L-20-276, Response to Request for Additional Information Regarding Steam Generator Inspection Report
| ML20304A140 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 10/30/2020 |
| From: | Penfield R Energy Harbor Nuclear Corp |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| EPID L-2019-LRO-0042, L-20-276 | |
| Download: ML20304A140 (6) | |
Text
energy harbor Rod L. Penfield Site Vice President, Beaver Valley Nuclear October 30, 2020 L-20-276 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001
Subject:
Beaver Valley Power Station, Unit No. 2 Docket No. 50-412, License No. NPF-73 Response to Request for Additional Information Energy Harbor Nuclear Corp.
Beaver Valley Power Station P.O. Box 4 Shippingport, PA 15077 724-682-5234 Regarding Steam Generator Inspection Report (EPID L-2019-LRO-0042)
By correspondence dated July 28, 2020 (Accession No. ML20211L853), Energy Harbor Nuclear Corp. submitted to the Nuclear Regulatory Commission (NRC) information related to steam generator inspections performed during the Beaver Valley Power Station, Unit No. 2 spring 2020 refueling outage 21 (2R21 ). By email dated October 8, 2020 (Accession No. ML20290B008), the NRC requested additional information regarding the steam generator inspections. The Energy Harbor Nuclear Corp. response to the NRC request is attached.
There are no regulatory commitments contained in this submittal. If there are any questions or if additional information is required, please contact Mr. Phil H. Lashley, Manager - Fleet Licensing, at (330) 696-7208.
Sincerely, Rod L. Penfield
Attachment:
Response to Request for Additional Information
Beaver Valley Power Station, Unit No. 2 L-20-276 Page 2 cc:
NRC Region I Administrator NRC Resident Inspector NRR Project Manager Director BRP/DEP Site BRP/DEP Representative
Attachment L-20-276 Response to Request for Additional Information Page 1 of 4 By letter dated July 28, 2020 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML20211L853), Energy Harbor Nuclear Corp.
submitted the Generic Letter (GL) 95-05 Voltage-Based Alternate Repair Criteria (ARC) and Steam Generator (SG) F Star (F*) Reports for SG tube inspections that were performed during the Beaver Valley Power Station (Beaver Valley), Unit 2, spring 2020 refueling outage 21 (2R21 ).
To complete its evaluation of the information provided regarding implementation of the voltage-based ARC and the F* methodology during 2R21, the U.S. Nuclear Regulatory Commission (NRC) staff requested additional information in an October 8, 2020 email.
The NRC staff requests for additional information are provided below in bold text and are followed by the Energy Harbor Nuclear Corp. response.
- 1. The GL 95-05 voltage-based ARC report for 2R20 reported a total of 1,161 (348 in SG-A, 449 in SG-B, and 364 in SG-C) distorted support indications (DSls) in all three SGs (ADAMS Accession No. ML19035A607). Section 3.1, "2R21 Inspection Results," of the GL 95-05 voltage-based ARC report for 2R21 states that there were 133 (43 in SG-A, 48 in SG-B, and 42 in SG-C) new DSls identified in 2R21, which results in a total of 1,294 DSls in all three SGs (1,161
+ 133 = 1,294). However, the GL 95-05 voltage-based ARC report for 2R21 reports a total of 1,292 DSls in all three SGs (390 in SG-A, 495 in SG-B, and 407 in SG-C). Please confirm the total number of DSls in all three SGs and the number in each SG.
Response
For SG-A, 348 distorted support plate signals with possible indications (DSl's) were reported in 2R20. 43 new DSl's were reported in 2R21. This brings the total number of DSl's in SG-A to 391. However, one OSI reported in 2R20 (Row 13 Column 39, 5th hot leg support plate) was reported as an indication not reportable (INR) during 2R21 and was not counted in the 2R21 OSI population. Therefore, the total of 390 DSl's in SG-A is correct.
For SG-B, 449 DSl's were reported in 2R20. 48 new DSl's were reported in 2R21. This brings the total number of DSls in SG-B to 497. However, one OSI reported in 2R20 (Row 2 Column 24, 2nd hot leg support plate) was in a tube plugged during 2R20.
Therefore, this OSI would not carryover to 2R21. Another OSI reported in 2R20 (Row 13 Column 56, 3rd hot leg support plate) was inadvertently counted twice in the OSI database. This means there was one less OSI in SG-B than reported in the 2R20 Generic Letter (GL) 95-05 90 Day Report. Subtracting these two 2R20 DSl's from 497 yields the correct 2R21 total of 495 DSl's in SG-B.
For SG-C, 364 DSl's were reported in 2R20. 43 new DSl's were reported in 2R21. This brings the total number of DSl's in SG-C to 407. It was later determined that 42 DSl's
Attachment L-20-276 Page 2 of 4 were erroneously reported on Page 3-3 of the 2R21 GL 95-05 90 Day Report as the number of new DSl's in SG-C during 2R21. The number of DSl's should have been 43.
This means that the total number of new DSl's is 134 rather than 133, also reported on Page 3-3. No analyses or results are affected by this transcription error.
Therefore, the correct number of DSl's for all three SG's (390 + 495 + 407) is 1292 as reported in the 2R21 GL 95-05 90 Day Report.
- 2. Section 3.2, "Voltage Growth Rates," of the GL 95-05 voltage-based ARC report for 2R21 states that "Growth is determined when the same indication can be identified in two successive inspections. Since there can be new indications in one outage, the number of indications for which growth can be defined is less than the number of indications detected." As previously stated, the GL 95-05 voltage-based ARC report for 2R21 reported 407 DSls in SG-C (this number may change based on Question 1 ). However, Table 3-6, "Voltage Growth Cumulative Distributions," of the same report shows 409 indications with growth and Table 3-7 shows 364 indications with growth.
Please confirm the number of indications with growth for SG-C, the number that was used for the growth analyses, and, if necessary, discuss any impacts this may have had on the results of the growth analyses.
Response
The 409 indications shown in Table 3-6 (Page 3-10) for SG-C was a transcription error.
Table 3-6 should have reported 364 indications with growth for SG-C. Table 3-6 is hereby corrected as shown on Page 4 of this response.
The 409 value for number of DSl's with growth in SG-C was a transcription error and was not used in the evaluations for calculating leak rate and probability of burst. The correct growth distribution is shown in Figure 3-7 (Page 5 of this response) and is based on the correct number of DSl's with growth data which for SG-C is 364. Also, as seen from Figure 3-7, a bounding growth curve was used for the evaluations. Therefore, there is no impact on the growth distribution used as input to the 2R21 operational assessment. The incorrect 409 value is not reported elsewhere in the 2R21 GL 95-05 90 Day Report.
Further, the totals for DSl's with growth of 34 7 in SG-A and 44 7 in SG-B reported in Table 3-6 are consistent with the findings associated with addressing RAI No. 1 on Page 2 of this response.
Attachment L-20-276 Page 3 of 4 Voltage Change :
EOC-21 minus EOC-20 L'lV<-0.79
-0.79:SL'l V:S-0.7
-0.69:SL'l V:S-0.6
-0.59:SL'l V:S-0.5
-0.49:SL'l V:S-0.4
-0.39:SL'l V'.S-0.3
-0.29:SL'l V'.S-0.2
-0.19:SL'l V'.S-0.1
-0.09:SL'l v:so.o 0.01:SL'l V'.S0.1 0.11:SL'l V'.S0.2 0.21:SL'l V:S0.3 0.31:SL'l V:S0.4 0.41:SL'l V:S0.5 0.51:SL'l V:S0.6 0.61:SL'l v:so. 7 0.71:SL'l V:S0.8 0.81:SL'l V'.S0.9 L'lV>0.9 Number of Indications with Growth Average Percentage Growth SG-A Number of Indications 0
0 1
0 2
1 4
21 132 131 31 13 4
3 1
1 1
0 1
347 16.5%
Table 3 Voltage Growth Cumulative Distribution SG-B SG-C Composite Cumulative Number of Cumulative Number of Cumulative Number of Cumulative Probability Indications Probability Indications Probability Indications Probability Distribution Distribution Distribution Distribution 0.0 1
0.002237 0
0.0 1
0.002237 0.0 1
0.004474 0
0.0 1
0.001727 0.002882 0
0.0 0
0.0 1
0.002591 0.0 2
0.008949 1
0.002747 3
0.006045 0.008646 4
0.017897 0
0.0 6
0.011226 0.011527 6
0.031320 3
0.010989 10 0.020725 0.023055 21 0.078300 11 0.041209 36 0.051 813 0.083573 40 0.167785 35 0.137363 96 0.136442 0.463977 191 0.595078 148 0.543956 471 0.546632 0.841499 129 0.883669 132 0.906593 392 0.889465 0.930836 33 0.957494 19 0.000000 83 0.985320 0.968300 15 0.991051 9
0.000000 37 0.000000 0.979827 1
0.993289 6
0.000000 11 0.000000 0.988473 1
0.995526 0
0.000000 4
0.000000 0.991354 1
0.997763 0
0.000000 2
0.000000 0.994236 0
0.0 0
0.0 1
0.000000 0.99711 8 0
0.0 0
0.0 1
0.000000 0.0 1
1.0 0
0.0 1
0.000000 1.0 0
0.0 0
0.0 1
1.0 447 364 1158 4.5%
3.9%
Attachment L-20-276 Page 4 of 4 Figure 3-7 DSI Voltage Growth/EFPY Curve for SG C r----------------------
- u.
C " -------- ----- -----~- ---- -- -- --- 0-.5 -
U
-1
-0.5 0
Growth 0.5 1
2R20 Cumu lative Distribution 2R21 Cumu lative Di stri butio n 2R21 Bounding Growth Curve
- 3. In the GL 95-05 voltage-based ARC report for 2R21, the third sentence in the fourth paragraph of Section 2, "Summary and Conclusions," states that "SG-B is predicted to be the limiting SG for leakage while SG-A is predicted to be the limited SG for probability of burst." The last sentence of the third paragraph in Section 1 of the same report indicates that SG-C is the limiting SG for probability of burst. Please confirm which SG is the limiting SG for probability of burst.
Response
The third sentence of the fourth paragraph in Section 2 (Page 2-1) is incorrect as stated.
The sentence is hereby corrected to state SG-C as the limiting SG for probability of burst (POB) instead of SG-A. This is consistent with the statement provided later in the same paragraph, as well as Section 1 (Page 1-1) and Table 7-1 (Page 7-2) which reports the leak rate and POB results.
- 4. In the GL 95-05 voltage-based ARC report for 2R21, the third and fourth columns in Table 7-2, "Operational Assessment Leak and Burst Results for EOC [End of Cycle]-22 (POD [Probability of Detection] = 0.6)," refer to EOC-21.
Please confirm whether these columns should refer to EOC-21 or EOC-22.
Response
The 3rd and 4th column labels of Table 7-2 (Page 7-2) are incorrect. The 3rd and 4th column labels are hereby corrected to read EOC-22 instead of EOC-21.
Revision 1 of the 2R21 Generic Letter 95-05 90 Day Report will be issued once these Energy Harbor Nuclear Corp. responses have been accepted and the need for additional information by the NRC is no longer required.