ML061430258
| ML061430258 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 05/15/2006 |
| From: | Jamil D Duke Energy Corp, Duke Power Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| TAC MC8256 | |
| Download: ML061430258 (12) | |
Text
kDuke W Energy.
D.M. JAMIL Vice President Catawba Nuclear Station 4800 Concord Rd. / CNO1 VP York, SC 29745-9635 803 831 4251 803 831 3221 fax May 15, 2006 U.S. Nuclear Regulatory Commission Attention:
Document Control Desk Washington, D.C. 20555
Subject:
Duke Power Company LLC d/b/a Duke Energy Carolinas, LLC (Duke)
Catawba Nuclear Station, Unit 1 Docket Number 50-413 Reply to Request for Additional Information Concerning Steam Generator Outage Summary 180-Day Report for End of Cycle 15 Refueling Outage
Reference:
Letter from Duke Energy Corporation to NRC dated November 28, 2005 Please find attached Catawba's reply to the subject Request for Additional Information (RAI).
The RAI was received on April 6, 2006 via electronic mail.
The format of the attachment is to restate the RAI question, followed by our reply.
There are no regulatory commitments contained in this letter or its attachment.
If you have any questions concerning this material, please call L.J. Rudy at (803) 831-3084.
LJR/s Attachment A00D(
www. duke-energy. corn
Document Control Desk Page 2 May 15, 2006 xc (with attachment):
W.D. Travers, Regional Administrator U.S. Nuclear Regulatory Commission, Region II Atlanta Federal Center 61 Forsyth St.,
SW, Suite 23T85
- Atlanta, GA 30303 E.F. Guthrie, Senior Resident Inspector U.S. Nuclear Regulatory Commission Catawba Nuclear Station J.F. Stang Jr., Senior Project Manager (addressee only)
U.S. Nuclear Regulatory Commission Mail Stop 8 H4A Washington, D.C. 20555-0001
ATTACHMENT REPLY TO NRC REQUEST FOR ADDITIONAL INFORMATION
REQUEST FOR ADDITIONAL INFORMATION CATAWBA UNIT 1, CYCLE 15 STEAM GENERATOR TUBE INSERVICE INSPECTIONS TAC NO.
MC8256 DOCKET NO.
50-413
- 1.
Please clarify the scope of your inspections.
In your August 30, 2005 (ML052500494),
submittal you indicated that the total number of tubes inspected with a bobbin probe in Steam Generator (SG)
A, SG B, SG C, and SG D were 3761, 3775, 3740, and 3758.
- However, in your November 28, 2005 (ML053410182),
submittal you indicated that 3761 tubes in SG A,
3776 tubes in SG B, 3735 tubes in SG C, and 3753 tubes in SG D were inspected with a bobbin probe.
In addition, the total number of tubes inspected in each SG is reported differently for the array probe inspections.
For example, the August 30, 2005, submittal indicates that 1618 tubes were inspected in SG A with an array probe while the November 28, 2005, submittal indicates that 1623 tubes were inspected in SG A.
Duke Response:
Minor differences in the number of tubes inspected as noted in the two referenced reports existed.
This is due to how the data base was queried for tubes on multiple inspection plans.
There were 3761 tubes inspected by bobbin full length in the A steam generator.
There were 3775, 3740, and 3758 tubes inspected full length by bobbin in the B, C, and D steam generators, respectively.
To explain the example, the steam generator A array plan included 809 tubes that were examined from the first support plate down to the tubesheet for loose parts around the periphery of the bundle.
Each tube's array data was analyzed on both the hot leg and the cold leg for a total count of 1618 inspections.
In addition to the periphery array inspection, there were 5 tubes with previous indications near the hot leg tubesheet that required array analysis.
This would give a total of 1623 array inspections for the A steam generator.
However, one of the 5 tubes with previous indications is a periphery tube and was also counted in the 1618 periphery array inspection count.
Due to dent and dings being areas of increased stress, discuss the scope and results of any dent and ding exams Attachment Page 1
performed during the end-of-cycle (EOC) 15 SG tube inspections.
Please include the number of dents/dings in each SG, whether there were any new d&nts/dings identified, whether any "anomalous" dent signals were identified, and the inspection criteria (i.e., greater than or equal to 2-volts).
Duke Response:
Degradation at dents and dings is not expected in the 690 thermally treated tubing in service for 6.5 EFPY.
The array data was evaluated for all new dents or dings, identified by bobbin, to ensure that there were no other forms of degradation present.
There are 7 dents in the A steam generator, 3, 2, and 4 dents in the B, C, and D steam generators, respectively.
There were new dents identified, but they are not believed to be service induced.
There were no "anomalous" dents or dings identified.
The bobbin threshold for dent identification is 2.00 volts.
Please discuss the scope and results of any foreign object search and retrieval inspections which may have been conducted during the EOC 15 SG tube inspections.
If any loose parts were left in the SGs, discuss whether analyses were performed to ensure that tube integrity would be maintained until the next inspection of these tubes.
In addition discuss the scope and results of any secondary side inspections performed during this outage.
Duke Response:
Top of tubesheet visual inspections were performed in all steam generators.
An analysis has been performed and determined that objects within 5 tube pitches from the bundle periphery might cause wear.
There were no parts identified in either the A or D steam generators.
There were 5 parts identified (gasket winding, machine turning, and small crimp of aluminum) in the B steam generator.
There were 3 parts identified (all are small "S, shaped hooks) in the C steam generator.
All parts identified were either small enough to move into the bundle into a lower flow region or fixed in place.
There was also an inspection performed of the upper bundle at the seventh lattice grid.
Nothing abnormal was noted.
Attachment Page 2
- 2.
On Page 1 of the November 28, 2005, submittal you indicated that no active degradation was identified in your SGs during the EOC 15 SG tube inspections based on the EPRI definition of active degradation which excludes loose part wear.
The staff has found that the industry's definition of active degradation is misleading since tubes could have degradation that is progressing (or present on the tubes) but the degradation could be classified as "not active" (refer to ML010320218 and ML012200349).
As a result, please confirm that other than wear at structures, that you did not find any service-induced indications (i.e.,
those not attributable to manufacturing) during your inspections.
Duke Response:
Tube wear at structures and loose part wear is the only form of service-induced degradation.
- 3.
In Technical Specification (TS)
Section 5.6.8.c, Nondestructive Evaluation Techniques, it was stated that bobbin and array probes were the only probes utilized during the EOC 15 SG tube inspections.
Is it correct for the staff to assume that the mechanisms listed in the table are those degradation mechanisms that Catawba Unit 1 SG tubes are susceptible to?
If this assumption is correct, why were probes not capable of finding the forms of degradation that the tubes are susceptible to used during the EOC 15 SG tube inspections (e.g., it appears that only the +PointTM and pancake coil are the only probes qualified to detect outside diameter (OD) intergranular attack at the expansion transition region and OD stress corrosion cracking at dents)?
Duke Response:
No, it is not correct for the staff to assume that the mechanisms listed in the table are those degradation mechanisms that CatawbaUnit 1 tubes are susceptible to.
The table lists all qualified techniques available for use on the Catawba Unit 1 steam generator tubing.
Bobbin and arrayprobe techniques were qualified for all forms of degradation which the tubes are expected to be susceptible to at this point of their service life.
The +PointTM, array (X-ProbeTm) and pancake coil are qualified for detection of intergranular stress corrosion cracking at expansion transitions and are considered to have equivalent detection Attachment Page 3
capabilities of potential IGA if it were to occur.
The bobbin coil and +Point' probes are qualified for ODSCC detection at dents.
- 4.
TS Section 5.6.8.d, Location of Service Induced Indications, requires information pertaining to service induced indications.
Your submittal indicated that Attachment 1 contains information regarding the service induced indications found during the EOC 15 SG tube inspections.
- However, it appears that Attachment 1 has more than service induced indications.
Are the dents, HNI (history with no indication),
and absolute drift indications service induced?
If not, please provide a list of only the service induced indications.
If any of the indications are not a result of wear at structures or loose parts, please discuss the causal mechanism.
Changes in eddy current signals since the baseline inspection attributed to eddy current repeatability should not be reported.
Duke Response:
Attached are tables of the service induced indications.
- 5.
To verify accurate TS inspection sampling requirements, please provide the effective full power years (EFPY) at the time of your first in-service inspection following SG replacement and the EFPY at the time of your EOC 12, 13, 14, and 15 SG tube inspections.
In addition, what is the u-bend radius for Row 1 and tht smallest u-bend radius (and associated row number)?
Duke Response:
The steam generators were replaced at End of Cycle (EOC) 9.
The first in-service inspection was at EOC 10 with 1.12 EFPYs.
Cycles 11, 12, 13, 14, and 15 had individual lengths of 1.18, 1.37, 1.41, 1.43, and 1.30 EFPYs, respectively.
The row one u-bends have a radius of 3.973 inches.
The smallest u-bend radius is 3.632 inches in row three.
- 6.
With respect to the design criteria, is the tubesheet 26.63-inches without the cladding and were the tubes in Rows 1 through 27 stress relieved (full-length) after bending?
Attachment Page 4
Duke Response:
The tubesheet is 26.63 inches thick without the cladding.
Tubes in rows 1 through 22 were stress relieved (full length) after bending.
- 7.
Please discuss whether all the tubes known to be in close proximity were inspected during this outage and provide the results of these inspections.
Please discuss whether the number of tubes in close proximity has been increasing or decreasing with time.
Duke Response:
There are no tubes in close proximity.
Attachment Page 5
Steam Generator A Service Induced Indications ROW COL VOLTS DEG PCT CHN 49 82 0.17 82 6
P2 57 38 0.15 48 5
P2 61 70 0.3 75 13 P2 77 82 0.29 99 9
P2 77 90 0.26 99 10 P2 81 80 0.26 107 10 P2 89 78 0.33 103 12 P2 89 80 0.34 105 13 P2 91 80 0.31 116 10 P2 91 84 0.25 99 9
P2 92 79 0.35 92 13 P2 94 81 0.21 111 8
P2 95 88 0.25 119 8
P2 96 109 0.2 101 7
P2 101 78 0.35 123 13 P2 103 78 0.31 0
10 P2 Steam Generator B Service Induced Indications ROW COL VOLTS DEG PCT CHN 66 73 0.31 96 10 P2 69 70 0.44 94 14 P2 74 83 0.36 116 11 P2 82 75 0.33 99 10 P2 82 83 0.37 81 11 P2 86 83 0.43 87 13 P2 86 83 0.39 85 12 P2 89 60 0.29 86 10 P2 91 70 0.28 74 10 P2 95 64 0.24 123 9
P2 97 70 0.18 106 6
P2 97 70 0.39 102 12 P2 97 70 0.61 100 18 P2 98 83 0.57 85 17 P2 103 70 0.28 83 10 P2 LOCATION UTIL 1 FB2 1.35 WAR FB3 1.09 WAR FB4 0.62 WAR FB5
-0.68 WAR FB5
-0.64 WAR FB7
-0.67 WAR FB5
-0.59 WAR FB5
-0.67 WAR F136 1.72 WAR FB4
-0.73 WAR FB4
-0.53 WAR FB5 1.73 WAR FB4
-0.68 WAR FB5 1.26 WAR FB4
-1.67 WAR FB5
-0.56 WAR LOCATION UTIL 1 FB5 0.63 WAR FB4 1.38 WAR FB4 1.26 WAR FB4
-1.1 WAR FB4 1.16 WAR FB5 1.04 WAR FB4 1.29 WAR FB6
-1.23 WAR FB6 1.37 WAR FB5
-1.13 WAR FB8 1.98 WAR F136
-1.18 WAR FB5
-1.28 WAR FB5 1.04 WAR FB4
-1.01 WAR
1 Steam Generator C Service Induced Indications ROW COL VOLTS DEG PCT CHN 63 44 0.17 99 5
P2 70 55 0.3 72 9
P2 72 61 0.45 0
12 P2 73 62 0.17 0
6 P2 74 65 0.2 0
5 P2 74 65 0.23 0
6 P2 74 65 0.18 0
5 P2 74 87 0.44 0
12 P2 75 60 0.5 82 14 P2 75 60 0.27 107 8
P2 75 62 0.61 15 P2 75 76 0.6 16 P2 76 59 0.23 0
8 P2 76 61 0.51 13 P2 77 68 0.23 0
6 P2 79 60 0.28 103 8
P2 79 62 0.31 0
8 P2 79 62 0.71 0
17 P2 79 66 0.16 0
4 P2 79 80 0.18 0
6 P2 79 86 0.26 0
9 P2 79 86 0.34 0
11 P2 80 59 0.25 0
9 P2 80 81 0.39 0
11 P2 83 76 1.02 23 P2 85 62 0.2 0
7 P2 85 64 0.31 0
8 P2 85 76 0.91 0
25 P2 86 59 0.28 78 8
P2 86 61 0.52 0
13 P2 86 61 0.27 0
7 P2 86 77 0.34 0
11 P2 90 87 0.51 0
14 P2 91 62 0.42 0
11 P2 91 62 0.38 0
10 P2 91 62 0.24 0
6 P2 92 87 0.42-0 14 P2 94 63 0.25 0
7 P2 96 87 0.38 0
11 P2 96 87 0.28 0
8 P2 97 86 0.31 0
9 P2 98 77 0.62 0
19 P2 LOCATION UTIL I FB4 FB5 FB5 FB6 FB6 FB5 FB4 FB4 FB4 FB6 FB4 FB5 FB6 FB5 FB6 FB4 FB5 FB4 FB8 FB4 FB6 FB5 FB5 FB4 FB5 FB5 FB5 FB5 FB4 FB5 FB4 FB8 FB5 FB5 FB5 FB4 FB5 FB6 FB5 FB4 FB6 FB5
-1.72 WAR
-1.19 WAR 1.59 WAR
-0.69 WAR
-1.94 WAR 1.54 WAR 0.62 WAR
-1.77 WAR
-1.13 WAR
-0.7 WAR
-0.67 WAR 1.24 WAR
-1.76 WAR 1.59 WAR
-0.59 WAR
-0.89 WAR 0.68 WAR
-1.24 WAR 0.81 WAR 0.63 WAR
-0.49 WAR
-0.87 WAR 1.71 WAR
-1.11 WAR
-0.6 WAR
-0.69 WAR
-0.65 WAR
-1.15 WAR 1.73 WAR
-0.59 WAR
-0.67 WAR 0.69 WAR 1.66 WAR 0.62 WAR
-0.67 WAR 0.59 WAR
-1.67 WAR
-1.7 WAR 1.63 WAR 1.61 WAR
-0.63 WAR
-1.12 WAR
Steam Generator C Service Induced Indications (continued)
ROW COL VOLTS DEG PCT CHN 98 85 0.22 0
6 P2 98 85 0.21 0
6 P2 98 85 0.17 0
5 P2 98 87 0.35 0
12 P2 98 87 0.34 0
11 P2 99 68 0.15 0
5 P2 100 87 0.46 0
13 P2 101 78 0.51 14 P2 101 78 0.49 13 P2 101 78 0.42 12 P2 101 78 0.42 12 P2 102 77 0.51 0
16 P2 102 77 0.52 0
16 P2 102 77 0.75 0
22 P2 102 77 0.39 0
13 P2 102 83 0.3 0
10 P2 102 87 0.45 0
14 P2 104 75 0.2 0
6 P2 106 69 0.39 10 P2 109 62 0.14 0
5 P2 LOCATION UTIL 1 FB5
-1.76 WAR FB4 1.87 WAR FB3 1.85 WAR FB6
-1.61 WAR FB5
-1.53 WAR FB7
-0.64 WAR FB4 1.66 WAR FB5
-1.68 WAR FB4 1.66 WAR FB4
-0.71 WAR FB4
-1.68 WAR FB7
-1.04 WAR FB5
-1.15 WAR FB4
-1.15 WAR FB3 0.98 WAR FB5
-1.64 WAR FB5
-1.67 WAR FB4
-0.65 WAR FB6 1.73 WAR FB4
-0.83 WAR
b Steam Generator D Service Induced Indications ROW COL VOLTS DEG PCT CHN LOCATION UTIL 1 52 79 0.36 103 12 P2 FB5
-0.84 WAR 52 91 0.31 120 12 P2 FB4
-0.9 WAR 53 76 0.69 74 21 P2 FB4 1.66 WAR 57 66 0.67 20 P2 FB5
-1.23 WAR 62 95 0.08 83 4
P2 FB4
-0.93 WAR 66 85 0.37 104 14 P2 FB4 1.5 WAR 67 74 0.37 84 13 P2 FB5 0.51 WAR 69 74 0.32 0
13 P2 FB5 0.71 WAR 71 66 0.23 100 8
P2 FB5 1.49 WAR 77 66 0.13 6
P2 FB5 1.09 WAR 79 66 0.29 109 10 P2 FB5 1.58 WAR 80 73 0.59 0
22 P2 FB5 1.67 WAR 80 73 0.39 0
16 P2 FB4 1.36 WAR 81 68 0.44 16 P2 FB6
-1.75 WAR 81 68 0.38 15 P2 FB4 1.67 WAR 85 84 0.33 87 12 P2 FB5
-1.13 WAR 86 73 0.74 0
26 P2 FB5 1.62 WAR 86 73 0.6 0
22 P2 FB4 1.45 WAR 86 73 0.57 0
21 P2 FB6
-1.7 WAR 88 73 0.53 92 17 P2 FB5 1.6 WAR 89 62 0.31 12 P2 FB5
-0.56 WAR 90 69 0.33 115 12 P2 FB4 0.79 WAR 91 62 0.23 67 9
P2 FB5
-0.51 WAR 92 69 0.36 99 12 P2 FB4 0.65 WAR 92 73 0.44 0
16 P2 FB5 1.62 WAR 93 62 0.64 90 20 P2 FB5
-0.62 WAR 93 70 0.2 8
P2 FB6
-1.19 WAR 93 70 0.51 0
18 P2 FB5
-1.08 WAR 95 62 0.2 117 8
P2 FB5
-0.68 WAR 95 68 0.43 97 14 P2 FB7
-0.73 WAR 95 68 0.59 106 18 P2 FB5
-1.3 WAR 95 68 0.37 81 12 P2 FB3
-0.54 WAR 97 68 0.69 0
23 P2 FB5
-1.24 WAR 99 64 0.19 9
P2 FB5 1.7 WAR 100 69 0.34 62 13 P2 FB6 1.84 WAR 100 69 0.29 101 11 P2 FB5 0.68 WAR 101 80 0.38 92 15 P2 FB6
-0.99 WAR 108 71 0.21 81 8
P2 FB5 0.48 WAR 108 73 0.27 0
10 P2 FB4 1.45 WAR 110 65 0.24 107 9
P2 FB4
-1.66 WAR 110 65 0.37 0
14 P2 FB5
-1.21 WAR 113 64 0.24 109 9
P2 FB5
-1.63 WAR 114 61 0.39 0
15 P2 FB4
-1.12 WAR 114 69 0.23 102 9
P2 FB5 0.71 WAR 114 69 0.21 136 8
P2 FB4 1.47 WAR