L-2016-141, Response to Request for Additional Information on Fifth Ten-Year Inservice Inspection (Isi) Interval Relief Request No. 4
| ML16217A458 | |
| Person / Time | |
|---|---|
| Site: | Turkey Point  |
| Issue date: | 07/27/2016 |
| From: | Summers T Florida Power & Light Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| CAC MF7277, CAC MF7278, L-2016-141 | |
| Download: ML16217A458 (11) | |
Text
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F=PL U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 Re:
Turkey Point Units 3 and 4 Docket Nos. 50-250 and 50-251 Fifth Ten-Year lnservice Inspection (ISi) Interval July 27, 2016 10 CFR 50.55a L-2016-141 Relief Request No. 4 - Response to Request for Additional Information
References:
- 1)
NRC Email from Audrey Klett (NRC) to Mitch Guth (FPL),
Subject:
"Request for Additional Information - Turkey Point 3 & 4 - 5th 10-Year ISi RR#4 (CACs MF7277 & MF7278)" dated June 27, 2016, ML16180A024.
By letter L-2016-006 dated January 14, 2006 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML16033A355), Florida Power & Light Company submitted Relief Request (RR) No. 4, which requested the approval of a Risk Informed lnservice Inspection (RI-ISi) program for use during the fifth ten-year lnservice Inspection (ISi) interval at Turkey Point Nuclear Unit Nos. 3 and 4. The program is a risk-informed lnservice Inspection Program (RI-ISi) for Class 1 and 2 piping based on Electric Power Research Institute (EPRI) Topical Report (TR) 112657 Revision B-A, "Revised Risk-Informed lnservice Evaluation Procedure," dated June 2012.
The U.S. Nuclear Regulatory Commission's (NRC's) Component Performance, NOE, and Testing Branch (EPNB) and PRA Licensing Branch (APLA) staff reviewed the application and identified areas where it needs additional information to support its review. Reference 1 provided the request for additional information. The FPL response to the request for additional information (RAI) is attached.
Please contact Mr. Mitch Guth, Licensing Manager, at 305-246-6698 if you have any questions or require any additional information about this submission.
- 4 __ _
Thomas Summers Site Vice President Turkey Point Nuclear Plant Attachment Enclosures cc:
Regional Administrator, USNRC Region II Senior Resident Inspector, USNRC, Turkey Point Nuclear Plant Florida Power & Light Company 9760 SW 344th St., Florida City, FL 33035
l-2016-141 Attachment Florida Power & Light Company Turkey Point Units 3 and 4 lnservice Inspection Program (ISi)
Fifth Ten-Year Interval Relief Request No. 4 Responses to NRC L-2016-141 Attachment Page 1of5 Request for Additional Information (RAI) Questions
RAl-EPNB-1 L-2016-141 Attachment Page 2of5 EPRI TR 112657 Revision B-A (Section 3.6.4.2) and Section 3.5 of the submittal dated January 14, 2016, both state that 25% of high risk elements and 10% of medium risk elements will be selected for examination. Table 3.5 of the submittal dated January 14, 2016, appears to indicate that the elements selected for examination are well below these percentages. The NRC staff requests FPL to explain this discrepancy.
FPL Response to RAl-EPNB-1:
There was a clerical error made when transferring the information from Table 3.4 to Table 3.5.
When Table 3.5 was assembled, the weld totals from the "With" column in Table 3.4 were mistakenly transferred into Table 3.5 instead of the values from the "Without" column. The "Total" column for each Risk Category in Table 3.5 should have reflected the number of welds excluding Flow Accelerated Corrosion (FAC) as identified in the "Without" column for each Risk Category in Table 3.4.
FAC is covered under a separate augmented examination program. During the re-validation of the numbers shown in Tables 3.4 and 3.5, an additional clerical error was identified in Table 3.4. In Table 3.4 for Unit 3, in the WDS system, the number of welds in the "Without" column in Risk Category 6 has been changed from "O" to "5" and the number of welds in the 'Without" column in Risk Category 7, has been changed from "19" to "14".*
The overall number of welds remains the same, the changes have no impact on the risk-informed application and there is no effect on Tables 3.6.1, 5.1.1 and 5.2.1 which already included the correct information. provides the updated Tables 3.4 and 3.5. Based on these corrected numbers, Table 3.5 properly shows that Turkey Point is examining 39% (Unit 3) and 52% (Unit 4) of their High Risk welds and 15% (Unit 3) and 14% (Unit 4) of their Medium Risk welds. These percentages exceed the 25% and 10% values stipulated in EPRI TR-112657 for High and Medium Risk welds, respectively.
RAl-EPNB-2 The NRC staff noted there appears to be discrepancies between the numbers shown in Table 3.5 and the other tables in the submittal dated January 14, 2016. For example, for Unit 3, Table 3.5 shows there are 164 "High Risk" (Categories 1, 2 and 3) elements and 572 "Medium Risk" (Categories 4 and 5) elements these do not match numbers shown in Tables 5.1.1 and 5.2.1. Similar discrepancies were noted for Unit 4 in Tables 3.5, 5.2.1 and 5.2.2. The NRC staff requests FPL to explain the differences or supply corrected Tables.
FPL Response to RAl-EPNB-2:
There was a clerical error made when transferring information from Table 3.4 to Table 3.5.
When Table 3.5 was assembled, the weld totals from the "With" column in Table 3.4 were mistakenly transferred into Table 3.5 instead of the values from the "Without" column. The
Total" column for each Risk Category in Table 3.5 should have reflected the number of welds
L-2016-141 Attachment Page 3 of 5 excluding Flow Accelerated Corrosion (FAC) as identified in the "Without" column for each Risk Category in Table 3.4. FAC is covered under a separate augmented examination program. provides the updated Tables 3.4 and 3.5.
RAl-EPNB-3 EPRI TR 112657 Revision 8-A (Section 3.6.4.2) and Section 3.5 of the submittal dated January 14, 2016, both state that if the percentage of Class 1 piping locations selected for examination falls substantially below 10%, then the basis for the low percentage shall be investigated. The submittal states the percentage of Class 1 welds selected per the RI-ISi process was 6.8% (54 of 789 welds) in Unit 3 and 6.9% (57 of 825 welds) in Unit 4. The licensee stated the 6.8% and 6.9% were not an extreme departure from 10%. However, the NRC staff notes that these percentages result in a greater than 30% reduction in the number of Class 1 welds to be examined: 54 versus 79 for Unit 3, and 57 versus 83 for Unit 4. The EPRI TR explains how the number of Class 1 welds can drop below 10% because of a high number of Class 1 segments being assigned to low risk categories. The NRC staff was unable to determine if this is the case with the licensee's submittal with the tables provided because of the ~ixing of Class 1 & 2 segments in the tables. The NRC staff requests FPL to provide further justification for the low percentage of Class 1 welds selected.
FPL Response to RAl-EPNB-3:
FPL provides further justification for the low percentage of Class 1 welds selected by documenting the breakdown shown below of the number of Class 1 piping welds listed by risk categories. (Note that the risk category breakdown is more accurately established based on the number of welds rather than the number of segments.) This breakdown can be extracted from Tables 5.1.1 (Unit 3) and 5.1.2 (Unit 4). The results shown in the table below are based upon considering only those welds in Class 1 Code Examination Categories 8-F and 8-J. During re-validation of the numbers in Tables 5.1.1, 5.1.2, 5.2.1 and 5.2.2, two additional clerical errors were identified in Table 5.1.1. The 8-J "Low Risk" total welds should be 513 welds instead of 512 welds and the total "Sur only" should be 89 welds instead of 87 welds. The correct number of 8-J welds were identified within each system and in the total combined population count for 8-F and 8-J welds were correct. The overall number of welds remains the same, the changes have no impact on the risk-informed application.
UNIT3 UNIT4 RISK CATEGORY NO.OF WELDS NO. OF WELDS NO. OF WELDS NO. OF WELDS SELECTED SELECTED High 31 12 23 12 Medium 240 41 258 44 Low 518 1
544 1
TOTAL 789*
54 825*
57
L-2016-141 Attachment Page 4 of 5 As shown in the table above, the majority of Class 1 welds fall into the Low Risk Category. The reason for this departure is because the Turkey Point Core Damage Frequency (CDF) is much lower than most plants as described in Section 3.5 of Tutkey Point Relief Request No. 4. provides the updated Table 5.1.1.
RAl-EPNB-4 Of the welds not selected for future examinations in the RI-ISi program or FPL's augmented inspection programs, have previous examinations of any of these welds identified service induced degradation? If so, then what was the degradation mechanism, and what was done to mitigate the degradation?
FPL Response to RAl-EPNB-4:
During the Risk Informed Element Selection process, no welds identified with service induced degradation were eliminated from selection.
RAl-EPNB-5 Have any of the welds selected for examination in the RI-ISi been previously examined and resulted in limited examination coverage (i.e. less than 90%)? If so, the NRC staff requests FPL to explain why other welds have not been selected to minimize the number of examinations with limited exam coverage.
FPL Response to RAl-EPNB-5:
During the RI-ISi Element Selection meeting, welds were preferentially selected to avoid known limited coverage issues, whenever possible. However, in some instances the RI-ISi selection process limited which welds could be selected due to the existence of a postulated degradation mechanism in only a few welds. As a result, there were a few isolated instances where this option was not achievable.
RAl-APLA-1 In its submittal dated January 14, 2016, the licensee provided a list of Facts and Observations (F&Os) including DA-D5-01, and DA-D6 in Table 3, "Turkey Point PRA Model -
SRs Not Met," with their associated supporting requirements (SRs) that do not meet the American Society of Mechanical Engineers (ASME)/American Nuclear Society (ANS) probabilistic risk assessment standard (ASME/ANS RA-Sa~2009) Capability Categories (CCs). Table 2-2 of EPRI TR 1021467-A, "Nondestructive Evaluation: Probabilistic Risk Assessment Technical Adequacy Guidance for Risk-Informed In-Service Inspection Programs," assigns CC-I to SRs DA-D6 and DA-D5 for RI-ISi applications using the EPRI traditional RI-ISi approach.
L-2016-141 Attachment Page 5 of 5 The NRC staff requests FPL to explain whether the F&Os associated with SRs OA-05 and OA-06 have been dispositioned and whether those SRs meet CC-I following the F&Os disposition. If those F&Os have not been dispositioned, then the NRC staff requests FPL to justify why not meeting CC-I (for those SRs) will not impact the RI-ISi application.
FPL Response to RAl-APLA-1:
The F&Os associated with SRs OA-05 and OA-06 have been dispositioned and changes have been made to ensure compliance with CC-II.
OA-05-01 was addressed in the CCF update for Revision 11 of the PTN PRA model. The CCF alpha factors were updated and the CAFTA CCF tool was used. The
. use of the CAFTA CCF tool resolved this F&O.
OA-06-01 was addressed in the data update PTN-BFJR-02-026, Rev. 2. No plant-specific CCFs were found. provides the updated tables.
Table 3.4 L-2016-141 Enclosure 1 Page 1of3 Number of Elements by Risk Category With and Without Impact of FAC High Risk Region Medium Risk Region Low Risk Region Unit System(1l Category 1 Category 2 Category 3 Category 4 Category 5 Category 6 Category.7 With Without With Without With Without With Without With Without With Without With Without RCS 0
0 8
8 0
0 50 50 0
0 45 45 118 118 eves 0
0 0
0 0
0 0
0 37 37 189 189 64 64 SIS 0
0 7
7 0
0 157 157 0
0 191 191 173 173 RHR 0
0 16 16 0
0 66 66 0
0 9
9 285 285 SGBD 0
0 0
0 32 0
0 0
58 0
0 32 0
58 3
FWS 0
0 0
0 39 0
0 0
77 5
0 43 0
68 MS 0
0 0
0 45 0
0 0
83 0
0 45 0
83 AFW 0
0 0
0 17 0
0 0
44 5
0 20 0
36 css 0
0 0
0 0
0 0
0 0
0 0
0 117 117 WDS 0
0 0
0 0
0 0
0 0
0 5
5 14 14 Total 0
0 31 31 133 0
273 273 299 47 439 579 771 1016 High Risk Region Medium Risk Region Low Risk Region Unit System(1>
Category 1 Category 2 Category 3 Category 4 Category 5 Category 6 Category.7 With Without With Without With Without With Without With Without With Without With Without RCS 0
0 10 10 0
0 51 51 0
0 47 47 119 119 eves 0
0 0
0 0
0 0
0 39 39 211 211 49 49 SIS 0
0 3
3 0
0 172 172 0
0 209 209 131 131 RHR 0
0
' 10 10 0
0 70 70 0
0 20 20 333 333 SGBD 0
0 0
0 25 0
0 0
55 0
0 25 0
55 4
FWS 0
0 0
0 25 0
0 0
69 4
0 30 0
60 MS 0
0 0
0 42 0
0 0
80 0
0 42 0
80 AFW 0
0 0
0 15 0
o-0 42 3
0 19 0
35 css 0
0 0
0 0
0 0
0 0
0 0
0 92 92 WDS 0
0 0
0 0
-o 0
0 0
0 6
6 15 15 Total 0
0 23 23 107 0
293 293 285 46 493 609 739 969 Note:
- 1.
Systems are described in Table 3.1.
Table 3.5 L-2016-141 Enclosure 1 Page 2 of 3 Number of Elements Selected for Inspection by Risk Category Excluding Impact of FAC High Risk Region Medium Risk Region Low Risk Region Unit System111 Category 1 Category 2 Category 3 Category 4 Category 5 Category 6 Category 7 Total Selected Total Selected Total Selected Total Selected Total Selected Total Selected Total Selected RCS 0
0 8
5 0
0 50 5
0 0
45 0
118 0
eves 0
0 0
0 0
0 0
0 37 9
189 1
64 0
SIS 0
0 7
2 0
0 157.
17 0
0 191 0
173 0
RHR 0
0 16 5
0 0
66 15 0
0 9
0 285 0
SGBD 0
0 0
0 0
0 0
0 0
0 32 0
58 0
3 FWS O*
0 0
0 0
0 0
0 5
1 43 0
68 0
MS 0
0 0
0 0
0 0
0 0
0 45 0
83 0
AFW 0
0 0
0 0
0 0
0 5
1 20 0
36 0
css 0
0 0
0 0
0 0
0 0
0 0
0
,117 0
WDS 0
0 0
0 0
0 0
0 0
0 5
0 14 0
Total 0
0 31 12 0
0 273 37 47 11 579 1
1016 0
High Risk Region Medium Risk Rei:iion Low Risk Rei:iion Unit System111 Category 1 Catei:iorv 2 Catei:iory 3 Category 4 Category 5 Category 6 Category 7 Total Selected Total Selected Total Selected Total Selected Total Selected Total Selected Total Selected RCS 0
0 10 7
0 0
51 6
0
.o 47 0
119 0
eves 0
0 0
0 0
0 0
0 39 5
211 1
49 0
SIS 0
0 3
1 0
0 172 18 0
0 209 0
131 0
RHR 0
0 10 4
0 0
70 18 0
0 20 0
333 0
SGBD 0
0 0
0 0
0 0
0 0
0 25 0
55 0
4 FWS 0
0 0
0 0
0 0
0 4
1 30 0
60 0
MS 0
0 0
0 0
0 0
0 0
0 42 0
80 0
AFW 0
0 0
0 0
0 0
0 3
1 19 0
35 0
ess 0
0 0
0 0
0 0
0 0
0 0
0 92 0
WDS 0
0 0
0 0
0 0
0 0
0 6
0 15 0
Total 0
0 23 12 0
0 293 42 46 7
609 1
969 0
N~te: Systems are described in Table 3.1.
L-2016-141 Enclosure 1 Page 3 of 3 Table 5.1.1 Unit 3 - Inspection Location Selection Comparison Between ASME Section XI Code and EPRI TR-112657 by Risk Region High Risk Region Medium Risk Region Low Risk Region System(1)
Code Section Xl(2l EPRI TR-112657 Section Xl(2l EPRI TR-112657 Section x1(2l EPRI TR-112657 Category Weld Weld Weld Count Vol/
Sur RI-ISi Other(3l Count Vol/
Sur RI-ISi Other(3l Count Vol/
Sur RI-ISi Other(3l Sur Only Sur Only Sur Only AFW C-F-2 0
0 0
0 0
5 0
0 1
0 56 0
0 0
css C-F-3\\4!
0 0
0 0
0 0
0 0
0 0
117 0
0 0
eves 8-J 0
0 0
0 0
37 0
6 9
0 253 0
48 1
FWS C-F-2, C-F-4(4l 0
0 0
0 0
5 1
0 1
0 111 9
1 0
MS C-F-2, C-F-4(4l 0
0 0
0 0
0 0
0 0
0 128 8
2 0
RCS B-F, 8-J 8
5 1
5 0
50 29 2
5 0
163 32 17 0
RHR B-J C-F-1 C~F-3(4l '
16 4
1 5
0 66 20 0
15 0
294 27 0
0 SG8D C-F-2 0
0 0
0 0
0 0
0 0
0 90 9
0 0
SIS B-J C-F-1 C~F-3(4),
7 0
3 2
0 157 0
25*
17 0
364 15 24 0
WDS 8-J 0
0 0
0 0
0 0
0 0
0 19 0
6 0
B-F 1
1.
0 1
0 12 12 0
0 0
5 5
0 0
8-J 30 8
5 11 0
228 37 28 41 0
513 28 89 1
Totals by C-F-1 0
0 0
0 0
70 0
5 5
0 380 41 6
0 Code C-F-2 0
0 0
0 0
10 1
0 2
0 371 26 3
0 Category C-F-3 <*>
0 0
0 0
0 0
0 O*
0 0
312 0
0 0
C-F-4 (4l 0
0 0
0 0
0 0
0 0
0 14 0
0 0
Notes:
- 1.
Systems are described in Table 3.1.
- 2.
Since a Risk-Informed program for Class 1 welds was implemented during the third period of the third interval, piping weld examinations performed prior to the third period of the third interval per the 1989 Edition of ASME Code Section XI were used for comparison purposes for Class 1 welds. However, since the Risk-Informed program implemented during the fourth interval was for Class 1 welds only, piping weld examinations performed during the fourth interval per the 1998 Edition with Addenda through 2000 of ASME Code Section XI were used for comparison purposes for Class 2 welds.
- 3.
The column labeled "Other is generally used to identify augmented inspection program locations credited per Section 3.6.5 of EPRI TR-112657. The EPRI methodology allows augmented inspection program locations to be credited if the inspection locations selected strictly for RI-ISi purposes produce less than a 10%
sampling of the overall Class 1 weld population. The Turkey Point RI-ISi application did not rely on augmented inspection program locations beyond those selected by the RI-ISi process. The "Other column has been retained in this table solely for uniformity purposes with the other RI-ISi application template submittals.
- 4.
Code Categories C-F-3 and C-F-4 consist of Code Examination Category C-F-1 and C-F-2 welds respectively that were previously excluded from examination per Table IWC-2500-1 due to being welds in "thin wall piping". For the RI-ISi application, this exclusion does not exist.
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
F&O SR II DA-DS-DA-01 DS L-2016-141 Enclosure 2 Page 1of2 Updated F&O DA-05-01 and DA-06-01 Basis for Possible Resolution Initial Comment Disposition Issue I
Significance For several CCF groups, !The missing CCF Two alternatives. The Could not find
!This was addressed in a "global common contribution from missing CCF terms guidance regarding the CCF update for cause event" (as the S-of-6 term could be added to the adding as to a6 to Revision 11 of the PTN described at the end of (or the 2-of-4 and CAFTA fault trees and approximate the PRA model. The CCF Section 4.2 of PTN-3-of-4) should not CCF basic events S/6 combinations alpha factors were BFJR-2008-012, Rev. O) be significant calculated for the new in INEL-94/0064, updated and the CAFTA is used. While this is a since the 6-of-6 terms. A simpler but it makes sense. CCF tool was used. The reasonable term (or 4-of-4 alternative is to revise Does the reviewer use of the CAFTA CCF simplification, the term) is included the calculation of the have a specific tool resolved this F&O.
global common cause and should a6 term to include the reference event needs to account dominate the CCF missing as value.
(document and for the common cause contribution.
Thus, a6' = as + a6.
page number) for combinations that are This overestimates the this?
not included explicitly.
as contribution, since However, for several 6-it is applied to the component groups case where all 6 (AFW AOVs FTO, AFW components fail, but CVs FTO, AFW MOVs this should be a small FTO), the S-of-6 term and conservative was not included and approximation.
the 6-of-6 term was not (Similar correction for adjusted. A simi lar issue the 4-component appears to be present group, a4' = a2 + a3 +
component group),
where only the 4-of-4 term is included (the 2-of-4 and 3-of-4 terms are missing and the 4-of-4 term was not adjusted).
Basis for F&O SR Issue Significance DA DA-The CCF notebook did The SR includes a 01 06 not include a review of check to assure plant failure data for the CCF common cause events.
parameters are consistent with available plant-specific experience.
Possible Resolution Review plant-specific component failure events from the most recent data update to identify any common cause failures. If CCFs are identified, verify that the CCF is modeled for the specific component and failure mode. If this data indicates a significantly larger fraction of failures are CCFs than the generic CCF parameters would predict, plant-specific CCF parameters should be calculated.
If the data is limited (one or two failures in a specific component group), this would not be sufficient evidence to justify plant-specific CCF parameters.
L-2016-141 Enclosure 2 Page 2 of 2 Initial Comment Disposition I
~his needs to be Addressed in data done to meet the update PTN-BFJR Standard, but I 026, Rev. 2. No plant-don't expect to find specific CCFs were any plant-specific found.
CCFs.