ML17349A566

LER 92-009-00:on 921117,measured Prestress Force on Containment Tendon Lower than Predicted Lower Limit.Caused by Increased Tendon Wire Steel Relaxation Loss at Higher Tendon temp.Lift-off Forces restored.W/921217 Ltr

ML17349A566
Person / Time
Site:	Turkey Point
Issue date:	12/17/1992
From:	Plunkett T, Tomonto R FLORIDA POWER & LIGHT CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
L-92-344, LER-92-009, LER-92-9, NUDOCS 9212290181
Download: ML17349A566 (22)

Text

ACCEI.ERAT~ DOCUMENT DIST UTION SYSTEM REGULATE INFORMATION DISTRIBUTIO SYSTEM (RIDS)

ACCESSION NBR:9212290181 DOC.DATE: 92/12/17 NOTARIZED: NO -DOCKET ¹ FAC1L:50-251 Turkey Point Plant, Unit 4, Florida Power and Light C 05000251 AUTH. NAME AUTHOR AFFILIATION TOMONTO,R.J. 'Florida Power a Light Co.

PLUNKETT,T.F. Florida Power 6 Light Co.

RECIP.NAME -

RECIPIENT AFFILIATION

SUBJECT:

LER 92-009-00.:on 921117,measured prestress force on containment tendon lower than predicted lower limit.Caused D by increased tendon wire steel. relaxation loss at higher tendon temp. Lift-off forces restored.W/921217 ltr.

DISTRIBUTION CODE: IE22T COPIES RECEIVED:LTR ENCL SIZE: C7 TITLE: '50.73/50.9 Licensee Event Report (LER), Incident Rpt, etc.

NOTES':NRR RAGHAVAN,L 05000251 A RECIPIENT COPIES RECIPIENT COPIES D ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD2-2 LA 1 1 PD2=2 PD 1 1 AULUCK,R 1 1 INTERNAL: ACNW 2 2 AEOD/DOA 1 1 AEOD/DSP/TPAB 1 1 AEOD/ROAB/DSP 2 2 NRR/DET/EMEB 7E 1 1 NRR/DLPQ/LHFB10 1 1 NRR/DLPQ/LPEB10 1 1 NRR/DOEA/OEAB 1 1 NRR/DREP/PRPB11 2 2 NRR/DST/SELB 8D 1 1 NRR/DST/SICB8H3 1 1 NRR DST/SPLB8D1 1 1 NRR/DST/SRXB 8E 1 1 4REG~ 02 1 1 RES/DSIR/EIB 1 1 RGN2 FILE 01 1 1 EXTERNAL EGSG BRYCE I J ~ H 2 2 L ST LOBBY WARD 1 1 NRC PDR 1 1 NSIC MURPHY i G. A 1 1 NSIC POOREIW ~ 1 1 NUDOCS FULL TXT 1 1 NOTES: 1 1

'S A,

D NOTE TO ALL"RIDS" RECIPIENTS:

PLEASE HELP US TO REDUCE WASTE! CONTACT THE DOCUMENT CONTROL DESK, ROOM Pl-37 (EXT. 504-2065) TO ELIMINATEYOUR NAME FROM DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T NEED!

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FULL TEXT CONVERSION REQUIRED TOTAL NUMBER OF COPIES REQUIRED: LTTR 30 ENCL 30

41 P.O. Box 029100, Miami, FL, 33102-9100 DH8 1'I 1992 L-92-344 10 CFR 50.73 10 CFR 50.36 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D. C. 20555 Gentlemen:

Re: Turkey Point Unit 4 Docket No. 50-251 Reportable Event: 92-009 Date of Event: November 17, 1992 Containment Tendon Surveillance Measured Prestress Force Lower than Predicted attached Licensee Event Report (LER) 251-92-009 is provided

'he pursuant to the requirements of 10 CFR 50.73 (a)(2) (i) (B) to provide information on the subject event. In accordance with NUREG-1022, Supplement 1, this LER will also satisfy the requirements of Technical Specification 3.6.1.6, submittal of a Special Report. ~

Very truly yours, O',P, i~uD/p.

T. F. Plunkett Vice President Turkey Point Nuclear TFPNRJTNrt Attachment cc: Stewart D. Ebneter, Regional Administrator, Region II, USNRC Senior Resident Inspector, USNRC, Turkey Point Plant PBI O7.

9212290181 921217 PDR *DOCK 05000251 rent

/f S PDR an FFL Grocp compan~

Cl LICENSEE EVENT REPORT (LER)

DOCKET NVNSXR (I) FACE (l)

'FACILITT NAKC (I)

Turkey Point Unit 4 05000251 OF 9 Containment Tendon Surveillance Measured Prestress Force Lower than Predicted RTT DATE (I) OTKtR FACILITItS INV. ( ~ )

EVENT DATE (5) LER NOMBER (6)

SEO I R( DOCKET ( (S)

MON YR NAME 11 17 92 92 009 00 1 17 92 OTIRATINC )COE (S)

~ xxtx txvtt OO 10 CFR 50.73 a 2 i B and OTHER S ecial Re ort (SPOCI(F lh Ahttthtt Nh)OV Xhd lh tezt) 100 LICENSEE CONTACT FOR THIS LER (12)

Robert J. Tomonto, Licensing Engineer 305-246-7327 CONSLETE ONt LINE FOR LACK'CONFONtNT FAILVRE DtSCRISED IN TKIS Rt)ORT (ll)

SISTTN CAVSE EST ECTTD SVFFLXNENTAL RTFORT EXTTCTSD (I ~ ) SVSNISSION MONTH DAY YEAR DAIt (ll)

((I Fhh, COXD)hth XXSSCTSD SVSNISSION CATt> NO AXSTRACT (1()

On November 17, 1992 at approximately 0917 EST, with Turkey Point Unit 3 in Mode 5 (COLD SHUTDOWN) and Unit 4 in Mode 1 (POWER OPERATION), Unit 4 entered LIMITING CONDITION FOR OPERATION (LCO) 3.6.1.6 a., with Unit 4 containment hoop tendon 35H38 measuring an observed lift-off value less than 90% of the predicted lower limit (PLL) . ACTION a. of Technical Specification 3.6.1.6 required that with one tendon below 90% of the PLL, restore the tendon to the required level of integrity within 15 days, perform an engineering evaluation of the containment and provide a Special Report to the Commission within 30 days. In accordance with SURVEILLANCE REQUIREMENTS 4.6.1.6.1, adjacent tendons were checked for their lift-off force. Tendons 35H39, 35H40, 35H41 and 35H42 measured lift-off values between PLL and 90% of PLL.

Tendons 35H38, 35H39, 35H40, 35H41 and 35H42 were retensioned and on November 19, 1992, at approximately 1715 EST, Unit 4 exited LCO ACTION 3.6.1.6 a.

This event is reportable under 10 CFR 50.73 (a) (2)(i) (B) . Operability of tendon 35H38 is established based upon a revision to the calculated value for the predicted lower limit and minimum required prestress force for the Unit 4 containment. These values were initially calculated assuming a maximum containment design pressure of 59 psig, and were subsequently revised to 55 psigx Technical Specification 5.2.2, DESIGN FEATURES DESIGN PRESSURE AND TEMPERATURE, states that "the containment building is designed and shall be maintained for a maximum .internal pressure of 59 psig". Operability of tendon 35H38 is established based upon the licensing basis provided in the original Turkey Point Safety Evaluation Report which states that 55 psig is an acceptable design pressure. FPL will submit license amendments to revise the Technical Specification design pressure to reflect the licensing basis design pressure.

x

~ I I ZCENSEE OENT REPORT (LER) TEXT (TZNUATZON FACILITY.NAME DOCKET NUMBER LER NUMBER PAGE NO.

TURKEY POINT UNIT 4 05000251 92-009 02 oF 09 X. DESCRIPTION OF THE EVENT The following sequence of events was derived from the Reactor Operator' log and the equipment out-of-service log.

0910 11/17/92 Unit 3 in Mode 5 (COLD SHUTDOWN) and Unit 4 in Mode 1 (POWER OPERATION) performed'he Unit 4 twentieth year tendon surveillance. Hoop tendon 35H38 measured a low lift-FPL off force of 5.94 kips/wire which is equivalent to 89.6% of the predicted lower limit (PLL). Unit 4 entered LIMITING CONDITION FOR OPERATION 3..6.1.6 a.,

with a 15 day ACTION statement requiring the tendon to be restored to the required level of integrity.

1530 ll/17/92 Hoop tendon 35H39 measured a low lift-off force of 6.09. kips/wire or 91.8% of PLL. Tendon 35H39 declared Out-of-Service.

1640 11/17/92 Hoop tendon 35H40 measured a low lift-off force of 6.12 kips/wire or 92.3% of PLY Tendon 3SH40 declared Out-of-Service.

1115 11/18/92 Hoop tendon 35H41 measured'a low lift-off force of 6.01 kips/wire or 90.6% of PLL. Tendon 35H41 declared Out-of-Service.

1200 11/18/92 Hoop tendon 35H42 measured a low lift-off force of 6.13 kips/wire or 92.5% of PLL. Tendon 35H42 declared Out-of-Service.

1130 11/19'/92 Retensioned tendon 35H42, returned tendon to service 1405 11/19/92 Reten ioned tendon 35H41, returned tendon to service 1715 11/19/92 Retensioned tendons 35H38, 35H39 and 35H40, returned tendons to service. Exited LCO ACTION 3.6.1.6 a.

This event- is reportable under 10 CFR 50.73 (a)(2)(i)(B). Operability of tendon 35H38 is established based upon a revision to the calculated value for the predicted lower limit and minimum required prestress force for the Unit 4 containment. These values were initially calculated assuming a maximum containment design pressure of 59 psig and were subsequently revised to 55 psig, which is 110% of current containment peak internal pressure based on design basis LOCA.

'echnical Specification 5.2.2, DESIGN FEATURES DESIGN PRESSURE AND TEMPERATURE states the following:

"The containment building is designed and. shall be maintained for a maximum internal pressure of 59 psig A maximum containment pressure of 55 psig was assumed in the original Turkey Point Safety Evaluation Report (Ref.,5.10) which stated the following:

0

~

I ICENSEE QENT REPORT (LER) TEXT CONTINUATION FACILITY NAME DOCKET NUMBER .LER NUMBER PAGE NO.

TURKEY POINT UNIT 4- 05000251 92-009-00 03 oF 09 "The applicant has now calculated that the peak accident pressure would be 50 psig. Since our current guidelines for .containment design suggest that the design'ressure should be at least 10%

highez than the calculated peak accident pressure, 55 psig would be an acceptable design pressure".

The methodology for calculating both the predicted lower limit and the minimum required pzestress limit has been transmitted to the NRC by FPL Letters L-92-262, dated September 14, 1992 and L-92-287, dated November 5, 1992.

In order to establish operability of tendon 35H38 the maximum containment pressure in the containment structural analysis assumed a value of 55 psig.

II. CAUSE OF THE EVENT By FPL letter L-92-262, dated September 14, 1992, FPL reached the following conclusion, from the Turkey Point Unit 3 twentieth year tendon surveillance:

Based on the engineering evaluation (FPL letter L-92-262), FPL determined that the tendon wire steel relaxation loss increases with the increase in temperature experienced by the tendon. It was also determined that the measured Unit 3 containment internal temperature during suzveillance averaged 114 'F which results in hoop tendon temperature of approximately 90 'F, which corresponds to higher tendon wire steel relaxation losses than those used in the original design. Therefore, the probable cause for the low lift-off forces measured for the Turkey Point Unit 3 containment tendons was increased tendon wire steel relaxation loss hoop occurring at a higher tendon temperature (approximately 90 'F).

Based on the results of this evaluation, it is estimated that a 12% tendon wire teel relaxation loss rate should be used to predict the undisturbed tendon lift-off forces in future surveillances. It is also concluded that creep loss calculated based on the average sustained concrete compressive stress should be used to more accurately predict the tendon lift-off forces in each group (hoop, vertical and dome) in future surveillances.

FPL believes the root cause of the Unit 4 low lift-off forces to be equivalent to the zoot cause of the low lift-off values observed in Unit 3. Consistent with the Unit 3 containment twentieth year surveillance tendon report, a more detailed engineering evaluation is being prepared to investigate the cause and the extent of low lift-off values in the Unit 4 containment structure post-tensioning system.

This evaluation will also determine the length of time that the Unit 4 Turkey Point post-tensioning system will continue to satisfy the licensing basis requirements.

III. ANALYSIS OF THE EVENT FPL's engineering evaluation provides the following:

The licensing basis for the containment design for the acceptability of the low lift-off condition pressure.'ustification on hoop tendon 35H38 and adjacent tendons.

0 I ICENSEE SENT REPORT (LEE) TEXT (TINURTION FACILITY NAME BOCKET NUMBER LER NUMBER PAGE NO.

TURKEY POINT UNIT 4 05000251 92-009-00 04 oF 09 1.0 Licensin Basis For Containment Desi n Pressure Containment tendon surveillance inspections performed .to date for Turkey Point,.Units 3 and 4 have assumed a containment internal pressure o'f 59 psig for calculating the minimum design prestress forces. However, due to the low lift-off forces data obtained for hoop tendon 35H38, FPL has calculated the minimum design lift-prestress force zequi.'red to meet 55 psig. The measured low off forces are then evaluated using the minimum design pzestzess force for 55 psig to determine the acceptability of the containment post-tensioning system.

Back round The containment licensing basis pressure of 55 psig was established during the early stages of plant licensing (circa 1965 1966) and has carried through to current licensing documents. The Preliminary Safety Analysis Report (PSAR) and Updated Final Safety Analysis Report (UFSAR) indicated that a 55 psig reference containment licensing basis pressure was conservatively established for the design basis (29-inch double-ended pipe break) loss-of-coolant accident (LOCA), based on a 49.9 psig calculated peak pressure plus a 10% safety margin. The structural proof test was conducted at 115% design pressure to verify structural integrity. .[Reference PSAR Sections 5.4.1.a and 12.2.3; and Reference UFSAR Revision 4 dated'ugust 12, 1970, Section 5.1.1]

Other LOCA cases, assuming partial safeguards availability, were also considered. These cases did not constitute design basis accident scenarios, but rather provided an indication of potential containment performance requirements beyond-the-licensing-basis for purposes of establishing a conservative design for the containment. These scenarios were considered in response to Atomic Energy Commission (AEC) questions, to address uncertainties in the availability of accumulators. As a result,,

these other cases assumed partial safeguards operation with no core cooling; conditions that are beyond the required postulation of a single active or passive failure [Re'ference PSAR Supplement 2, Questions 1.0 and 3.0, dated 9/2/66]. The value of 55 psig was determined as the licensing basis analysis for partial safeguards availability, by operating on diesel power, and providing core cooling by having 2/3 of the available safety injection water reach the core.

To accommodate these hypothetical, beyond-the-licensing-basis scenarios, the containment structure was originally designed assuming a peak pressure of 59 psig; however, the design basis LOCA calculated peak pressure was 49.9 psig, and "55 psig was considered as nominal structural design pressure, thus allowing a margin of 10% over the calculated peak accident pressure."

[Reference UFSAR Revision 4 dated August 12, 1970, Section 5.1.1]

0 t LICENSEE ~T REPORT (LER) TEXT ClINURTION'ACILXTY NAME DOCKET NUMBER LER NUMBER PAGE NO.

TURKEY POINT UNIT 4 05000251 92-009-00 05 oF 09 Based on the AEC Safety Evaluation Report (SER): 55 psig is the licensing basis containment design pressure; this value is based on a calculated design basis LOCA peak pressure of 49.9 psig plus a safety margin; and the internal pressure of 59 psig was selected based on non-licensing basis LOCA scenarios. This is consistent with the AEC conclusions presented in the plant SER, (Section 5.4 of Reference 5.10) which states:

"Although the building is designed to withstand a pressure of 59 psig, the preopezational structural proof test was performed at about 63 psig rather than at 68 psig (115% of 59 psig) .

The design pressure was established at the construction permit stage based upon an early containment pressure transient analysis which did not take credit for the action of the accumulators in suppressing a secondary pressure peak. The applicant has now calculated that the peak accident pressure would be 50 psig. Since our current guidelines for containment design suggest that the design pressuie should be at least 10's higher than the calculated peak accident pressure, 55 psig would be an acceptable design pressure. On this basis we have accepted the 63 psig proof test (115% of 55 psig)".

The LIMITING CONDITION FOR OPERATION foz structural integrity ensures that the containment will withstand the maximum pressure the event of a LOCA. [Reference 5.2, Bases Section 3/4.6.1.6;

'n and Reference 5.1, Section 5.1.1]

1.1 Licensin Basis Early performance requirements for the containment were added to address the uncertainty in component availability for LOCA scenarios. The licensing basis for containment design pressure is 55 psig based on a calculated design basis LOCA peak pressure of 49.9 psig plus a margin of safety. Because the calculated peak pressure is less than the licensing basis containment design pressure'f 55 psig, as required at the operating license stage, using 55 psig for calculating minimum design prestress forces does not impact the margin of safety.

2.0 En ineerin Evaluation of Hoo Tendon 35H38 Low Lift-Off Condition The Turkey Point Unit 4 containment is a post-tensioned, reinforced concrete structure comprised of a vertical cylinder with a shal'low 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 in the dome consist of three groups of tendons oriented apart'endons at 120 degrees with respect to each other and are anchored at the vertical face of the dome ring girder.

II 0 LICENSEE ENT REPORT (LER) 'EXT CTINCRTION FACILITY NAME DOCKET NUMBER LER NUMBER PAGE No.

TURKEY POINT UNIT 4 05000251 92-009-00 06 oF 09 The tendon surveillance program for the Turkey Point Nuclear Plant Unit 4 containment structure post-tensioning system has been. performed at one, three and five years after the containment Initial Structural Integrity Test, (ISIT), and every five years thereafter. Three dome, five hoop, and, four vertical tendons were selected for the t'wentieth year tendon surveillance on a random basis, excluding those tendons which were previously inspected for earlier surveillances. The Turkey Point Unit 4 twentieth year tendon surveillance i's performed in accordance with the requirements of References 5.6 and 5.9.

To date, a wire has been zemoved for inspection from dome tendon 1D40, and hoop tendon 42H83. In addition, grease samples have been removed for each surveillance tendon inspected to date. The visual inspection of the tendon wire 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 hoop tendons has been inspected. This inspection has revealed that no cracks were found which exceed the acceptance width of 0.01 inches noted in Reference 5.8, Section IWL-3221.3(d).

FPL has calculated that the minimum design prestress force for hoop tendons required to withstand 55 psig containment internal pressure is 5.94 kips/wire at the anchorage (Reference 5.5) .

Considering the 55 psig internal pressure and the minimum required prestress force of 5.94 kips/wire for hoop tendons, this calculation has determined that the conclusions of the original containment analysis will not be adversely affected.

The following are the predicted lower limit (PLL) and the minimum design prestress force at the anchorage for hoop tendons:

e Twentieth Year Predicted Lower Limit 6.63 kips/wire (Reference 5.6)

Minimum Design Prestress Force 5. 94 kips/wire (at anchorage for Hoop Tendons)

(Reference 5.5)

The lift-off forces which are below the predicted lower limit occurred in one of the hoop surveillance tendons (35H38) and its adjacent tendons (35H39, 35H40, 35H41 and 35H42). Due to accessibility problems below tendon 35H38, all adjacent tendon lift-off testing was performed above tendon 35H38. The following summari'zes the results of the lift-off forces on hoop tendon 35H38 and its adjacent tendons:

Oi V

LICENSEE ENT REPORT (LER), TEXT dQTINURTION FACILITY NAME DOCKET NUMBER LER NUMBER PAGE NO.

TURKEY POINT UNIT 4 05000251 92-009-00 07 OF '09 Measured Normalized 'Percentage Tendon Lift-Off Force ki s wire of PLL 35H38 5.94 89 ..6%

35H39 6.'09 91.9%

35H40 6.12 92.3%

35H41 6.01 90.6%

35H42 6.13 92.'5%

Average 6. 06 kips/wire 91.4%

As shown, the individual lift-.off force and the average lift-off force for the group is equal to or larger than the minimum design prestzess force (5.94 kips/wire). Therefore, it that the subject tendon group presently provides adequate is concluded prestzess force to maintain the containment integrity. This conclusion is consistent with the guidance provided in Section 7.1.5 of Regulatory Guide 1.35 (Reference 5..7) and Section IWL-3221.1 (a) of ASME Code (Reference 5.8).

A more detailed engineering evaluation is being prepared to investigate the cause and the extent of low lift-off values in the Unit 4 containment structure post-tensioning system. This evaluation will also determine the length of time that the Unit 4 Turkey Point post-tensioning system will continue to satisfy the licensing basis requirements. A report will be submitted to the NRC by January 29, 1993.=

3.0 Desi n Mar ins Available in the Post-Tensionin S stem Turkey Point UFSAR (Reference 5.1), 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.

4.0 Conclusion The licensing basis containment design pressure is 55 psig as established in the original Turkey Point Safety 'Evaluation Report (Reference 5.10) and is the appropriate basis for containment structural analysis to evaluate the containment post-tensioning system.

Based on the available margins existing in the design of the Turkey Point post-tensioning system and the level of pzestress force available in the subject hoop tendons, it is concluded that the Unit 4 hoop tendon group presently have sufficient prestress force to maintain the containment integrity.

A more detailed engineering evaluation is being prepared to investigate the cause and the extent of low lift-off condition in the Unit 4 containment structure post-tensioning system. This evaluation will also determine the length of time that the Unit 4 Turkey Point post-tensioning system will continue to satisfy the Turkey Point licensing basis requirements. A report will be submitted to the NRC by January 29, 1993.

4i LICENSEEVENT REPORT .(LER) TEXT QNTZNUlLTZON FACILITY NAME DOCKET NUMBER LER NUMBER PAGE NO.

TURKEY POINT UNIT 4 05000251 92-009-00 08 oF 09 5.0 References 5..1 Turkey Point Units 3 and 4 Updated Final Safety Analysis Report (UFSAR), Revision 10, dated July 1992, Section 5.0 5.2 Technical Specifications, Amendment 152/147,, Sections 4.6.1.6.1(a) and 3.6.1.6.

5.3 Bechtel Calculation No. C-SJ539-05, "Evaluation of the Fifteenth Year Tendon Surveillance Lift-Off Forces",

Revision 0

=5.4 Non-Conformance Report N-92-0306 5.5 Bechtel Calculation No. C-SJ561-03, "Evaluation. of the Unit 4 Twentieth Year Tendon Surveillance Low Lift-Off Forces",

Revision 0 5.6 Bechtel Technical Requirements Document 21701-561-CP-1, Revision 0, for Unit 4'wentieth Year Tendon Surveillance 5.7 Regulatory Guide 1.35, "In-service Inspection of Ungrouted Tendons in Prestressed Concrete Containment", Revision 3, dated July 1990 5.8 ASME Code, 1989 Edition,Section XI Division 1, Article INL-3000 "Acceptance Standards" 5.9 Turkey Point Plant Procedure O-SMM-51.2, "Containment Tendon Inspection", dated June 26, 1992 5.10 AEC Letter from R. C. DeYoung to Dr. J. Coughlin, Florida Power and Light Company, Safety Evaluation by the Divis'ion of Reactor Licensing, Turkey Point Units 3 and 4, dated March. 16, 1972

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t LICENSEE ENT REPORT (LER) TEXT CTTNUATTON FACILITY NAME DOCKET NUMBER LER NUMBER PAGE NO.

TURKEY POINT UNIT 4 05000251 92-009-00 09 oF 09 ZV. CORRECTIVE ACTZONS 1n accordance with Turkey Point Technical Specifications ACTION 3.6.1 6 (a), the

~ lift-offPlant forces in tendons 35H38, 35H39, restored to their required level 35H40, 35H41 and 35H42 have been of integrity by retensioning each tendon to a level equal to or above the twentieth year predicted lower limit (6.63 'kips/wire).

The following summarizes the new lift-off forces for the subject tendons:

Measured Percenta e of Tendon Avera e Lift-Off ki s Predicted Lower Limit 35H38 622.3 104.3%

35H39 618.7 103.7%

35H40 631.8 105.9%

35H41 614.4 103.0%

35H42 623.2 104.4%

2. A more detailed engineering evaluation is being prepared to investigate the cause and the extent of low lift-off values in the Unit 4 containment structure post-tensioning sy'tem. This evaluation will also determine the length of time that the Unit 4 Turkey Point post-tensioning system will continue to" satisfy the Turkey Point licensing basis requirements. A report will be submitted to the NRC by January 29, 1993. (This report will be submitted as a Supplemental LER, only if the cause of the low lift-off condition differs from the cause stated in this LER.)

3. License amendments will be submitted to the NRC revising the design pressure of the containment buildings from 59 psig to 55 psig (Technical Specification 5.2.2 and BASES 3/4.6.1.4). These amendments will be submitted to the NRC no later than June 1, 1993.

V. ADDITIONAL INFORMATION No similar LERs have been identified.