a comparison of average growth rates for the recent operating cycles; data for the last five cycles are provided. It is evident that for the cycle just completed (Cycle 11) there is a substantialincrease in the indication population below 0.75 volts. This could be attributed to improved ECT practice which has resulted in more accuracy and discrimination of bobbin probe signals, so that more low voltage j
indications are being reported. The average growth rates decrensed consistently between Cycles 7 through 10, but Cycle 11 shows a larger growth raw than Cycle 10.
However, Cycle 11 has lower growth than prior Cycles 7 through 9.
l Average growth rates for each SG during Cycle 11 are summarized on Table 3-5.
Those growth rates vary between 7.7% and 23.6%, between SGs, with an overall average of 13.9%, on an effective full power year (EFPY) basis. The average growth forindications with a BOC bobbin voltage above 0.75 volt is 10.2% per EFPY and for indications below 0.75 volt it is 16.5% per EFPY. SG A had the highest average bobbin voltage at EOC-11 whereas SG B had the largest average growth during Cycle 11.
Another cycle growth comparison is provided in more detail by the cumulative probability distribution functions (CPDF) for Cycles 11 and 10 summarized on Tables 3-6 and 3-7, respectively, and also illustrated on Figure 3-7. Average growth rates for Cycle 11 are clearly higher than those observed for Cycle 10. The NRC generic letter recommends that the more conservative growth distribution from the last two cycles be used for projecting EOC distributions. Accordingly, Cycle 11 bobbin voltage growth rates will be used for predicting the EOC-12 conditions; these rates are developed from l
the 1996 EOC-11 inspection data and a reevaluation of the same indications from the l
previous (1995) inspection ECT signals.
Table 3-6 shows CPDF for each SG during Cycle 11, and the same data is presented in a graphical form on Figure 3 8. Clearly, growth rates for SG B are higher than l
those of the other two SGs. According to the Westinghouse ARC analysis methodology i
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f presented in Reference 9.5, the larger of the composite growth rate for all SGs and the
}
SG-specific growth rate should be used in projecting SLB leak rate and tube burst probability forindividual SGs. Since the growth rates for SGs A and C are below the l
composite growth rate, the composite growth rate is applied to those two SGs to provide a conservative basis for predicting EOC-12 conditions. However, predictions for SO B are obtained using its own growth rate since it is higher than the composite j
rate.
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3.3 PROBABILITY OF PRIOR CYCLE DETECTION (POPCD) i The inspection results at EOC-11 permit an evaluation of the probability of detection j
at the prior EOC-10 inspection. For ARC /APC applications, the important indications are those that could significantly contribute to EOC leakage or burst probability.
These significant indications can be expected to be detected by bobbin and confirmed
[
by RPC inspection. Thus, the population ofinterest for ARC POD assessments is the EOC RPC confirmed indications that were detected or not detected at the prior inspection. The probability of prior cycle detection (POPCD) for the EOC-10 inspection can then be defined as:
EOC-10 cycle reported
+
Indications confirmed indications confirmed by and repaired in EOC-10 RPC in EOC-11 inspection inspection -
POPCD =
(EOC-10)
{ Numerator}
+
New indications RPC confirmed in EOC-11 inspection POPCD is evaluated at the 1995 EOC-10 voltage values (from 1996 reevaluation for growth rate) since it is an EOC-10 POPCD assessment. The indications at EOC-10 that were RPC confirmed and plugged are included as it can be expected that these indications would also have been detected and confirmed at EOC-11. It is also appropriate to include the plugged tubes for ARC applications since POD adjustments to define the BOC distribution are applied prior to reduction of the EOC indication distribution for plugged tubes. Indication in tubes deplugged and returned to service at EOC-11 are not included in the evaluation since it is not appropriate to include them.
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It should be noted that the above POPCD definition includes all new EOC-11 l
indications not reported in the EOC-10 inspection. The new indications include EOC-10 indications present at detectable levels but not reported, indications present at EOC-10 below detectable levels and indications that initiated during Cycle 11. Thus, this definition, by including newly initiated indications, differs from the traditional l
POD definition. Since the newly initiated indications are appropriate for ARC l
applications, POPCD is an acceptable definition and eliminates the need to adjust the traditional POD for new indications.
l The above definition for POPCD would be entirely appropriate if all EOC-11 indications were RPC inspected. Since only a fraction of bobbin indications are l
generally RPC inspected, POPCD could be distorted by using only the RPC inspected indications. Thus, a more appropriate POPCD estimate can be made by assuming that all bobbin indications not RPC inspected would hnve been RPC confirmed. This definition is applied only for the 1996 EOC-11 indications not RPC inspected since inclusion for the EOC-10 inspection could increase POPCD by including indications on l
a tube plugged for non-ODSCC causes. This POPCD can be obtained by replacing the EOC-11 RPC confirmed by RPC confirmed plus not RPC inspected in the above definition of POPCD. For this report, both POPCD definitions are evaluated for Beaver Valley Unit-1.
The POPCD evaluation for the 1995 EOC 10 inspection data is shown on Figure 3-9 and summarized in Table 3 8. Figure 3 9 shows POPCD evaluated for both RPC l
confirmed indications only and for RPC confirmed plus not RPC inspected indications.
Also shown is the EPRI POD developed by analyses of field indications for 3/4 inch l
diameter tubing in Model D SGs. From Table 3-8,it is seen that between 0.0 to 1.8
)
i volts POPCD based on only RPC confirmed indications is significantly higher than l
. POPCD based on RPC confirmed plus not RPC inspected indications, which is to be expected since only a small fraction of the indication not RPC inspected are RPC confirmed in that voltage range. The Beaver Valley Unit-1 POPCD defined using RPC confirmed plus not inspected indications is in good agreement with the EPRI POD l
l while the distribution defined with RPC confirmed only indications is much above the EPRI POD.
In summary, the Beaver Valley Unit-1 EOC-10 POPCD strongly supports a voltage dependent POD substantially higher than the NRC mandated POD value of 0.6 above about 0.6 volts and approaching unity at about 2 volts, and it is in good agreement i
with the EPRI proposed POD. It is concluded that the POD applied for ARC leak and burst projections needs to be upgraded from the constant POD value of 0.6 to a voltage j
dependent POD.
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3.4 ASSESSMENT
OF RPC CONFIRMATION RATES l
This section tracks the 1995 EOC-10 indications left in sorvice at BOC-11 relative to RPC inspection results in 1996 at EOC-11. The data for the three SGs are shown I
individually in Tables 3 9 to 3-11, and the composite results for all SGs are given in Table 312. For 1995 bobbin indications left in service, the indications are tracked relative to 1995 RPC confirmed,1995 RPC NDD,1995 bobbin indications not RPC inspected and 1995 bobbin indications with no indication found in 1996. Also included are new 1996 indications. The table shows, for each category of indications, the number of indications RPC inspected and RPC confirmed in 1996 as well as the l
percentage of RPC confirmed indications.
l The 1996 RPC confirmation rate for 1995 RPC NDD indications left in service was GG.7% for SGs A and B. For SG C, only one 1995 RPC NDD indication was RPC tested in 1996 and it was not confirmed. Thus, the overall confirmation rate for the 1995 RPC NDD indications was 60%. None of the 1995 RPC NDD indications RPC tested in 1996 had a bobbin voltage below 1.0 volt, so the data represent bobbin indications above 1.0 volt. This overall confirmation rate is slightly higher than that found for 1993 RPC NDD indications tested in 1995 (50.9 %) as well as that for 1991 to 1993 Cycle 9 indications (27.2%, Reference 9.2). For successive ARC inspections at other i
plants, the confirmation rate for RPC NDD indications left in service was typically <
. 40%.
The NRC SER (Reference 9.3) allows for consideration of only a fraction of RPC NDD indications from current inspection in establishing BOC voltage distribution for the next cycle. The fractional value applicable is the largest RPC ::onfirmation rate for prior cycle RPC NDD indications found during the last two outages, but it may not be less than 0.7. Thus, the fraction that can be applied for 1995 RPC NDD indications is l
0.7.
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3.5 NDE UNCERTAINTIES The NDE uncertainties applied for the EOC-11 voltage projections in this report are those given in the prior Beaver Valley-1 ARC reports (References 9.1 and 9.4). 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 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-11 voltage distributions.
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Table 31 l
Beaver Valley Unit 11996 EOC-11 Summary ofInspection and Repair For Tubes in Service During Cycle 11 Steam Generator A Steam Generator B l
In.Semce Dunn8 Cycle 11 EOC.i t Cycle 12 In.5emce Dunns Cycle 11 EoC ll Cycle 12 1
r.y Rein.g Dgluend sJ Tubee' y,y g,,,,a Dgheyd A8T M RPC RPC Tebes Rotuned m
g Voltage m
g RPC RPC Tubee Rehemed am lastestd Comannd Rgend Rawaad to legoced Coa 6nned Rgemed gtee.ned se to sem e some to somse sawwe 02 4
0 0
0 4
0 4
13 0
0 l
12 1
13 03 49 I
O I
4 2
50 M
2 0
2 32 1
33 04 102 3
3 1
101 3
104 64 2
0 6
58 1
59 l
05 122 4
2 4
118 8
126 92 I
i 3
89 4
93 I
06 130 3
2 4
126 8
134 90 3
2 4
86 5
91 07 116 3
3 5
Ill 8
119 90 I
I 9
Si 10 91 08 88 2
0 3
85 9
94 80 1
1 7
73 9
82 09 76 3
1 3
73 13 86 67 2
2 3
64 7
71 I
66 3
3 1
65 11 76 55 1
1 5
50 7
57 l
1l di 2
2 3
38 6
44 di 3
3 2
39 12 SI 12 26 5
3 2
24 9
33 21 1
I I
20 15 35 l
13 10 0
0 0
to il 21 20 l
0 1
19 10 29 14 7
0 0
1 6
13 19 11 0
0 1
10 10 20 15 2
0 0
0 2
5 7
9 2
l 0
9 5
14 16 2
0 0
0 2
10 12 4
0 0
1 3
11 14 17 4
0 0
0 4
7 11 4
0 0
0 4
5 9
18 1
0 0
0 1
5 6
1 0
0 0
1 2
3 19 I
I I
O I
4 5
1 0
0 0
1 5
6 2
0 0
0 0
0 1
1 0
0 0
0 0
2 2
21 1
l i
1 0
0 0
0 0
0 0
0 1
1 l
~ 22 0
0 0
0 0
0 0
0 0
0 0
0 0
0 l
23 I
I O
O I
O l
0 0
0 0
0 0
0 34 0
0 0
0 0
0 0
1 l
i 1
0 0
0 Total 849 32 21 29 820 133 953 698 21 14 47 651 123 774
>lV 96 10 7
7 89 71 160 113 5
6 7
106 78 184
>2V 2
2 I
I i
0 1
1 1
1 1
0 1
I Steam Generator C Composite Of AllThree Steam Generator Data In semce Dunns ycle Ii soc-1i cycle 12 In.senice During cycle iI soc ll cycle 12 c
Deplussed A8 Tess' Dgiugyd A8 Tehes' Vehage rield Reenned Tubes Retunud rund Retuned Tubee Reewned Be Bobham kPC RPC andweemme to Reenned to Bobbe RPC RPC t Am --
to Renrud to 1 A*-
Inesected Conanned Reensed Semse W 5emco Semse inhostname inesected Ceannned Resered Semse to Semco Semco 02 3
0 0
0 3
1 4
20 0
0 1
19 2
21 03 24 0
0 0
24 10 34 107 3
0 3
IN 13 117 04 47 0
0 0
47 14 6l 213 5
3 7
206 18 224 l
05 51 0
0 2
49 14 63 265 5
3 9
256 26 282 l
06 62 1
1 1
61 20 81 282 7
5 9
273 33 306 07 59 8
2 1
58 22 80 265 12 6
15 250 40 290 08 45 8
3 0
45 23 68 213 11 4
10 203 41 244 09 37 2
1 2
35 20 55 180 7
4 8
172 40 212 1
28 I
O i
27 19 46 149 5
4 7
142 37 179 11 15 4
1 0
15 21 36 97 9
6 5
92 39 131 I
I2 8
0 0
0 8
19 27 55 6
4 3
52 43 95 I3 4
0 0
0 4
12 16 34 1
0 1
33 33 66 14 4
0 0
0 4
16 20 22 0
0 2
20 39 59 15 0
0 0
0 0
11 Il 11 2
1 0
11 21 12 16 8
0 0
0 1
10 11 7
0 0
1 6
31 37 17 0
0 0
0 0
7 7
8 0
0 0
8 19 27 18 I
O O
O I
8 9
3 0
0 0
3 15 18 l
19 0
0 0
0 0
3 3
2 1
1 0
2 12 14
(
2 0
0 0
0 0
I I
O O
0 0
0 4
4 l
21 0
0 0
0 0
0 0
1 1
I 1
0 I
I
(
22 0
0 0
0 0
1 I
O O
O O
O I
l_
23 0
0 0
0 0
0 0
1 1
0 0
1 0
l_
34 0
0 0
0 0
0 0
I I
I I
O O
O l
Total 389 24 8
7 382 252 634 1936 77 43 83 1853 508 2Ml_
>IV 13 4
1 0
33 109 142 242 22 14 14 228 258 486 4
>2V 0
0 0
0 0
1 I
3 3
2 2
1 2
3 1
- Includes indications in depiged tubes rehamed to service 3-8
_,m,,,,,e.,,,,
Table 3 -2 Beaver VaBey Usset 11996 EOGil Sesumary ofInspecelen ased Repair For Tishes Deptu8ged at EOC-11 SeesemGenerseer A Seesmi Genernest B 5eessaGenerseer C Caushimsel Dana frena AE 11ree SGs Votage Ramenso Farid Retuned Reemmed Pmid n====d Ibn Fidd Bobten RPC RFC h
to Betem RFC RPC h
e Fadd Bettui RPC RFC becuares to Bettus RFC RPC W
to besshans insperud Cen5nned Repumed Sernre bukeseems buyered Cendruned Rapsed
$srvere Iparum==
buyerted Canessed Repared
$sreum h
tugueted Coudneed Reseed
$srome 0.2 0
0 0
0 0
1 0
0 0
1 2
0 0
1 1
3 0
0 1
2 0.3 2
0 0
0 2
3 0
0 2
1 10 0
0 0
10 15 0
0 2
13 0.4 3
0 0
0 3
3 0
0 2
1 16 0
0 2
14 22 0
0 4
18 0.5 8
0 0
0 8
8 0
0 4
4 17 0
0 3
14 33 0
0 7
26 0.6 8
0 0
0 8
9 0
0 4
5 22 0
0 2
20 39 0
0 6
33 0.7 8
0 0
0 8
14 0
0 4
10 23 0
0 1
22 45 0
0 5
40 0.8 10 0
0 1
9 14 0
0 5
9 26 0
0 3
23 50 0
0 9
41 0.9 18 0
0 5
13 14 0
0 7
7 26 0
0 6
20 58 0
0 18 40 1
13 0
0 2
11 13 0
0 6
7 21 0
0 2
19 47 0
0 10 37 1.1 9
0 0
3 6
14 0
0 2
12 23 0
0 2
21 46 0
0 7
39 12 10 I
I I
9 19 I
I 4
15 21 0
0 2
19 50 2
2 7
43 1.3 Il I
I O
11 14 0
0 4
10 14 0
0 2
12 39 I
I 6
33 1.4 15 0
0 2
13 10 1
1 0
10 16 0
0 0
16 41 1
1 2
39 1.5 5
0 0
0 6
0 0
1 5
13 0
0 2
Il 24 0
H 3
21 1.6 10 0
0 0
10 12 I
I I
II 12 0
0 2
10 34 I
I 3
31 1.7 7
0 0
0 7
6 2
2 1
5 7
0 0
0 7
20 2
2 1
19 1.8 6
0 0
I 3
0 0
1 2
9 0
0 1
8 18 0
0 3
15 1.9 4
0 0
0 4
7 0
0 2
5 4
0 0
1 3
15 0
0 3
12 2
1 0
0 0
I 4
I I
2 2
1 0
0 0
1 6
I I
2 4
2.1 3
3 3
3 0
3 2
2 2
1 7
7 6
7 0
13 12 Il 12 1
2.2 5
5 5
5 0
2 2
2 2
0 4
4 1
12 12 11 11 1
2.3 0
0 0
0 0
5 5
5 5
0 2
2 2
2 0
7 7
7 7
0 2.4 I
I I
I O
4 4
4 4
0 2
2 1
2 0
7 7
6 7
0 2.5 0
0 0
0 0
3 3
3 3
0 1
1 I
1 0
4 4
4 4
0 b0 2
2 2
2 0
5 5
5 5
0 26 1
1 1
I O
2 2
2 2
2.7 1
1 1
1 0
1 1
I I
~
0 1
-1 1
I O
3 3
3 3
0 2.8 0
0 0
0 0
2 2
2 2
0 t
I i
1 0
3 3
3 3
0 19 1
1 I
I O
0 0
0 0
0 0
0 0
0 0
1 I
I I
O 3
1 0
0 1
0 0
0 0
0 0
0 0
0 0
0 1
0 0
1 0
3.4 0
0 0
0 0
1 1
1 1
0 0
0 0
0 0
1 1
1 I
o 3.7 0
0 0
0 0
0 0
0 0
0 1
1 1
1 0
l I
I I
O 3.9 0
0 0
0 0
0 0
0 0
0 1
1 1
1 0
I I
I I
0 44 0
0 0
0 0
I I
I 1
0 0
0 0
0 0
1 1
1 I
0 Total 161 14 le 28 133 198 29 29 75 123 306 23 20 54 252 665 66 63 157 508
> IV 91 14 14 20 71 119 29 29 41 78 143 23 20 34 109 353 66 63 95 258
> 2V 13 12 12 13 0
24 23 23 23 1
23 23 20 22 1
60 58 55 58 2
3-9
- - =.
_ _. _ ~ - _ _ _ _ - - -. _,
~.
Table 3 -3 Beaver Valley Unit 11996 Outage TSP ODSCC Indication Distributions for Tubes in Service During Cycle 11 Steam Generator A Steam Generator B Tube Nunber Nunber Support hfanimen Awrage Larpst A wrnge Masimum A wrsge Larpet g
g GM Plate Vokage Voltage Growth Growth Vokage Voltage Growth 111 503 1.21 0.69 0.550 0.043 3%
335 0.76 0.830 0.140 211 278 1.69 0.62 0360 0.042 206 1.46 0.67 0.630 0.127 311 49 1.27 0.67 0330 0.060 58 1.61 0.61 0.500 0.084 411 10 1.54 0.64 0320 0.073 31 1.23 0.58 0.280 0.088 511 7
0.74 0.45 0.150 0.071 5
0.85 0.44 0.130 0.028 611 0
1 0.52 0.52 0.050 0.050 711 2
0 31 0.28 0.080 4 020 1
035 0.35 0.000 0.000 Total 849 698 Steam Generator C Composite of All Three SGs Sup Maximum A wrage Largest Average Mashmen A wrsge Larpst g
Plate Voltage Voltage Growth GM Indications lli 207 1.79 0.71 0.410 0.072 1106 335 0.72 0.83 0.083 21I 133 1.51 0.60 0350 0.069 617 1.69 0.63 0.63 0.076 311 35 1.14 0.55 0310 0.091 142 1.61 0.61 0.5 0.077 411 6
1.1 0.61 0.290 0.103 47 1.54 0.60 032 0.087 511 5
03 0.26 0.090 0.018 17 0.85 0.39 0.15 0.043 611 3
0.39 035 0.070 0.043 4
0.52 0.07 711 0
3 0.35 0.08 Total 389 1936 3 -10 rx-oar m r._u rm e,.
Table 3 - 4 Beaver Valley Unit-1 1996 Outage Average Voltage Growth IIistory Composite of All Steam Generator Data Bobbin Voltage Number of Average Voltage Average Voltage Growth Average Percentage Gemth Range Indications BOC Entire Cycle Per EFPV Entire Cycle Per EFPV Cycle 11 (1995-1996) - 352.94 EFPD Entire Voltage Range 1936 0.60 0.08 0.08 13.5 %
13.9 %
V noc <.75 Volts 1434 0.48 0.08 0.08 15.9 %
16.5 %
2.75 Volts 502 0.94 0.09 0.10 9.9%
10.2%
Cycle 10 (1993 - 1995) - 435.79 EFPD Entire Voltage Range 1089 0.66 0.02 0.02 3.0%
2.5%
V soc <.75 Volts 751 0.50 0.04 0.03 8.0%
6.7%
f 2.75 Volts 338 1.01
-0.01
-0.01
-1.0%
-0.8%
Cycle 9 (1991 - 1993) - 492.75 EFPD Entire Voltage Range 1125 0.57 0.09 0.07 15.8 %
11.7 %
V noc <.75 Volts 918 0.47 0.09 0.07 19.1%
14.2 %
2.75 Volts 207 1.02 0.09 0.07 8.8%
6.5%
Cycle 8 (1989 - 1991) - 390.82 EFPD Entire Voltage Range 952 0.95 0.18 0.17 18.9 %
17.7%
V soc <.75 Volts 366 0.58 0.16
_ 0.15 27.6%
25.8 %
2.75 Volts 586 1R 0.19 0.18 16.1%
15.0 %
Cycle 7 (1987 - 1989) - 438.3 EFPD Entire Voltage Range 918 0.66 0.29 0.24 43.9 %
36.6%
V soc <.75 Volts 622 0.49 0.27 0.23 55.1 %
45.9 %
2.75 Volts 296 1.01 0.34 0.28 33.7 %
28.1%
rmownstr.u._u rimmo n m 3 - 11
O Table 3 - 5 Beaver Valley Unit-11996 Outage Average Voltage Growth During Cycle 11 Number of Average Voltage Average Voltage Growth Percent Growth Indications BOC Entire Cycle Per EFPY
- Entire Cycle Per EFPY
- Composite of All Steam Generator Data Entire Voltage Range 1936 0.60 0.080 0.083 13.5%
13.9 %
V noc <.75 Volts 1434 0.48 0.076 0.078 15.9 %
16.5 %
2.75 Volts 502 0.94 4.093 0.096 9.9's 102 %
Steam Generator A Entire Voltage Range 849 0.62 0.044 0.046 7.5%
7.7%
V noe <.75 Volts 611 0.48 0.049 0.051 10A%
10.8%
2.75 Volts 238 0.96 0.033 0.034 3.6%
3.7%
Steam Generator B Entire Voltage Range 698 0.58 0.128 0.133 22.8 %
23.6 %
V moc <.75 Volts
$24 0.47 0.109 0.113 24 2 %
25.1%
2.75 Volts I74 0.93 0.185 0.192 20.7 %
21 A%
Steam Generator C Entire Voltage Range 389 0.57 0.072 0.075 13.0 %
13.5%
V moe <.75 Volts 299 0.47 0.072 0.075 15.8 %
16.3 %
2.75 Volts 90 0.91 0.072 0.075 82%
8.5%
- Beed on Cyde 11 dwstion of 352.94 EFTD m@AYMRTaNe-WM90 M PM 3 - 12
I i
Table 3 - 6 Beaver Valley Unit 1 Signal Growth Statistics For Cycle 11 ('95 to '96) on EFPY Basis Steam Generator A Steam Generator B Delta Volts No. of No. of CPDF CPDF Obs Obs
-0.5 0
0.000 0
0.000
-0.4 2
0.002 0
0.000
-0.3 3
0.006 0
0.000
-0.2 13 0.021 1
0.001
-0.1 42 0.071 4
0.007 0
206 0.313 87 0.132 0.1 387 0.769 258 0.501 0.2 144 0.939 180 0.759 0.3 32 0.976 104 0.908 0.4 15 0.994 36 0.960 0.5 4
0.999 17 0.984 0.6 1
1.000 8
0.996 0.7 1
0.997 0.8 1
0.999 0.9 1
1.000 Total 849 698 Steam Generator C Cumulative Delta Volts No. of No. of CPDF CPDF Obs Obs
-0.5 0
0.000 0
0.000
-0.4 0
0.000 2
0.001
-0.3 0
0.000 3
0.003
-0.2 1
0.003 15 0.010
-0.1 11 0.031 57 0.040 0
77 0.229 370 0.231 0.1 180 0.692 825 0.657 j
0.2 75 0.884 399 0.863 0.3 33 0.969 169 0.950 0.4 11 0.997 62 0.982 O.5 1
1.000 22 0.994 0.6 9
0.998 0.7 1
0.999 j
0.8 1
0.999 j
0.9 1
1.000 Total 389 1936 l
l r!O90 DAY.XL5 Table) 6 7/31% 3 57 PM 3 - 13 1
I -
Table 3 -7 Beaver Valley Unit 1 Signal Growth Statistics For Cycle 10 ('93 to '95) on EFPY Basis Steam Generator A Steam Generator B Delta Volts No. of No. of CPDF CPDF Obs Obs l
-0.5 1
0.002 0
0.000 l
-0.4 3
0.008 0
0.000
-0.3 1
0.010 2
0.005
-0.2 13 0.037 7
0.023
-0.1 53 0.147 23 0.080 l
0 181 0.521 113 0.363 0.1 172 0.876 166 0.778 0.2 44 0.%7 64 0.938 0.3 14 0.996 20 0.988 0.4 1
0.998 4
0.998 l
0.5 1
1.000 1
1.000 Total 484 400 Steam Generator C Cumulative Delta Volts No. of No. of -
CPDF CPDF Obs Obs 0.5 0
0.000 -
1 0.001
-0.4 0
0.000 3
0.004
-0.3 0
0.000 3
0.006
-0.2 1
0.005 21 0.026
-0.1 14 0.073 90 0.108 0
57 0.351 351 0.431 0.1 96 0.820 434 0.829 0.2 28 0.956 136 0.954 0.3 6
0.985 40 0.991 0.4 2
0.995 7
0.997 0.5 1
1.000 3
1 Total 205 1989 i
t l
\\
{
l I
i i
4 l
nO90 DAY ES Me 3.7 7/31% 3 57 PM 3 - 14 i
4
Table 3-8 Beaver Valley Un't - 1 1996 EOC-11 Evaluation for Probability of Prior Cycle Detection (EOC-10)
Composite of All Steam Generator Data New Indications 1996 Bobbin, Field Callin 1995 1995 Bobbin POPCD 1996 RPC 1996 RPC RPC I
10 Confirmed Confirmed Con 5nnM RP p
Confi ed Voltage ant n
ant Confirmed Confirmed and Plugged Bin inspected inspected inspected Fraction Count Fraction Count 0
39 0
11 0
0/0 0.220 11 /50
> 0 - 0.2 0.2 - 0.4 6
271 0
187 3
0.333 3/9 0.412 190/461 0.4 - 0.6 8
239 3
376 10 0.619 13 / 21 0.618 386/625 0.6 -0.8 4
110 7
315 19 0.867 26/30 0.752 334/444 s
0.8 - 1.0 1
42 8
226 18 0.963 26 /27 0.853 244/286 1.0 - 1.2 1
16 2
37 50 0.981 52/53 0.845 87/103 1.2 - 1.4 0
4 0
16 26 1
26 /26 0.913 42/46 1.4 - 1.6 0
1 1
5 19 1
20/20 0.960 24/25 1.6 - 1.8 0
1 0
5 11 1
11 /11 0.941 16/17 1.8 - 2.0 0
0 1
1 5
1 6/6 1
6/6 2.0 - 2.2 0
0 0
0 5
1 5/5 1
5/5 2.2 - 2.5 0
0 0
0 4
1 4/4 1
4/4 2.5 - 3.0 0
0 1
1 5
1 6/6 1
6/6 3.0-40 0
0 0
0 6
1 6/6 1
6/6 4.0 - 5.5 0
0 0
0 5
1 5/5 1
5/5 20 723 23 1180 186 TOTAL 1
22 5
65 C6 Total > 1 3 - 15 ncamvnstr.wamwm m
Table 3-9 Beaver Valley Unit 1 Analysis of RPC Data from 1995 and 1996 Inspections Steam Generator A Total Total Total Total Percent j
I I
I I
I Group of Indications I
Bobbin Bobbin RPC RPC RPC indication Indication inspected Confirmed Confirmed Less than or Equalto 1.0 Volt in 1996 95 Bobbin Left in Service 458 450 11 6
54.5
- 175 RPC Connrmed 63 63 1
1 100.0
- 1P5R,"C NDD 25 25 0
0
- 95 RPC Not inspected 371 371 to 5
50.0
- No 116 Bobbin
- O New16 Indiceten 294 11 6
72.7 Surn of M D6 Indicaten 459 753 22 14 63.6 Greater than 1.0 Volt in 199e 175 Bobbin Left in Servico 76 76 8
6 75.0
- 45 RPC ConArmed 29 29 2
2 100.0
- 1P5RPC NDD 36 36 6
4 66.7
- '95 RPC Not inspected 11 11 0
0
- No 16 Bobbin
- O New DS trweicetion 20 2
1 50.0 Sum of All '96 trdcation 76 96 10 7
70 0 AllVoltages in1996
'95 Bobbin Left in Serwce 535 535 19 12 63.2
- 15 RPC Confirmed 92 92 3
3 100.0
- 95RPC NDD 61 61 6
4 66.7 _
- '95 RPC Not inspected 362 362 10 5
50.0 No 56 Bobbin
- O New D6 Indication 314 13 9
69.2 Sum of All 16 Indcation 535 649 32 21 65 6 Indications split is based on '95 bobbin voltage 3 -16
- mm. - -
Tatde 3-10 Beaver Valley Unit 1 Analysis of RPC Data from 1995 and 1996 Inspections Steam Generator B Total Total Total Total Percent I
l#
I#
l#
l#
Group of Indications Bobbin Bobbin RPC RPC RPC Indication Indication Inspected Confirmed Confirmed Less then et Egeelto 1.0 Volt in 1996 D5 BotMn LeR in Service 370 370 7
3 42.9
- 16 RPC CenArmed 47 47 0
0
- 15RPCNDO 24 24 0
0
- D5 RPC Not inspected 290 290 7
3 42.9 _
- No D8 BotMn
- O New D8 Indication 215 8
5 83.3 Sum et M 18 Indication 370 585 13 8
81.5 Greaterthen1.0 Volt in1998 45 BotMn LeR in Sennco 100 100 8
5 83.3
- 15 RPC ConArmed 35 35 1
1 100.0 D5RPC NDO 28 28 3
2 88.7
- D5 RPC Not inspected 37 37 2
2 100.0 No D8 BotMn
- O New18 Indication 13 2
1 50.0 Sum etM 18 Indication 100 113 8
8 75 0
_AllVoltages in1998 D5 BotMn Let in Service 470 470 13 8
81.5
- D5 RPC ConArmed 82 82 1
1 100.0 D5RPC NDO 52 52 3
2 88.7
- 95 RPC Not inspected 336 338 9
5 55 8
- No D8 BotMn
- O New18 tr=me=han 228 8
8 75.0 Sum of M DS Indication 470 808 21 14 88.7
' Indications spht is based on '95 bobbin voltage 3 - 17
Table 3-11 Beaver Valley UnM 1 Analysis of RPC Data from 1995 and 1996 Inspections Steam Generator C Total Total Total Total Percent 1995 1996 1996 1996 1996 Group of Indications Bobbin Bobbin RPC RPC RPC Indication Indication inspected Confirmed Confirmed Less than or Equal to 1.0 Volt in 1996 DS Bobbin Left in Service 172 172 9
2 22 2
- D5 RPC Confirmed 2
2 0
0
'95RPC NDD 1
1 0
0
- D5 RPC Not inspected 189 189 9
2 22.2
- No D6 Bobbin
- O New16 Indication 184 11 5
45.5 Sum of M D6 Indication 172 356 20 7
35.0 Greater than 1.0 Volt In 1996 15 Bobbin Left in Service 24 24 4
1 25.0
- 15 RPC Confirmed 0
0 0
0
- D5RPC NDO 7
7 1
0 0,0
- D5 RPC Not inspected 17 17 3
1 33.3 No D6 Bobbin
- O New 16 Indication 9
0 0
Sum of M 16 Indication 24 33 4
1 25.0 AllVoltages in1996 DS Bobbin Left in Service 196 196 13 3
23.1
- D5 RPC Confirmed 2
2 0
0
- D5RPC NDO 8
8 1
0 0.0
- 15 RPC Not inspected 186 186 12 3
25.0
- No 16 Bobbin
- O New D6 Indication 193 11 5
45.5 Sum of M 16 Indication 196 389 24 8
33.3
- Indications split is based on '95 bobbin voltage 3 - 18
.. a
Table 3-12 Beaver Valley Unit 1 Analysis of RPC Data from 1995 and 1996 Inspections Composite of All Steam Generator Data Total Total Total Total Percent Group of Indications Bobbin Bobbin RPC RPC RPC Indication Indication inspected Confirmed Confirmed Less than or Equal to 1.0 Voet in 1996 D5 BotMn LaR in SeMee 1001 1001 27 11 40.7
- 15 RPC ConArmed 112 112 1
1 100.0
- 15RPC NDO 50 50 0
0
- 15 RPC Not inspected 638 630 26 10 36.5
- No '96 BotMn
- O NewD6 tndicehon 893 26 18 64.3 Sum of M 16 Indication 1001 1994 55 29 52.7 Greater than 1.0 Volt in 190s O BotMn Let in SeMee 200 200 16 12 66.7
- D5 RPC ConArmed 64 64 3
3 100.0
- D5RPC N00 64 71 10 6
00 0
- 95 RPC Not inspected 85 85 5
3 80.0
- No 16 Bothn
- O 42 4
2 50.0 New D6 Indicehon Sum of M 16 Indicehon 200 242 22 14 63 6 AsVoeta9es in190s 0
D5 OctMn LeR in Service 1201 1201 45 23 51.1
- 35 RPC Cordlemed 176 176 4
4 100.0 _
- '95RPC NOD 121 121 10 6
60.0
- 95 RPC Not inspected 904 904 31 13 41.9
- No16 BotMn
- O-735 32 20 62.5 New16 Indication Sum of M 16 Indicehon 1201 1936 77 43 55.6
- Indications split is based on '95 bobbb voltage 3 -19
-ua,m nw
Figure 3-1 Beaver Valley Unit -1 1996 Outage j
Bobbin Voltage Distributions for Tubes in Service During Cycle 11 140 120
~^
100-
=
=.
'j go _
m OSG-B 5
.$ 60 -
=
ESG-C z
I 40-l 20 0
I ':"
l l
l l
l l
l l
l l
E El" l
l l-l-l-
l-l
~
0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.1 2.3 3.4 Bobbin Voltage 3 - 20 nO90 DAY.XLSFt -17/31/96 3 57m 3
e Figure 3 -2 Beaver Valley Unit -1 1996 Outage Bobbin Voltage Distribution for Tubes Plugged After Cycle 11 Service 10 9-8-
ESG-A 7-1 j
6-OSG-B 5$5-b 3:
ESG-C
$4-b l
3-
--I c
2-0 l
l l
l l
l l
l 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
1.1 1.2 1.3 1.4 1.6 2.1 3.4 Bobbin Voltage nGWDAYJCLSFig 3-27/31% 3 57 PM 3 -21
4 Figure 3-3 Beaver Valley Unit -1 1996 Outage Bobbin Voltage Distributions for Tubes in Service During Cycle 11 and RTS for Cycic 12 i
i 120-BSG-A 100-E OSG-B 80 -
s
$ 60 -
E ESG-C e
40 -
=
20
=
=
=
U 0
E ':"
l l" ";"
E :
El"
- ^:0 l 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.3 Bobbin Voltage 3 - 22 nemDAYXLSFqg 3-37/31S6 3 57 PM O
l Figure 3 - 4 Beaver Valley Unit -1 1996 Outage i
Bobbin Voltage Distributions for Deplugged Tubes Returned to Service for Cycle 12 Operation j
30 j
ESG-A
= 20 -
E i
Ill ill 15 g
10 -
E!
E n
f 5
..Ill Ullh..
al.Ill....
0 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2
2.1 2.2 Bobbin Voltage 3 - 23 MMODAYX.SFag 3 4 7/31% 3 57 m
t l
i i
Figure 3 - 5 Beaver Valley Unit -1 1996 Outage Bobbin Voltage Distributions for AII Tubes Returned to Service at BOC-12 l
140 l
l 120-ESG-A 100-
=
.E OSG-B 3 80 -
=
= '
it ESG-C 60 -
=
=
e I
40 -
=
=
20 -
0- O El l
l l
"l l"
l l
l l
l l
l^l
~l
-l-0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2
2.1 2.2 2.3 Bobbin Voltage 3 - 24 nG90DAYXLSFg 3-5 7/31/96 3 57 N
l Figure 3 - 6 Beaver Valley Unit 1 1995 Outage ODSCC Axial Distributions for Tubes in Service During Cycle 11 600 500 --
400 --
=
8_
3 OSG-A E
h 300 --
ESG-B u
.8 E
200 --
ESG-C 100 --
0 1
1 I
Z Z
Z Z
Z Z
n m
t n
e e-Tube Support Plate 3 - 25 RO90DAYESF(34 7/31/96 3.57 mt
e Figrre 3-7 Beaver blicy Unit - 1 Cumulative Probability Distributions for Voltage Growth History on an EFPY Basis Composite of All Three Steam Generator Data 1.0 a.
-3,.....e---
,,.. ~,
s 0.9
/
,e
,E 0.8
=
1 c
=
f A 0.7
~
c
-f
?
$ 0.6 l
- + - Cycle 11 b
i
.5 O
I b 0.5 l
5
.' l 1
a l
10.4
/
l
--a-- Cycle 10 u
n.
o
/
j 0.3
/
~
2 l
E e
d 0.2 l
~
/
0.1 s
s' 4
0.0 ---'^'~~*
-0.5
-0.4
-0.3
-0.2
-0.1 0
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 Voltage Growth nomarm.sronst* m m 3 - 26
. =. _
o i
Figure 3 - 8 Beaver Valley Unit -1 Cycle 11 ( 1995 to 1996 )
Cumulative Probability Distributions for Voltage Growth on an EFPY Basis 1.0
,-,;,_ __ s___
...., i,
.f 0.9 -
- s/
./.1:
i
~#
~
- 0. 3
/
/
,o o'g -
- r
'E
- /
- +- - SG A c
- ll 0.6 -
c
-E ill
--o-SG B 3
.1 I)
'c 0.5
- J 6
!1
-- s -- SG C
._5 0.4 -
I)[
[
.5 j*1
- 4:- Cumulative
= 0.3 U
/
I i.L
/'
O.2 -
/ f
.f (/
/
0.1
< f" 0.0 c 0
- -O'#Y l
l l
l l
l l
l l
m
-r m
e o
n m
e c
w y
(
(
y y
6 6
6 6
6 6
Voltage Growth 3 - 27
-v m o mv n,.
a Figure 3-9 Beaver Valley Unit - 1 1996 EOC-11 Evaluation for POPCD at EOC-10 1.0 c
P _ _ _ _ g- - - - - o
...-r..-------
- o. _ _ _ _.s' 0.9 I
0.8 l
s
,. ~
0.7 a
.o y
2 0.6
/ ~
,. /
%=
/
- 0.5
-o-RPC Confirmed Only b
2
/
i 0.4
-+-RPC Confirmed Plus i
Not inspected e
,!r---
4
~>
0.2 I
I 0.1 s
1 0.0 d
l l
l l
l l
l l
0 0.2 0.4 0.6 0.8 1
1.2 1.4 1.6 1.8 2
Bobbin Amplitude HO90 DAY.XLS; Fig 3-9 [7/3 t/96[3:57 PM 3 - 28
i 4.0 DATA BASE APPLIED FOR ARC CORRELATIONS The database used for the ARC correlations that are applied in the analyses of this 1
report are consistent with the NRC SER applicable to the Beaver Valley Unit 1 EOC-11 inspection (Reference 9.3). The SER recommended data for the burst pressure correlation is the same as the EPRI recommended database as noted in Reference 9.2.
Per NRC requests, this database has been updated to include more recent pulled tube data from Plants A-1, A-2 and W-1 as well as the Beaver Valley Unit-1 pulled tube data from the EOC-10 inspection.
For the SLB leak rate correlation, the NRC recommends that Model Boiler specimen 542-4 and Plant J-1 pulled tube R8C74, TSP 1 be included in the database. This database is referred to as the NRC database and is applied for the leak rate analyses of this report. The probability ofleakage correlation of Reference 9.2 is also accepted by the NRC SER and applied in this report. The SLB leak rate data do not satisfy the NRC guidelines for a voltage dependent correlation, as discussed in Section 5.0.
Correlations have been developed for the evaluation of ODSCC indications at TSP locations in steam generators of nuclear power plants which relate bobbin voltage amplitudes, free span burst pressure, probability ofleakage and associated leak rates.
The Westinghouse methodology used in the calculation of these parameters, documented in References 9.2 and 9.5, is consistent with NRC criteria and guidelines of References 9.1 and 9.3.
The analysis process starts with the receipt of bobbin voltage from the site ECT inspection team. The site data consists of electronic files which include Row, Column, TSP identification number, and bobbin voltage. This data, sorted by bobbin voltage into " voltage bins" consisting of number ofindications in discrete voltage ranges in increments of 0.1 volt, constitutes one major component ofinput for the subsequent voltage distribution, leak and burst probability calculations. It is noted that reference to " volts" in this report invariably applies to " voltage bins", when cited to one significant figure after the decimal (e.g.,1.8 volts). The true value of an indication would be cited to two significant figures after the decimal (e.g.,1.71 volts).
The calculation consists of determining the initial conditions (i.e., the bobbin indication population distribution), projecting the indication growth over the operating period, and then evaluating the tube leak and burst probabilities at the end of the operating period. Since indication growth is considered proportional to operating time, the limiting tube conditions occur at the end of any given time period or cycle.
sAape\\dlw96\\dlw90 day.wp5 41
B 5.0 SLB ANALYSIS METHODS Monte Carlo analyses are used to predict the EOC-12 voltage distributions and to calculate the SLB leak rates and tube burst probabilities for both the actual EOC-11 voltage distribution and the predicted EOC-12 voltage distribution. These methods are consistent with the requirements of the Beaver Valley Unit-1 NRC SER and are described in the generic methods report of WCAP 14277 (Reference 9.5) and the prior reports for Beaver Valley Unit-1 (References 9.2 and 9.4), and are in accord with NRC Generic Letter 95-05.
The NRC SER recommended leak rate database does not satisfy the requirement for applying the SLB leak rate versus bobbin voltage correlation. The NRC requirement is that the p value obtained from the regression for the slope parameter be less than or equal to 5%. For the NRC recommended data, the p value is about 6.5% and the leak rate versus voltage correlation is not applied. Licensing-basis analyses were carried out using a SLB leak rate correlation based on an average of all leak rate data independent of voltage. The analysis methods for applying this leak rate model are given in Section 4.6 of WCAP-14277 (Reference 9.5). Since application ofleak data independent of voltage yields very conservative results, sensitivity analyses using leak rate data correlated to voltage were also performed to demonstrate the degree of conservatism in the calculated SLB leak rates. A Monte Carlo analysis is applied to account for parameter uncertainties even though the leak rate is independent of voltage. This method ofleak rate analysis is similar to that of draft NUREG-1477 except for the uncertainty treatment.
s;\\ ape \\dlw96\\dlw90 day.wp5 5-1
6.0 BOBBIN VOLTAGE DISTRIBUTIONS 6.1 PROBABILITY OF DETECTION (POD)
The number of bobbin indications used to predict tube leak rate and burst probability is obtained by adjusting the number of reported indications to account for measurement uncertainty and confidence level in voltage correlations. This is accomplished by using a POD factor. Adjustments are also made for indications either removed from or returned to service. The calculation of projected bobbin voltage frequency distribution is based on a net total number ofindications returned to service, defined as:
N N,,,7,
- N,,,,,,,,. N,,,3,,,,,,
7 where:
N.roiars = Number of bobbin indications being returned to service for the next cycle.
N = Number of bobbin indications (in tubes in service during the previous 3
cycle) reported in the current inspection.
POD = Probability of Detection.
N,,,,i,,a = Number of N which are repaired (plugged) after the last cycle.
i Na,io,,,a = Number ofpreviously-pluggedindications which are deplugged after the last cycle and are returned to service.
The NRC generic letter (Reference 9.1) 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.
6.2 CYCLE OPERATING TIME The operating periods used in the voltage projection calculations are:
Cycle 10 = 435.79 EFPD Cycle 11 = 325.94 EFPD Cycle 12 = 425. EFPD s:\\apo\\dlw96\\dlw90 day.wp5 61 l
6.3 CALCULATION OF VOLTAGE DISTRIBUTIONS Bobbin voltage projections start with a cycle initial voltage distribution which is projected to the corresponding cycle final voltage distribution, based on the growth rate adjusted for the anticipated cycle operating time period. The overall growth rates for each of the Beaver Valley Unit 1 steam generators during the previous two operating periods, as represented by their cumulative probability distribution functions, are shown on Figure 3-7. The 1995 - 1996 operation (Cycle 11) growth rates exceed those of the 1993 - 1995 (Cycle 10) operation and are used to predict the EOC-12 bobbin voltage distributions. Further conservatism for the EOC-12 bobbin voltage prediction is provided by the use of the larger of the composite growth rate for all SGs and the SG specific growth rate in projecting EOC voltages each SG. The methodology used in the calculations of EOC bobbin voltage distributions is described in Reference 9.5.
For each SG, the initial bobbin voltage distribution ofindications being returned to service for the next cycle (BOC-12) is derived from the actual EOC-11 inspection results adjusted for tubes that are either (c) taken out of service by plugging, or (b) have been recovered for Cycle 12 service by deplugging of tubes plugged in previous outages based on prior repair criteria. The Cycle 12 bobbin voltage population, summarized on Table 6-1, shows EOC-11 bobbin voltage indications; the subsequent plugged indications (which were in service for Cycle 11 and then taken out of service, albeit not all for reasons of ODSCC at TSP); those indications recovered for service from previously plugged tubes, which were deplugged during this outage and were inspected and returned to service in accordance with ARC criteria (otherwise they were replugged); and also shows the BOC-12 indications corresponding to a constant POD value of 0.6.
As mentioned in Section 3.4, the NRC SER (Reference 9.3) allows for consideration of only a fraction of RFC NDD indications from the current inspection in establishing the BOC voltage distribution for the next cycle. The fractional value applicable is the largest RPC confirmation rate for prior cycle RPC NDD indications found during the last two outages, but it may not be less than 0.7. The fraction that can be applied for 1995 RFC NDD indications is 0.7 and it is used in the calculation of the BOC-12 indication distri'aution shown in Table 6-1.
s:\\apc\\dlw96\\dlw90 day.wp5 62 I
j
.~
6.4 PREDICTED EOC 12 VOLTAGE DISTRIBUTIONS The licensing-basis calculation for the predicted EOC-12 bobbin voltage distributions is performed for all SGs with a constant POD value of 0.6 in accordance with NRC direction. However, for the limiting SG (SG B) calculations were also performed using a voltage dependent POD distribution developed based on bobbin and RPC data from 11 eddy current inspections at 8 different plants. This voltage dependent POD distribution is described here (Section 8.0) and is discussed in a greater detail in Reference 9.6.
The NRC SER (Reference 9.3) allows for consideration of only a fraction of RPC NDD indications from the current inspection in establishing BOC voltage distribution for the next cycle. Based on the data presented in Section 3.4 and NRC directives in Reference 9.3, the fractional value applicable for EOC-12 analysis is 0.7. Thus, only 70% of the 1995 RPC NDD indication population was included in the BOC-12 voltage distributions shown in Table 6-1.
Using the methodology previously described, analyses were performed to predict the performance of the Beaver Valley Unit-1 steam generators at EOC-12, based on the BOC-12 voltage distribution shown in Table 6-1. As mentioned earlier, the EOC-11 composite growth rate data shown in Table 3-6 were applied to SGs A and C (since their own growth rates are smaller than the composite growth rate) whereas its own growth rate distribution was used for SG B (since it is higher than the composite growth rate). This approach is recommended in Reference 9.5. The EOC-12 voltage distributions projected using the BOC-12 ARC voltage distribution shown in Table 6-1 are summarized in Table 6-2. As anticipated, the largest number ofindications is predicted for SG A,1513.5 indications predicted for POD = 0.6. For each steam generator, the assumed BOC-12 and the EOC-12 predicted bobbin voltage frequency distributions are shown on Figure 6-1 for all three SGs. The maximum bobbin voltage 4
predicted for EOC-12 is 3.7 volts for POD = 0.6, in SG B.
6.5 COMPARISON OF PREDICTED AND ACTUAL EOC-11 VOLTAGE DISTRIBUTIONS '
The actual EOC-11 bobbin voltage distributions and the corresponding predictions, summarized on Table 6-3 and shown on Figure 6-2, provide a comparison of the EOC-11 voltage distributions. SG A was predicted to be limiting for EOC-11 which is consistent with the actual measurement since the highest number ofindications were detected in it. Also, as predicted, the largest indication was found in SG B, but the s:\\apc\\dlw96\\dlw90 day.wp5 6-3
predicted voltage value is slightly below the measurement (3.1 volts vs. 3.4 volts).
Total number ofindications were under predicted for SG-C.
1 1
As shown on Figure 6-2, calculations based on a constant POD value of 0.6 overpredicted the actual EOC-11 bobbin voltage population for voltage bins over 0.8 volts for all SGs, while underpredicting the population for voltages below 0.7 volt. The overprediction in the higher volt range demonstrates the conservatism in the growth rate distribution used for the prediction. The predicted peak bobbin voltages of 3.0 volts and 2.3 volts for SGs A and C, respectively, are conservative relative to the corresponding actual measured bobbin voltage indication of 2.2 volts and 1.8 volts.
I i
l l
s:\\ ape \\dlw96\\dlw90 day.wp5 64
Table 6-1 Beaver Valley Unit - 1 April 1996 Summary ofInspection and Repair During EOC - 11 Outage Steam Generator A Steam Generator B Steam Generator C EOC-11 MEASURED EOC-11 N OtS 008 4
in me in -
Volt AN Tubes Tubes P00m.S AR Tubes Tubes PODS.S M
Tubes
'.ubes
,ODs.S Sin Inds.
Ony Ony Inds.
Ony Onh In.s.
Onh Onh 0.2 4
0 0
6.67 13 1
1 21.67 3
1 0
6.00 03 49 2
1 82.17 34 1
2 54.67 24 le 0
50.00 0.4 102 3
1 172.00 64 1
6 100.67 47 14 0
9233 05 122 8
4 206.33 92 4
3 154.33 51 14 2
97.00 0.6 130 8
4 220.17 90 5
4 15050 62 20 1
12233 0.7 116 8
5 19633 90 10 9
151.00 59 22 1
11633 0.8 88 9
3 151.67 80 9
7 13533 45 23 0
95.50 0.9 76 13 3
135.67 67 7
3 115.67 37 20 2
79.17 1.0 66 11 1
120.00 55 7
5 93.67 21 19 1
64.17 1.1 41 6
3 71.33 41 12 2
7833
- S 21 0
4450 1.2 26 9
2 4933 21 15 1
49.00 8
19 0
3233 13 10 11 0
27.67 20 10 1
41.83 4
12 0
18.67 1.4 7
13 1
23.67 11 10 1
2733 4
16 0
22.67 15 2
5 0
833 9
5 0
19.50 0
11, 0
11.00 1.6 2
10 0
1333 4
11 1
16.67 1
/
0 11.67 1.7 4
7 0
13.67 4
5 0
11E7 0
7 0
7.00 1E 1
5 0
6.67 1
2 0
3.67 t
8 0
9.67 1.9 1
4 0
5.67 1
5 0
6.67 0
3 0
3.00 2.0 0
1 0
1.00 0
2 0
2.00 0
1 0
1.00 2.1 1
0 1
0.67 0
1 0
1.00 0
0 0
0.00 2.2 0
0 0
0.00 0
0 0
0.00 0
1 0
1.00 23 1
0 0
1.17 0
0 0
0.00 0
0 0
0.00 3.4 0
0 0
0.00 1
0 1
0.67 0
0 0
0.00 Total 849 133 29 1513.50 698 123 47 1235.83 389 252 7
88533
>1V 96 71 7
151.17 113 78 7
258.33 33 109 0
226.67
> 2V 2
0 1
1.83 1
1 1
1.67 0
1 0
1.00 1
- Only 70 % of RPC NDD indications are included in establishing the DOC-12 indication population.
6-5 no,earm.sroma mmm m
Table 6 - 2 BeaverValley Unit-1 April 1996 Voltage Distribution Projection for EOC - 12 i
Steam Steam Steam Generator A Generator B Generator C Voltage E"
Projected Indications Distributions at EOC -12, POD = 0.6 0.1 0.08 0.1G 0.07 0.2 4.74 G.68 3.02 0.3 38.73 22.88 23.63 0.4 96.80 50.G3 53.37 0.5 149.47 86.03 77.51 0.0 181.GG 114.88 96.28 0.7 188.64 131.61 104.88 0.8 176.45 135.82 101.71 0.9 150.3G 129.58 91.26 1.0 132.49 11G.75 77.29 1.1 10G.03 100.34 62.32 l.2 80.22 82.66 48.3G i
1.3 58.13 65.81 36.79 1.4 41.12 51.07 27.87 l.5 29.06 38.91 21.19 1.G 20.92 29.26 16.25 1.7 15.35 21.70 12.45 1.8 11.38 15.8G 9.43 1.9 8.35 11.41 G.9G 2.0 5.96 7.99 4.96 2.1 4.13 5.48 3.40 2.2 2.77 3.66 2.24 2.3 1.79 2.37 1.43 2.4 1.14 1.49 0.88 2.5 0.71 0.91 0.21 2.6 0.04 0.54 0.70 2.7 0.70 0.32 0.00 2.8 0.00 0.05 0.30 2.9 0.30 0.00 0
3.0 0
0.00 0
3.1 0
0.70 0
3.2 0
0.00 0
3.3 0
0.00 0
3.4 0
0.00 0
3.5 0
0.00 0
3.6 0
0.00 0
3.7 0
0.30 0
Total 1513.50 1235.83 885.33 naasnwicay.xunm 6-6
i Table 6 - 3 BeaverValley Unit-1 April 1996 Comparison of Predicted and Actual EOC-11 Voltage Distributions Steam Generator A Steam Generator B Steam Generator C EOC-11 EOC-11 EOC-11 EOC-11 EOC-11 EOC-11 Prediction Actual Prediction Actual Prediction Actual y
Bh POD =.6 POD =.6 POD =.6 No. of No. of No. of No. of No. of No. of Indications Indications Indications indications Indications Indications 0.1 0.05 0
0.11 0
0.00 0
0.2 2.47 4
4.63 13 0.34 3
0.3 19.55 49 23.51 34 5.43 24 0.4 49.86 102 48.57 64 16.43 47 0.5 81.37 122 78.03 92 31.88 51 0.6 101.56 130 91.15 90 41.52 62 0.7 110.99 116 93.12 90 44.68 59 0.8 109.14 88 91.27 80 43.61 45 0.9 96.91 76 83.32 67 40.25 37 1.0 79.13 66 68.49 55 34.04 28 1.1 59.75 41 51.14 41 25.68 15 1.2 42.52 26 35.50 21 17.57 8
1.3 29.54 10 23.73 20 11.41 4
1.4 20.58 7
15.62 11 7.27 4
1.5 14.64 2
10.17 9
4.69 0
1.6 10.68 2
6.53 4
3.03 1
1.7 7.94 4
4.15 4
1.92 0
1.8 5.95 1
2.61 1
1.19 1
1.9 4.42 1
1.63 1
0.73 0
2.0 3.23 1
1.00 0
0.01 0
l 2.1 2.30 0
0.62 0
0.70 0
2.2 1.61 0.38 0
0.00 0
2.3 1.10 0
0.25 0
0.30 0
i 3
2.4 0.74 0
0.16 0
0 0
j J
2.5 0.50 0
0.00 0
0 0
2.6 0.15 0
0.00 0
0 0
2.7 0.00 0
0.70 0
0 0
2.8 0.70 0
0.00 0
0 0
2.9 0.00 0
0.00 0
0 0
3.0 0.30 0
0.00 0
0 0
3.1 0
0 0.30 0
0 0
3.4 0
0 0
1 0
0 TOTAL 857.67 849 736.67 698 332.67 389
> 1.0 V 206.65 96 154.47 113 74.48 33
>2V 7
1 2.40 1
1 0
DO90 DAY.XL3 MO90 DAY.XL3 7/31/96 3:57 PM 6-7
r Figure 6-1 Beaver Valley Unit-1 April 1996 Comparison of BOC-12 Bobbin Voltage Distributions with Predicted EOC-12 Distributions 1
i Steam Generator A - POD = 0.6 l
250 l
l 200 D Assumed BOC-12 S
150 2
l 100 E Predicted EOC-12 o
E E
Q 50
- [ d j ri rs,,.... _. _.
g m.
m n
a N
c) e n
m N
cn e
n a
k c) o o
6 6
o d
J J
d d
d d
d Bobbin Voltage Steam Generator B - POD = 0.6 160 140 120 O Assumed BOC-12 E 100 1-80 a Predicted EOC-12 o
y 60 l 40 2
20 ---
0 M E ' = "; --
5 9 m N c) n M e h 9 9 m o N 9 9 9 m h o o o o o e
e e
e e
n n n n n n n n n Bobbin Voltage 140 Steam Generator C - POD = 0.6 120 O Assumed BOC 12 f100 5
80 g
C E Predicted EOC-12 0
60 EE 40 z
20
- 0 ibl,s _1 ; _.... _. _.
9 M
m M
9 M
o N
9 O
e h
l o
o o
o o
e e
e e
e n
n n
n Bobbin Voltage l
6-8
Figure 6-2 Beaver Valley Unit-1 April 1996 Comparison of Predicted EOC-11 Bobbin Voltage Distributions with Actual Measured Distributions Steam Generator A 140
{120 O Actual n100 SV 80 5
0 60 a Predicted I
3E 40 N
20
^"
5 N^' ^^-
1 0
n~;
n o
s m
n n
e.
m n
m s
on t
6 6
6 6
6 J
a J
o d
d d
a d
Bobbin Voltage i
l Steam Generator B 100 g 90 D Actual g 80 g 70 j 60
- - 50 40 a Predicted 2 30 E 20 7
~
~
~
~
~
~
~
~
Il rf.ru m. _.
e n
a s
a n
a s
e e
n o
s a
1 6
6 6
6 6
o o
e J
e d
a d
d d
j Bobbin Voltage Steam Generator C 70 60 g
OActual 2 50 g
] 40 5 Predicted 2
o 30 u
E 20 E
- s2 jo
- f. F5. E a ;
0
^;
- N n v o e s e e o - n n w n e s e m o
-n n
6 6 6 6 6 6 6 6 6 e eo e e a e ; e oaad a Bobbin Voltage 6-9
l 7.0 TUBE LEAK RATE AND TUBE BURST PROBABILITIES j
7.1 CALCULATION OF LEAK RATE AND TUBE BURST PROBABILITIES
}
Correlations have been developed for the evaluation of ODSCC indications at TSP locations in steam generators of nuclear power plants which relate bobbin voltage
)
amplitudes (either measured or calculated), free span burst pressure, probability of leakage and associated leak rates. The Westinghouse methodology used in the calculation of these parameters, documented in References 9.2 and 9.5, is consistent with NRC criteria and guidelines of References 9.1 and 9.3.
7.2 PREDICTED AND ACTUAL LEAK RATE AND TUBE BURST PROBABILITY FOR EOC-11 i
j Using the methodology previously described, analyses were performed to calculate EOC-11 SLB tube leak rate and probability of burst for the actual bobbin voltage I
j distribution at EOC-11 (with no growth projection applied) previously presented in this i
report. The results of Monte Carlo calculations performed for the actual voltage distributions are compared to the predictions based on the EOC-10 data, as shown on j
Table 7-1. To ensure meaningfulness of this data comparison, projections for EOC-11 l
conditions were repeated for all three SGs using the same Monte Carlo code used for l
the calculations with the actual voltage data. This assures that the database and i
methods used for EOC-11 projections are consistent with those applied for the actual l
EOC-11 analyses.
j In reviewing the present EOC-11 projection results it was found that Table 8-2 of l
Reference 9.2 reported that a 95% confidence limit on the predicted total leak rate in l
SG A during a postulated SLB event at the EOC-11 would be on the order of 0.31 gpm while the present prediction yields 2.37 gpm. An investigation of the differences re-l vealed that an error had been made in the prior calculation in that the variability of i
the leak rate had not been properly included in the analysis. In essence, the previ-
{
ously reported value corresponds more to an expected average leak rate than a 95%
i confidence value. The distribution ofindications in SG A was reanalyzed with the I
result that the 95% confidence value for the total leak rate during a postulated SLB event would be expected to be 2.37 gpm.
I i
A comparison of the EOC-11 actuals with the corresponding projections indicates the following:
i i
a:\\apc\\dlw96\\dlw90 day.wp5 7-1
l a)
Actual ECT bobbin measurements at EOC-11 confirm the prediction oflargest indication at EOC-11 in SG B, but the projected peak voltage is below that actually measured (3.4 volts measured vs. 3.1 volts projected).
b)
SG A was predicted to be the mostlimiting steam generator for Cycle 11 from the standpoint of SLB leak rate and tube burst probability (although SG B was predicted to have the largest indication at EOC-11).
c)
The same EOC-11 SLB leak rate value (1.50 gpm) was predicted with actual i
measured voltage distributions for SGs A and B and it is below the leak rates projected for those two SGs. The SLB leak rate calculated from the actual EOC-11 voltage distributions for all three SGs are well below the Beaver Valley Unit-1 allowable limit of 4.5 gpm (Reference 9-3) j d)
The tube burst probabilities calculated from actual EOC-11 voltage distributions for SGs A and B are slightly above the values projected for them, but the absolute 3
magnitudes are very small, and all calculated burst pressures are well below the NRC reporting threshold of 1x 10 8.
I 7.3 PROJECTED LEAK RATE AND TUBE BURST PROBABILITY FOR EOC-12 Using the methodology previously described, calculations have been conducted to predict the performance of all three steam generators in Beaver Valley Unit-1, and the results are summarized in Table 7-2. EOC 12 bobbin voltage distributions as well as leak rates and tube burst probabilities based on those distributions are predicted. Two sets of results are shown in Table 7-2: 1) one set of results for all three SGs based on the present licensing-basis database and method, and 2) another set from more realistic analyses for the limiting SG, which is SG B.
Results based on the present licensing-basis database and method for all three SGs meet the ARC acceptance for Beaver Valley Unit-1. The predicted EOC-12 SLB leak rate for SG B is calculated to be at the Beaver Valley Unit 1 allowable SLB limit of i
4.50 gpm' (Reference 9-5), whereas SG A yields 4.28 gpm. However, as discussed in the following paragraphs, the leak rate results based on the present licensing-basis database and method are very conservative and, therefore, the true margin to the acceptance limit for SG B is expected to be significantly higher. The EOC-12 SLB tube 2 The number of simulations in the Monte Carlo analysis for SG B was increased to 1 million (from 250,000 simulations used normally) to estimate projected leak rate to two decimal digit accuracy.
s:\\ ape \\dlw96\\dlw90 day.wp5 72
I burst probability for all three SGs are well below the NRC reporting guideline for tube i
burst probability of 1.0 x 10.
To demonstrate conservatism in the leak rate results based on the present licensing-basis database and method, two other calculations were performed for the limiting SG (SG B) using an ARC updated database and one additional calculation using the present licensing database but a more realistic method of accounting for leak rate data l
uncertainties in Monte Carlo simulations as explained below. As discussed in Section 5.0, the present NRC recommended database for leak rates for 7/8 inch diameter tubes l
does not meet the requirement for correlating leak rate to bobbin voltage and, i
l therefore, leak rate calculations assume that leak rate data are independent of voltage.
l However, parameter uncertainties are considered in the projections using Monte Carlo l
methods of Reference 9.5 which assumes a conservative log-normal distribution for l
leak rate. The method used presently to estimate non-log leak parameters from the i
logleak rate distribution is known to be biased towards overestimating the leak rate
)
actually used in the Monte Carlo simulations. Therefore, an alternate method that l
yields unbiased, best estimates for leak rates from the sample data oflog leak rates was also used to project EOC-12 leak rate for the limiting SG (SG B). As shown in Table 7-2, the use of best estimate non-log leak rate parameters in the Monte Carlo l
simulations reduces the EOC-12 SLB leak rate projection for SG B by 20 percent to i
3.58 gpm. Thus, even with the present NRC approved database and methodology, the l
margin in the projected EOC-12 SLB leak rate for SG B can be increased significantly l
by eliminating undue conservatism in establishing non-log leak rate parameters from l
log rate distribution parameters.
The reason for the current 7/8 inch tube leak rate database not satisfying the requirement for applying the SLB leak rate versus bobbin voltage correlation is inclusion of leak and burst data from the French plants. A detailed evaluation presented in Reference 9.6 that includes all available French data shows that they do not behave as they are from the same population as the data from the U. S. plants and, thus, it is justifiable to exclude them from the ARC database. With the French data removed, the requirement for applying the SLB leak rate versus bobbin voltage correlation can be met, and Reference 9.6 presents the distribution parameters for such correlations for leak rate as well as burst probability. As shown in Table 7-2, SLB leak rate calculated with that leak rate versus bobbin voltage correlation is 1/9th of that predicted with the present NRC database. Thus, there is substantial margin in the predicted SLB leak rates for all SGs, including SG B. Once Reference 9.6 (which excludes the French Data)is accepted by the NRC, Duquesne Lights' intention is to use l
the updated database in its EOC calculations. The new predicted EOC-12 SLB tube L
leak rate for SG B is calculated to be 0.52 gpm.
i
(
s:\\apc\\dlw96\\dlw90 day.wp5 7-3 l
-=...
g.
i Yet another source of conservatism in the present methodology is application of a constant POD value for the entire bobbin voltage range. Sufficient database now exists to define an alternate POD that is dependent on the bobbin voltage, and the development of such a POD is discussed in Section 8. Bobbin and RPC data from 11 inspections at 8 different plants have been analyzed to establish a voltage dependent 1
POD termed as POPCD. As the results in Table 7-2 indicate, the use of this voltage dependent POD results in a further 20 percent reduction in leak rates and about a 16 j
percent reduction in tube burst probability for SG B.
I In summary, the EOC-12 SLB leak rates and tube burst probabilities calculated for all three SGs using the present NRC-approved database and method meet the SER limits j
for Beaver Valley Unit-1. Results based on an updated database show that the margin between the EOC-12 predictions and acceptance limits can be increased substantially.
I s:\\ ape \\dlw96\\dlw90 day.wp5 74
i Table 7-1 Beaver Valley Unit 1 1996 EOC-11 Outage Summary of Calculations ofTube Leak Rate and Burst Probability Based on Actual Bobbin Voltage - 250k Simulations Burst Probability SLB Steam Number Max.
Leak Generator POD ofIndi-Voltsm 1 Tube 2 Tubes Rate cations gpm EOC - 11 PROJECTIONS
- A 0.6 857.7 3.0 5.50x 10'5
< 3.3 x10-e l
2.37 B
0.6 736.7 3.1 5.42x 10' 5
< 3.3 x10 5 1.76 0
0.6 332.7 2.3 1.16x 10' 5
< 3.3 x10'8 0.76 EOC-11 ACTUAL A
1 849 2.6 6.07x10' 5
< 3.3 x10 s 1.50 B
1 698 3.7 6.48x 10' 5
< 3.3 x10 8 1.50 C
1, 389 2.1
< 33 x 10 e
< 3_3 x 10~ 8 OE7 Notes (1)
Voltages include NDE uncertainties from Monte Carlo analyses and exceed measured voltages.
(2) lhojection analyses were repeated using the same Monte Carlo code used for the analysis based on the actual voltages.
s:\\ ape \\dlw90\\dlw90 day.wp5 7-5
i Table 7-2 Beaver Valley Unit 1 1996 EOC-11 Outage Projections of Tube Leak Rate and Burst Probability for EOC-12 Based on Actual Bobbin Voltage - 250k Simulations Burst Probability SLB Steam Number Max.
Leak Generator POD ofIndi-Volts")
1 Tube 2 Tubes Rate cations gpm EOC - 12 PROJECTIONS -- Present Licensing Basis Calculations A
0.0 1513.5 2.9 1.23x10 4
< 4 x 10 '
4.28 B
0.0 1235.8 3.7 1.76x104
< 4x10 4.50*
8 C
0.6 885.3 2.8 1.02x10 4
< 4 x 10
2.76 EOC - 12 PROJECTIONS -- Realistic Calculations for the Limiting SG (SG B)
Unbiased Non-Log 0.6 1235.8 3.7 1.22x 10
< 4 x10 3.58 8
Parameter Leak Rate Correlated to 0.6 1235.8 3.7 1.51x10
< 4 x 10' 8 0.52 Volts Leak Rate Correlated to POPCD 1091.4 2.9 1.2Gx 10
< 4x10
O.40 Volts N2tu (1)
Voltages include NDE uncertainties from Monte Carlo analyses and exceed measured voltages.
(2)
Based on a Monte Carlo analysis with 1 million simulations.
s:\\apc\\dlw96\\dlw90 day.wp5 7-6
a i
l, f
8.0 COMPARISON OF PROBABILITY OF PRIOR CYCLE DETECTION FOR 15 INSPECTIONS,8 PLANTS WITH EPRI POD i
The evaluation of the POPCD for Beaver Valley Unit-1 is described in Section 3.4. At this' time, POPCD evaluations are available for 15 inspections at eight plants, j
including two evaluations for Beaver Valley Unit-1. The available data include ten j
inspections of plants with 7/8" diameter tubing and five inspections of plants with 3/4" diameter tubing. This section summarizes these POPCD evaluations for comparison j
with the EPRI proposed POD. The POPCD evaluations performed since 1992 show j
significant improvement over the earlier assessments which represent the first ARC inspections. Bobbin data analysis guidelines (Appendix A guidelines) have been revised since the first inspections to reflect the initial ARC experience. Thus, it is appropriate to assess POPCD for inspections performed since 1992. Eleven of the i
fifteen inspections for which POPCD has been evaluated were performed since 1992.
i s
Table 8-1 shows the combined POPCD evaluation for plants with 7/8" diameter tubing i
and includes results for six inspections performed since 1992. These data are also i
plotted in Figure 81, and they include data from the present Beaver Valley Unit-1 1
assessment (EOC-10 results representing February 1995 inspection) as well as the
{
data reported in Reference 9 2 for the EOC-9 inspection. The POPCD value approaches l
unity at about 3 volts, and the average value independent of voltage is about 0.67. The j
POPCD evaluation in Figure 8-1 is in good agreement with the EPRI POD except in i
i the one to two volt range where POPCD is about 0.83 and the EPRI POD increases from about 0.82 to about 0.97.
i i
Table 8-2 and Figure 8-2 show the combined POPCD evaluation for the five plants l
with 3/4" tubing and inspections performed since 1992. These results tend to support a POD approaching unity above about 3 volts. The POPCD assessment is in very good j
agreement with the EPRI POD. The average POPCD independent of voltage is about 0.64 which is in general agreement with the NRC Generic Letter 95-05 proposed voltage independent POD of 0.60.
a i
The definition of POPCD includes indications which were not present at the prior inspection and thus could be expected to be somewhat lower than the EPRI POD which is based on " expert" evaluations ofinspection results and does not include indications i
clearly below detectable levels.
i i
The combined data for the eleven inspections since 1992 are given in Table 8-3 and the POPCD evaluation is shown in Figure 8-3 for RPC confirmed plus not inspected i
I l
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4 w
- - - ~
l The combined data for the eleven inspections since 1992 are given in Table 8-3 and the
]-
POPCD evaluation is shown in Figure 8-3 for RPC confirmed plus not inspected indications. It is seen that the inspections s.nce 1992 yield a POPCD in good agreement with the EPRI POD which was a 1994 evaluation. POPCD supports a POD approaching unity at about 3.5 volts while the EPRI POD is about 0.98 at 2 volts and unity at 3 volts. Figure 8-3 also includes POPCD evaluated at the lower 95%
confidence limit on the data for individual voltage bins j
i The POPCD evaluations shown in Figures 8-1 to 8 3 are based on the definition of
" truth" as RPC confirmed plus not RPC inspected indications. Since many of the i
indications not RPC inspected would be expected to be found NDD ifinspected, this represents a lower bound POPCD evaluation. Figure 8-4 shows the POPCD evaluation i
for all eleven inspections since 1992 based only on RPC confirmed indications. This results in a significant increase in POPCD below 1.0 volt and a modest increase above 1.0 volt. The data of Table 8-3 show 400 to 8600 indications in all voltage bins below 2 volts, more than 200 between 2.0 and 3.2 volts and about 5 indications above about 3.2 volts. Thus, the collective data provide a substantial database for defining a POD.
i 1
l The results of Figure 8-3 clearly support an increase in the POD for ARC applications j
j above the POD = 0.6, independent of voltage, required by NRC Generic Letter 95-05.
i For indications above 1.0 volt, the POD exceeds 0.9 and is 0.97 to near unity at 2.0 j
volts. A POD of 0.6 is only applicable to indications below about 0.6 volts.
l An alternate, voltage dependent POD is developed as POPCD evaluated at the lower l
95% confidence level and the mid-voltage of each voltage bin. The result is then j
smoothed to obtain the alternate POD as shown in Figure 8-5. The alternate POD is j
tabulatedin Table 8-4 and compared with the EPRI POD in Figure 8-6. This POPCD l
distribution was used to perform an alternate EOC-12 projection for SG B as discussed j
in Section 7.3.
i 5
I 1
l 4
i i
i i
i s:\\ ape \\dlwSG\\dlw90 day.wp5 82 l
l
Table 8-1 Evaluation for POPCD for Plants with 7/8" SG Tubes Combined Data from 6 Post-92 Inspections NewIndications Bobbin Callin Both inspections First inspection POPCD RPC RPC Voltage Confirmed Confirmed RPC RPC RPC Confirmed Bin RPC plus not RPC plus not Confirmed Confirmed Plus Notinspected Confirmed Inspected Confirmed Inspected and Plugged Frac.
Count Frac.
Count
>0 - 0.2 2
133 0
37 5
0.714 5/7 0.240 42/175 0.2-0.4 8
726 3
549 70 0.901 73 / 81 0.460 619/1345 0.4 - 0.6 12 797 10 1108 152 0.931 162/174 0.613 1260 /2057 0.6 - 0.8 12 479 19 1160 124 0.923 143/155 0.728 1284 / 1763 0.8 - 1.0 10 231 24 792 72 0.906 96 /106 0.789 864 /1095 1.0 - 1.2 17 109 28 389 91 0.875 119/136 0.815 480/589 1.2 - 1.6 17 71 61 286 79 0.892 140/157 0.837 365/436 1.6 - 2.0 8
17 33 59 34 0.893 67/75 0.845 93/110 2.0 - 3.2 1
1 15 15 23 0.974 38/39 0.974 38 / 39 3.2 - 3.5 0
0 0
0 0
0/0 0/0 TOTAL 87 2564 193 4395 650 Total > tv 43 198 137 749 227 8-3 rmmxtur.=momu m
Table 8-2 Evaluation for POPCD for Plants with 3/4" SG Tubes Combined Data from 5 Post-92 Inspections New Indications Bobbin Callin Both Inspections First inspection POPCD RPC RPC Voltage Confirmed Confirmed RPC RPC RPC Confirmed Bin RPC plus not RPC plus not Confirmed Confirmed Plus Not inspected Confirmed Inspected Confirmed Inspected and Plugged Frac.
Count Frac.
Count
>0-02 8
1010 0
466 0
0 018 0.316 466 /1476 0 2 - 0.4 95 3920 19 3154 31 0.345 501145 0.448 3185/7105 0.4 - 0.6 103 2456 120 4064 86 0.667 206 /309 0.628 4150/6606 0.6 - 0.8 85 918 267 2920 116 0.818 383/468 0.768 3036I3954 0.8 - 1.0 77 316 371 1701 114 0.863 485/562 0.852 181512131 1.0-12 46 90 S1 456 883 0.955 974 /1020 0.937 1339/1429 12-1.6 33 53 140 265 774 0.965 914 /947 0.951 1039/1092 1.6 - 2.0 4
4 48 48 245 0.987 293/297 0.987 293/297 2.0-32 6
6 20 20 161 0.968 1811187 0.968 1811187 32-3.5 0
0 0
0 5
1.000 5/5 1.000 SIS TOTAL 457 8773 1076 13093 2415 Total > tv 89 153 299 789 2068 8-4 nmen nsrr.msenw322 m
Y 9
Table 8-3 Combined POPCD Evaluation for 11 post-92 Assessments POPCD Based on RPC Confirmed Plus Not Inspected Indications Carm N
New Indications POPCD Both inspections inspecten RPC RPC Voltage Confirmed Confirmed RPC RPC RPC Confirmed Bin RPC plus not RPC plus not Confirmed Confirmed Plus Not inspected Confirmed Inspected Confirmed Inspected and Plugged Frac.
Count Frac.
Count Limit Limit
>0-02 10 1143 0
503 5
0333 5/15 0.142 0308 508/1651 0.289 02-0.4 103 4646 22 3703 101 0.544 123 /226 0.487 0.450 3804/8450 0.441 0.4 - 0.6 115 3253 130 5172 238 0.762 368/483 0.728 0.624 5410/8663 0.616 0.6 - 0.8 97 1397 286 4080 240 0.844 526/623 0.818 0.756 4320/5717 0.746 0.8 - 1.0 87 547 395 2493 186 0.870 581/668 0.846 0.830 2679/3226 0.819 1.0-12 63 199 119 845 974 0.946 1093/1156 0.933 0.901 1819/2018 0.890 1.2 - 1.6 50 124 201 551 853 0.955 1054/1104 0.943 0.919 1404 /1528 0.906 1.6 - 2.0 12 21 81 107 279 0.%8 360/372 0.948 0.948 386/407 0.927 2.0-32 7
7 35 35 184 0.%9 219/226 0.943 0.969 219/226 0.943 1.000 5/5 32-3.5 0
0 0
0 5
1.000 5/5 i
TOTAL 544 11337 1269 17489 3065 Total > 1V 132 351 436 1538 2295 FIG 90 DAY.XLS Table 8-3 7!31/96 3:57 PM 8-5
)
Table 8-4 Comparison of Alternate POD with EPRI POD Voltage EPRI Alternate Bin POD POD 0.1 0.30 0.24 0.2 0.38 0.34 O.3 0.49 0.44 0.4 0.57 0.53 0.5 0.62 0.62 0.6 0.66 0.67 0.7 0.71 0.73 0.8 0.76 0.77 0.9 0.80 0.81 1
0.83 0.83 j
1.2 0.90 0.88 i
1.4 0.93 0.91 1.6 0.96 0.92 1.8 0.98 0.93 2
0.984 0.94 3
1.00 0.98
)
3.5 1.00 1.00 i
FIO90 DAY.X13 Table 8-4 8/1/96 3:53 AM 8-6
Figure 8-1 Combined POPCD Evaluation for 6 Post-92 Inspections for 7/8" Dia Plants POPCD Based on RPC Confirmed Plus Not Inspected Indications 1.0
,.,,y_,_,_,_________._____---
- ,. ~
0.9 X
i 5
0.8
-,~I
}f 0.7
/
Mean
____jf-_____________________
p 56 u D
(]
o
- 0.5
/
=
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.o 0.4 B
o Aa
/
Combined POPCD Data 0.3 -t from 6 Inspections
+--o 0.2
l l
l l
l 0
0.5 1
1.5 2
2.5 3
3.5 Bcbbin Amplitude 8-7 nmoonnsr s-mmm;3 57m
9 Figure 8-2 Combined POPCD Evaluation for 5 Post-92 Inspections for 3/4" Dia Plants POPCD Based on RPC Confirmed Plus Not Inspected Indications 1.
~~?_________________.---
y 1.0
,r ,.
0.9
.x 0.8
../
P 0.7 Mean 8
---,,d l 0.6 t'
.J O
w 0.5
.I
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O
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j 0.4 Combined POPCD Data et
/
from 5 Assessments 0.3 - b
l l
l l
l 0
0.5 1
1.5 2
2.5 3
3.5 Bobbin Amplitude 8-8 RG90 DAY.RSTigt-2l7/31/96l3.57 Phi
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Figure 8-4 Combined POPCD Evaluation for 11 Post-92 Inspections POPCD Based on RPC Confirmed Indications Only 1.0
_ _,,,_ _ _ _ _ _ _ _ _ __________,___7 g _ g. - -,.,a f ~. - - - - - -6. -
' ~
O.9 y
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0.7
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0.5 x
n- - i --a Data from 11 Inspections f
.E 0.4 o
it I
a.
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0.3 --f j
--x-EPRI POD 1
0.2 a--A
-*-- 95% Lower Confidence Limit 0.1 0.0 l
l l
l l
l l
l 0
0.5 1
1.5 2
2.5 3
3.5 l
Bobbin Amplitude l
l 8 - 10 nowoAy.xis:r.s+mman m l
a Figure 8-5 Combined POPCD Evaluation for 11 Post-92 Inspections POPCD Based on RPC Confirmed Plus Not Inspected Indications 1.0 g_
m
_,r_,
1
_-R 2 ;
1,_._.
0.9 f. _. Q' - *"" - - "
x
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k=7,Y
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0.7
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--+-Data from 11 Inspections 3
n-p - -u
.E 0.4 JI cI:
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--x-EPRI POD 0.3 --pj
--a-- 95% Lower Confidence Umit 0.2
--o-Altemate POD 0.1 0.0 l
l l
l l
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0.5 1
1.5 2
2.5 3
3.5 Bobbin Amplitude 0
- II nG90 DAY ESFs8-5ffmWO 57 N
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9.0 REFERENCES
9.1 NRC Generic Letter 95-05, " Voltage-Based Repair Criteria for Westinghouse Steam Generator Tubes Affected by Outside Diameter Stress Corrosion Cracking", USNRC Office of Nuclear Reactor Regulation, August 3,1995.
9.2 SG-95-06-006, " Beaver Valley Unit-1, Interim Plugging Criteria 90 Day Report,"
1 Westinghouse Electric Corporation, May 1995.
9.3 U.S. N.R.C. Report, " Safety Evaluation by the OfHee of Nuclear Reactor Regulation Related to Amendment No.198 to Facility Operating License DPR-66 Duquesne Light Company, Ohio Edison Company and Pennsylvania Power Company, Beaver Valley Power Station, Unit No.1 Docket No. 50-334",
April 1,1996.
i 9.4 WCAP-14123 (SG-94-07-009), " Beaver Valley Unit 1 Steam Generator Tube Plugging Criteria for Indications at Tube Support Plates", Westinghouse Electric Corporation, Proprietary Class 2, July 1994.
j 9.5 WCAP-14277,"SLB Leak Rate and Tube Burst Probability Analysis Methods for ODSCC at TSP Intersections," Westinghouse Nuclear Services Division, t
January 1995.
9.6 Draft of Addendum-1 to EPRI Report NP-7480-L, " Steam Generator Outside Diameter Stress Corrosion Cracking at Tube Support Plates - Database for Alternate Repair Criteria," June 1996.
i i
i s:\\ ape \\dlw96\\dlw90 day wp5 9-1