LR-N15-0118, Response to Request for Additional Information Spring 2014 Steam Generator Tube Inspections
| ML15141A117 | |
| Person / Time | |
|---|---|
| Site: | Salem  |
| Issue date: | 05/21/2015 |
| From: | Jamila Perry Public Service Enterprise Group |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| LR-N15-0118, TAC MF5117 | |
| Download: ML15141A117 (11) | |
Text
MAY 21 2015 LR-N15-0118 PSEG Nuclear LLC P.O. Box 236, Hancocks Bridge, NJ 08038-0236 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001
SUBJECT:
REFERENCES:
Salem Nuclear Generating Station Unit 2 Renewed Facility Operating License No. DPR-75 NRC Docket No. 50-311 Response to Salem Nuclear Generating Station, Unit 2, Request for Additional Information Re: Spring 2014 Steam Generator Tube Inspections {TAC No. MF5117)
- 1. Salem Nuclear Generating Station, Unit No. 2 - Request for Additional Information Re: Spring 2014 Steam Generator Tube Inspections, dated March 24, 2015 (TAC No. MF5117)
- 2. LR-N14-0232, Steam Generator Tube Inspection Report -
Twentieth Refueling Outage (2R20), dated October 30, 2014, (ML14303A032)
On March 24, 2015, the Nuclear Regulatory Commission (NRC) provided to Mr. Thomas Joyce of PSEG Nuclear LLC (PSEG) a request for additional information (Reference 1 ). PSEG hereby formally documents its response to the request for additional information. Attachment 1 contains the NRC's questions followed by PSEG's response. There are no regulatory commitments contained in this letter.
Should you have any questions regarding this submittal, please contact Mr. D. Lafleur at (856) 339-1754.
Sincerely,
<Je-Cr&_
John F. Perr
Site Vice Prent - Salem Attachments ( 1 )
MAY 21 2015 Page 2 LR-N15-0118 Cc:
Mr. D. Dorman, Administrator - Region 1, NRC Ms. C. Parker, Licensing Project Manager-Salem, NRC Mr. P. Finney, USNRC Senior Resident Inspector, Salem (X24)
Mr. P. Mulligan, Manager IV, NJBNE Mr. R. Braun, President and Chief Nuclear Officer - Nuclear Mr. T. Cachaza, Salem Commitment Tracking Coordinator Mr. L. Marabella, Corporate Commitment Tracking Coordinator Mr. D. Lafleur, Salem Regulatory Assurance
LR-N15-0118 Response to Salem Nuclear Generating Station, Unit 2, Request for Additional Information Re: Spring 2014 Steam Generator Tube Inspections (TAC No. MF5117)
LR-N15-0118
- 1.
Please provide the cumulative effective full power months of operation that the steam generators (SGs) have operated as of RFO 20.
PSEG Response:
The approximate cumulative effective full power months (EFPM) of operation that the steam generators (SGs) have operated as of RFO 20 (2R20) is 66 EFPM.
- 2.
Please discuss the scope and results of any secondary side inspections.
PSEG Response:
There were no secondary side inspections planned or required for outage 2R20, consistent with the pre-outage Degradation Assessment. However, PSEG planned contingent secondary side foreign object search and retrieval (FOSAR) dependent on the in-outage eddy current inspection results. During 2R20, a total of 3 possible loose part (PLP) indications were identified and confirmed by eddy current inspection. All three PLP-indications were identified in SG 24 near the Top-of-Tubesheet {TTS) on the cold leg in three (3) adjacent tubes (Row 81 Column 49, Row 82 Column 48, and Row 83 Column 49). FOSAR was initiated in this steam generator to investigate the PLP signals. The PLPs were confirmed to be caused by a thin metallic foreign object. This object was subsequently removed from the SG, and post removal eddy current inspection of these tubes verified that the foreign object had been removed and that no foreign object tube wear was present.
- 3.
Please summarize the number of indications and tubes with wear at the anti vibration bars. Please summarize the number of indications and tubes with wear at the tube support plates (TSPs). Please discuss whether the number of new wear indications and wear growth rates have continued to decrease from RFO 19 to RFO 20, for both anti-vibration bar and TSP wear.
PSEG Response; Below is a table summarizing the bobbin eddy current inspection results for the number of indications and tubes with wear at the anti-vibration bars (AVB) and tube support plates (TSP), and four graphs representing the trends for the number of new anti vibration bar wear indications, AVB wear growth rates, and TSP wear growth rates. The growth rate graphs provide the trends with the upper 95th percentile growth rate and the average growth rate for AVB wear indications with history (with exception of 2R17, since all indications in 2R17 are new). As shown in these graphs, the trends for the number of new anti-vibration bar wear indications, AVB wear growth rates, and TSP wear growth rates at each inspection outage have continued to decline with each inspection outage; or have essentially no change (i.e. - stabilized). The number of TSP wear indications returned to service following outage 2R19 was 24 (Attachment 2 of LR-N14-0009, ML 1401 OA428). During outage 2R20, 35 bobbin TSP wear indications were reported (one additional bobbin indication was reported as a Distorted Support Indication (OSI) bringing the bobbin indication total to 36). The overall population of TSP wear indications is limited and relatively small, with a change of 12 new TSP wear indications detected by eddy current bobbin inspection during outage 2R20. Subsequent to outage 2R20 tube plugging, 24 bobbin TSP wear indications were returned to service.
1 LR-N15-0118 Indication Summary of Number of Tubes and Indications from 2R20 Bobbin Inspections Code SG21 SG22 SG23 SG24 Total Tubes lndic Tubes lndic Tubes lndic Tubes lndic Tubes lndic TSP 5
8 3
4 6
6 12 18 Note 1 26 36 AVB 235 632 176 422 53 127 143 397 607 1578 Notes:
- 1.
This includes a Distorted Support Indication (OSI) bobbin indication which was confirmed as wear with Rotating Probe Coil (RPC/+Point').
Salem-2 Replacement SGs, Number of New AVB Wear Indications vs. Outage Salem-2 Upper 95th AVB Wear Growth Rates 2R17 2R1S 2R19 2R20 O!Jtage 2
LR-N15-0118 7
6 5
4 3
Salem-2 Average AVB Wear Growtl'I Rates I : : I
- * * * * * *
- I I
--SG24 i
--**All Si:iis t
... J..
0
- i******************************************************rn rn rn rn
+
- rn rn rnrn rnrn rnrn rnrn+**************** **
2R17
-5 0
2R1ll 2R19 2R20 outage TSP % TW Growtl'I Distribution (Repeats Only}
Salem 2R11 furu 2R20 5
10 Bobbin %TW/EFPY
--2R19 All SGs Growth
.....-2R1S All SGs Growth
....-2R.17 All SGS Growth 15 20
- 4.
Please clarify whether the tube in row 104, column 66 in SG 24 has two wear indications at 06C (one at 06C-0.58-inches and one at 06C+0.40-inches).
Please discuss whether these indications are associated with TSP lands.
PSEG Response:
The tube in row 104, column 66, in SG 24 has two wear indications at 06C. One of the wear indications is at 06C-0.58 and the other is at 06C+0.40 inches. Both wear indications are associated with the TSP lands.
3 LR-N15-0118
- 5.
Please discuss the scope and results of any primary channel head inspections.
PSEG Response:
During outage 2R20, PSEG performed a visual examination of the steam generator channel head internal (primary side) cladding surfaces in all four steam generators, both on the hot leg and cold leg. With the exception of the as-found channel head foreign material identified in three of the four steam generators, the steam generator channel head bowl examinations resulted in satisfactory conditions and did not identify any signs of degradation, rust, deformation or abnormal conditions. The foreign material was identified in the cold legs of SG 21, 22, and 24. The foreign material consisted of a few small pieces of unidentifiable material including metal shavings, a piece of metal possibly from a lanyard, and two bolt heads that were determined to be from the reactor coolant pumps. The steam generator cold leg channel head cladding, tubesheet and tube plug surfaces were visually examined with no degradation identified. All foreign material was removed from the channel head of the steam generators. The corrective action process resulted in major repairs to the reactor coolant pumps as described in NRC Integrated Inspection Report 05000272/2014005 and 05000311/2014005, dated January 30, 2015 (ML15030A400).
- 6.
Please identify the tubes plugged during RFO 20.
PSEG Response:
The table below lists the tubes plugged during RFO 20 (2R20) for each SG.
SG ROW COLUMN 21 1
63 21 64 66 21 65 75 21 66 60 21 66 64 21 68 60 21 68 62 21 69 73 21 69 75 21 7 1 69 21 72 56 21 73 59 21 73 61 21 74 58 21 74 62 21 74 70 21 75 63 21 76 54 4
LR-N15-0118 SG 21 21 21 21 21 21 21 21 21 21 21 21 21 21 21 21 21 21 21 21 21 21 21 21 21 21 21 21 21 21 21 21 21 21 21 21 21 21 22 22 22 22 ROW 76 76 77 77 78 78 79 79 80 8 1 8 1 8 1 8 1 8 1 82 82 83 83 85 85 86 88 88 89 92 93 94 95 96 96 97 97 97 97 98 98 100 101 1
57 62 67 COLUMN 58 64 59 61 52 54 61 69 62 59 61 63 65 67 60 62 59 63 57 67 66 60 62 61 74 63 68 59 58 62 57 59 61 67 58 60 58 67 63 55 114 63 5
LR-N15-0118 SG 22 22 22 22 22 22 22 22 22 22 22 22 22 22 22 22 22 22 22 22 22 22 22 22 22 22 22 22 22 22 23 23 23 23 23 23 24 24 24 24 24 24 ROW 69 72 73 73 73 74 7S 7S 76 78 78 79 80 82 82 84 8S 86 86 87 88 89 90 92 9S 96 97 98 99 99 64 70 7S 88 92 100 1
1 Sl S9 62 68 COLUMN 67 62 61 63 7S 64 SS 6S 72 S8 60 67 60 60 66 62 67 S4 S6 61 62 SS 62 S2 S9 62 Sl so Sl S9 74 S8 6S S8 S8 78 63 89 79 6S 44 74 6
LR-N15-0118 SG 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 ROW 69 69 70 71 72 73 73 73 77 78 79 79 80 81 81 82 83 83 85 85 85 85 91 91 92 93 94 94 95 98 100 COLUMN 69 71 66 71 68 65 67 69 67 66 63 67 68 61 71 66 61 63 55 61 65 71 65 69 62 69 58 70 65 54 56
- 7.
Previously, the tube located in row 1, column 63 in three of the four SGs had wear at various TSP intersections. Please discuss any insights into the cause of wear given the limited number of indications of TSP wear and the general random nature of this form of degradation.
PSEG Response:
It is observed that 3 of the 4 SGs have shown TSP wear in the tube at row 1 column 63.
PSEG did not identify any unique cause related to these specific tubes. The TSP wear in these tubes was not significantly different as compared to the prior outage (2R19).
The wear was nearly the same depth, or within a few percent through-wall of the 2R19 7
LR-N15-0118 measured depths, and well below the Technical Specification (TS) tube plugging criteria (TS 6.8.4.i.c). However, PSEG administratively plugged and stabilized all three of these tubes during outage 2R20.
- 8.
Please discuss whether the two inaccessible nuts on secondary components (hatches, camera ports), where other nuts were found to be loose in prior inspections, were able to be accessed to ensure tightness.
PSEG Response:
Secondary side inspections of the upper internals were not performed, or required, during outage 2R20. The nuts that were previously found loose and retightened, and the nuts that were inaccessible and left as-is, were not inspected during 2R20. The evaluations performed previously in 2R17 and 2R18, and in the pre-outage Degradation Assessment for 2R20, determined that the conditions within the upper internals do not require re-examination at this time; including the loose nuts (ML102440037 item #2, ML12088A010 item #1, and ML 1401 OA428 item #2). In summary of the loose nuts evaluations, the two (2) inaccessible nuts remain bounded by evaluation which allows use as-is. The nuts that were previously found loose in 2R17 on various hatches or camera ports, and tightened to higher torque, were re-examined in 2R18. These inspections confirmed the adequacy of the corrective actions conducted in 2R17, since none of the re-tightened nuts in 2R17 were found loose in 2R18.
8