ML20113F493
| ML20113F493 | |
| Person / Time | |
|---|---|
| Site: | Braidwood  |
| Issue date: | 09/20/1996 |
| From: | Stanley H COMMONWEALTH EDISON CO. |
| To: | NRC (Affiliation Not Assigned), NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9609240257 | |
| Download: ML20113F493 (9) | |
Text
Commonwealth Iklium Company 1400 Opus Place Downers Grove, IL 605155701 September 20,1996 Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, DC 20555 Attn: Document Control Desk
Subject:
Braidwood Station Unit 1 NRC Docket Number: 50-456 j
Supplement to Response to Request for Additional Information Pertaining to Operating Interval Between Eddy Current Inspections for Circumferential Indications in the Braidwood Unit 1 Steam Generators
References:
1.
H. Stanley letter to the Nuclear Regulatory Commission dated August 2, 1996, transmitting Operating Interval Between Eddy Current Inspections for Circumferential Indications in the Braidwood Unit 1, Steam Generator Tubes i
2.
H. Stanley letter to the Nuclear Regulatory Commission dated August 20,
)
1996, transmitting Operating Interval Between Eddy Current Inspections for Circumferential Indications in the Braidwood Unit 1, Steam Generator Tubes 3.
D. Lynch letter to I. Johnson letter transmitting Requests for Additional j
Information dated September 9,1996, Pertaining to Operating Interval j
Between Eddy Current Inspections for Circumferential Indications in the Braidwood Unit 1 Steam Generators 4.
H. Stanley letter to the Nuclear Regulatory Commission dated September 10,1996, transmitting Response to Request for Additional Information 5.
H. Stanley letter to the Nuclear Regulatory Commission dated September
)
17,1996, transmitting Response to Request for Additional Information
/
l In the Reference 1, the Commonwealth Edison Company (Comed) provided the Nuclear Regulatory Commission (NRC) with the "Braidwood Unit 1 Cycle Length Assessment Report
'i l
Addendum" whichjustified operation of the Braidwood Unit I for a full cycle prior to steam generator tube inspection. This report was supplemented via Reference 2. Reference 3
.,e
=1 9609240257 960920' "
PDR ADOCK 05000456 G
PDR A Unicom Company
l I
I
(
NRC Document Control Desk September 20,1996 transmitted the NRC's Request for Additional Information (RAI) on the elimination of the i
Braidwood Cycle Length.' References 4 & 5 transmitted Comed's response to 21 of the 31 RAls.
A subsequent submittal will be forwarded to the Stafi'to complete Comed's response to the RAI.
f Additional statistical analyses for the evaluation of normalization and coil size correction factors have been completed. This addit'onal work has identified an improved method of determining the l
correction factors. These methods are discussed in response to Questions 19 and 20. The F
attached pages 15 and 16 should supplement the existing pages submitted via Reference 5. The l
attached Tables 19b,19c and 20b have been updated and therefore should supercede Table 19b, 19c,20b and 20c. The attached Figures 19 and 20 have also been updated and therefore should n'
replace Figures 19a,19b,20a and 20b.
If you have any questions concerning this correspondence please contact Denise Saccomando,
'I 4
i Senior PWR Licensing Administrator at (630) 663-7283, Sincere,
/
)V o
Harold Gene Stanley Site Vice President Braidwood Station A' ttachment cc:
D. Lynch, Senior Project Manager-NRR R. Assa, Braidwood Project Manager-NRR C. Phillips, Senior Project Manager-Braidwood A. W. Beech, Regional Administrator-RIII Office of Nuclear Safety-IDNS I
Rc_sintim An evaluation of the application of dic 0.58 nonnalization correction factor to other reflectors in the calibration standard has been performed. The results are shown in Table 19a. The table includes: the other reflectors included in the evaluation, the voltage nonnalized to 10 Volts on a 100% throughwall hole (TWil),
the voltages nomialized to 20 Volts on the 100% axial EDM notch and the ratio of the two voltages. The results indicate that the voltages nonnalized to 10 Volts on a 100% TWH and corrected with a 0.58 correction factor are consistent for the different ref1cetors included in the analysis.
l Furdier assessment of the application of the 0.58 correction factor has been perfonned on the 50 field data points using the voltage integral software to evaluate the impact on the Braidwood Unit I cycle length assessment. The results of this field data assessment are presented in Table 19b for maximum and average volts. The data is provided for analysis of both the 0.115" and 0.080" RPC data nonnalized to 10 volts on the 100% throughwall hole (TWH) and 20 volts on the 100% axial EDM notch. Because industry data was acquired with the both the 0.080" and 0.115" RPC,it is necessary to have a nonnalization correction factor established for each coil size. The previous submittal (September 17,1996) included a single nonnalization correction factor which was detennined from 0.080" RPC data. This nonnalization correction factor was applied to both the 0.080" and 0.115" RPC data. Nomialization correction factors can be detennined for both the 0.115" and 0.080" RPC using the data in Table 19b. A summary of the different methods used for calculation of the nonnalization correction factors is included in Table 19c. A statistical analysis of the licld data (maximum and average voltage combined) has been perfonned using a linear regression analysis. The results from the statistical evaluation indicate that the normalization correction factor is 0.51 and 0.68 for the l
0.080" and 0.115" RPC, respectively, as determined from the slopes of the mean regression lines (see Figure 19).
Two nonnalization correction factors were provided in the September 17,1996 submittal, one for maximum voltage and one for average voltage. The correction factors were nearly the same, and the maximum ami average voltages are put into a single population for detennination of the nonnalization correction factors.
j Normalization correction factors are provided for the 0. I 15" and 0.080" pancake coils for assessment of industry tube pull and insitu pressure test ECT data. The statistical coil size based correction factors provide the most statistically correct result and will be used.
- 20. A 0.76 correction factor was applied to adjust 0.ll5-inch probe coil EC soltages to equivalent 0.080-inch probe coil EC voltages. Describe in detail the development of this correction factor, including a discussion on the number of samples reviewed, the types of defects analyzed, and the mean and standard deviation of the study sample. Additionally, provide the recorded EC voltages, l.
if practical, or the range of circumferentialindication EC voltages included in the sample.
l Provide a statistical analysis based on field data which supports the use of the 0.76 correction factor.
Resnonse:
During a k>ok-back of three hmxtred and fifty 1996 Byron Unit i indications in SG C, analysis of the indications was perfonned using the 0.115" and 0.080" RPC. The kiok-back was perfonned prior to development of the voltage integral software. Because all the 0.080" RPC indications in one SG were included, a rar.ge of indication sizes (0.06 to 1.11,0.080" RPC Volts) is included in the data set. The average of the thn'e hundred and fifty 0.080" RPC voltages (mean of 0.326 Volts) was compared to the average of the 0.115" RPC voltages (mean 0.431 Volts). From this result a scale factor for the 0.115" RPC is calculated from the ratio of the mean voltages or 0.326/0.431 = 0.76. This scale factor was applied to some of the insitu 15 l
F l
pressure test data included in the industry data base diat was collected on 0.115" RPC. The scale factor was not applied to any tube pull burst data points because the data was acquired with the 0.080" RPC. Many of the data points used in the leak rate assessment had the scale factor applied since much of the data was l
obtained from 0.115" RPC. A listing of the data included in the study is provided in Table 20a.
Further assessment of the application of the 0.76 correction factor has been perfomied on 50 field data points using the voltage integral software. The results are presented in Table 19b for maximum and average volts.
In the previous submittal (September 17,1996) the coil size correction factor was detennined from data nomialized to 20 volts on a 100% EDM notch. The data in Table 19b can be used to detemiine a coil size correction factor nonnalizing the data in two ways (10 volts on the 100% TWH and 20 volts on a 100% EDM notch). Because the industry tube pull and insitu pressure test data was nonnalized to 10 volts on the 100%
TWH, this nonnalization is appropriate to use in detennining a coil size correction factor. A summary of the different methods used for calculation of the coil size correction factors is included in Table 20b. A statistical i
analysis of the field data (maximum and average combined) has been perfonned using a linear regression analysis. The results from the statistical evaluation indicate that the coil size correction factor for the field data 0.75 (for nonnalization to 10 volts on a 100% throughwall hole) as detennined from the ratio of the slope l
of the 0.080" and 0.115" RPC mean regression lines from Figure 19. Figure 20 shows the 0. I 15" RPC data corrected using the 0.75 correction factor and the 0.080" RPC data in the same plot. The two data sets are now consistent as detennined by the overlay of the 2 data sets linear regression lines. Therefore, a 0.75 coil l
size correction factor is appropriate.
l l
Two coil size correction factors were pmvided in the September 17,1996 submittal, one for maximum voltage l
and one for average voltage. The corrections factom were nearly the same. The maximum and average
(
voltages can be put into a single population for detennination of the coil size correction factor. Statistical analyses support the statistical 10 V approach as being correct.
- 21. Provide a summary of the essential variables of the inspection techniques as documented in the EC l
acquisition technique sheets (ACTS) and the analysis technique sheets (ANTS) for the Byron Unit i SG EC inspections in 1994,1995, and 1996 and for the 1995 Braidwood Unit 1 SG EC inspections.
Additionally, provide the ACTS and ANTS associated with the SG EC inspections conducted at other plants where data were obtained for use in the SG tube burst and leakage correlation's l
presented in the August 2,1996, submittal. Identify anc discuss how the differences in the acqu sition and analysis of EC data will affed the EC vn!! age nieashi enients iised iii the aiialysis.
Resnonse:
Resportse to be pn vided in subsequent correspondence.
- 22. Some studies have identified a lift off effect in SG tube expansion transitions for gimbaled probes due to SG tube geometry changes. This lift-off can decrease a probe coil's response to SG tube indications. If gimbaled probes were used in any of the inspections where data is used to support the Braidwood Unit I cycle length assessment, explain the basis for not accounting for this affect for EC voltage measurements in expansion transitions. Some of the data in the SG tube burst and leakage correlations were obtained from 56 tubes w hich had been explosively expanded into the SG tubesheet. Describe any differences between the transition geometry, particularly with respect to the length of the expansion of the explosively expanded tubes and that for roll-expanded SG tubes.
Discuss the elTects of the SG tube transition geometry on the recorded EC voltages. Discuss the need to account for liftoffin the EC voltage measurements for both the data used in the proposed j
correlations and the data obtained for the field indications.
l 16
4 Table 19b Field Data for Statistical Analysis of Industry ECT Correction Factors Voltage Normalced @ 10 volts on the 100% TWH Voltage Normalced @ 20 volts on the 100% AXIAL EDM NOTCH
.080 PANCAKE COLL
,115 PANCAKE COIL
.080 PANCAKE CO!L
.115 PANCAKE COIL Row Col Volts VM Max VoltsVM Ava Volts VM Max Volts VM Avo Volts VM Max Volts VM Ava Volts VM Max Volts VM avl 1
10 0.88 0.37 1.01 0.36 0 45 0.19 0.47 0.1f r
18 20 1.23 0.54 1.56 0.69 0 65 029 0.75 0.34
. 25 22 129 0.81 1.75 0.81 0.72 0.46 1.14 0.38 5
24 1.05 0.50 0.96 0 46 0.49 0.24 0.42 0 ".J 40 32 1.00 0.42 1.01 0.48 0.55 023 0.57 0.27 47 31 0.39 0.24 0.58 0.23 0.31 0.14 0.36 0.35
- 42 31 0.49 0.29 0.67 0.34 0.30 0.15 0.39 0 19 41 31 0.94 0.39 1.11 0.52 0.52 0.21 0.63 0.29 13 34 0.75 0.42 0.77 0.39 0.43 024 0 63 0.32
{
45 35 0.85 0.21 0 95 0.28 0.49 0.12 0.78 023 i
35 38 0.35 0.19 0.34 0.19 020 0.11 0.28 0.16 14 41 0.92 0.34 0.80 0.25 0.40 0.14 0.50 0.15 l
21 42 2.62 1.11 2.21 0.87 120 0.51 1.43 0.56 i
38 43 2.10 1.00 1.85 0.84 0.97 0 46 1.21 0.56 39 43 1.22 0.88 1.08 0.68 0.55 0.37 0.70 0 44 17 45 1.35 0 68 1.26 0.71 0.62 0.31 0.81 0.47 26 45 1.22 0.52 1.17 0.55 0.55 024 0.75 0.36 42 59 0.43 027 0.56 0.33 0.21 0.12 0.57 0.27 17 59 0.58 0.19 0.53 0.18 0.32 0.16 0.44 0.18 j
16 60 0.63 0.33 0.65 0.28 0.33 0.18 0.52 0.23 18 61 0.51 0.19 0.68 0.25 0.29 0.10 0.59 0.22 14 60 1.00 0.43 1.17 0.47 0.53 0.22 0.96 0.37 1
13 59 124 0.55 1.23 0.53 0.65 0.28 1.00 0.43 8
61 1.40 0.55 1.59 0.52 0.73 0.29 1.27 0.43 8
60 0.80 0.41 0.76 0.35 0.42 021 0.61 0.28 4
59 0.52 026 0.70 0.37 0.31 0.16 0.52 0.26 4
63 0.52 0.19 0.71 0.32 026 0.11 0.57 025 15 62 1.00 0 49 0.80 0.23 0.52 026 0.66 0.18 16 63 0.75 0.29 0.99 0 40 0.47 0.18 0.87 0.36 19 62 0.69 0.31 0.52 0.23 0.35 0.16 0.22 0.11 20 61 1.15 0.57 1.19 0.41 0.61 0.30 1.06 0.45 25 62 1.11 0.49 0 87 0.33 0.57 0.26 0.71 0.26 28 64 0.79 0.31 0.72 0.21 0.38 0.14 0.92 0.39 37 64 129 0.57 1.30
'O.57 0.67 0.30 1.04 0.46 45 66 1.22 0.59 1.31 0.58 0 64 0 31 1.06 0.41 41 65 1.37 0.58 1.24 0.55 0.67 0.27 0.99 0.44 38 46 1.13 0.27 1.20 0.35 0.69 0.17 0.88 0.26 24 47 1.30 0.61 1.11 0.52 0.79 0.37 0 81 0.38 26 49 0.73 0.34 1.01 0.47 0 43 0 20 0.75 0.35 38 49 1.43 0.58 1.49 0.64 0.86 0.35 1.09 0.47 41 49 1.16 0.50 1.18 0 58 0.71 0.30 0.87 0 43 36 66
-0.42 0.20 0 60 0.36 024 0.11 0.34 0.21 25 65 0.73 0.46 0.61 0.47 0.38 024 0.37 028 20 66 0.55 0.28 0.46 021 0.26 0.12 0.34 0.15 21 65 0.95 0.61 0 89 0.73 0.50 0.32 0.53 0.44 13 64 1.54 0.41 1.68 0.51 0.80 0.21 1.00 0.30 7
65 0.74 0.30 0.54 0.23 0.38 0.15 0.32 0.14 6
66 0 70 0.30 0.69 0.24 0.45 0.20 0.37 0.14 16 67 1.80 0.90 1.83 0.87 0 90 0.45 1.03 0.48 21 69 1 46 0 70 1 69 0 84 0 75 0 36 1 02 0 50 l
l Table 19c Summary of Normalization Correction Factor Determination Methods i
i Result Submittal Data Result Approach Date Data Source Coil Used Max. Volt Avg. Volt Applied to:
Calibration Calibration 0.080" and Standard 8/2/96 Standards 0.080" 0.58 0.115" l
Statistical 0.080" 0.080" and Based 9/17/96 50 Field Ind's 0.080" 0.52 0.51 0.115" Statistical Coil Size Based 9/20/96 50 Field Irid's 0.080" 0.51 0.080" 0.115" 0.68 0.115" i
I l
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1
Figure 19. Voltage Normalization Regression Analysis, 0.080 and 0.115 inch Coils, Maximum and Average Voltage 2.5 3
+
Data from 0.080 inch Coil o
g o
Data from 0.115 inch Coil o 2.0 E
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Regression Line for 0.080 Coil Data (Slope = 0.51)
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Regression Line for 0.115 Coil Data E 1.5 (Stope = 0.68)
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0.0 O.0 0.5 1.0 1.5 2.0 2.5 3.0 Voltage for 10 Volt Normalization,100% TWH, Volts m
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Figure 20. Correlation of 20 Volt to 10 Volt Normalization Data, 0.115 inch /20V Coil Data Adjustified by 0.75 Factor, Average & Maximum Voltage 2.0
- Data from 0.080 inch Coil
.6 o Data Frorn 0.115 inch Coil y
g1.5 (20 Volt Data Adjusted by 0.75)
Regression Line for Data from 0.080 and 0.115 Coils o
(Slope = 0.51) un 6
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51.0 E
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O 0.0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 Voltage for 10 Volt Normalization,100% TWH, Volts
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Table 20b
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Summary of Coil Size Correction Factor l
Determination Methods Result Voltage Submittal Normalization Data Result Approach Date Data Source Used Max. Volt Avg. Volt Applied to:
1996 Look.
20 Volts 100%
10 Volts 100%
Average 8/2/96 Back Data EDM 0.76 TWH Statistical 20 Volts 100%
10 Volts 100%
20V 9/17/96 50 Field Ind's EDM 0.72 0.74 TWH Statistical 10 Volts 100%
10 Volts 100%
10V 9/20/96 50 Field Ind's TWH 0.75 TWH l
-