Text

Unit - 1 EOC 7A Interim Plugging Criteria Rept
	ML20101E765
Person / Time
Site:	Byron
Issue date:	03/31/1996
From:	; WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP.
To:	;
Shared Package
ML20101E747	List: ML20101E744; ML20101E765;
References
	SG-96-03-001, SG-96-3-1, NUDOCS 9603250206
	Download: ML20101E765 (52)
	v • d • e

_ _ _ _ _ _ _ _ _ _ _ _ _

WESTINGHOUSE PROPRIETARY CLASS 3 NSD-DDM-1214 SG-96-03-001 BYRON UNIT-1 END-OF-CYCLE 7A INTERIM PLUGGING CRITERIA REPORT Mardi 1996 O

Westinghause Electric Corporation Energy Systems Business Unit Nudear Services Division P.O. Bom: 158 Madison, Pennsylvania 15663-0158 9603250206 960319 PDR ADOCK 05000454 P

PDR

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WESTINGHOUSE PROPRIETARY CLASS 3 i

NSD-DDM-1214 SG-9643-001 l

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1-BYRON UNIT - 1 END-OF-CYCLE 7A INTERIM PLUGGING CRITERIA REPORT 4

+

March 1996

i Table of Contents Page No.

1.0 Introduction 1-1 2.0 Summary and Conclusions 2-1 3.0 EOC-7A Inspection Results and Voltage Growth Rates 31 3.1 EOC-7A Inspection Results 3-1 3.2 Voltage Growth Rates 3-2 3.3 NDE Uncertainties 3-3 1

3.4 Assessment of RPC Confirmation Rates 3-4 4.0 Database Applied for IPC Correlations 4-1 5.0 SLB Analysis Methods 5-1 6.0 Bobbin Voltage Distributions 6-1 6.1 Calculation of Voltage Distributions 6-1 6.2 Probability Of Detection (POD) 6-2 6.3 Limiting Growth Rate Distribution 62 6.4 Cycle Operating Period 6-2 6.5 Projected EOC-7B Voltage Distributions 6-2 6.6 Comparison of Actual and Projected EOC-7A Voltage Distributions 6-3 7.0 SLB Leak Rate and Tube Burst Probability Analyses 7-1 7.1 Leak Rate and Tube Burst Probability for EOC-7A 7-1 7.2 Leak Rate and Tube Burst Probability for EOC-7B 7-2 8.0 References 8-1

.i a:\\apcNeae95Ney7B_90 day.wp5 i

/

Bymn Unit - 1 End-of-Cyde 7A i

Interim Plugging Criteria Report 1.0 Intr delion This report provides the Byron Unit 1 steam generator tube Eddy Current (EC) inspection results at the end of Cycle 7A* together with Steam Line Break (SLB) leak rate and tube burst probability analysis results calculated according to NRC guidelines, in support of the implementation of the recently approved 3.0 volt Interim Plugging Criteria (IPC). SLB leak rates and tube burst probabilities were calculated for end of cycle (EOC) conditions of both the recently completed cycle (Cycle 7A) and the ongoing cycle (Cycle 7B).

Analyses for Cycle 7A were carried out using the -actual bobbin - voltage distributions measured during the EOC-7A outage and the results compared with corresponding values from projections performed based on the last (EOC-6) inspection bobbin voltage data. The analyses based on the actual measured bobbin voltage distributions for Cycle 7A considered conditions both before and after tube support plate (TSP) locking (to support a 3 volt IPC). However, since the EOC-7A results represent completion of a cycle implementing a 1 volt IPC consistent with NRC guidelines, leak and burst analyses based on the free span analysis methods are the reference analyses. The results based on the assumptions of TSP locking are provided for information as sensitivity analyses.

Analyses were also performed to project leak rates and tube burst probability for postulated SLB conditions at the end of the ongoing cycle (Cycle 7B) based on tile 3.0 volt repair criteria. Those analyses utilized bobbin voltage distributions measured during the recent (EOC-7A) inspection and a limiting growth rate distribution established using growth data from EOC-6 and EOC-7A inspections.

The methodology used in these evaluations is in accordance with previously published Westinghouse reports (References 8-1, 8-2 and 8-6)

Since the current inspection is a mid-cycle inspection, for clarity the first half of Cycle 7 is referred to as Cycle 7A and the second-half as Cycle 7B.

s:\\apc\\cae96%cy7B 90daywp5 1-1 J

2.0 Summary and Condusians SLB leak rate and tube burst probability analyses were performed for the actual EOC-7A EC bobbin voltage distributions as well as the projected EOC-7B bobbin voltage distributions. Results for the EOC-7A actual measured bobbin voltages are considerably lower than the corresponding projections performed using the EOC-6 outage bobbin voltage data and a probability of detection of 0.6, by at least a factor of 14. The large differences between the projections and actuals are due primarily to reduction in voltage growth, particularly for the large voltage tail of the growth distribution. This is also evident from comparison of the highest bobbin voltage projected for each SG at EOC-7A with those actually measured, both shown in Table 7-1. The largest measured voltage was 3.5 volts (adjusted for NDE uncertainty by a Monte Carlo technique) compared to projected 11.7 volts for a constant POD value of 0.6 and 7.8 volts for the EPRI POD. Projections based on a constant POD of 0.6 for EOC-7A predicted SG-C to be the limiting SG; however, analyses based on EOC-7A actual measured voltage distributions indicate a slightly higher leak rate and burst probability for SG B in comparison to SG-C, but the absolute differences are small. Projections for EOC-7A using the EPRI POD correctly predicted SG-B as the limiting SG. The leak rate and tube burst probability projections at EOC conditions for the current cycle (Cycle 7B) are also well within acceptable limits, with SG-B being the limiting SG for leak. The corresponding tube burst probability is below 4 x 104 for all four SGs.

For the actual EOC-7A bobbin voltage distribution, free span SLB leak rate (applicable prior to TSP locking) and tube burst probability are calculated to be 0.075 gpm and 1.3x10-a, respectively, for the limiting SG which is SG-B. These values are considerably below the corresponding EOC-7A projections for SG B based on EOC-6 voltage distribution adjusted using the NRC SER endorsed probability of detection of 0.6.

Also, these values are much lower than the allowable Cycle 7A SLB leakage limit of 12.5 gpm and the NRC reporting guideline of 10-8 for the conditional tube burst probability. The corresponding EOC-7A values calculated for a locked TSP condition are 0.075 gpm leak rate and a burst 4

probability ofless than 4x10 (only cold leg indications contribute to burst). Leak rate is not signi6cantly affected by the locked TSP condition due to a low free span burst probability (i.e., only a few indications restrained from burst, would have had a higher leakage). As expected, the tube burst probability is substantially reduced for the locked TSP condition.

Limiting SLB leak rate projected for the EOC-7B conditions (locked TSPs) using the NRC SER endorsed probability of detection of 0.6 is 0.25 gpm. This value is projected for SG B and it is well below the allowable EOC-7B leakage limit of 12.5 i

gpm. The corresponding limiting tube burst probability value is less than 4 x10 8 which is also well below the NRC reporting guideline of 10-8. The burst probability is controlled by cold leg indications (TSPs are not lecked on the cold leg side). The projected EOC-7B leak rates are higher than found at the actual EOC-7A condition s:\\apc\\cae95\\cy7B_90 day.wp5 2-1 s

due to the requirement to adjust the number of indications upwards using a probability of detection factor of 0.6.

A total of 5005 indications were found in the EOC-7A inspection ofwhich 219 were inspected with a Rotating Pancake Coil (RPC) probe (including a minimum of 20

% of hot leg indications between 1 and 3 volts and all hot leg indications above 3 volts), and 161 were confirmed as flaws. The RPC confirmed indications included 156 above 1.0 volt. SG B had the largest number among the four SGs with 1602 bobbin indications, of which 264 were above 1.0 volt, 67 of these were inspected by RPC and 51 were confirmed as flaws. Only one indication was found above 3 volts, 3.17 volts in SG-A, and it was confirmed by RPC. 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.

l l

k 1

l j

s:\\apcNcme95Ney7B.90 day.wp5 2-2

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3.0 EOC-7A Inspedian Results and Voltage Growth Rates 3.1 EOC-7A Inspedian Results 4

l In accordance with the IPC guidance provided by the NRC Generic Letter 95-05, the end of Cycle 7A inspection of the Byron Unit-1 steam generators (SG) consisted of a complete,100% EC bobbin probe fulllength examination of the tube bundles in all four SGs. A 0.610 inch diameter probe was used for all hot and cold leg TSPs where IPC was applied. Subsequently, RPC examination was performed for a minimum of 20 percent of hot leg indications with an amplitude between 1 and 3 volts, all of hot leg indications with an amplitude above 3 volts, and all of cold i

leg indications with an amplitude above 1 volt. There was only one hot leg indication above 3 volts. It was confirmed as a flaw and plugged. None of the cold leg indications had a bobbin voltage above 1 volt.

An augmented RPC inspection was also performed consistent with the NRC requirements. All dented intersections with a bobbin voltage greater than 5 volts and a minimum of 20 percent ofintersections with a bobbin dent voltage between 2.5 and 5 volts were inspected with RPC. The augmented RPC inspection also l

included 8 TSP intersections with mixed residual artifact signals (MRI). There were no RPC Daw indications reported in the augmented inspection.

There was no evidence of any unexpected results in the EOC-7A eddy current inspection data. There were no RPC circumferential indications at the TSPs, no indications extending outside the TSPs, no RPC indications with potential PWSCC i

phase angles, no flaw indications at dented TSP intersections at any dent voltage and there was no signal interference from copper deposits.

Thus, 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 EC indications for all four steam generators is shown on Table 3-1, I

which tabulates the number of field bobbin indications, the number of these 6 eld bobbin indications that were RPC inspected, the number of RPC confirmed indications, and the number of plugged indications. Also shown are the total number indications and the number of RPC confirmed or not RPC inspected indications that remain active for Cycle 7B operation. A further separation of bobbin coil data in Table 3-1 into hot and cold leg indications is given in Section 6.

Overall, the combined data for all four steam generators of Byron Unit-1 shows that:

Out of a total of 5005 indications identi6ed during the inspection, a total of 219 were RPC inspected.

.:wpev uvy7s_soa.y.* 6 3-1

i Of the 219 RPC inspected, a total of 161 were RPC confirmed.

4 A total of 525 indications were removed from service, but only 40 indications were in tubes repaired for TSP IPC related causes (and the rest in tubes repaired for other reasons). Consistent with the new 3 volt IPC, RPC

)

confirmed hot leg indications with bobbin amplitude ofless than or equal 3.0 volts and RPC confirmed cold leg indications less than or equal to 1 volt are not considered for removal from service.

A review of Table 3-1 indicates that although a few more indications were found in SG-B (1602) than in SG-C (1595), more indications (a quantity of 1544, with 244 indications above 1.0 volt) are returned to service in SG C. However, SG B has more larger indications (above 2 volts, which are the dominant contributors to i

SLB leak rate and tube burst probability) returned to service, thereby it potentially could be the limiting SG at EOC-7B. Also, it is noted that SG-A has the largest indication (3.17 volts) found in the EOC-7A inspection. As discussed in Section 7, SG B bobbin voltage distribution yielded the largest SLB leak rate projected for the EOC-7B condition.

Figure 3-1 shows the actual bobbin voltage distribution determined from the EOC-7A EC inspection; Figure 3-2 shows the population distribution of those EOC-7A indications removed from service due to tube repairs; Figure 3-3 shows the distribution forindications returned to service for Cycle 7B. Of the 525 indications removed from service, only 40 indications are in tubes repaired for TSP IPC-related issues and the rest are in tubes plugged for degradation mechanisms other than.ODSCC at TSP's. Among the 40 ODSCC indications removed from service due to IPC-related issues, only one indication was above the 3 volt IPC limit.

Among the remaining 39 indications, 23 are in tubes near the wedge supports for which TSP IPC does not apply and 16 are in tubes expanded to lock TSPs for application of a 3 volt IPC. Of the 16 indications in expanded tubes, tube expansions were performed at four TSP intersections having indications with small voltages of 0.42,0.51,0.72 and 0.97 volt.

The distribution of EOC-7A indications as a function of support plate location is summarized in Table 3-2 and plotted in Figure 3-4. The data show a strong predisposition of ODSCC to occur in the first few hot leg TSPs (4689 out of 5005 indications occurred at the first three hot leg TSP intersections), although the mechanism extended to higher TSPs. Only 8 indications were detected on the cold leg side. This distribution indicates the predominant temperature dependence of ODSCC at Byron Unit-1, similar to that observed at other plants.

8.2 Valtage Growth Rates For projection ofleak rates and tube burst probabilities at the end of Cycle 7B s:\\apcNcme96%cyTB_90 day.wp5 3-2 j

i operation, voltage growth rates were developed from EOC-7A (November 1995) inspection data and a reevaluation of the same indications from the EOC-6 (December 1994) inspection EC signals.

Table 3-3 shows the cumulative probability distribution of growth rate for each Byron Unit-1 steam generator during Cycle 7A (January '95 - November '95) on an EFPY basis, along with the corresponding Cycle 6 growth rate distributions.

Cycle 7A growth data is also plotted in Figure 3-5. Among the four steam generators, SG D has a slightly larger average voltage growth during Cycle 7A. The curve labelled ' cumulative'in Figure 3-5 represents averaged composite growth data from all four SGs. Average growth rates for each SG during Cycle 7A are summarized in Table 3-4. The average growth rates over the entire voltage range vary between 43.8% and 59.5%

(of the BOC voltage) per EFPY, between SGs, with an overall average of 48.3% per EFPY. The average growth for indications greater than or equal to 0.75 volts is 37.7% per EFPY and for indications less than 0.75 volts it is 52.1% per EFPY.

Steam generators B and C had the highest average voltage at BOC-7A whereas SG D had the largest average voltage growth during Cycle 7A. Steam generator A had the largest voltage growth rate during the last (EOC-6) inspection.

j Averaged composite voltage growth data from all four steam generators for the last two operating periods are summarized in Table 3-5.

For EOC-4 and EOC-5 inspections, growth rates are available only for tubes plugged during the inspection

)

and those data are also included in Table 3-5. Figure 3-6 provides a comparison of the growth rate distributions for the last two operating periods. Growth rates for Cycle 7A are signi6cantly below those observed for Cycle 6.

Table 3-6 lists top 30 indications on the basis of Cycle 7A growth rates, in descending order. Eight of those indications were either RPC NDD or were not RPC inspected. Six of the 30 indications shown are new indications, and EOC-6 I

voltages used to estimate growth rates for them were obtained by revaluating the last inspection data.

The guidelines in the Generic Letter 95-05 require the use of the more conservative growth rate distributions from the past two inspections for projecting EOC distributions for the next cycle. From Figure 3-6 it is evident that growth rates for Cycle 6 are higher than those of Cycle 7A. Therefore, Cycle 6 growth rates were used to develop the EOC-7B predictions. The actual growth distribution used for EOC-7B projection is a worst case hybrid growth distribution that was developed during the last inspection (EOC-6) and applied to project EOC-7A voltage distributions. This limiting growth rate distribution envelopes the actual EOC-6 distribution with the simultaneous limitations of SG-A (highest average growth) and of SG-C (highest growth increment of 9.9 volts). Table 3-7 compares this hybrid growth distribution with the growth distributions observed for SG-B (highest growth rate for indications above 0.75 volts at BOC-7A) and SG-D (highest average growth rate) during Cycle-7A. It is evident that the hybrid growth distribution is more conservative than the Cycle 7A growth rate distribution. This a:\\apcNeese,5Ney7B_90 day.wp5 3-3 y

conservative growth distribution was imposed on all four steam generators, to I

provide a conservative basis for predicting EOC-7B performance.

Separate voltage projections to EOC-7B are required for the hot and cold legs since tube expansion to limit TSP displacement has been implemented only in the hot j

leg. Table 3-2 shows average and maximum growth rates by TSP elevation including the cold leg. It is seen that no large growth rates were found for the cold leg with 0.23 volts as the largest growth value. The cold leg results tend to indicate lower growth rates than found for hot leg indications. It is therefore very conservative to use the bounding growth rate (Cycle 6 distribution) for the cold leg as well as the hot leg indications, and this conservatism is applied for the EOC-7B analysis in Sections 6 and 7.

8.8 NDE Uncertainties

{

The NDE uncertainties applied for the Cycle 7A voltage distributions in the Monte Carlo analyses for leak rate and burst probabilities are the same as those j

previously reported in the Braidwood Unit-1 IPC report of Reference 8-1 and NRC i

GL 95-05. They are presented in Table 3 8 as well as graphically illustrated in j

Figure 3 7. 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 l

standard. The analyst variability uncertainty has a standard deviation of 10.3%

j about a mean of zero with no cutoff. These NDE uncertainty distributions are i

included in the Monte Carlo analyses used to project the EOC-7B voltage l

distributions.

1 8.4 kr

=1 of RPC Con 6rmation Rates i

This section tracks the 1994 EOC-6 indications left in service at BOC-7A relative to RPC inspection results in 1995 at EOC-7A. The composite results for all SGs are given in Table 3 9. For 1994 bobbin indications left in service, the indications are tracked relative to 1994 RPC confirmed,1994 RPC NDD,1994 bobbin indications not RPC inspected and 1994 bobbin indications with no indication found in 1995. Also included are new 1995 indications. The table shows, for each 3

category of indications, the number of indications RPC inspected and RPC l

confirmed in 1995 as well as the percentage of RPC confirmed indications.

1 Of the 149 RPC NDD indications left in service at BOC-7A, 27 were RPC tested during the EOC-7A inspection and 13 were confirmed. This RPC confirmation rate

' for prior RPC NDD indications (48%) is slightly higher than that typically found for other plants during recent inspections. It has been recommended by industry that the largest RPC NDD confirmation rates over the prior two cycles be used for projections. Since data from only one inspection is currently available, it is s:\\ ape \\cae95Ncy7B 90 day.wp5 3-4 4

. _ =

_ ~ _ - -

i recommended that future Byron-1 IPC applications include only about 50% of the RPC NDD indications in the BOC voltage distribution used for EOC projections, and leak rate and burst probability analyses.

However,100% of RPC NDD indications reported in the EOC-7A inspection are considered in the SLB leak rate and tube burst probability analyses presented in this report for EOC-7A and EOC-7B conditions.

l 2

5 a:\\apcNeae95\\cy7B 90 day.wp5 3-5

Tatde 3-1 ( Sheet 1 of 2)

Byron Unit-1 Novesaber 1995 Outage Suninsary ofInspection and Repair For Tubes in Senice During Cycle 7A Steam Generator A Steam Generator B Steam Gesurator C he-Serstec Durteg Cycle 7A RTS fler Cyete 73 h Durtug Cyrte 7A RTS Sur Cycle 7B In-8ervice Durteg Cycle 7A RTS for Cycle 7B Comansed Camarmed Caen,.es YN FI'I8 A I8 P8'88 A PIst M

E RFC h

Ag AM RFC RPC Immeseems A5 RFC RFC mh AN 3emported CouArmed Reymend Emmenelaus Emmposeed Camarmoed Reystred Immeer los W

Ceemrmed W g,gg,,g,,,

=

_L=

=

0.2 6

0 0

0 6

6 8

0 0

0 13 1

0 0

13 12 03 47 0

0 4

43 43 95 2

1 2

93 92 71 0

0 0

71 71 0.4 132 3

0 13 119 116 199 1

0 10 189 188 157 3

0 3

154 151 0.5 I41 3

1 13 128 126 209 2

1 16 193 193 251 1

I 3

248 248 0.6 149 2

0 16 133 131 221 4

2 13 208 206 225 7

3 5

220 216 0.7 98 1

0 7

91 90 216 2

1 17 199 198 214 3

1 8

206 204 0.8 56 2

0 12 74 72 171 1

0 15 156 155 171 1

0 4

167 166 0.9 79 1

1 8

71 71 124 3

1 6

118 116 129 I

I 6

123 123 1

50 0

0 7

43 43 95 I

I 2

93 93 101 3

1 3

98 96 1.1 32 I

I 5

27 27 72 8

6 13 59 57 78 6

2 3

75 71 1.2 37 I

I 4

33 33 56 8

6 17 39 37 54 0

0 I

53 53 13 22 2

2 I

21 21 39 8

7 13 26 26 39 4

4 1

38 38 I.4 11 3

2 0

11 10 16 3

3 4

12 12 35 9

7 0

35 33 13 7

3 3

1 6

6 26 2

2 8

18 18 14 8

8 0

14 14 1.6 10 7

7 I

9 9

15 6

5 7

8 8

14 9

9 5

9 9

1.7 3

1 0

0 3

2 5

I i

1 4

4 11 7

7 2

9 9

1.8 4

2 2

1 3

3 11 0

0 1

10 10 5

2 2

1 4

4 f.9 4

2 2

2 9

1 1

4 5

5 2

2 2

1 I

I 2

I I

I 0

t i

2 I

I I

3 2

2 3

0 0

11 0

0 0

0 2

2 1

0 2

1 2

2 2

0 2

2 12 0

0 0

0 4

4 4

1 3

3 2

I I

O 2

2 2.3 2

2 2

0 2

2 I

i 1

0 I

1 0

0 0

0 2.4 0

0 0

0 3

3 3

1 2

2 0

0 0

0 15 0

0 0

0 2

2 2

I I

I 2.6 0

0 0

0 17 0

0 0

0 1

1 1

0 1

1 2

2 2

1 I

1 3

0 0

2 2

2 1

1 1

0 0

3.2 I

i i

1 0

0 0

0 Tetel 922 38 26 96 826 814 1602 67 51 153 1449 1436 1595 76 57 51 1544 1525

>1V 134 26 24 16 118 116 264 51 44 72 192 187 263 56 50 19 244 238 namesenemsem ein.nns 3-6 b-

Table 3-1 ( Sheet 2 of 2)

Byron Unit -1 November 1995 Outage Summary of Inspection and Repair For Tubes in Service During Cycle 7A stesma Gesuratur D M ofAR4EIGe Im4ervke Dartas Cyde 7A RTS Ser Cyde 7B th During Cyde 7A RTS ter Cycle 78 Cameresse Cemenmed RPC RPC Im W AB RPC RPC Indicateams Ag Inspected Camerased Repaired Indkatemas lampacted Cemenmed Repaired Indkattums y

Only Omh i

0.2 9

1 0

4 5

5 36 2

0 4

32 31 03 88 0

0 25 63 63 301 2

I 31 270 269 i

0.4 144 4

I 31 113 110 632 11 1

57 575 565 0.5 121 0

0 23 98 98 722 6

3 55 667 665 0.6 126 3

1 33 93 91 721 16 6

67 654 644 O.7 109 3

3 35 74 74 637 9

5 67 570 566 0.8 70 2

2 21 49 49 498 6

2 52 446 442 0.9 62 0

0 20 42 42 394 5

3 40 354 352 1

43 2

0 13 30 28 289 6

2 25 264 260 1.1 30 2

2 7

23 23 212 17 11 28 184 178 1.2 20 1

1 3

17 17 167 10 8

25 142 140 13 15 I

I i

14 14 115 15 14 16 99 99 1.4 13 4

3 3

to 9

75 19 15 7

68 64 1.5 7

3 3

2 5

5 54 16 16 11 43 43 I.6 5

2 2

1 4

4 44 24 23 14 30 30 1.7 9

1 0

3 6

5 28 to 8

6 22 20 1.8 5

0 0

3 2

2 25 4

4 6

19 19 1.9 0

0 0

0 15 5

5 7

8 8

2 3

2 2

0 3

3 9

6 6

4 5

5 2.1 1

1 1

0 1

I 5

4 0

5 4

2.2 1

1 I

I O

O 7

6 6

2 5

5 13 I

I O

O I

O 4

4 3

0 4

3 2.4 0

0 0

0 3

3 3

1 2

2 2.5 0

0 0

0 2

2 2

I I

I 2.6 I

I I

O I

I I

O I

I 2.7 I

I i

1 0

0 4

4 4

2 2

2 3

2 2

2 I

I I

4 4

4 2

2 2

3.2 0

0 0

0 1

I I

I O

O Total 886 38 27 231 655 645 5005 219 161 531 4474 4420

>IV 114 23 20 26 88 85 775 156 138 133 642 626 i

cm m3.e 3-7

\\

Table 3-2 (Sheet 1 of 2)

Byron Unit-1 November 1995 TSP ODSCC Indication Distributions for Tubes in Service During Cycle 7A Steam Generator A Steams Generator B Stenan Generator C Tube k

Maximum Average Maximum Average Maxzmum Average Maximum Average Maximum Average Maximum Average S

Voltage Voltage Growth Growth Voltage Voltage Growth Growth Voltage Voltage Growth Growth 311 479 3.17 0.70 1.42 0.21 959 2.95 0.76 2.13 0.23 992 2.67 0.73 1.79 0.20 Sil 256 2.21 0.67 1.28 0.21 421 2.36 0.66 1.43 0.19 469 2.17 0.70 1.09 0.20 711 103 1.62 0.67 0.86 0.21 111 1.85 0.59 0.85 0.13 48 1.53 0.61 0.84 0.18 8H 45 1.71 0.62 0.71 0.18 82 1.38 0.56 0.55 0.15 53 1.27 0.58 0.64 0.12 9H 26 1.36 0.52 0.35 0.11 21 0.87 0.51 0.37 0.10 24 1.11 0.48 0.6 0.17 1011 10 0.85 0.54 0.44 0.21 5

0.54 0.41 0.21 0.13 2

0.%

0.84 0.28 0.27 1111 0

0 6

0.78 0.46 0.18 0.08 11C 0

2 0.78 0.61 0.21 0.09 0

10C 1

0.42 0.42 0.21 0.21 0

0 9C 1

0.4 0.40 0.01 0.01 0

0 SC 1

0.34 0.34

-0.09

-0.09 0

0 7C 0

1 1.05 1.05 0.23 0.23 0

SC 0

0 1

0.59 0.59 0.2 0.20 Total 922 1602 1595 3-8

Table 3-2 (Sheet 2 of 2)

Byron Unit-1 November 1995 TSP ODSCC Indication Distributions for Tubes in Service During Cycle 7A Steam Generator D Composite of All Four SGs Maxunum Average Maximum Average Mammum A wrage Maximum Average Simpgnt Voltage Voltage Growth Growth Voltage Voltage Growth Growth 311 534 2.93 0.70 1.87 0.25 2964 3.17 0.73 2.13 0.22 511 251 2.57 0.59 1.49 0.20 1397 2.57 0.66 1.49 0.20 7II 66 2.3 0.55 0.89 0.16 328 2.3 0.61 0.89 0.17 811 12 0.72 0.46 0.36 0.13 192 1.71 0.57 0.71 0.15 911 14 0.55 0.33 0.22 0.05 85 1.36 0.47 0.6 0.12 1 011 4

0.33 0.28 0.06

-0.01 21 0.96 0.49 0.44 0.16 1111 4

0.5 0.37 0.13 0.07 10 0.78 0.42 0.18 0.08 IIC 0

2 0.78 0.61 0.21 0.09 IOC 0

1 0.42 0.42 0.21 0.21 9C 0

1 0.4 0.40 0.01 0.01 BC 0

1 0.34 0.34

-0.09

-0.09 7C 0

1 1.05 1.05 0.23 0.23 SC 1

0.15 0.15 0

0.00 2

0.59 0.37 0.2 0.10 Total 886 5005 3-9

_ n== =:-,. m

- - - - - - - - - - - - - - - - - - =

I Table 3-3 Byron Unit-1 November 1995 Signal Growth Statistics For Cycle 7A on an EFPY Basis Steam Generator A Steam Gesnerator B Steam Gesserater C Steam Geswrator D Omnmulative O

Cyde 6 C W 7A Cyde 6 Cyde 7A Cyde 6 Cyde7A Cyde 6 Cyde 7A Cyde6 Cyde7A CPDF

' I

'I

'I I

CPDF CPDF CPDF CPDF CPDF CPDF CPDF CPDF CPDF Ohs Obs Obs Obs Obs

-0.5 0.001 0

0 0

0 0.000 0

0

-0.4 0.004 0

0 0

I 0.0006 0

0 0

0.000 0

0 0.001 1

0.0002

-03 0.004 0

0 0.005 1

0.0012 0.009 0

0 0.000 1

0.0011 0.005 2

0.0006

-0.2 0.011 2

0.002 0.035 6

0.0050 0.027 5

0.003 0.017 1

0.0023 0.024 14 0.0034

-0.1 0.026 15 0.018 0.081 25 0.0206 0.072 29 0.021 0.052 12 0.0158 0.060 81 0.01 %

0 0.057 58 0.081 0.170 151 0.1149 0.152 166 0.125 0.124 70 0.0948 0.128 445 0.1085 0.1 0.1%

206 0305 0350 409 03702 0.297 407 0381 0339 205 03262 0.293 1227 03536 0.2 0399 181 0.501 0.546 327 0.5742 0.443 291 0.563 0.537 183 0.5327 0.476 982 0.5499 03 0.590 180 0.6%

0.660 248 0.7291 0.591 244 0.716 0.739 141 0.6919 0.633 813 0.7123 0.4 0.726 124 0.831 0.770 150 0.8227 0.720 183 0.831 0.846 87 0.7901 0.755 544 0.8210 0.5 0.805 61 0.897 0.868 84 0.8752 0.825 85 0.884 0.907 56 0.8533 0.845 286 0.8781 0.6 0.874 38 0.938 0.923 69 0.9182 0.891 64 0.924 0.930 52 0.9120 0.902 223 0.9227 0.7 0.928 21 0.961 0.955 41 0.9438 0.924 43 0.951 0.%1 25 0.9402 0.940 130 0.9487 08 0.951 13 0.975 0.974 20 0.9563 0.945 27 0.%8 0.987 16 0.9582 0.%2 76 0.% 38 0.9 0.%9 12 0.988 0.984 19 0.9682 0.%9 20 0.981 0.989 8

0. % 73 0.976 59 0.9756 1

0.976 4

0.992 0.988 15 0.9775 0.978 8

0.986 0.993 10 0.9786 0.983 37 0.9830 1.1 0.979 0

0.992 0.991 12 0.9850 0.980 7

0.990 0.993 5

0.9842 0.985 24 0.9878 1.2 0.984 3

0.996 0.993 4

0.9875 0.983 6

0.994 0.996 3

0.9876 0.988 16 0.9910 13 0.985 1

0.997 0.995 9

0.9931 0.986 5

0.997 0.996 5

0.9932 0.990 20 0.9950 1.4 0.988 1

0.998 0.995 3

0.9950 0.991 1

0.997 0.996 1

0.9944 0.992 6

0.9962 1.5 0.991 1

0.999 0.996 3

0.9969 0.992 I

0.998 0.996 1

0.9955 0.993 6

0.9974 1.6 0.994 0

0.999 0.997 0

0.9969 0.993 1

0.999 0.996 0

0.9955 0.995 1

0.9976 1.7 0.995 I

I 0.997 I

0.9975 0.994 0

0.999 0.996 0

0.9955 0.995 2

0.9980 1.8 0.995 0.997 2

0.9988 0.997 1

0.999 0.998 2

0.9977 0.996 5

0.9900 1.9 e.995 0.997 0

0.9988 0.997 0

0.999 0.998 0

0.9977 0.996 0

0.9990 2

0.995 0.998 0

0.9988 0.997 0

0.999 0.998 1

0.9989 0.997 1

0.9992

2. I 0.995 0.998 1

0.9994 0.997 I

I 0.998 0

0.9989 0.997 2

0.9996 2.2 0.995 0.998 0

0.9994 0.997 0.998 I

I 0.997 1

0.9998 23 0.996 0.998 0

0.9994 0.998 0.998 0.997 0

0.9998 2.4 0.996 0.999 0

0.9994 0.999 0.998 0.998 0

0.9998 2.5 0.995 0.998 I

I 0.997 0.998 0.998 1

1 2.9 0.996 1

0.999 0.998 0.998 3

0.996 0.999 i

0.999 43 0.998 0.999 0.999 4.7 0.999 0.999 0.999 53 1

0.999 0.9997 7.8 1

1 Total 922 1602 1595 886 5005 cntowTitxts Tek s.s 3-10 k

Table 3-4 Byrom Unit-1 November 1995 Ostage Average Vokage Growth During Cycle 7A Voltage Number of Average Voltage Range Indications BOC Entire Cycle Per EFPY' En6te Cycle Per EFPY

Composite of All Steam Generator Data Entire Voltage Range 5005 0.49 0.204 0.235 41.9%

48.3 %

V eoe <.75 Volts 4276 0.42 0.189 0.217 45.3 %

52.1 %

2.75 Volts 729 0.90 0.298 0.343 32.9%

37.9 %

SteamGenerator A FEJre Voltage Range 922 0.47 0.207 0.238 44.0 %

50.6 %

V eoe <.75 Volts 803 0.41 0.192 0.221 47.3 %

54.4%

2.75 Volts 119 0.91 0.309 0.356 34.0 %

39.1%

Steam Generator B Entire Voltage Range 1602 0.51 0.203 0.233 40.1 %

46.2 %

V ooc <.75 Volts 1356 0.44 0.178 0.205 41.0 %

47.2 %

2.75 Volts 246 0.89 0.337 0.388 37.8 %

43.5 %

Steam Generator C Entire Voltage Range 1595 0.51 0.195 0.225 38.1%

43.8 %

V soe <.75 Volts 1328 0.43 0.184 0.212 42.5 %

48.9 %

2.75 Volts 267 0.90 0.251 0.288 27.7 %

31.9 %

Steam Generator D Entire Voltage Range 886 0.43 0.221 0.254 51.7 %

59.5 %

V noe <.75 Volts 789 0.37 0.210 0.241 57.3 %

65.9 %

2.75 Volts 97 0.92 0.314 0.361 33.9 %

39.0 %

' Based on Cycle 7A duration of 317.4 EFPD (0.869 EFPY) 3-11 GROWMXISTTable.3 42/299PS:49PM

\\

Table 3-5 Byron Unit-1 November 1995 Average Voltage Growth for Cycle 7A Composite of All Steam Generator Data Bobbin Voltage Number of Average Voltage Average Voltage Growth Average Percentage Growth Range Indications BOC Entire Cycle Per EFPY Entire Cycle Per EFPY Cycle 7A (1994 - 1995) - 317.4 EFPD Entire Voltage Range 5005 0.49 0.204 0.235 41.9 %

48.3 %

V noc <.75 Volts 4276 0.42 0.189 0.217 45.3 %

52.1 %

2.75 Volts 729 0.90 0.298 0.343 32.9 %

37.9 %

Cycle 6 (1993 - 1994) - 466.5 EFPD Entire Voltage Range 2851 0.47 0.320 0.251 68.1 %

53.3 %

V noc <.75 Volts 2377 0.37 0.35 0.274 94.6 %

74.I%

2.75 Volts 474 0.99 0.I80 0.I41 18.2%

14.2%

Cycle 5 (1991 - 1993) - 411.6 EFPD (Plugged Tubes Only)

Entire Voltage Range 532 l

0.46 l

0.310 l

0.275 l

67.4 %

l 59.8 %

Cycle 4 (1990- 1991) - 463.9 EFPD (Plugged Tubes Only)

Entire Voltage Range 550 l

0.32 l

0.260 l

0.205 l

81.3%

l 64.0 %

onowntxts.uo.5 pane.22 m 3-12 k

i l

Table 3-6 Byron Unit-1 November 1995 Summary of Largest Voltage Growth Rates for BOC-7A to EOC-7A Steam Generator Bobbin Voltage RPC New SG Row Col Elevation EOC-7A BOC-7A Growth B

21 99 03H 2.93 0.8 2.13 Y

Y D

15 63 03H 2.62 0.75 1.87 Y

N C

4 10 03H 2.67 0.88 1.79 Y

N

{

B 2

5 03H 2.62 0.87 1.75 Y

N D

14 42 03H 2.92 1.18 1.74 Y

N C

34 87 03H 2.44 0.89 1.55 Y

N B

2 51 03H 2.39 0.87 1.52 Y

N B

19 104 03H 2.95 1.45 1.5 Y

Y D

16 53 03H 1.76 0.27 1.49 N

Y D

14 42 05H 2 57 1.08 1.49 Y

N B

5 44 05H 2.36 0.93 1.43 Y

N C

7 73 03H 1.82 0.51 1.31 Y

N A

13 4

03H 2.23 0.81 1.42 Y

N A

3 69 05H 2.21 0.93 1.28 Y

N B

4 2

03H 1.77 0.49 1.28 N

N B

21 107 03H 2.23 0.95 1.28 Y

N B

17 6

03H 2.16 0.89 1.27 Y

N D

15 55 03H 1.77 0.52 1.25 N

N C

20 10 03H 2.15 0.92 1.23 Y

N B

4 56 03H 2.18 0.97 1.21 Y

N B

7 100 03H 2.32 1.12 1.2 Y

Y B

10 67 03H 2.14 0.96 1.18 Y

Y D

13 85 03H 2.07 0.9 1.17 Y

N C

10 51 03H 1.91 0.75 1.16 N

N A

7 61 03H 1.61 0.47 1.14 N

N C

21 7

03H 2.07 0.94 1.13 Y

N D

19 42 03H 1.51 0.4 1.11 Y

N B

2 55 05H 1.94 0.84 1.1 N

N B

28 89 05H 1.53 0.43 1.1 N

Y D

13 33 05H 1.72 0.62 1.1 N

N cownouw. u mm um 3-13

~ _

l 3

Table 3-7 Byron Unit-1 November 1995 Signal Growth Statistics (on EFPY Basis) Assumed for Limiting Case Projections for C)tle 78 Cycle 7A Cycle 6 Steaan Generator B Steam Gmerator D Hybrid Growth

g Volts No. of l

CPDF CPDF

'I CPDF Obs Obs Obs

-0.5 0

0 0

0 0.4 1

0.001 0

0 0

0

-03 1

0.001 1

0.001 0

0

-0.2 6

0.005 1

0.002 0

0 0.1 25 0.021 12 0.016 0

0 0

151 0.115 70 0.095 46 0.057 0.1 409 0370 205 0326 11I 0.1%

0.2 327 0.574 183 0.533 163 0399 0.3 248 0.729 141 0.692 153 0.589 0.4 150 0.823 87 0.790 109 0.725 0.5 84 0.875 56 0.853 64 0.804 0.6 69 0.918 52 0.912 55 0.873 i

0.7 41 0.944 25 0.940 43 0.927

]

0.8 20 0.956 16 0.958 19 0.950 8'

O.9 19 0.%8 8

0.967 14 0.%8 1

15 0.978 10 0.979 6

0.975 1.1 12 0.985 5

0.984 2

0.978 1.2 4

0.988 3

0.988 4

0.983 1.3 9

0.993 5

0.993 1

0.984 1.4 3

0.995 1

0.994 2

0.986 1.5 3

0.997 1

0.995 3

0.990 1.6 0

0.997 0

0.995 2

0.993 l.7 1

0.998 0

0.995 1

0.994 1.8 2

0.999 2

0.998 0

0.994 l.9 0

0.999 0

0.998 0

0.994 2

0 0.999 1

0.999 0

0.994 2.1 1

0.999 0

0.994 2.2 0

0.999 1

1 0

0.994 23 0

0.999 1

0.995 2.4 0

0.999 0

0.995 2.5 1

1 0

0.995 2.9 0

0.995 3

0 0.995 43 1

0.996 4.7 1

0.998 53 1

0.999 7.8 I

I Toint 1602 886 803

' Cycle 6 steam generator A growth distribution plus the largest growth in steam generator C.

GtoWDLXL8 Tahis M 3-14

Table 3-8 Probe Wear and Analyst Variability - Tabulated Values Analyst Variability Probe Wear Variability

~

Std. Dev = 10.3% Mean = 0.0%

Std. Dev = 7.0%

Mean = 0.0%

No Cutoff Cutoff at +/- 15%

Value Curnul. Prob.

Value Cumul. Prob,

-40.0%

0.00005

< -15.0%

0.00000

-38.0%

0.00011

-15.0%

0.01606

-36.0%

0.00024

-14.0%

0.02275

-34.0%

0.00048

-13.0%

0.03165

-32.0%

0.00095

-12.0%

0.04324

-30.0%

0.00179

-11.0%

0.05804

-28.0%

0.00?28

-10.0%

0.07656

-26.0%

0.00580

-9.0%

0.09927

-24.0%

0.00990

-8.0%

0.12655

-22.0%

0.01634

-7.0%

0.15866

-20.0%

0.02608

-6.0%

0.19568

-l 8.0%

0.04027

-5.0%

0.23753

-16.0%

0.%016

-4.0%

0.28385

-14.0%

0.08704

-3.0%

0.33412

-12.0%

0.12200

-2.0%

0.38755

-10.0%

0.16581

-1.0%

0.44320

-8.0%

0.21867 0.0%

0.50000

-6.0%

0.28011 1.0%

0.55680

-4.0%

0.34888 2.0%

0.61245

-2.0%

0.42302 3.0%

0.66588 0.0%

0.50000 4.0%

0.71615 2.0%

0.57698 5.0%

0.76247 4.0%

0.65112 6.0%

0.80432 6.0%

0.71989 7.0%

0.84134 8.0%

0.78133 8.0%

0.87345 10.0 %

0.83419 9.0%

0.90073 12.0 %

0.87800 10.0 %

0.92344 14.0 %

0.91296 11.0 %

0.94196 16.0 %

0.93984 12.0 %

0.95676 18.0 %

0.95973 13.0 %

0.96835 20.0 %

0.97392 14.0 %

0.97725 22.0 %

0.98366 15.0 %

0.98394 24.0 %

0.99010

> 15.0%

l.00000 26.0 %

0.99420 28.0 %

0.99672 30.0 %

').99821 32.0 %

0.99905 34.0 %

0.99952 36.0 %

0.99976 38.0 %

0.99989 40.0 %

0.99995 DOBNRPC XI.S Table 3-8 3n/966:20 PM

Tatdo 3-9 Byron Unit-1 Analysis of RPC Data from 1994 and 1995 Inspections Comtdned Data from AR Four Steam Generators Total Total Total Total Percent 5

MS Group ofIndcations Bobtwn Bobbin RPC RPC RPC Indcation Indk tv.

Inspected Cv.T...=1 Confirmed Lees than or Equal to 1.0 Volt in 1996 94 Bobtxn Left in Service 1651 1561 17 8

47.1

- 94 RPC Confirmed 11 11 0

0

- D4RPC NDD 89 89 11 3

27.3

- 14 RPC Not inspected 1461 1461 6

5 83.3

- nod 5Bobb C 90 New D5 Indication 2669 46 17 37.0 Sum of At 95 Indication 1651 4230 63 25 39.7 Greater than 1.0 Volt in 1996 D4 Bobbin Left in Service 594 587 122 116 95.1

- D4 RPC Confirmed 6

6 2

2 100.0

- 14RPC NDO 60 60 16 10 62.5

- 14 RPC Not inspected 521 521 104 104 100.0

- No 95 Bobbin

7 New15 Indication 188 34 25 73.5 SumofM 95 Indication 594 775 156 141 90.4 All Voltages in 1996 "M Bobbin Letin Serece 2245 2148 139 124 89.2

- 94 RPC Confirmed 17 17 2

2 100.0

- 14RPC NDD 149 149 27 13 48.1

- D4 RPC Not inspected 1982 1982 110 109 99.1

- No '95 Bobbin

97 New D5 Indicaten 2857 80 42 52.3 Sum of M D5 Indication 2245 5005 219 166 75.8

Indications split is based on '94 bobbin voltage 3-16

s w

e EsflCj53E e

w 1

1 1

2 2

2 4

6 8

0 2

4 6

8 0

2 4

6 0

0 0

0 o

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i o,

o, l

o, B

o, ob b

o, in V

o, o

lt a

o, E

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D o,

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T1 o e -

r r 1 o

l u9 ta 9

g b 5 e

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Sa eg r e v

ic e

m -

D u

r i

m, '

n g

m, C

y c

l a,

e 7

l A

a, o,

B B

O 5

S S

G G

m,

^

D C

B A

a, m,

i il e

L

Number ofIndications o

u o

G O

d d

8 x

0.2 0.3 unummmum mmmmmm 0'4 0'5..N W

0.6 o

E 0.7 I'

.P

<o 0.8 RIMMMhuummmmme mmmmmun m

~immmmmmupu 5

0.9 ge m,

d.

I e$

mamm aC 1.1 O E.

o, 5 1.2 3

co m

-r H=1 L

g. 1.3

['4g 8

=

e

.g s

5* l 4

.m__,

3gY

,N

8. $

1.5 9

.==

m Es@

1.6 1.7 9

1.8 h

4 1.9 b

a a

3 2

o.

m m

m 2.2 O

O O

O.

i i

D O

N k

2.4 %

2.5 m

2.7..g

.E 3

l l

l

l Fipn L3 Byron Unit -1 November 1995 Outage Bobbin Voltage Distributions for Tubes Returned to Service for Cycle 7B 260 240 220 200 ESG-A 180-3 OSG-B

.g 160 -

5 i

j 140 l -

l -

l l

B SG -C 120-

.p-l -

100-ESG-D Z

80 i

60 -

l -

l i

40 --

l' 20 -

t d.

.( l.I

.I &. A.fli.. rt. _.. _, n,_ _. -

.m 0

0.20.30.40.50.60.70.80.9 1

1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2 2.1 2.22.32.42.52.62.7 3

Bobbin Voltage ammem.sr4 s-s 3-19

lll C

S

--+

A B

C D

- 7

- C G

G G

G S

S S

S O

B E

E C

8 A

t 7

-- C e

lc

- 9 yC

-+

gn C

i r

- O u

I D

5 e I

9 c

- C i

9 v 1 r 1

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1 t

rS a

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b n I

P i

t 4 ms r

- e e H

op 3 vb l

l p

e o u u

0 rNT u

l S

2-r e

g1 o

b 3

i Ft f H

u 0

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s n n Uo 1

i nto u I

rb yi H

r Bt 9

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l I

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5 t

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==

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9 8

7 6

5 4

3 2

1

(

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3g iF

4.0 Database Applied f(r IPC Correlations The database used for the IPC correlations that are applied in the analyses of this report are an updated version of the IPC database described in Reference 8-3.

Model Boiler specimen 598-1 is excluded from the IPC database based on application of EPRI data exclusion criterion for very high voltage indications and concurrence by the NRC.

Byron-1 and Braidwood-1 pulled tube 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 less than 60% and there are less than 2 remaining uncorroded ligaments. Plant S pulled tube indication R28C41 is included in the leak rate correlation at a SLB leak rate of 24961ph consistent with NRC recommendations.

Recently, South Texas pulled tube data have been added to that IPC database per NRC request. The updated database 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. The updated IPC database was used to perform the SLB leak rate and tube burst probability analyses reported here, sNpebe95W7B_90 day.wp5 4-1

5.0 SLB Analysis Methods Monte Carlo analyses are used to calculate the SLB leak rates and tube burst probabilities for both actual EOC-7A and projected EOC-7B voltage distributions.

The Monte Carlo analyses account for parameter uncertainty and they are consistent with the Byron Unit-1 SER. The analysis methodology is described in Braidwood-1 document Reference 8-1 as well as in the Westinghouse generic methods report of Reference 8-2.

In general, Monte Carlo analyses include POD adjustments, voltage growth and NDE uncertainties in the projected analyses for the next operating cycle while only NDE uncertainties are included in the analyses based on the actual measured voltage distribution (for the cycle just completed). 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 satis 6ed and the correlation is applied for the leak rate analyses of this report.

Two sets of evaluations were performed for this outage evaluation - the first set for i

the Return-to-Power (RTP) evaluation in December 1995 (Reference 8-7) and the second set for this 90 Day evaluation. To apply the recently NRC approved 3 volt IPC for Byron Unit-1 Cycle 7B operation, tube support plates (TSP) are locked by performing tube expansion on the hot leg side during the recent outage. Therefore, SLB leak rates and tube burst probabilities for the 90 day report were calculated considering the locked TSP condition. With TSP's locked by tube expansion, indications in the hot leg side are restrained from bursting so the burst probability calculations are based only on indications found on the cold side. Since only a small fraction of the indication population are on the cold leg side, the burst probability is expected to be substantially smaller than estimated with the usual IPC/APC methodology (which includes the entire indication population). SLB leak rates and tube burst probabilities for the RTP report were calculated considering conditions both before and after TSP locking; although the analysis without TSP locking assumption is the reference analysis, since a 1 volt IPC applied to Cycle 7A operation.

Comparisons of the leak rates and tube burst probabilities calculated by both methods using the actual voltage distributions are made with the corresponding prior projections for EOC-7A.

.:\\ ape \\cae95\\cyTB 90 day.wp5 5-1

6.0 Bobbin Voltage Distributions This section describes salient input data used to calculate EOC bobbin voltage distributions and presents the results of calculations to project EOC-7B voltage distributions. Also, EOC-7A voltage distributions projected based on the EOC-6 inspection bobbin voltage data are compared with the actual bobbin distributions from the current inspection.

6.1 Calanlation of Voltage Distributions The analysis for EOC voltage distribution starts with a cycle initial voltage distribution which is projected to the end of cycle conditions based on the growth rate and the anticipated cycle operating period. The number of indications assumed in the analysis to project EOC voltage distributions, and to perform tube leak rate and burst probability analyses, is obtained by adjusting the number of reported indications to account for detection uncertainty and birth of new indications over the projection period. This is accomplished by using a Probability of Detection (POD) factor, which is defined as the ratio of the actual number of indications detected to total number ofindications present. A conservative value is assigned to POD based on historic data, and the value used herein is discussed in Section 6-2. The calculation of projected bobbin voltage frequency distribution is based on a net total number ofindications returned to service, defined as:

Nu ars = N / POD - N,,,u + Nupi g i

where, Nu ars =

Number of bobbin indications being returned to service for the next cycle N,

Number of bobbin indications (in tubes in service) identified

=

after the previous cycle POD Probability of detection

=

N,,,,i,,,

=

Number of N which are repaired (plugged) after the last cycle i

Na,,ig = Number of N, which are deplugged after the last cycle and are returned to service in accordance with IPC applicability.

There are no deplugged tubes returned to service at BOC-7B.

The methodology used in the projection of bobbin voltage frequency predictions is described in Reference 8-2, and it is essentially the same as that used in performing similar predictions during the last (EOC-6) inspection. Salient input data used for projecting EOC-7B bobbin voltage frequency are further discussed below.

a:\\ ape \\cae95\\cy7B_90 day.wp5 6-1

6.2 Pmbability of Detedian (POD)

The Generic Letter 95-05 (Reference 8-4) requires the application of a constant POD value of 0.6 to define the BOC distribution for the EOC voltage projections, unless an alternate POD is approved by the NRC. A POD value of 1.0 represents the ideal situation where all indications are detected; a voltage-dependent POD may provide a more accurate prediction of voltage distributions consistent with IPC/APC experience. In addition to a constant POD of 0.6, a voltage dependent POD developed for EPRI is also used. The EPRI POD is based on expert opinion and multiple analyst's evaluation for plants with 3/4" diameter tubes, and it represents the lower 95% confidence bound. This POD distribution is graphically illustrated in Figure 6-1.

6.3 Limiting Growth Rate Distribution As discussed in Section 3.2, the NRC guidelines in Generic Letter 95-05 stipulate that the more conservative growth rate distributions from the past two inspections should be utilized for projecting EOC distributions for the next cycle. Since growth rates for Cycle 6 are higher than those of Cycle 7A, Cycle 6 growth rate distribution is used to develop the EOC-7B predictions. The actual growth distribution used for EOC-7B projections is a worst case hybrid growth distribution which envelopes the highest average growth on a SG basis as well as the highest growth increment during Cycle 6. This limiting growth distribution was developed during the EOC 6 inspection for projecting EOC distributions for Cycle 7A. The same conservative growth distribution was imposed on all four steam generators to provide a conservative basis for predicting EOC-7B performance. In addition, as discussed in Section 3.2, it is conservative to apply the same conservative growth rate distribution for the cold leg indications.

6.4 Cyde Operating Period The operating periods used in the growth rate /EFPY calculations and voltage projections are:

Cycle 6 BOC-6 to EOC-6

- 466.4 EFPD or 1.277 EFPY (actual)

Cycle 7A - BOC-7 to MOC 317.4 EFPD or 0.869 EFPY (actual)

Cycle 7B - MOC-7 to EOC 116.1 EFPD or 0.318 EFPY (estimated) 6.5 Prtieded EOC-7B Voltage Distribution Calculation of the predicted EOC-7B bobbin voltage distributions was performed for all four SGs based on the EOC-7A distributions shown in Table 61. The snapc\\cae95\\cy7B 90 day.wp5 62

bobbin voltage distributions are shown separately for hot leg and cold leg indications in Table 6-1; since tube burst analyses need only be performed for the cold leg indications (locked TSPs constrain rupture of hot leg indications). The beginning of cycle distributions were adjusted to account for probability of detection as described above, and the adjusted number ofindications at BOC-7B are also shown in Table 6-1. Calculations were performed using a constant POD of 0.6 as well as the EPRI POD distribution. A conservative hybrid growth distribution which envelopes the highest average growth rate on a SG basis as well as the largest growth rate observed for Cycle 6 operation, shown in Table 3-7, was used. The IPC voltage distributions projected for EOC 7B for all four SGs are summarized on Table 6-2. These results are also shown graphically on Figures 6-2 to 6-5.

Only 8 indications were found on the cold leg side for all four SGs combined during the EOC-7A inspection, two of them were removed from service due to tube repairs, and the total at EOC-7B is projected to be about 11 for a POD of 0.6.

Because of their small population, results for cold leg indications are combined with the hot leg results in Table 6-2 and Figures 6-2 to 6-5. The results based on a constant POD of 0.6 are more conservative than those using the voltage-dependent EPRI POD.

Although SG-C has the largest number of indications at BOC-7B, SG-B has a few more larger indications (over 2 volts) than SG-C and, consequently, SG.B is predicted to be the limiting SG.

6.6 Cornparison of Adual and Prqieded EOC-7A Voltage Distributions Table 6-3, and Figures 6-6 and 6-7 provide a comparison of the EOC-7A actual measured bobbin voltage distributions with the corresponding projections performed using the last (EOC-6) inspection bobbin voltage data.

EOC-7A projections based on a constant POD of 0.6 as well as the voltage-dependent EPRI POD are shown. As reported in Reference 8-5 at BOC-7A, SG-C was projected to be the limiting SG. A comparison of the actual and projected voltage distributions show that the indication population above 0.9 volts is substantially overestimated in the projections based on a constant POD of 0.6. This POD value is conservative for voltages above about 1 volt but non conservative below 1 volt. The voltage-dependent EPRI POD shows a much better agreement with the actual measured distribution; although the projected distribution is still conservative.

The conservatism in the projections for voltages above 0.9 volts using the EPRI POD is attributed to utilization of a conservative growth rate distribution that bounds the highest average voltage growth observed as well as the largest voltage growth, which occurred in different SGa.

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Table 8 -2 Byron Unit-1 November 1995 Voltage Distribution Projection for EOC - 7B Combined Data for Hot and Cold Leg Indications steem Generator A steamGenerator a steam Generator c steam Generator D y

Projected NumberofIndications at EOC-7B pod EM POD EM POD EM POD Em 0.6 POO 0.6 POD 0.4 POO 0.6 POD 0.1 0.04 0.08 0.06 0.10 0.09 0.17 0.04 0.00 0.2 3.87 6.94 5.84 10.14 7.99 14.34 5.24 9.39 0.3 31.21 45.03 59.96 84.87 50.86 73.99 45.80 69.43 0.4 101.87 125.12 176.41 216.57 145.99 178.35 122.31 158.07 0.5 174.25 191.99 275.86 304.22 267.79 291.03 169.40 192.71 0.6 205.86 208.29 321.14 326.13 345.15 348.09 174.67 179.75 0.7 194.50 183.90 330.11 310.61 349.96 330.96 160.02 151.31 0.8 163.95 145.94 304.59 269.50 317.05 281.35 133.35 116.86 0.9 134.25 111.37 255.95 213.55 265.82 222.47 104.62 84.98 1.0 107.24 83.09 202.14 159.49 212.97 168.81 80.24 60.79 1.1 82.46 61.26 153.69 114.65 166.06 125.47 60.81 43.06 1.2 62.89 44.75 113.00 79.84 127.31 92.47 45.64 31.39 1.3 47.71 32.73 81.77 55.05 95.99 67.41 33.96 22.66 1.4 35.26 23.63 57.87 36.97 71.22 48.52 25.24 16.38 1.5 25.40 16.83 41.58 25.10 51.60 34.30 18.88 11.88 1.6 18.06 11.63 30.16 17.70 36.48 23.60 14.19 8.58 1.7 12.96 8.22 22.70 13.02 25.39 16.07 10.84 6.41 1.8 9.47 5.94 17.32 10.00 17.57 10.88 8.40 4.91 1.9 6.98 4.36 13.64 7.83 12.22 7.50 6.49 3.80 2.0 5.13 3.20 10.09 6.22 8.63 5.26 4.95 2.93 2.1 3.80 2.37 8.41 4.96 6.25 3.83 3.78 2.21 2.2 2.78 1.76 6.68 3.94 4.64

-2.84 2.87 1.69 2.3 2.04 1.32 5.19 3.10 3.54 2.16 2.21 1.30 2.4 1.54 1.00 4.00 2.44 2.78 1.71 1.75 1.05 2.5 1.14 0.75 3.20 1.96 2.25 1.37 1.44 0.84 2.6 0.85 0.59 2.54 1.57 1.85 1.15 1.22 0.71 2.7 0.69 0.51 2.10 1.34 1.59 1.04 1.10 0.68 2.8 0.65 0.53 1.88 1.31 1.45 1.02 1.11 0.77 2.9 0.65 0.55 1.74 1.23 1.39 1.04 1.06 0.70 3.0 0.00 0.48 1.48 1.05 1.27 0.97 0.91 0.57 3.1 0.50 0.37 1.24 0.89 1.05 0.79 0.76 0.47 3.2 0.40 0.00 1.05 0.71 0.84 0.61 0.62 0.31 3.3 0.33 0.00 0.79 0.53 0.64 0.45 0.47 0.00 3.4 0.04 0.70 0.60 0.27 0.48 0.00 0.31 0.70 3.5 0.00 0.00 0.43 0.00 0.21 0.00 0.00 0.00 3.6 0.70 0.30 0.00 0.00 0.00 0.70 0.70 0.00 3.7 0.00 0.00 0.70 0.70 0.00 0.00 0.30 3.8 0.00 0.70 0.00 0.00 0.30 0.00 3.9 0.30 0.00 0.30 0.30 0.30 4.0 0.30 TOTAL 1440.37 1325.93 2516.90 2287.86 2607.37 2361.11 1245.68 1188.28

>1V 323.33 223.58 584.84 392.68 643.70 451.55 249.99 164.90

> 3V 2.27 1.37 5.11 3.40 4.22 2.94 3.16 1.78 6-6 mammeweswa.u

l i

Table 64 (Sheet 1 of 2)

Byron Unit 1 November 1995 Comparison of Predicted and Actual EOC-7A Voltage Distributions SteamGenerator A SteamGenerator B SteamGenerator C SteamGenerator D Number ofIndice6one EOC-7A Preelsson EOC45 EOC-7A Pre 4Ption ROC 48 EOC-7A Pimacean EOC45 EOC-FA Proulceon EOC45 venseo

^~

=

POo.r.

E.,e o 0.1 0.02 0 04 0

0.01 0.01 0

0.00 0.00 0

0.02 0.04 0

0.2 1.50 2.55 6

0.39 0.64 8

0.17 0.23 13 1.21 2.06 5

0.3 14.43 20.55 47 4.19 5.77 95 3.62 4.74 71 8.25 11.78 21 0.4 41.77

$3.06 132 17.04 20.41 199 15.82 18 43 157 25.81 32.36 89 0.5 75.80 88.78 141 43.50 47.67 209 39.88 43.65 251 50.21 57.36 141 0.6 103.31 113.22 149 80.19 82.31 221 70.89 72.81 225 69.94 75.52 145 0.7 118.14 121.74 98 114.88 111.86 216 101.24 -

96.62 214 80.06 82.64 144 0.8 121.64 118.60 86 138.76 128.46 171 124.43 114.90 171 82.50 80.92 136 0.9 116.80 106.37 79 148.73 131.27 124 137.27 119.89 129 78.68 73.39 111 1.0 105.30 91.94 50 145.64 122.79 95 137.46 114.42 101 69.73 62.32 88 1.1 88.92 73.46 32 132.17 105.98 72 126.20 99.83 78 57.79 49.17 63 1.2 72.16 54.98 37 111.68 84.40 56 107.20 80.28 54 45.79 36.95 36 1.3 55.58 39.35 22 89.00 63.03 39 85.78 60.16 39 34.68 26.64 36 1.4 42.40 27.15 11 68.39 44.87 16 65.65 42.72 35 25.88 18.55 19 1.5 31.30 18.73 7

50.85 31.02 26 49.17 29.26 14 19.10 12.06 13 1.6 23.37 12.87 10 36.95 20.96 15 36 09 19.42 14 13.80 8.70 5

1.7 17.42 8.85 3

26.46 14.05 5

26.39 12.88 11 10.05 6.04 7

1.8 12.86 6.05 4

18.75 9.49 11 19.53 8.61 5

7.28 4.18 4

1.9 9.38 4.12 4

13.24 6.46 9

14.64 5.87 2

5.00 2.78 2

2.0 6.89 2.76 1

9.30 4.41 2

11.05 4.09 3

3.52 1.88 1

2.1 5.45 1.90 0

6.50 2.98 2

8.34 2.90 2

2.41 1.22 0

2.2 4.20 1.29 0

4.56 2.00 4

6.22 2.03 2

1.60 0.82 1

]

2.3 3.26 0.88 2

3.24 1.32 1

4.67 1.42 0

1.05 0.53 0

2.4 2.59 0.58 0

2.33 0.86 3

3.41 1.00 0

0.70 0.36 1

2.5 2.06 0.40 0

1.71 0.56 0

2.59 0.67 2

0.46 0.25 0

2.6 1.54 0.26 0

1.33 0.38 0

2.02 0.47 0

0.33 0.17 0

2.7 1.28 0.20 0

1.08 0.27 1

1.55 0.34 2

0.22 0.12 1'

8 2.8 1.01 0.15 0

0.87 0.20 0

1.23 0.25 0.17 0.10 2.9 0.81 0.13 0

0.71 0.15 0

0.97 0.18 0.13 0.07 3.0 0.69 0.11 0

0.59 0.12 2'

O.77 0.14 0.12 0.06 3.1 0.55 0.09 0

0.49 0.10 0.61 0.11 0.11 0.05 3.2 0.47 0.08 1'

O.40 0.09 0.50 0.10 0.12 0.05 3.3 0.43 0.08 0.34 0.00 0.40 0.00 0.11 0.05 3.4 0.39 0.07 0.28 0.06 0.34 0.00 0.12 0.05 3.5 0.34 0.08 0.24 0.08 0.29 0.08 0.12 0.05 3.6 0.31 0.07 0.20 0.06 0.26 0.07 0.12 0.05 3.7 0.28 0.07 0.17 0.08 0.25 0.07 0.12 0.05 3.8 0.26 0.07 0.16 0.07 0.23 0.07 0.12 0.04 3.9 0.25 0.07 0.14 0.08 0.22 0.07 0.12 0.05 4.0 0.23 0.08 0.14 0.06 0.23 0.07 0.12 0.06 Table continue 8 on the next page

Bn wah 1he ler9est Indicehon found in the steem generator 6-7

i

)

Table 6-3 (Sheet 2 of 2)

Byron Unit 1 November 1995 Comparison of Predicted and Actual EOC-7A Voltage Dietributions SteamGenerator A SteamGenerator B SteamGenerator C SteamGenerator D Number of Indicadons EOC-7A Puedomen EOC48 EOC-7A Pio46seen EOC-as EOC-7A Pvesceon EOCJS EOC 7A Prediction EOC45 venne.

Sin gpg Actual gpg Actual EPg Actual Actual POo = ec POo = e.s POD e 0.6 POO = 0.8 EPR POO POD 4.1 0.23 0.12 0.15 0.09 0.23 0 08 0.14 0.08 4.2 0.27 0.16 0.17 0.12 0.23 0.11 0.18 0.11 4.3 0.31 0.21 0.22 0.17 0.25 0.15 0.20 0.14 44 0.32 0.24 0.27 0.21 0.28 0.19 0.21 0.16 4.5 0.33 0.26 0.31 0.25 0.31 0.22 0.22 0.17 4.6 0.31 0.26 0.35 0.27 0.34 0.24 0.22 0.17 4.7 0.34 0.26 0.37 0.26 0.35 0.26 0.23 0.17 48 0.31 0.25 0 38 0.28 0.34 0.26 0.21 0.17 49 0.26 0.23 0.37 0.27 0.34 0.25 0.21 0.16 5.0 0.25 0.21 0.35 0.25 0.31 0.23 0.17 0.13 6.1 0.22 0.17 0.32 0.23 0.29 0.21 0.15 0.11 5.2 0.16 0.14 0.29 0.19 0.25 0.18 0.13 0.10 6.3 0.17 0.11 0.24 0.16 0.22 0.15 0.11 0.08 54 0.12 0.00 0.21 0.13 0.18 0.12 0 09 0.07 5.5 0.12 0.06 0.17 0.10 0.15 0.10 0.08 0 05 58 0.10 0.07 0.15 0.00 0.13 0.08 0.06 0.05 57 0 09 0 06 0.12 0.08 0.11 0.07 0.06 0.05 58 0.08 0.06 0.11 0 07 0.13 0.06 0.05 0.04 59 0 07 0.06 0.10 0.07 0 09 0.06 0.05 0.04 60 0.13 0.06 0.09 0.06 0 09 0.06 0 04 0 04 6.1 0.14 0.06 0.09 0.06 0.08 0.06 0.05 0.04 6.2 0.17 0.06 0.06 0.06 0.09 0.05 0.04 0 03 63 0.14 0.06 0.06 0 06 0.07 0.06 0.04 0 04 6.4 0.12 0.05 0.08 0 06 0.08 0.06 0.04 0.04 6.5 0.11 0.06 0 08 0 06 0.07 0.05 0.03 0 04 66 0.12 0 05 0.06 0.06 0.07 0.06 0.04 0.04 67 0 09 0 06 0.07 0.06 0.07 0.05 0.04 0 04 6.8 0 07 0.06 0 06 0 06 0.07 0.05 0 04 0.04 6.9 0 09 0.06 0.07 0.06 0.08 0.05 0.04 0.05 7.0 0.13 0.10 0.00 0.07 0.08 0.06 0.06 0.00 7.1 0.19 0.22 0.12 0 12 0.12 0.11 0.03 0.00 7.2 0.34 0.15 0.19 0.19 0.19 0.17 0.00 0 00 7.3 0.32 0.00 0.28 0.26 0.24 0.17 0.00 0.70 7.4 0 33 0.70 0.29 0.03 0.26 0.00 0.70 0.00 75 0.26 0.00 0.13 0.00 0.26 0.00 0.00 0.00 76 0.21 0.00 0.00 0.70 0.24 0.70 0.00 0.30 7.7 0.22 0.30 0.70 0.00 0.20 0.00 0.30 7.8 0.19 0.00 0.30 0.12 0.30 7.9 0 01 0.30 0.00 80 0.00 0 00 8.1 0,70 0.00 86 0.00 0.70 88 0.30 0.00 11.7 0.30 70TAL 1093.67 978.92 922 1283.33 1050.88 1602 1215.36 906.10 1595 702.62 653.59 1069

>1V 304.96 200 07 131 569.91 399.80 264 584.78 378 41 263 235.61 175.20 189

>3V 11.97 5 85 1

10.11 6.40 0

11.31 5.89 0

5.44 3.95 0

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Figure 6 - 2 Byron Unit-1 SG A Predicted Bobbin Voltage Distribution for Cycle 7B Combined Data for Hot and Cold Leg Indications POD = 0.6 2So 200 O BOC-7B so u Pmdicted Eoc.7s i

1 100 so IL.

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Figure 6 - 3 Byron Unit-1 SG B Predicted Bobbin Voltage Distribution for Cycle 7B Combined Data for Hot and Cold Leg Indications POD = 0.6 4c0 350 300

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O BOC-78 250 a Predicted EOC-7B 2c0

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j iso 100 50 0

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POD = EPRI 400 350 300 0 BOC-78 2s0 a Predicted EOC-7B 200 1s0 100 50 I L.___ ____

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Figure 6-4 Byron Unit-1 SG C Predicted Bobbin Voltage Distribution for Cycle 7B Combined Data for Hot and Cold Leg Indications POD = 0.6 450 400 350 D BOC-75 300 250 M Predicted EOC-75 200 150 100 so--

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Figure 6 - 5 Byron Unit-1 SG D Predicted Bobbin Voltage Distribution for Cycle 7B Combined Data for Hot and Cold Leg Indications POD = 0.6 2bo 2co asoc-7s

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7.0 SLB Tak Rate and Tube Burst Pmbability Analyses This section presents results of analyses carried out to predict leak rates and tube burst probabilities for postulated SLB conditions using the actual voltage distributions from EOC-7A inspection as well as for the projected EOC-7B voltage distributions. The methodology used in these analyses is described in Section 5.0.

For the TSP locked condition during Cycle 7B (to support a 3 volt IPC), analyses were performed separately fcr the indication population on the hot leg and cold leg sides of each generator since only indications on the cold leg are to be considered for tube burst probability analysis. As discussed in Section 6.5, although SG C has the largest number ofindications on the hot leg side, SG-B is expected to yield the limiting SLB leak rate for Cycle 7B since it has a few more larger (over 2 volts) indications returned to service than SG-C (10 in SG-B vs 6 in SG-C, see Table 6-1) and the SLB leak rate is primarily dependent on the larger indications. SG-A with the largest number of indications on the cold leg side is expected to be limiting from the tube burst probability standpoint.

7.1 Imk Rate and Tube Burst Pmbability for EOC-7A Analyses to calculate EOC-7A SLB leak rate and tube burst probabilities were performed using the actual bobbin voltage distributions presented in Table 3-1 (all indications together) and Table 6-1 (separately for hot leg and cold leg indications).

These analyses considered both conditions prior to and after TSP locking (for application of a 3 volt IPC). Results of Monte Carlo calculations are summarized on Table 7-1. Free span analyses (without TSP locking) are the reference analyses for Cycle 7A and their results are to be compared with the allowable limits.

The report prepared for the last (EOC-6) inspection, Reference 8-5, contains EOC-7A projections only for the limiting SG, which is SG-C. Leak rate and burst probability projections for EOC-7A were performed for all four SGs during this outage to enable comparison of results based on actual measured bobbin voltage distributions with those projected using the prior inspection data. Comparison of the EOC-7A actuals with the corresponding predictions indicates that:

a)

For a POD of 0.6 SG-C was predicted to be the most limiting steam generator for EOC-7A based on a voltage distribution projection performed during the EOC-6 inspection. However, SG-B was predicted to be the limiting steam generator for EOC-7A for the EPRI POD.

b)

SG-B was determined to have the highest tube leak rate and tube burst probability based on actual EC bobbin measurements for EOC-7A, although the absolute differences in the results for SG-B and SG-C are small, c)

The leak rate and tube burst probability predictions for the projected EOC-7A indication population distribution, based on the EOC 6 inspection data, s:\\ ape \\cae95Ncy7B_90 day.wp5 7-1 l

are very conservative for all four SGs compared to the corresponding values calculated using actual measured bobbin measurements for EOC-7A (by a factor of at least 14). The large differences between projections and actuals are attributable to a reduction in voltage growth. Figures 6-5 and 6-6 show the actual and projected EOC-7A bobbin distributions used in the leak rate and burst analyses. The projected indication population based on EPRI POD being greater than the measured population above 0.9 volts indicates that the actual growth rates in Cycle 7A were below the growth rates assumed for projections (Cycle 6 rates). A comparison of Cycle 6 and Cycle 7A growth data shown in Figure 3-6 and Table 3-3 confirms this. The use of a constant POD of 0.6, per the GL 95-05 requirement, results in further overestimation of indication population in higher voltage bins, and consequently, introduces additional conservatism in the results.

d)

The leak rate and tube burst probability predictions for all four SG's based EOC-7A bobbin measurements are well within the allowable limits.

e)

With TSP's locked, tube burst probability decreases by more than two orders of magnitude.

f)

The effect of indications restrained from burst on the SLB leak rate compared to free span analysis is negligible due to the low free span tube burst probability for the actual distributions.

In summary, the free span SLB leak rate and tube burst probability calculated using the actual EOC-7A bobbin voltage distributions for all four SGs are far below the corresponding projections assuming a voltage distribution based on the NRC SER endorsed probability of detection of 0.6 (by at least a factor of 14). Limiting values for SLB leak rate (0.075 gpm) and tube burst probability ( 1.3 x 10 ) were 4

calculated for SG-B. These results are much lower than the allowable Cycle 7A SLB leakage limit of 12.5 gpm and the NRC reporting guideline of 10'8 for the tube burst probability. The major impact of restraining indications on the hot leg side from bursting is to decrease the tube burst probability by over two orders of magnitude.

7.2 14ak Rate and Tube Burst Probability for EOC-7B Calculations to predict the performance of the limiting steam generator in Byron Unit-1 at EOC-7B conditions were carried out using two values for POD: 1) NRC required constant value of 0.6,2) voltage dependent EPRI POD distribution. The methodology used in these predictions is the same as previously described for EOC-7A. Results of the EOC-7B predictions are summarized on Table 7-2. With a constant POD of 0.6, the projected limiting EOC-7B SLB leak rate is 0.25 gpm and s:\\apc\\cae95\\cy7B_.90 day.wp5 72

it is predicted for SG B. The tube burst probability for all four SGs are below 4.0x10 8 These limiting values are much lower than the allowable SLB leakage limit for Cycle 7B of 12.5 gpm and the NRC reporting guideline of 102 for the tube burst probability.

1 1

i E

a:\\ ape \\cee96W1B_90 day.wp5 7-3

l Table 7-1 Bym1 Unit-1 1995 EOC. 7A Outsee Summary of Caladations dTube IAak Rate and Burst Penhahility Based on Adual Bobbin Voltage - 250k Sinndations Burst PenhahiHty SLB Steam Number

Max, Imk Generator POD ofIndi-Volts

1 Tube 2 Tubes Rate oations gym EOC - 7A PROJECTIONS Based an EOO4 Iw:en Data

A 0.6 1094 8.8 2.58x10- 8 5.53x10

2.50 EPRI 979 7.7 1.12x10' 8 4.07x10

1.22 B

0.6 -

1283 7.9 2.01x10' 8 3.33x10*

1.94 EPRI 1051 7.8 1.48x10' 8 1.04x10 4 1,44 C

0.6 1215 11.7 3.94x10 8 8.85x10'

3.69 EPRI 966 7.8 1.33x10' 8 2.08x10

1.29 D

0.6 703 7.7 9.17x10' *

< 4.0x10

O.95 EPRI 654 7.6 9.28x10' 8 1.90x10' '

O.87 EOC - 7A AUIVAL (Free Span - With Displaced Tube Support Plates)

A 1

922 3.5 1.07x10

< 4 x10

O.000 B

1 1602 3.5 1.30x10 8

< 4 x10

O.075 C

1 1595 3.2 5.33x10

< 4 x10

O.064 D

1 886 3.5 6.49x10

< 4 x10

O.056 EOC - 7A AUIVAL (Tube Suppet Plates Assim=1 I/wirarf)

Hot Side 1

919 3.5 Negligible

Negligible

0.060 A

Cold Side 1

3 0.7

< 4 x10

1x10' '

Total 922 3.5

< 4 x10

O.06 Hot Side 1

1599 3.5 Negligible

Negligible

0.075 B

Cold Side 1

3 1.3 1.90x10

< 4 x10

1x10'

Total 1602 3.5 1.90x10' '

< 4 x10

O.075 Hot Side 1

1594 3.2 Negligible

Negligible

0.064 C

Cold Side 1

1 0.8

< 4 x10

1x10'

Total 1595 3.2

< 4 x10 *

< 4 x10

O.064 Hot Side 1

885 3.5 Negligible

Negligible

0.056 U

Cold Side

-1 1

0.4

< 4 x10

1x 10

Total 886 3.5

< 4 x10 '

< 4 x10-'

-' O.056 Notes.

1 Voltages include NDE uncertainties from Monte Carlo analyses and exceed measured voltages.

2 Based on actual Cycle 7A duration of 317.4 EFPD.

3 Below 10 (Reference 7-4)

/

a:\\ ape \\cae95\\cy7B_90 day.wp5 74

Table 7-2 Byron Unit 1 November 1995 Outage Summary of Projected Tube Leak Rate and Burst Probability for EOC-7B - 250k Simulations Burst 1%bability SLB Steam Na of Max.

Leak Generator POD Indio.

Volts

1 Tube 2 Tubes Rate ations*

gpm EOC - 7B PROJECTIONS Hot Side 0.6 1436 3.9 Negligible

Negligible

0.11 A

Cold Side 0.6 5

0.8

< 4.0x104

< 4.0x104 1x10 0.02 44 Total 0.6 1441

< 4.0x104

< 4.0x104 0.11 Hot Side EPRI 1321 3.6 Negligible

Negligible

0.07 A

Cold Side EPRI 5

0.8

< 4.0x104

< 4.0x104 1x104 Total EPRI 1326

< 4.0x104

< 4.0x104 0.07 Hot Side 0.6 2513 4.0 Negligible

Negligible

0.25 B

Cold Side 0.6 4

1.5

< 4.0x104

< 4.0x104 1x104 Total 0.6 2517

< 4.0x104

< 4.0x104 0.25 Hot Side EPRI 2285 3.9 Negligible

Negligible

0.16 0

Cold Side EPRI 3

1.4

< 4.0x104

< 4.0x104 1x104 Total EPRI 2288

< 4.0x104 4

< 4.0x10 0.16 Hot Side 0.6 2606 3.9 Negligible

Negligible

0.21 C

Cold Side 0.6 2

~1

< 4.0x104

< 4.0x104 1x10-'

Total 0.6 2608

< 4.0x104

< 4.0x104 0.21 Hot Side EPRI 2360 3.8 Negligible

Negligible

0.14 C

Cold Side EPRI 2

~1

< 4.0x104

< 4.0x104 1x10

Total EPRI 2362

< 4.0x104

< 4.0x104 0.14 Hot Side 0.6 1245 3.9 Negligible

Negligible

0.14 D

Cold Side 0.6 1

~0.5

< 4.0x104

< 4.0x104 1x104 Total 0.6 1246

< 4 0x104

< 4.0x104 0.14 Hot Side EPRI 1186 3.7 Negligible

Negligible

0.01 D

Cold Side EPRI 2

0.5

< 4.0x10

< 4.0x104 1x10 4

4 Total EPRI 1188

< 4.0x104

< 4.0x104 0.01 Notes (1) Number ofindications adjusted for POD.

(2) Voltages include NDE uncertainties from Monte Carlo analyses and exceed measured voltages.

(3) Below 10* (Reference 8-6) 4 l

s:\\apc\\cae95\\cy7B_90 day.wp5 7-5

8.0 Refennoes 8.1 WCAP-14047, "Braidwood Unit 1 Technical Support for Cycle 5 Steam Generator Interim Plugging Critoria", 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 Westinghouse Report SG 95-01-003, " Byron Unit 1 End-of-Cycle 6 Interim Plugging Criteria Report,"

Westinghouse Nuclear Service Division, January 1995.

8.4 NRC Generic Letter 95-05, " Voltage-Based Repair Criteria for the Repair

. of Westinghouse Steam Generator Tubes Affected by Outside Diameter Stress Corrosion Cracking", USNRC Office of Nuclear Reactor Regulation, August 3,1995.

8.5 Westinghouse Report SG-95 06 005, "Braidwood Unit-1,1995 Interim Plugging Criteria 90 Day Report," Westinghouse Nuclear Service Division, June 1995.

9.6 ' WCAP-14273, " Technical Support for Alternate Plugging Criteria with Tube Expansion at Tube Support Plate Intersections for Braidwood-1 and Byron-1 Model D Steam Generators," Westinghouse Nuclear Service Division, February 1995.

9.7 Westinghouse Report NSD-SGD-1187, " Byron Unit-1, Interim Plugging Criteria Return to Power Report," Westinghouse Nuclear Service Division, December 1995.

s:\\ ape \\cae95Ney7B_90 day.wp5 7-6 i

.1

ML20101E765

Text

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