L-2018-176, Subsequent License Renewal Application, Responses to the August 2018 NRC On-Site Regulatory Audit Follow-Up Items
| ML18292A641 | |
| Person / Time | |
|---|---|
| Site: | Turkey Point  |
| Issue date: | 10/17/2018 |
| From: | Maher W Florida Power & Light Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| EPID L-2018-RNW-0002, L-2018-176 | |
| Download: ML18292A641 (30) | |
Text
l=PL.
L-2018-176 10 CFR 54.17 October 17, 2018 U.S. Nuclear Regulatory Commission Attn : Document Control Desk Washington, D.C. 20555-0001 Re: Florida Power & Light Company Turkey Point Units 3 and 4 Docket Nos. 50-250 and 50-251 Turkey Point Units 3 and 4 Subsequent License Renewal Application Responses to the August 2018 NRC On-Site Regulatory Audit Follow-Up Items
References:
- 1. FPL Letter L-2018-004 to NRC dated January 30, 2018, Turkey Point Units 3 and 4 Subsequent License Renewal Application (ADAMS Accession No. ML18037A812)
- 2. FPL Letter L-2018-082 to NRC dated April 10, 2018, Turkey Point Units 3 and 4 Subsequent License Renewal Application - Revision 1 (ADAMS Accession No. ML18113A134)
- 3. Turkey Point Nuclear Generating Units 3 and 4 - Plan for the On-Site Regulatory Audit Regarding the Subsequent License Renewal Application Review (EPID No.
L-2018-RNW-0002) (ADAMS Accession No. ML18232A576)
Florida Power & Light Company (FPL) submitted a subsequent license renewal application (SLRA) for Turkey Point Units 3 and 4 to the NRC on January 30, 2018 (Reference 1) and SLRA Revision 1 on April 10, 2018 (Reference 2).
The purpose of this letter is to provide, as attachments to this letter, FPL's voluntary responses to three follow-up items associated with the NRC on-site regulatory audit conducted at the Turkey Point facility on August 27 - 31, 2018 (Reference 3). These responses include revisions to the SLRA addressing Aging Management Program (AMP) XI.S7, Inspection of Water Control Structures Associated with Nuclear Power Plants, and Section 4.5, Concrete Containment Tendon Prestress Time-Limited Aging Analysis (TLAA).
If you have any questions, or need additional information, please contact me at 561-691-2294.
Florida Power & Light Company 700 Universe Boulevard, Juno Beach, FL 33408
Turkey Point Units 3 and 4 Docket Nos. 50-250 and 50-251 L-2018-176 Page 2 of 2 I declare under penalty of perjury that the foregoing is true and correct.
Executed on October 17, 2018.
Sincerely, William Maher Senior Licensing Director Florida Power & Light Company WDM/SF Attachments
Regional Administrator, Region II, USNRC Senior Resident Inspector, USNRC, Turkey Point Plant Project Manager, USNRC, Turkey Point Nuclear Project Manager, USNRC, SLRA Project Manager, USNRC, SLRA Environmental Ms. Cindy Becker, Florida Department of Health
Turkey Point Units 3 and 4 Docket Nos. 50-250 and 50-251 FPL Response to NRC On-Site Audit Follow Up Item 1: XI.S7 AMP L-2018-176 Attachment 1 Page 1 of 4 On-Site Regulatory Audit Regarding the Turkey Point Nuclear Generating Unit Nos. 3 and 4 - Subsequent License Renewal Application, August 27-31, 2018 During the NRC site audit at Turkey Point from August 27 through 30, 2018, a question was raised regarding whether the PTN inspection of water-control structures associated with nuclear power plants AMP should be considered an existing or new AMP.
FPL Response:
Based on a review of the specifics related to the AMP, FPL has determined that it would be appropriate to change the AMP from an existing to a new AMP. Updates to the SLRA as a result of this change are provided below.
References:
None Associated SLRA Revisions:
The following changes to SLRA Table 17-1, Table 17-3, Section 17.2.2.36, Table B-1, Table B-4, and Section B.2.3.36 will be made in a future SLRA revision as indicated by text deletion (strikethrough) and text addition (red underlined font).
Revise SLRA Table 17-1 as follows:
XI.S7 Inspection of Water-Control Structures Associated with Existing New Nuclear Power Plants (Section 17.2.2.36)
Revise SLRA Section 17.2.2.36 as follows:
Inspection of Water-Control Structures Associated with Nuclear Power Plants The PTN Inspection of Water Control Structures Associated with Nuclear Power Plants AMP is an existing new AMP, formerly a portion of the PTN Systems and Structures Monitoring Program. The AMP manages age-related degradation due to environmental conditions and the effects of natural phenomena that may affect water-control structures through periodic monitoring and maintenance activities. Although PTN has not formally committed to implement RG 1.127, this AMP addresses inspection of water-control structures, commensurate with RG 1.127.
Revise SLRA Table 17-3 as follows:
Turkey Point Units 3 and 4 Docket Nos. 50-250 and 50-251 FPL Response to NRC On-Site Audit Follow Up Item 1: XI.S? AMP L-2018-176 Attachment 1 Page 2 of 4 40 Inspection XI.S? Continue the existing Implement the new PTN of Water-Inspection of Water-Control Structures Control Associated with Nuclear Power Plants AMP.c Structures The following items shall be included in the new Associated AMP., including enhancement to:
with a) Store high strength bolts in accordance with Nuclear Section 2 of Research Council for Structural Power Connections publication "Specification for Plants Structural Joints Using High-Strength Bolts";
(17.2.2.36) b) Monitor structural bolting for loss of material, loose bolts, missing or loose nuts, and other conditions that indicate loss of preload.
Loose bolts and nuts are not acceptable unless accepted by engineering evaluation ;
c) Monitor for increases in porosity, permeability, and conditions at junctions with abutments and embankments; d) Perform focused inspections of below-grade, inaccessible concrete structural elements exposed to aggressive groundwater/soil, on an interval not to exceed 5 years.
Submerged concrete structures may be inspected during periods of low tide or when dewatered or using divers. Areas covered by silt, vegetation, or marine growth are not considered inaccessible and are cleaned and inspected in accordance with the standard inspection frequency; e) Include monitoring for siltation or undesirable vegetation, with respect to cooling canal inspections, so that the cooling canal function does not become impaired ;
f)
Include the Reinforced Concrete Shield Wall for the Discharge Structure in the list of components inspected in the pertinent implementing procedure.
9.l Perform a baseline survey of the cooling canal system 6 months prior to the SPEO.
Additional surveys will be conducted at least once everv 10 years with the first survey being the baseline survey performed prior to the SPEO.
l No later than 6 months prior to the SPEO, i.e.:
PTN3:
1/19/2032 PTN4:
10/10/2032
Turkey Point Units 3 and 4 Docket Nos. 50-250 and 50-251 FPL Response to NRC On-Site Audit Follow Up Item 1: XI.S7 AMP L-2018-176 Attachment 1 Page 3 of 4 Revise SLRA Table B-1 as follows:
IXI.S7 I
B.2.3.36 Inspection of Water-Control Structures Associated with Nuclear Power Plants Existing New Revise SLRA Table B-4 as follows:
Inspection of Water-Control B.2.3.36 No XI.S7
¥es New No Structures Associated with Nuclear Power Plants Revise SLRA Section B.2.3.36 as follows:
Program Description The PTN Inspection of Water-Control Structures Associated with Nuclear Power Plants AMP is an existing new program, formerly a portion of the PTN Systems and Structures Monitoring Program. The AMP manages age-related degradation due to environmental conditions, and the effects of natural phenomena that may affect water-control structures, through periodic monitoring and maintenance activities.
NUREG-2191 Consistency The PTN Inspection of Water-Control Structures Associated with Nuclear Power Plants AMP, with enhancements, will be consistent with the 10 elements of NUREG-2191,
Section XI.S7, "Inspection of Water-Control Structures Associated with Nuclear Power Plants."
Enhancements None. The PTN Inspection of VVater Control Structures Associated with Nuclear Power Plants AMP will be enhanced as follo*.vs, for alignment with NU REG 2191. The enhancements are to be implemented no later than six months prior to entering the SPEO.
ElemeRt Affecte~
ERRaRcemeRt
- 1. Scope of Program Update the governing AMP proceElure to incluEle the ReinforceEl Concrete Shield V\\lall for the Discharge Structure in the list of components inspecteEl.
- 2. Preventive Actions UpElate the pertinent AMP specification to include the pre*.ienti*.ie action reEJuirements for proper storage of high strength bolts.
Turkey Point Units 3 and 4 Docket Nos. 50-250 and 50-251 FPL Response to NRC On-Site Audit Follow Up Item 1: XI.S7 AMP L-2018-176 Attachment 1 Page 4 of 4
- 3. Parameters bJfJElate tl=le §everRiR§ AMP 13reeeEl1:1re te iRel1:1Ele MeRitereEl er tl=le meRiteriR§ ef less ef material, lease eelts, I A s13ecteEl missiR§ er lease Rl:lts, aRd etl=ler ceRElitieRs tl=lat iRElicate less ef 13releaEl.
bJ13Elate tl=le §ei..ierRiR§ AMP 13receEl1:1re te meRiter fer iRcreases iR 13eresity aREl 13ermeaeility, aREl ceRElitieRs at j1:1RctieRs witl=I ae1:1tmeRts aREl emeaRkmeRts.
- 4. DetectieR efA§iR§ bJ13Elate tl=le §91.iemiR§ AMP 13receEl1:1re te iRcl1:1ae Effects foc1:1seEl iRs13ectieRs ef eelew §raEle, iRaccessiele ceRcrete str1:1ct1:1ral elemeRts ex13esea te a§§ressive §Fel:lRElwater/seil, eR aR iRterval Ret te exceeEl 5 years.
bl13aate tl=le §everRiR§,A,MP 13recea1:1re te iRGl1:1ae iRs13ectieR ef ceeliR§ caRals fer siltatieR er 1:1Raesiraele ve§etatieR tl=lat ce1:1la im13air tl=le ceeliR§ caRal f1:1RctieR.
- 6. Accef:)taRce Criteria bl13aate tl=le §everRiR§ AMP 13recea1:1re testate tl=lat lease eelts aREl R1:1ts are Ret acce13taele 1:1Rless accef:)teEl ey eR§iReeriR§ eval1:1atieR.
Conclusion The PTN Inspection of Water-Control Structures AMP, witl=I eRl=laRcemeRts, will provide reasonable assurance that the effects of aging will be managed so that the intended function(s) of components within the scope of the AMP will be maintained consistent with the CLB during the SPEO.
Associated
Enclosures:
None
Turkey Point Units 3 and 4 Docket Nos. 50-250 and 50-251 FPL Response to NRC On-Site Audit Follow Up Item 2: TLAA L-2018-176 Attachment 2 Page 1 of 15 On-Site Regulatory Audit Regarding the Turkey Point Nuclear Generating Unit Nos. 3 and 4 - Subsequent License Renewal Application, August 27-31, 2018 Concrete Containment Tendon Prestress TLAA During the NRC site audit at Turkey Point from August 27 through 30, 2018 questions were raised regarding SLRA Section 4.5 Concrete Containment Tendon Prestress TLAA and the supporting calculations. These questions included clarification of:
Whether the predicted lower limit (PLL) is evaluated as a TLAA Why a greater number of tendons were included than those required for examination Why certain plotted data exhibits considerable tendon lift-off force variation Why the reportable data for regression analysis for trending of tendon prestress force and safety evaluation is not limited to the prestress minimum required value (MRV) and PLL line.
Why the regression analyses trend lines were omitted from the SLRA Figures 4.5-1 through 4.5-6.
The staff is not clear on how ascending tendon prestress force trend lines are possible when concrete experiences creep and shrinkage and the tendons undergo relaxation.
FPL Response:
The Containment Tendon Loss of Prestress Time Limited Aging Analysis (TLAA) for License Renewal and Subsequent License Renewal calculation was updated to differentiate the containment tendons that were affected by the PTN Unit 3 and Unit 4 Reactor Vessel Closure Head (RVCH) Replacement project. The analysis was also updated to only include "physical" surveillance data where the tendon force is measured. The two units alternate between "physical" and "visual" inspections at each surveillance period. These updated basis documents are available on the Portal for NRC review. In addition, the requested clarifications are summarized as follows:
Added statement in the calculation that the PLL is evaluated as a TLAA.
As part of the tendon surveillance during the period of extended operation,
tendons are selected to undergo a "physical" inspection, where the tendon force is measured. Additionally, Turkey Point Unit 3 and Unit 4 meet the criteria of Section IWL-2421, which allows for the condition that one unit undergo a physical surveillance and the other unit only undergo a "visual" inspection (no force monitoring or sample wire testing required). The two units alternate between "physical" and "visual" inspections at each surveillance period. The tendon loss of prestress calculation was updated to only include
Turkey Point Units 3 and 4 Docket Nos. 50-250 and 50-251 FPL Response to NRC On-Site Audit Follow Up Item 2: TLAA L-2018-176 Attachment 2 Page 2 of 15 "physical" surveillance data.
The Turkey Point Unit 3 and Unit RVCH Replacement Projects required a containment access opening to provide for the removal and later replacement of a section of the containment structures. The Unit 3 and Unit 4 tendons affected by the RVCH modification are considered as augmented scope tendons and are analyzed separately from the Unit 3 and Unit 4 tendons for SLR. The tendon loss of prestress calculation was updated to separate the augmented scope tendons from the original scope tendons which eliminated the considerable tendon lift-off force variation.
Although the trending of tendon prestress force can be limited to the MRV and PLL line, additional, non-critical data is included in the regression analysis to be consistent with the analysis from the PTN original license renewal regression analysis.
SLRA Figures 4.5-1 through 4.5-6 will be updated to include regression analysis trendlines consistent with the containment loss of prestress calculation update.
The Unit 3 and Unit 4 tendons affected by the RVCH modification are considered as augmented scope tendons and are analyzed separately from the Unit 3 and Unit 4 tendons for SLR. The containment loss of prestress calculation was updated to separate the augmented scope tendons from the original scope tendons for the regression analysis to remove the false impression of an ascending (rather than descending) trend of the tendon prestress force.
References:
None J
Turkey Point Units 3 and 4 Docket Nos. 50-250 and 50-251 FPL Response to NRC On-Site Audit Follow Up Item 2: TLAA L-2018-176 Attachment 2 Page 3 of 15 Associated SLRA Revisions:
The following changes to SLRA Sections 4.5 will be made in a future SLRA revision as indicated by text deletion (strikethrough) and text addition (red underlined font).
Revise the TLAA Description in Section 4.5 on page 4.5-1 as follows:
TLAA Description The Turkey Point Units 3 and 4 containment buildings are post-tensioned, reinforced concrete structures composed of vertical cylinder walls and a shallow dome, supported on a conventional reinforced concrete base slab. The cylinder walls are provided with vertical tendons and horizontal hoop tendons. The dome is provided with three groups of tendons oriented 120-degrees apart.
Over time, the containment prestressing forces decrease due to relaxation of the steel tendons and due to creep and shrinkage of the concrete. The containment tendon prestressing forces were calculated during the original design considering the magnitude of the tendon relaxation and concrete creep and shrinkage over the 40-year life of the plant. The Concrete Containment Un bonded Tendon Prestress AMP (Section B.2.2.3) and ASME Section XI, Subsection IWL AMP (Section B.2.3.31) perform periodic surveillances of individual tendon prestressing values. Predicted lower limit (PLL) force values are calculated for each tendon prior to the surveillances to estimate the magnitude of the tendon relaxation and concrete creep and shrinkage for the given surveillance period. The prestressing forces are measured and plotted, and trend lines are developed, to ensure the average tendon group prestressing values remain above the respective minimum required values (MRVs) until the next scheduled surveillance.
The predicted lower limit force values and regression analyses, utilizing actual measured tendon forces, are used to evaluate the acceptability of the containment structure to perform its intended function over the current 60-year life of the plant, and therefore, are TLAAs requiring evaluation for the SPEO.
The PTN Unit 3 and Unit 4 Reactor Vessel Closure Head (RVCH) Replacement Projects required a temporary containment access opening to provide for the removal and later replacement of a section of the containment structures which was necessary for RVCH replacement. The Unit 3 and Unit 4 tendons affected by the RVCH modification are considered as augmented scope tendons and are analyzed separately from the Unit 3 and Unit 4 tendons for SLR. Since the Unit 3 and Unit 4 tendons affected by the RVCH modification are considered as augmented scope. the RVCH tendons are considered with a separate regression analysis than those in the original scope
Turkey Point Units 3 and 4 Docket Nos. 50-250 and 50-251 FPL Response to NRC On-Site Audit Follow Up Item 2: TLAA L-2018-176 Attachment 2 Page 4 of 15 Add the following after the Predicted Lower Limit (PLL) on page 4.5-2:
Baseline Predicted Force (BPF)
The regression analysis for the RVCH tendons is based on comparing the tendon surveillance data versus the BPF and MRV. As an alternative to the PLL, Reg.
Guide 1.35.1 allows for the use of the expected force based directly on plant design losses. It states, "In lieu of the variations [for concrete shrinkage, concrete creep, and steel relaxation], the designer may use the conservatively estimated design values for the time-dependent factors." The "actual" predicted prestress force will always be greater than the PLL. Using this method, the RVCH-affected tendon's Predicted Force uses the actual expected losses listed in PTN TS, Section 5.1.4.4, and does not consider the tolerance allowance of Reg. Guide 1.35.1. The calculation of a tendon's individual Predicted Force, which is used as the final acceptance criteria for that tendon, begins with the calculation of the Baseline Predicted Force (BPF) described in Reg. Guide 1.35.1. The BPF considers the expected stress losses for the type of tendon and the time period over which the losses occur for each specific tendon. Equations are generated to calculate the expected force for any tendon at any particular time after installation.
Revise the Assessment in Section 4.5 on page 4.5-2 as follows:
Assessment The regression analyses associated with the tendons have been reanalyzed to extend the trend lines from 60 years to 80 years. The extended trend lines have been calculated using individual tendon prestressing force values based on data incorporating the latest surveillances for Turkey Point Units 3 and 4 in 2017. In all cases, the regression analyses predict the prestressing forces will remain above the respective group MRVs through the SPEO.
Figures 4.5-1 through 4.5-6 contain the reanalyzed regression analyses for each tendon group at PTN. Extended trend lines have been developed for both the group control tendons, as well as for all tendons within the respective group, including the control tendons, and plotted with the MRVs over the 80-year period.
Figures 4.5-7 through 4.5-10 contain the reanalyzed regression analysis for the tendon groups affected by the RVCH replacement project. The surveillance data is plotted with the MRVs over the 80-year period.
The Concrete Containment Unbonded Tendon Prestress AMP (Section B.2.2.3) will monitor and manage the TLAA and the associated loss of tendon prestressing forces during the SPEO. The regression analyses are periodically updated following successive surveillances to ensure that estimated values remain above the MRVs until the next scheduled surveillance, and potentially for the life of the plant. Individual
Turkey Point Units 3 and 4 Docket Nos. 50-250 and 50-251 FPL Response to NRC On-Site Audit Follow Up Item 2: TLAA L-2018-176 Attachment 2 Page 5 of 15 measured tendon prestressing forces will be compared to predicted PLL values, BPF values (as related to the containment tendons affected by the PTN RVCH replacement project), and trend lines developed for the SPEO.
New upper limit curves, lower limit curves, BPF curves (as related to the containment tendons affected by the PTN RVCH replacement project). and trend lines of measured prestressing forces have been established for all tendons through the SPEO as part of the Concrete Containment Unbonded Tendon Prestress AMP (Section B.2.2.3). The predicted final effective preload at the end of 80 years exceeds the minimum required preload for all containment tendons.
Consequently, the post-tensioning system will continue to perform its intended function throughout the SPEO.
Turkey Point Units 3 and 4 Docket Nos. 50-250 and 50-251 FPL Response to NRC On-Site Audit Follow Up Item 2: TLAA L-2018-176 Attachment 2 Page 6 of 15 Replace Figures 4.5-1, 2, 3, 4, 5, 6 pages 4.5-4 -4.5-9 as follows:
- a.
700 680 660 640 620 R 600 QI
~
o 580
- u.
C:
0
~ 560
{!!.
540 520 500 480 1
Figure 4.5-1 Unit 3 Hoop Tendons 1st Through 45th Year Tendon Surveillance 10 Time (Years) from Tensioning Date y = -21.09ln(xl + 660.04 Tendon Force
...._ M in. PF
_.,_ PTF
...._Pll
...._ PUL
- Log. (Tendon Force) 100
Turkey Point Units 3 and 4 Docket Nos. 50-250 and 50-251 FPL Response to NRC On-Site Audit Follow Up Item 2: TLAA L-2018-176 Attachment 2 Page 7 of 15 Figure 4.5-2 Unit 4 Hoop Tendons 1st Through 45th Year Tendon Surveillance 700 680 660 640 620 Q.
~ 600 Q) u...
0 580 I.I.
C 0
"O C
560
{:!.
540 520 500 480 1
10 Time (Years) from Tensioning Date 100 y = -21.61n(x) + 648.69 Tendon force
~
Min. PF
...,_PTF
...,_ PLL
~
PUL
- Log.(Tendonforce)
Turkey Point Units 3 and 4 Docket Nos. 50-250 and 50-251 FPL Response to NRC On-Site Audit Follow Up Item 2: TLAA L-2018-176 Attachment 2 Page 8 of 15 740 720 700 680 660
-;;:. 640 C.
~
(IJ 620 V...
0
- u.
600 C
0 "O
C 580 (IJ 560 540 520 500 1
Figure 4.5-3 Unit 3 Dome Tendons 3rd Through 45th Year Tendon Surveillance I *
- ,............. !-----~*-**********-.*
- ******1 *********************
10 Time (Years) from Tensioning Date v = -2.321n(x) + 684.08 Tendon Force
--e-- Min. PF
--e-- PTF
--e--PU
--e-- PUL
- log. (Tendon Force) 100
Turkey Point Units 3 and 4 Docket Nos. 50-250 and 50-251 FPL Response to NRC On-Site Audit Follow Up Item 2: TLAA L-2018-176 Attachment 2 Page 9 of 15 Figure 4.5-4 Unit 4 Dome Tendons 1st Through 45th Year Tendon Surveillance 700 680 660 640
-;;, 620 Q.
~
600
- ******** I I
QI u....
0.....
C 580 0
"'C C
~ 560 540 520 500 1
10 Time (Years) from Tensioning Date v = -17.621n{x) + 665.82 Tendon Force
....,_Min. PF
....,_ PTF
....,_ PLL
....,_ PUL
- log. {Tendon Force) 100
Turkey Point Units 3 and 4 Docket Nos. 50-250 and 50-251 FPL Response to NRC On-Site Audit Follow Up Item 2: TLAA L-2018-176 Attachment 2 Page 10 of 15 Figure 4.5-5 Unit 3 Vertical Tendons 3rd Through 45th Year Tendon Surveillance 740.00 720.00 700.00 680.00 660.00
-;;, 640.00 Cl.
~
cu 620.00 u...
0
.... ******************-~**********: ****************************
- u.
C:
600.00 0
"O C:
cu I-580.00 560.00 540.00 1
10 Time (Years) from Tensioning Date y = -4.3721n(x) + 632.35 100 Tendon Force --e-Min. PF -+- PTF --e-PLL --e-PUL
.... ***** log. {Tendon Force)
Turkey Point Units 3 and 4 Docket Nos. 50-250 and 50-251 FPL Response to NRC On-Site Audit Follow Up Item 2: TLAA L-2018-176 Attachment 2 Page 11 of 15 Figure 4.5-6 Unit 4 Vertical Tendons 1st Through 45th Year Tendon Surveillance a
760.00 740.00 720.00 700.00 680.00 660.00 g
640.00 el... o 620.00 u..
C 0
'U C
{!!.
600.00 580.00 560.00 540.00 520.00 500.00 1
I 10 Time (Years) from Tensioning Date I
y = -18.llln(x) + 676.53 100 TendonForce -.- Min. PF...,.__ PTF -.-Pll -.- PuL
- Log. (TendonForce)
Turkey Point Units 3 and 4 Docket Nos. 50-250 and 50-251 FPL Response to NRC On-Site Audit Follow Up Item 2: TLAA L-2018-176 Attachment 2 Page 12 of 15 Add Figures 4.5-7, 8, 9, 10 as follows:
Figure 4.5-7 Unit 3 RVCH Hoop Tendons 35th Through 45th Year Tendon Surveillance 700 680 660 640 620 600
- 0.
g
~ 580 u...
0 I.I.
560 C
0
-0 540 C
~
~
520 500 480 1
10 Time (Years) from Tensioning Date Tendon Force..... Min. PF..... BPF 100
Turkey Point Units 3 and 4 Docket Nos. 50-250 and 50-251 FPL Response to NRC On-Site Audit Follow Up Item 2: TLAA L-2018-176 Attachment 2 Page 13 of 15 Figure 4.5-8 Unit 4 RVCH Hoop Tendons 35th Through 45th Year Tendon Surveillance 700 680 660 640 620 600
- a.
~
QI 580 u...
0
- u.
C 560 0
"O C
540
{E 520 500 480 1
I 10 Time (Years) from Tensioning Date Tendon Force..... Min. PF..... BPF 100
Turkey Point Units 3 and 4 Docket Nos. 50-250 and 50-251 FPL Response to NRC On-Site Audit Follow Up Item 2: TLAA L-2018-176 Attachment 2 Page 14 of 15 Figure 4.5-9 Unit 3 RVCH Vertical Tendons 35th Through 45th Year Tendon Surveillance 760 740 720 700 680 660 vi' 640
- a.
~ 620 (II u
600 0
LL.
C 580 0
"C 560 C
(II._
540 520 500 480 1
10 Time (Years) from Tensioning Date Tendon Force
~
M in. PF
~
BPF 100
Turkey Point Units 3 and 4 Docket Nos. 50-250 and 50-251 FPL Response to NRC On-Site Audit Follow Up Item 2: TLAA L-2018-176 Attachment 2 Page 15 of 15 Figure 4.5-1 O Unit 4 RVCH Vertical Tendons 35th Through 45th Year Tendon Surveillance 740 720 700 680 660 640 620 C.
~
Cl/
600 I
I I
u...
0 580
- u.
C 560 0
'l:l C
Cl/
540 I-520 500 480 1
10 Time (Years) from Tensioning Date Tendon Force..... Min. PF -e-BPF Associated
Enclosures:
None 100
Turkey Point Units 3 and 4 Docket Nos. 50-250 and 50-251 FPL Response to NRC On-Site Audit Follow Up Item 3: X.S1, XI.S2 AMPs L-2018-176 Attachment 3 Page 1 of 9 On-Site Regulatory Audit Regarding the Turkey Point Nuclear Generating Unit Nos. 3 and 4 - Subsequent License Renewal Application, August 27-31, 2018 Concrete Containment Tendon Prestress (X.S1) and ASME Section XI, Subsection IWL (XI.S2) AMPs During the NRC site audit at Turkey Point from August 27 through 30, 2018, questions were raised regarding the subject aging management programs (AMPs) in relation to the questions raised on the TLAA calculation (#1 above). These include clarification of:
Whether and how the guidance of Regulatory Guide (RG) 1.35.1 was followed during the 45th year of IWL inspections and is part of the CLB?
How the tendon prestress force history was developed and how past observed data correlates with those to be obtained from future inspections?
Whether alterations made to the concrete containments and tendon prestressing system(s) affected the use of the twin containment stipulation for alternating the frequency of tendon lift-off force measurements?
What actions have been taken, relative to grease leakage from tendons, for IWL AMP to ensure that tendon degradation does not cause a loss of containment prestress during the SPEO?
FPL Response:
The basis documents have been updated as a result of the prestress calculation update and to include the above clarifications. These updated basis documents are available on the Portal for NRC review. In addition, the requested clarifications are summarized as:
The guidance of RG 1.35.1 was followed during the 45th year of IWL inspections as a comparison to previous inspections. It is included in the Turkey Point CLB as described in SLRA Sections 17.2.1.3, 17.2.2.31, B.2.2.3, B.2.3.31 and Table 17-3 item 3.
With the update to the prestress calculation, tendon prestress history from the 1st IWL inspection is captured with MRV, PLL, PUL and trend information identified and considered in the projection of the lines to end-of-license (life). The enhancements addressed in SLRA Sections 17.2.1.3, 17.2.2.31, B.2.2.3, B.2.3.31 and Table 17-3 item 3 will ensure that this correlation continues through the SPEO.
Alterations made to the containments and their tendon prestressing systems did not affect the use of twin containment stipulation. The alterations were temporary in relation to reactor vessel closure head (RVCH) replacement. The alterations affected the same tendons for each unit plus 3 additional tendons for Unit 4. All of the affected tendons, whether replaced or retensioned, were
Turkey Point Units 3 and 4 Docket Nos. 50-250 and 50-251 FPL Response to NRC On-Site Audit Follow Up Item 3: X.S1, XI.S2 AMPs L-2018-176 Attachment 3 Page 2 of 9 removed from the sample population and included in a separate augmented scope population. A baseline predicted force (BPF) has been determined and projected for these tendons. A tendon is selected from this augmented scope population per IWL-2521-2 and the force measured.
An action request was issued, which included an apparent cause evaluation (ACE), and an engineering evaluation performed. The engineering evaluation concluded that the grease residue (film) left on the tendons adequately protected the tendons, no water was identified, and the issue is common to both Turkey Point and other sites with similar containments and prestressing systems. The gasket for the bottom end cap of the tendon sheath with excessive leakage was repaired and grease replenished. Furthermore, per Turkey Point Technical Specification 3/4.6.1.6.1, non-conformance reports are developed each interval for engineering evaluation when replenished grease exceeds 10% of the net volume (of grease in the tendon sheath). Such instances are typically resolved through repair/replacement of the gasket and replenishing the grease.
Therefore, the ASME Section XI, Subsection IWL AMP as described in SLRA Sections 17.2.2.31 and B.2.3.31 and Table 17-3 item 35 is adequate to ensure that tendon degradation does not cause a loss of containment prestress during the SPEO.
Corresponding updates to the SLRA for these clarifications are provided below.
References:
None Associated SLRA Revisions:
The following changes to SLRA Sections 17.2.1.3, 17.2.2.31, B.2.2.3, and B.2.3.31 will be made in a future SLRA revision as indicated by text deletion (strikethrough) and text addition (red underlined font).
Revise the Concrete Containment Unbonded Tendon Prestress AMP in Section
- 17. 2. 1. 3 on page A-11 as follows:
The PTN Concrete Containment Unbonded Tendon Prestress AMP is an existing AMP that is part of the PTN lnservice Inspection (ISi) Program that is based on ASME Section XI, Subsection IWL, criteria, as supplemented by the requirements of 10 CFR 50.55a(b)(2)(viii). This AMP monitors and manages the loss of tendon prestress in the concrete containment prestressing system for the SPEO.
Loss of containment tendon prestressing forces is a TLAA evaluated in accordance with 10 CFR 54.21 (c)(1 )(iii). The PTN Concrete Containment Unbonded Tendon Prestress AMP, as part of the PTN ASME Section XI, Subsection IWL AMP, manages loss of containment tendon prestressing forces in the current period of extended operation
Turkey Point Units 3 and 4 Docket Nos. 50-250 and 50-251 FPL Response to NRC On-Site Audit Follow Up Item 3: X.S1, XI.S2 AMPs L-2018-176 Attachment 3 Page 3 of 9 (PEO). This TLAA AMP consists of the assessment of measured tendon prestressing forces from examinations performed through the PTN ASME Section XI, Subsection IWL AMP. The adequacy of the prestressing force for each tendon group based on type (i.e., hoop, vertical, and dome) and other considerations (e.g., geometric dimensions, whether affected by repair/replacement, etc.) establishes (a) acceptance criteria in accordance with Subsection IWL and (b) trend lines constructed based on the guidance provided in NRC IN 99-10, "Degradation of Prestressing Tendon Systems in Prestressed Concrete Containments." The calculation of prestressing losses, predicted upper limits and predicted lower limits for each tendon group is in accordance with the guidelines of the NRC RG 1.35.1, "Determining Prestressing Forces or Inspection of Prestressed Concrete Containments."
The loss of concrete containment tendon prestressing forces is detected by comparing the measured data against the predicted force values from the respective containment tendon loss of prestress TLAA. Loss of prestressing forces are also detected by comparing the tendon force trend lines, constructed from surveillance measurements, against predicted force values. In addition to PTN Unit 3 and Unit 4 ASME Section XI,
Subsection IWL examination requirements, all measured prestressing forces, up to the current examination, are plotted against time. This examination includes common (historical/control) tendons, and randomly sampled tendons from each group plus random sampling of tendons affected by the reactor vessel closure head (RVCH) replacements for each unit. The predicted lower limit (PLL), MRV, and trend-line curves are developed for each tendon group examined for the SPEO. The trend line represents the general variation of prestressing forces with time based on the actual measured forces in individual tendons of the specific tendon group. The trend line for each tendon group is constructed by regression analysis of measured prestressing forces in individual tendons of that group obtained from previous examinations. The inspections lift-off forces are measured every five years (i.e., 1, 3, 5, 10, 15, 20, 25, 30, 35, 40, 45th year, etc.) on alternating units. The trend lines from the tendon loss of prestress TLAA will be updated after each scheduled examination using methods consistent with RG 1.35.1.
The prestressing force trend line for each tendon group shall not cross the appropriate MRV linecurve prior to the next scheduled examination. In addition, the constructed trend line shall not cross the appropriate PLL linecurve for any of the tendon groups. In case any of the two precedent criteria fail, the cause shall be determined, evaluated and corrected in a timely manner. If acceptance criteria are not met, then either systematic re-tensioning of tendons or a reanalysis of the concrete containment is warranted so that the design adequacy of the containment is demonstrated.
Revise the ASME Section XI, Subsection IWL AMP in Section 17.2.2.31 on pages A-35 and A-36 as follows:
Turkey Point Units 3 and 4 Docket Nos. 50-250 and 50-251 FPL Response to NRC On-Site Audit Follow Up Item 3: X.S1, XI.S2 AMPs L-2018-176 Attachment 3 Page 4 of 9 The PTN ASME XI, Subsection IWL, AMP is an existing AMP that was formerly the PTN ASME Section XI, Subsection IWL, ISi Program. This AMP is in accordance 1Nith ASME Code Section XI, Subsection IWL, and consistent with 1 O CFR 50.55a, "Codes and Standards." The inspections associated with this AMP assess the quality and structural performance of the containment structure post-tensioning system components. The current program complies with ASME Code Section XI, Subsection IWL, 2001 Edition through 2003 Addenda (Reference B.3.132), supplemented with the applicable requirements of 10 CFR 50.55a(b)(2). This program is consistent with provisions in 10 CFR 50.55a that specify the use of the ASME Code edition in effect 12 months prior to the start of the start of the inspection interval. PTN will use the ASME Code edition consistent with the provisions of 10 CFR 50.55a during the SPEO. In accordance with 10 CFR 50.55a(g)(4)(ii), the ISi program is updated each successive 120-month inspection interval to comply with the requirements of the latest edition of the ASME Code specified twelve months before the start of the inspection interval.
This AMP manages the aging effects of loss of material and confirms the results of the containment tendon loss of prestress TLAA. This AMP includes inspection of tendon and anchorage hardware surfaces and measurement of tendon force and elongation.
This AMP also includes inspection of containment reinforced concrete above ground for evidence of concrete degradation. This AMP iHW consists of:
(a) Periodic visual inspection of accessible concrete surfaces for the reinforced and prestressed concrete containment structure; (b) Periodic visual inspection and sample tendon-testing of un-bonded post-tensioning system components for signs of degradation, assessment of damage, and corrective actions and ;
(c) Testing of the tendon corrosion protection medium and free water.
Loss of tendon prestress is a TL/V\\; the results of which are confirmed by this /\\MP.
Measured tendon lift-off forces in select common (historical/control) or random sample tendons are compared to predicted tendon forces calculated in accordance with NRC RG 1.35.1, "Determining Prestressing Forces for Inspection of Prestressed Concrete Containments." The Subsection IWL requirements are supplemented to include quantitative acceptance criteria for the evaluation of concrete surfaces based on the "Evaluation Criteria" provided in Chapter 5 of American Concrete Institute (ACI) 349.3R, "Evaluation of Existing Nuclear Safety-Related Concrete Structures." Inspection results are compared with prior recorded results in acceptance of components for continued service.
Inaccessible containment concrete surfaces, such as foundations below groundwater, are managed by the PTN Structures Monitoring AMP.
Revise the Concrete Containment Unbonded Tendon Prestress AMP in Section
Turkey Point Units 3 and 4 Docket Nos. 50-250 and 50-251 FPL Response to NRC On-Site Audit Follow Up Item 3: X.S1, XI.S2 AMPs L-2018-176 Attachment 3 Page 5 of 9 B.2.2.3 on pages B-36 and 8-37 as follows:
Program Description The PTN Concrete Containment Unbonded Tendon Prestress AMP is an existing condition monitoring AMP. The PTN Concrete Containment Unbonded Tendon Prestress AMP is based on the ASME Code Section XI, Subsection IWL requirements in the 2001 Edition, with 2003 Addenda (Reference B.3.132). The PTN Concrete Containment Unbonded Tendon Prestress AMP includes confirmatory actions that monitor and evaluate loss of containment tendon prestressing forces during the current term and will continue through the SPEO.
Loss of containment tendon prestressing forces is a TLAA evaluated in accordance with 10 CFR 54.21 (c)(1 )(iii). The PTN Concrete Containment Un bonded Tendon Prestress AMP, as part of the PTN ASME Section XI, Subsection IWL ISi program~
manages loss of containment tendon prestressing forces in the current period of extended operation (PEO).
This TLAA AMP consists of the assessment of measured tendon prestressing forces from examinations performed through the PTN ASME Section XI, Subsection IWL AMP.
The adequacy of the prestressing force for each tendon group based on type (i.e., hoop, vertical, and dome) and other considerations (e.g., geometric dimensions, whether affected by repair/replacement, etc.) establishes (a) acceptance criteria in accordance with Subsection IWL and (b) trend lines constructed based on the guidance provided in NRC IN 99-10 (Reference B.3.44), "Degradation of Prestressing Tendon Systems in Prestressed Concrete Containments." The calculation of prestressing losses, predicted upper limits and predicted lower limits for each tendon group is in accordance with the guidelines of the NRC RG 1.35.1 (Reference B.3.18), "Determining Prestressing Forces or Inspection of Prestressed Concrete Containments."
This AMP periodically evaluates tendon forces measured by the PTN ASME Section XI,
Subsection IWL AMP (Section B.2.3.31 ), such that corrective action can be taken, if required, prior to tendon forces falling below minimum required values (MRV) established in the design. This AMP addresses the TLAA assessment of unbonded tendon prestressing forces measured at common (historical/control} and randomly selected tendon samples (dome, hoop, and vertical) at PTN Unit 3 and Unit 4. This includes random sampling of tendons affected by the temporary modifications associated with reactor vessel closure head (RVCH) replacements for each unit, an augmented scope group. The prestressing forces of the concrete containment tendons are measured for sample tendons using the lift-off method, or equivalent method.
The loss of concrete containment tendon prestressing forces is detected by comparing the measured data against the predicted force values from the respective containment
Turkey Point Units 3 and 4 Docket Nos. 50-250 and 50-251 FPL Response to NRC On-Site Audit Follow Up Item 3: X.S1, XI.S2 AMPs L-2018-176 Attachment 3 Page 6 of 9 tendon loss of prestress TLAA. In addition, loss of prestressing forces are also detected by comparing the tendon force trend lines, constructed from surveillance measurements, against predicted force values. In addition to PTN Unit 3 and Unit 4 ASME Section XI, Subsection IWL examination requirements, all measured prestressing forces, up to the current examination, are plotted against time. The predicted lower limit (PLL), MRV, and trend-line curves are developed for each tendon group examined for the SPEO. The trend line represents the general variation of prestressing forces with time based on the actual measured forces in individual tendons of the specific tendon group. The trend line for each tendon group is constructed by regression analysis of measured prestressing forces in individual tendons of that group obtained from previous examinations. The inspections force measurements are obtainedconducted every five years (i.e., 1, 3, 5, 10, 15, 20, 25, 30, 35, 40, 45th year, etc.) on alternating units. The PLL line, MRV, and trend line for each tendon group have been projected to the end of the SPEO as described in Section 4.5. The trend lines will be updated after each scheduled examination using methods consistent with RG 1.35.1.
The prestressing force trend line for each tendon group shall not cross the appropriate MRV lineWPJe prior to the next scheduled examination. In addition, the constructed trend line shall not cross the appropriate PLL lineWPJe for any of the tendon groups. In case any of the two precedent criteria fail, the cause shall be determined, evaluated and corrected in a timely manner. If acceptance criteria are not met, then either systematic re-tensioning of tendons or a reanalysis of the concrete containment is warranted so that the design adequacy of the containment is demonstrated.
Revise the ASME Section XI, Subsection IWL AMP in Section B.2.3.31 on pages B-236 and B-237 as follows:
The PTN ASME Section XI, Subsection IWL AMP is an existing condition monitoring AMP, formerly the PTN ASME Section XI, Subsection IWL ISi Program, which implements the examination requirements of the ASME Code Section XI, Subsection IWL, as mandated by 10 CFR 50.55a "Codes and Standards." The scope of the program includes reinforced concrete and unbonded post-tensioning system.
The current program complies with ASME Code Section XI, Subsection IWL, 2001 Edition through 2003 Addenda (Reference B.3.122), supplemented with the applicable requirements of 10 CFR 50.55a(b)(2). This program is consistent with provisions in 10 CFR 50.55a that specify the use of the ASME Code edition in effect 12 months prior to the start of the start of the inspection interval. PTN will use the ASME Code edition consistent with the provisions of 10 CFR 50.55a during the SPEO. In accordance with 10 CFR 50.55a(g)(4)(ii), the ISi program is updated each successive 120-month inspection interval to comply with the requirements of the latest edition of the ASME Code specified twelve months before the start of the inspection interval.
Turkey Point Units 3 and 4 Docket Nos. 50-250 and 50-251 FPL Response to NRC On-Site Audit Follow Up Item 3: X.S1, XI.S2 AMPs L-2018-176 Attachment 3 Page 7 of 9 The primary inspection method is a visual examination, supplemented by testing. The inspections associated with this AMP assess the quality and structural performance of the containment structures and associated post-tensioning systems. Accessible concrete surfaces are subject to periodic visual inspections to detect deterioration and distress, including loss of material (spalling, scaling), cracking, increase in porosity and permeability, and loss of bond in the air-outdoor (uncontrolled) environments.
Tendon wires and tendon anchorage hardware surfaces are inspected for loss of material, cracking, and mechanical damage, with caps and gaskets inspected for leakage and repaired or replaced and corrosion prevention medium replenished as warranted. The tendon corrosion protection medium (grease) is tested for pH,
presence of free water, and soluble ion concentration.
The PTN ASME Section XI, Subsection IWL AMP tests selected sample tendons for yield strength, ultimate tensile strength, and elongation. The sample includes hoop tendons, vertical tendons, and dome tendons. The frequency of tendon inspections is consistent with IWL-2421 for sites with two units as a) both Unit 3 and Unit 4 utilize the same prestressing system described in UFSAR Sections 5.1.3 and 5.1.4; b) the units are essentially identical in design, with the RVCH replacements affecting the same tendons in each unit plus three additional tendons in Unit 4; c) post-tensioning occurred within 2 years of each other; and c) both units are exposed to the outdoor environment at Turkey Point. The assessment and trending of measured tendon prestressing forces is managed by the PTN Concrete Containment Unbonded Tendon Prestress AMP (Section B.2.2.3).
The Subsection IWL requirements are supplemented to include quantitative acceptance criteria for the evaluation of concrete surfaces based on the "Evaluation Criteria" provided in Chapter 5 of American Concrete Institute (ACI) 349.3R, "Evaluation of Existing Nuclear Safety-Related Concrete Structures." Inspection results are compared with prior recorded results in acceptance of components for continued service through the IWL AMP.
Additionally, inaccessible areas of the reinforced containment concrete structure, such as the dome, wall, basemat, ring girders and buttresses, are managed by the PTN ASME Section XI, Subsection IWL AMP, supplemented by the Structures Monitoring AMP (Section B.2.3.35). Steel liners for the concrete containments, and their integral attachments, are included within the scope of the PTN ASME Section XI, Subsection IWE AMP (Section B.2.3.30).
Quantitative acceptance criteria for document and trending inspection results through photography is provided in Chapter 5 of ACI 349.3R.
This AMP includes enhancements, as listed in the table below, to ensure that calculation of predicted tendon forces are in accordance with RG 1.35.1, which provides an acceptable methodology for use during the SPEO.
Turkey Point Units 3 and 4 Docket Nos. 50-250 and 50-251 FPL Response to NRC On-Site Audit Follow Up Item 3: X.S1, XI.S2 AMPs L-2018-176 Attachment 3 Page 8 of 9 Revise the ASME Section XI, Subsection IWL AMP site-specific OE discussion in Section B.2.3.31 on pages B-238 and B-239 as follows:
Site-Specific Operating Experience The containment tendon examination program has been conducted since initial startup of both Units 3 and 4 on 5-year intervals. The initial containment tendon surveillance examination requirements incorporated the general criteria and requirements of NRC RG 1.35, "lnservice Inspection of Ungrouted Tendons in Prestressed Concrete Containments." The program transitioned to the requirements of ASME Code Section XI, Subsection IWL due to the incorporation of the code into 10 CFR 50.55a.
Following the RVCH replacement for each unit (in 2004/2005), the temporary opening was closed and the existing liner plate, with its existing stiffeners, were reinstalled. The concrete was poured at the affected containment structure wall section to close the temporary opening and the vertical and horizontal tendons that had been de-tensioned prior to the RVCH replacement were re-tensioned.
The vertical and horizontal tendons that were removed as part of this modification were replaced with new tendons and were also re-tensioned. Both the new and old tendons affected by the RVCH replacement were inspected in the 35th interval as augmented scope. These previously undisturbed tendons were removed from the sample population and included in the augmented scope population for inspection and testing during the 40th and 45th inspection intervals with acceptable results. As described in the program description above. the tendons affected by RVCH replacement are the same for both units, except for three additional tendons in Unit 4.
The effectiveness of the PTN ASME Section XI, Subsection IWL AMP was reviewed in inspection notebooks compiled in support of the July 2012 NRC post-approval site inspection (ML12089A040, Reference B.3.62) prior to entering the original period of extended operation (PEO). The containment structure post-tensioning system surveillances performed as part of this program were more recently performed on the PTN Units 3 and 4 containment buildings in 2012 (40 year inspection) and 2017 (45-year inspection). These surveillances demonstrated that the actual measured pre-stressing forces were well above the predicted effective preload and the condition of the tendon wires and tendon anchorage hardware surfaces acceptable.
Examinations for the 40-year inspection for subsection IWL began in February 2011 and continued until February 2013 for the second 10-year interval work. The 40th year inspection report concluded that the containment structure had experienced no abnormal degradation of the post-tensioning system. Excessive leakage of corrosion protection medium (grease) was identified for a Unit 4 vertical tendon. That lower end cap and gasket for the tendon sheath were repaired and the grease replenished.
No water/moisture was identified during this repair and the excessive leakage
Turkey Point Units 3 and 4 Docket Nos. 50-250 and 50-251 FPL Response to NRC On-Site Audit Follow Up Item 3: X.S1, XI.S2 AMPs L-2018-176 Attachment 3 Page 9 of 9 was identified for engineering evaluation consistent with Technical Specification 3/4.6.1.6.1. The evaluation concluded that leakage of the grease, though excessive per IWL-3221.4, was not a concern for tendon degradation due to the protection afforded by grease residue (film) left on the tendon wires, the repair of the gasket with replenished grease through the next interval, and similar tendon sheath leakage not being uncommon at Turkey Point or other nuclear sites with similar containments/post-tensioning systems.
In 2012, the NRC Senior Resident Inspector visually identified a number of indications in the Unit 4 dome concrete. An IWL qualified concrete inspector examined the indications in the identified and surrounding area. CE 1737608-02 concluded that the cracks were measured to be less than 0.015 in (width) and did not exhibit any indication of being active. Therefore, the condition was classified as acceptable. An issue/event entry was added to the program health report for future reference.
During the 2017 Unit 3 and Unit 4 RFOs, examinations were performed by the Nuclear Engineering Component, Support, and Inspections Group for the 45-year inspection for Subsection IWL for the second 10-year interval work. The final inspection reports concluded that the containment structure had experienced no abnormal degradation of the post-tensioning system. Various tendons were identified to have excessive leakage of grease from their sheath, including the one repaired in 2012. This excessive leakage was evaluated by engineering and corrected through typical gasket replacement and grease being replenished until the next inspection interval.
Associated
Enclosures:
None