L-92-203, Special Rept:Three Surveillance Tendons,Inspected on 920612, 19 & 29 Found W/Measured Normalized lift-off Force Below Predicted Lower limit.Lift-off Forces Restored to Required Level of Integrity.Addl Rept Will Be Sent by 920915
| ML17349A305 | |
| Person / Time | |
|---|---|
| Site: | Turkey Point  |
| Issue date: | 07/10/1992 |
| From: | Plunkett T FLORIDA POWER & LIGHT CO. |
| To: | Ebneter S NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| L-92-203, NUDOCS 9207200269 | |
| Download: ML17349A305 (13) | |
Text
ACCELERATED DISTRIBUTION DEMONSTPA,TION SYSTEM REGULA RY INFORMA ION DISTRIBUTI SYSTEM (RIDS)
ACCESSiON NBR:9207200269 DOC.DATE: 92/07/10 NOTARIZED:
NO FACIL:50-.250 Turkey Point Plant, Unit 3; Florida Power and Light C AUTii.NAME AUTHOR AFFILIATION PLUNKETT,T.F.
Florida Power E Light Co.
RECIP.NAM" RECIPIENT AFFILIATION EBNETER,S.D.
Region 2 (Post 820201)
DOCKET 05000250
SUBJECT:
Special rept:three surveillance tendons, inspected on 920612, 19 6
29 found w/measured normalized lift-off force below predicted lower limit.Lift-offforces restored to required level of integrity.Addi rept will be sent by 920915.
DISTRIBUTION CODE:
IE22D COPIES RECEIVED:LTR ENCL SIZE:
TITLE: 50.73/50.9 Licensee Event Report (LER), Incident Rpt, etc.
NOTES:NRR RAGHAVAN,L 05000250 RECIPIENT ID CODE/NAME PD2-2 LA AULUCK,R INTERNAL: ACNW AEOD/DSP/TPAB NRR/DET/EMEB 7E NRR/DLPQ/LPEB10 NRR/DREP/PRPBll NRR/DST/SICB8H3 NRR/DST/SRXB 8E RES/DSIR/EIB EXTERNAL EG&G BRYCE g J
NOTES:
COPIES LTTR ENCL 1
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1 RECIPIENT ID CODE/NAME PD2-2 PD AEOD/DOA AEOD/ROAB/DSP NRR/DLPQ/LHFB10 NRR/DOEA/OEAB NRR/DST/SELB 8D LB8D1 REG FILE 02 E
01 L ST LOBBY WARD NSIC MURPHY,G.A NUDOCS FULL TXT COPIES
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1 NOTE TO ALL"RIDS" RECIPIENTS:
PLEASE HELP VS TO REDUCE WASTE! CONTACTTHE DOCUMENT CONTROL DESK, ROOM Pl-37 (EXT. 20079) TO ELIMINATEYOUR NAME FROM DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T NEED!
TOTAL NUMBER OF COPIES REQUIRED:
LTTR 31 ENCL 31
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P.O. Box 029100, Miami, F133102-9100 PPL JUL 1.0 19%.
L-92-203 10 CFR 50.36 Stewart D. Ebneter Regional Administrator U. S. Nuclear Regulatory Commission 101 Marietta Street, N.W,, Suite 2900
- Atlanta, Georgia 30323
Dear Mr. Ebneter:
Re:
Turkey Point Unit 3 Docket No. 50-250 Special Report Twentieth Year Tendon Inspection Hoo Tendons Low Lift-OffForce In accordance with Florida Power and Light Company (FPL)
Turkey Point Nuclear Plant Technical Specification 3.6.1.6 a ~, the attached Special Report is provided.
This report addresses the low lift-off force inspection results for tendons
- 13H33, 64H61 and 35H52.
An additional report will be submitted to the Commission by September 15,
- 1992, summarizing the surveillance testing of all hoop tendons inspected during -the Unit 3 Twentieth Year Inspection.
Should there be any questions, please contact us.
Very truly yours, T. F. Plunkett Vice President Turkey Point Nuclear TFP/RJT/rt cc:
- USNRC, Document Control Desk, Washington, D.C.
Senior Resident Inspector, USNRC, Turkey Point Plant g(a (1 ii 92072002b9 920710 PDR ADOCK 05000250 S
NRC S ecial Re ort Turkey Point Unit 3 Twentieth Year Tendon inspection Low Lift-OffForce on Hoop Tendons
- 13H33, 64H61 and 35H52
L-92-203 Special Report Page 2 of 7 TABLE OF CONTENTS 1.0 2.0 3.0 4.0 5.0 6.0 PURPOSE/SCOPE ENGINEERING EVALUATION CONCLUSION VERIFICATION
SUMMARY
CORRECTIVE ACTIONS REFERENCES
L-92-203 Special Report Page 3 of 7
1.0
~
Pur ose Sco e
2.0 During the performance of the twentieth year tendon surveillance of the Turkey. Point Unit 3 containment post-tensioning
- system, three
'urveillance
- tendons, 13H33 (inspected on June 12, 1992),
64H61 (inspected on June 19, 1992),
and 35H52 (inspected on June 29, 1992) of the hoop tendon group, were-found to have a measured normalized lift-offforce below the predicted lower limit (References 6.4, 6.5, and 6.9).
Consequently, in'ccordance with the requirements of the Turkey Point Plant Technical Specifications 4.6.1.6.1 (a), additional lift-offmeasurements on a tendon located below and a tendon located above (13H32 a
- 13H34, inspected on June 15, 1992; 64H60
& 64H62i inspected on June 19,
- 1992, and 35H51
& 35H53, inspected on June 30, 1992) were taken for each of the applicable surveillance tendons.
In each case, since the measured normalized lift-offforces in these tendons were between the predicted lower limit and 90% of the predicted lower limit, Tuzkey Point Unit 3 entered a
15 day ACTION statement to the Limiting Condition for Operation (Technical Specification 3.6.1.6)
This ACTION statement required restoration of the tendon(s) to the required level of integrity within 15 days and performance of an engineering evaluation of the containment, and the submittal of a Special Report to the USNRC within 30 days.
The evaluation of the structural integrity of the containment post-tensioning system is included in this engineering evaluation.
En ineerin Evaluation The Turkey Poi.nt Unit 3 containment is a post-tensioned, reinforced concrete structure comprised of a vertical cylinder with a shallow dome and supported on a conventional reinforced concrete foundation base slab, The vertical cylinder wall is provided with a system of vertical and hoop tendons.
Vertical tendons are anchored at the top surface of the ring -girder and at the bottom of the base slab.
Each hoop tendon is anchored at alternate vertical buttresses nominally 120 degrees apart.
Tendons in the dome consist of three groups of tendons oriented at 120 degrees with respect to each other and aze anchored at the vertical face of the dome zing girder.
The 'Turkey Point tendon surveillance is performed every fifth year from the date of the initial structural integrity test.
Three dom'e, five hoop, and four vertical tendons were selected for the twentieth year tendon surveillance on a random basis, excluding those tendons which were previously inspected for earlier surveillances.
The Turkey Point twentieth year tendon surveillance is performed in accordance with the requirements of References 6.6 and 6.10.
To date, lift-offforces for all four vertical and all three dome surveillance tendons have been measured.
In each case, the measured normalized lift-offforce exceeded the predicted lower limit.
Wires have been removed for inspection from hoop tendon
- 64H61, vertical tendon
- 34V11, and dome tendon 3DS.
In addition, gxease samples have been removed for each surveillance tendon inspected to date.
The visual inspection of the tendon wires and sheath filler samples have revealed no abnormal wire corrosion or grease discoloration.
Also, the concrete at the tendon anchorage area adjacent to the bearing plates for all subject hoop tendons have been inspected.
This inspection has revealed that width of the cracks does not exceed 0.01 inches which is the acceptance limit noted in Reference 6.8, Section IWL-3221.3(d).
L 203 Special Report Page 4 of 7 The following are.the predicted lower limit (PLL) and the minimum required prestress force at the anchorage for hoop tendons:
Twentieth Year Predicted Lower Limit 6.63 kips/wire (Reference 6.6)
Minimum Required Prestress Force
~ 6.29 kips/wire at Anchor'age for Hoop Tendons (Reference 6.3)
The lift-offforces which are below the predicted lower limit occurred in three of the hoop surveillance tendons (13H33,
- 64H61, and 35H52) and in six additional adjacent tendons (13H32,
- 13H34, 64H60,
- 64H62, 35H51, and 35H53).
From References 6.4, 6.5, and 6.9, the results of the surveillance on hoop tendons are as follows:
Tendon Measured Normalized Lift-OffForce ki s wire Percentage of PLL
,13H32 13H33 13H34 6.58 6.26 6.48 99.2%
94.4%
97.7%
Average (Buttress 1-.3) 6.44 kips/wire 97.1%
64H60 64H61 64H62 6.39 6.33 6.14 96.4%
95.5%
92.6%
Average (Buttress 6-4) 6.29 kips/wire 94 '%
35H51 35H52 35H53 6.32 6.40 6.39 95.3%
96.5%
96.4%
Average (Buttress 3-5),
6.37 kips/wire 96.1%
The overall average tendon force for all nine hoop tendons is as follows:
Tendon 13H32f 13H33f 13H34 64H60f
- 64H61, 64H62
- 35H51, 35H52, 35H53 Average Measured Normalized Lift-OffForce ki s wire 6.37 Percentage of PLL 96.1%
As shown, the average hoop tendon lift-offforce for the group (overall or individual buttress group) is equal to or larger than the minimum required prestress force (6.29 kips/wire).
Therefore, it is concluded that the subject tendon group will provide adequate prestress force to maintain the containment integrity.
This conclusion is consistent with the guidance provided in Section 7.1.5 of Reference 6.7 and Section INL-3221.1 (a) of Reference 6.8.
L-92-203 Special Report Page 5 of 7 2.1 Review Of Re ulator Guides and ASME Code Section XI Acce tance Criteria Regulatory Guide 1.35 (Reference 6.7), Section 7.0, and ASME Code Section XI (Reference 6.8), Section IWL-3221.1, were reviewed relative to the tendon lift-offacceptance criteria to provide additional justification for the adequacy of the containment post-tensioning system.
The following summarizes this review:
a)
Section 7.1.5 of Reference 6.7 and Section IWL-3221.1 (a) of Reference 6.8 require that the average of all measured tendon forces be equal to or greater than the minimum required pzestress force at the anchorage.
b)
Section 7.1.2 of Reference 6.7 implies that, if the measured lift-offforce for a surveillance tendon lies above 95% of the predicted lower limit, no additional lift-offtesting of adjacent tendons is required and the condition should be considered acceptable.
c)
Section 7.1.2 of Reference 6.7 states that if the measured prestressing force of a selected tendon in a group lies between 9S% of the predicted lower limit and 90% of the predicted lower limit, two additional tendons, one on each side of the first
- tendon, should be checked for their prestressing forces.
If the prestressing forces of each of the second and third (i.e.,
adjacent) tendons are above 95% of the predicted lower limit, all three tendons should be restored to the required level of integrity and the tendon group should be considered acceptable.
The measured normalized lift-offforces for tendons 13H32 and 13H34 were above 95% of the predicted lower limit.
This meets the requirement of Reference 6.7 (Criterion (c) above)
~
The measured normalized lift-offforce for surveillance tendons 64H61 and 35H52 was above 95% of the predicted lower limit.
This meets the requirement of Reference 6.7 (Criterion (b) above),
and no additional testing would have been required if this criterion had been applied.
Finally, as'hown in Section 2.0, the average tendon lift-offforce (overall or individual buttress group) is equal to or larger than the minimum required prestress force (6.29 kips/wire) which satisfies criterion (a) above.
Therefore, based on this review, it can also be concluded that the Unit 3 noop tendon group has sufficient prestress force to maintain the containment integrity and the intent of the acceptance criteria included in References 6.7 and 6.8 is satisfied.
2.2 Desi n Mar ins Available in the Post-Tensionin S stem Turkey Point UFSAR (Reference 6.1), Section 5.1.2 states that any three adjacent tendons in any tendon group can be lost without significantly affecting the strength of the containment structure.
This design feature considers the load redistribution capabilities of the containment shell.
According to Reference 6.1, Section 5.1.1, the containment is structurally designed to withstand a pressure of 59 psig.
This section also states that the transient analysis calculated peak accident pressure is 49.9 psig.
This provides additional margin of safety.
k
L-92-203 Special Report Page 6 of 7 3.0 Conclusion Based on the available margins existing in the design of the Turkey Point post-tensioning system and the level of prestress force available in the subject hoop tendons, it is concluded that the Unit 3 hoop tendon group has sufficient prestzess force to maintain the containment integrity.
As part of the twentieth year surveillance, lift-offtesting will be performed for the remaining two hoop surveillance tendons.
These additional lift-offreadings will provide additional data to investigate the cause and extent of this condition.
Upon campletion of the lift-offtesting, an engineering evaluation will be prepared to include the additional data and the results of the investigation relative to this condition.
A more detailed report will be submitted to USNRC following completion of the tendon surveillance.
4.0 Verification Surmnar The engineering evaluation was reviewed to ensure that the overall conclusion meets the applicable UFSAR and Plant Technical Specif ications requirements.
The criteria and design inputs required to evaluate the containment building structural integrity were adequately described, reasonable, and appropriately identified for subsequent reverification.
The codes, standards, design bases and regulatory requirements were properly identified and this engineering evaluation was shown to meet those requirements.
This engineering evaluation has been correctly specified as Safety Related.
5.0 Corrective Actions According to the Turkey Point Plant Technical Specifications 3.6.1.6 (a), the lift-offforces in tendons
- 13H32, 13H33y 13H34,.
- 64H60, 64H61,
'64H62,
- 35H51, 35H52, and 35H53 have been restored to their required level of integrity by retensioning each tendon to a level equal to or above the twentieth year predicted lower limit.
The following summarizes the new lift-offforces for the subject tendons:
Tendon Measured Avera e Lift-Off ki s Percenta e of Predicted Lower Limit 13H32 13H33 13H34 64H60 64H61 64H62 35H51 35H52 35H53 625. 5 630 634. 5 613.5 606 613 636 612 609 104.8%
105.6%
106.3%
102.8%
~ 101.6%
102.7%
106.6%
102.6%
102.1%
L-92-203 Special Report Page 7 of 7 6 '
References 6.1 Turkey Point Units 3 and 4 Updated Final Safety Analysis Report (UFSAR), Revision 9, dated July 1991 Section 5.0 6.2.
Turkey Point Units-3 and 4 Technical Specifications Amendment 151/146 6.3 Bechtel Calculation No. C-SJ539-05 "Evaluation of the Fifteenth "Year Tendon Surveillance Lift-OffForces",
Revision 0
6.4 Non-Conformance Report N-92-0123 6.5 Non-Conformance Report N-92-0128 6.6 6.7 6.8 Bechtel Technical Requirements Document 21701-539-CP-1, Revision 3 for Unit 3 Twentieth Year Tendon Surveillance Regulatory Guide 1.35 "In-service Inspection of Ungrouted Tendons in Prestressed Concrete Containment",
Revision 3 Dated July 1990 ASME Code
- 1989,Section XI Division 1, Article IWL-3000 "Acceptance Standards" 6.9 Non-Conformance Report N-92-0136 6:10 Turkey Point Plant Procedure O-SMM-51.2 "Containment Tendon Inspection" dated May 22, 1992
0