ML19340A170

Reactor Bldg Post-Tensioning Sys Initial Surveillance Rept.

ML19340A170
Person / Time
Site:	Oconee
Issue date:	07/23/1975
From:	DUKE POWER CO.
To:
References
NUDOCS 8001100648
Download: ML19340A170 (12)

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DUKE PO'n'ER COMPAM OCONEE NUCLEAR STATION UNIT 3 REACTOR BUILDING POST-TENSIONING SYSTEM INITIAL SURVEILLANCE July 23, 1975 8001100bf8

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TABLE OF CONTENTS-St. : tion . Page 1.0 . INTRODUCTION 1-I' l 2.0- '

SUMMARY

-AND CONCLUSIONS 2 2.1

SUMMARY

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2.2 CONCLUSION

S 2 3.0 'RESULTS 3 3.1 SHEATHING FILLER 3

3.2 END ANCHORAGE COMPONENTS 3 3.3'

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LIFT-OFF FORCES 3 l

l 3. 4' WIRE SURVEILLANCE AND TESTING 4 3.5 RETENSIONING AND FILLER REPLACEMENT. 4 p

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1.0 INTRODUCTION

The surveillance program for the Oconee Nuclear Station, Unit 3, reactor building post-tensioning system was defined, and is executed, in order to assure the continued quality of the system. The program consists of periodic inspections of_nine pre-selected tendons - three horizontal l tendons, three vertical tendons-and three dome tendons - for symptoms of material deterioration or force reduction. The program assesses the condition and functional capability of the system and, therefore, I

l verifies the adequacy of the system and provides an opportunity to take proper corrective action should adverse conditions be detected.

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l The requirements for the program are detailed in the Oconee Technical Specifications, Sections 4.4.2.1 and 4.4.2.2. Surveillance was conducted April 7 through April 24, 1975 in accordance with the approved test

_p rocedure, Reactor Building Tendon Surveillance Program, and the results of this initial inspection are reported herein.

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SUMMARY

AND CONCLUSIONS 2.1

SUMMARY

No abnormal discoloration of the sheathing filler was observed.

Laboratory analysis of sheathing filler. samples showed impurities to bi well within acceptable limits.

The end anchorage components were' found to be in excellent condition with.no sign of the development of adverse conditions such as cracking or excessive corrosion, or missing or deformed buttonheads.

The lift-off forces for all surveillance tendons were within the range of predicted values, considering the effects of concrete creep and shrinkage, steel ~ relaxation and initial structural deformation.

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4 The tendon wires were in excellent condition and no corrosion along the length of the wires was observed. It was determined that no wire breaks had occurred during the interval since the initial Reactor Building Structural Integrity Tect.

Mechanical tests of specimens showed no significant changes in the ultimate strength of the wire as compared to results obtained during initial acceptance tests.

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2.2 CONCLUSION

S Based on the tests and inspections described herein, it is concluded that the post-tensioning system for Oconee. Nuclear Station, Unit 3, is in excellent -condition that. the functional capability of the system has not diminished, and.that the system shows no detectable evidence of the occurrence of any adverse deterioration.

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3.0 RESULTS 3.1 SHEATHING FILLER The sheathing filler at the ends of the nine surveillance tendons was visually examined. The filler coating on the end anchorage components, and the color and consistency of the filler, were found to be acceptable, with no evidence of water being present - see Table 1.

Samples of sheathing filler were obtained from each of three tendons from which a wire was removed. This filler was visually examined and no signs of water nor any discoloration of the sheathing filler was evident. Laboratory analysis of the filler samples found impurities to be within acceptable limits - see Table 2.

3.2 END ANCHORAGE COMPONENTS The results of the end anchorage component inspections are given in Table 3. Buttonheads were inspected for acceptable shape, general appearance, cracks and corrosion. A button head located on one wire on the field end of tendon 2D28 did not pass the Go-No-Go gage test. This button-head will be re-examined at the next surveillance interval.

Stress washers, shims and bearing plates were visually inspected for cracking and corrosion. Slight corrosion (no pitti,ng) was noted on the upper 25 percent of the anchorage components at the field end of tendon 13H9. This condition was apparently caused by a small air pocket during the initial tendon grease filling. The tendon was repacked with grease.

3.3 LIFT-OFF FORCES Lift-off forces were obtained for each surveillance tendon - see Table 4.

(The field end of tendon 53H10 was not tested due to a physical inter-ference by an emergency feedwater bypass line.) From these readings an average force per wire was determined. The long-term trend of these wire forces is shown graphically in Figure 1. -Lift-off forces were withia the range of predicted values, considering the effects of concrete creep and shrinkage, steel relaxation and iaitial structural deformation.

3.4 W11tE SURVEILLANCE ~ AND TESTINC '

One surveillance. tendon of each directional group was relaxed -.lD23, 13H9 and 23V14 One wire was rctoved from tendons IL28, 23V14, and 13H9. The wires removed were visually checked fer corrosion and pitting and to determine their general condition. The tendon wires were found to contain minor surface scratches, resulting froci insertion of the tendons into their sheaths at the t ime c i installation, and ncat trea*ing discoloration. The general conditfor or the wires was deters:tnec to be equivalent to their condition at time at initial installation.

Three specimens were cut from each of the extracted vires tor tensile testing. The samples were taken from the ends and the middle of each~of the wires. The ultimate strength'of each of the specimens was determined by tensile testing by the Prescon Corporation, Simpsonville, South Carolina. These tests are summarized in Table 5 and revealed no signifi-

cant changes in the ultimate strength of the wire as compared to results i obtained during initial acceptance tests.

l-l 3.5 RETENS10NING AND FILLER REPLACEMENT i

Following wire removal the tendons were retensioned to approximately the same stress level indicated by the lift-off force data obtained'during l this surveillance. The sheathing filler which was removed during the surveillance process was replaced with new filler.

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Si!EATHING FILLER INSPECTION Filler Coating Acceptable Filler Color and Button Stress Bearing Tendon End lleads Washer Shims Plate Cap Acceptable ID28 Shop Yes Yes Yes Yes Yes kes Field Yes Yes Yes Yes Yes Yes 2D28 Shop Yes Yes Yes Yes Yes Yea Field Yes Yes Yes Yes Yes Ye, 3D28 Shop Yes Yes Yes Yes Yes Yes Field Yes Yes Yes Yes Yes T e-tY

$ 1 3119 Shop Yes Yes Yes Yes Yes Yeq

1. Field Yes Yes Yes Yes Yes Ye' w

51119 Shop Yes Yes Yes Yes Yes Y e t, Field Yes Yes Yes Yes Yes Ye-531110 Shop Yes Yes Yes Yes Yes Yes Field Yes Yes Yes Yes Yea Yo 23V14 Shop Yes Yes Yes Yes Yes Yen Field Yes Yes Yes Yes Yes Ycu 45V16 Shop Yes Yes Yes Yes Yes Yea Field Yes Yes Yes Yes Yes Ye-61V16 Shop Yes Yes Yes Yes Yes Yes Fleid Yes Yes Yes Yes Yes Yes 4

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Ii LABORATORY ANALYSIS OF SHEATHING FILL 2.2 l

Water Soluble Water Soluble Water Soluble Tendon End CHLORIDES NITRATES SULFIDES (Limit 5.0 ppm) (Limit 5.0 ppm) (Limit 5.0 ppm) l l

Shop 0.40 0.10 <2.0 1D28 0.20 <2.0 i Field 1.20 ,

l Shop 0.75 0.20 <2.0 4

23Vl* 1.00 0.50 <2.0 Field l Shop 1.00 0.10 <2 O 13H9 Field 0.60 0.10 <2.0 4

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Table 2

END ANCHORAGE COMPONENT INSPECTION Buttonheads Stress Washer Shims Bearing Plate Tendon End Corrosion Cracks Shape Corrosion Cracks Corrosioi Cracks orrosion Cracks 1D28 ' Shop None None Good None None None None None None Field None None Good None None None None None None 2D28 Shop None None Good None None None None None None Field None None

• None None None None None None 1

3D28 Shop None None Good None None None None None None Field None None Good None None None None None None H None Shon None None Good None None None None None

$ 13H9

• • ** None ** None ** None y Field None Good ta 51H9 Shop None None Good None None None None None None Field None None Good None None None None None None

~53H10 Shop None i None Good None None' None None None None Field None None Good None None None None None None -

23V14 Shop None None Good None None None None None None None Field None None Good None None None None None 45V16 Shop None None Good None None None None None None Field None None Good None None None None None None 61V16 Shop None None Good None None None None None None Field None None Good None None None None None None

• 0ne buttonhead did not pass Co-No-Go Gauge test

• • Reddish brown color on upper 25 percent, no pitting

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. TENDON LIFT-OFF FORCES l

l 4 Tendon End Force (Psi) 1D28 Shop 5566 Field 5616 2D28 Shop 5666 Field 5800 -

3D28 Shop 5716 Field 5900 13H9 Shop 5750 Field 5800 SlH9 Shop 5700 4 Field 5583 53H10 Shop 56'83 Field *

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J 23V14 dhop 6100 Field 6000

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45V16 Shop 5700 l

Field 6000 l .

61V16 Shop 5766

-Field 6000

• Unable to obtain lift-off force due to a physical interference by the Emergency Feedwater Bypass Line.

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Table 4

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i ULTIMATE STRENGTH OF TENDON SPECIMENS 1

Break Tensile Specimen Force Diameter Area Strength Tendon Location (Lbs.) (In.) (In2) (pag)

Shop 12,20d 0.250 0.0491 248473 1D28 Center 12,050 0.250 0.0491 245418 Field 12,150 0.250 0.0491 247454 Shop 12,750 0.250 0.0491 259674 23V14 Center 12,850 0.250 0.0491 261711 Field 12,850, 0.250 0.0491 26.1.711 Shop 12,800 0.250 0.0491 260693 13H9 Center 12,800 0.250 0.0491 260693 Field 12,750 0.250 0.0491 259674 e

Table 5' l

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i i TENDON SURVEILLANCE FORCE-TIME PLOT Upper .timit = 8.6 kips f 9.0 - -

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• 1D28 8.0 a 2D28

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7.0 Lower Limit = 7.2 kips DOME TENDONS l Upper Limit = 8.6 kips j 9.0

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~a 7-Lower Limit = 7.22 kips J g l HORIZONTAL TENDONS

, l Upper Limit = 8.6 kips f O 9.0 R -

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Lower Limit = 7.34 kipe d I

l VERTICAL TENDONS I

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