ML19322B620

Reactor Bldg Post-Tensioning Sys Surveillance Program.

ML19322B620
Person / Time
Site:	Oconee
Issue date:	03/12/1975
From:	DUKE POWER CO.
To:
Shared Package
ML19322B619	List: ML19322B618 ML19322B620
References
NUDOCS 7912040645
Download: ML19322B620 (12)

Text

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DUKE POWER COMPANY I

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OCONEE NUCLEAR STATION

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REACTOR BUILDING i

I I POST-TENSIONING SYSTEM' i

SURVEILLANCE PROGRAM 4

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! March 12, 1975 i

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TABLE OF CONTENTS Section Page,

1.0 INTRODUCTION

1 2.0

SUMMARY

AND CONCLUSIONS 2 2.1

SUMMARY

2

2.2 CONCLUSION

S 2 3.0 RESULTS 3 3.1 SHEATHING FILLER 3 3.2 END ANCHORAGE COMPONENTS 3 3.3 LIFT-OFF FORCES 3 3.4 WIRE SURVEILLANCE AND TESTING 4 3.5 RETENSIONING AND FILLER REPLACEMENT 4 i

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1.0 INTRODUCTION

The surveillance program for the Oconee Nuclear Station, Unit 1, 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 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, verifies the adequacy of the system and provides an opportunity to take proper corrective action should adverse conditions be detected.

The require 7 ants for the program are detailed in the Oconee Technical Specifications, Sections 4.4.2.1 and 4.4.2.2. Surveillance was conducted November 15 to December 12, 1974 in accordance with approved test procedure PT/0/A/150/14 Reactor Building Tendon Surveillance Program, and the results of this initial inspection are reported herein.

2.0

SUMMARY

AND CONCLUSIONS 2.1

SUMMARY

No significant discoloration of the sheathing filler was observed. Labo-ratory analysis of sheathing filler samples showed impurities to be 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 ex-cessive 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.

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 Tendon Surveillance Test.

Mechanical tests of specimens showed no significant changes in the ultimate strength of the wire as compared to results obtain2d during acceptance tests.

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 1, 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 showed 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. No buttonhead defects or missing buttonheads were observed. Stress washers, shims and bearing plates were visually inspected for cracking and corrosion. (Some millscale and minor surface corrosion were p esent on the edges and faces of shims and bearing plates. However, this condition existed at the time of installation and no deterioration has occurred in the interval since installation.)

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

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 within the range of predicted values, considering the effects of concrete creep and shrinkage, steel relaxation and initial structural deformation.

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3.4 WIRE SURVEILLANCE AND TESTING One surveillance tendon of each directional group ws; relaxed - 2L28 SlH9 and 45V16. One wire was removed from tendons 2D28, 45V16, and SlH9. The wires removed were visually checked for corrosion and pitting and to determine their general condition. The tendon wires were found to contain minor surface scratches, resulting from insertion of the tendons into their sheaths at the time of installation, and heat treating dis-coloration. The general condition of the wires was determined to be equivalent to their condition at time of initial installation.

Three specimens were cut from each of the extracted wires for 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 obtained during initial acceptance tests.

3.5 RETENSIONING AND FILLER REPLACDIEh"I Following wire removal the tendons were retensioned to approximately the same stress level indicated by the lift-off force data obtained during this surveillance. The sheathing filler which was reuoved during the surveillance process was replaced with new filler.

Si!EATilING FILLER INSPECTION Filler Coating Acceptable Filler Color and Button Stress Bearing Tendon End lleads Washer Shims Plate Cap Acceptable 1D28 Shop Yes Yes Yes Yes Yes Yes

, Field Yes Yes Yes Yes Yes Yes 2D28 Shop Yes Yes Yes Yes Yes Yes Field Yes Yes Yes Yes Yes Yes 3D28 Shop Yes Yes Yes Yes Yes Yes Field Yes Yes Yes Yes Yes Yes Y

1 3119 Shop Yes Yes Yes Yes Yes Yes Field Yes Yes Yes Yes Yes Yes e

5 1119 Shop Yes Yes Yes Yes Yes Yes Field Yes Yes Yes Yes Yes Yes 531110 Shop Yes Yes Yes Yes Yes Yes

, Field Yes Yes Yes Yes Yes Yes

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23V14 Shop Yes Yes Yes Yes Yes Yes Field Yes Yes Yes Yes Yes Yes 45V16 Shop Yes Yes Yes Yes Yes Yes Field * * * * *

• 61V16 Shop Yes Yes Yes Yes Yes Yes Field Yes Yes Yes Yes Yes Yes The field end of tendon 45V16 is a dead-end plate and inaccessible for this Inspection.

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,e LABORATORY ANALYSIS OF SHEATHING FILLER Water Soluble Water Soluble Water Soluble CHLORIDES NITRATES SULFIDES Tendon (Limit 5.0 ppm) (Limit 5.0 ppm) (Limit 5.0 ppm) 2D28 1.29 0.0 0.0 15H9 1.85 . 0.0 0.0 45V16 1.20 0.0 0.0 Table 2

END ANCHORAGE COMPONENT INSPECTION Buttonheads Stress Washer Shims Bearing Plate Tendon End Corrosion Cracks Shape Corrosioni Cracks Corrosion Cracks :orrosion Cracks ID28 Shop None None Good None None None None None None Field None None Good None None None None None None

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2D28 Shop None None Good None None None None None None Field None None Good None None None None None None 3D28 Shop None None Good None None None None None None Field None None Good None None None None None None

@H . 1 3119 Shop None None Good None None None None None None y Field None None Good None None None None None None to 5 1119 Shop None None Good None None None None None None .

Field None None Good None None None None None None 5 3111 0 Shop None None Good None hon'e 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 l Field None None Good None None None None None None 45V16 Shop None None Good None None None None None None Field * * * * * * * *

• i 61V16 Shop None None Good None None None None None None Field None None Good None None None None None None

• The field end of tendon 45V16 is a dearl-end plate and inaccessible for this inspection.

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f% g l TENDON LIFT-OFF FORCES Lift-Off Force (PSI)

Tendon End Previous Current 1D28 Shop 5933 5917 Field 6133 6033 2D28 Shop 6225 6225 Field 6117 6050 3D28 Shop 6383 5825 Field 5766 6350 .

13H9 Shop 5600 6008 Field 5700 5900 51H9 Shop 5950 5725 Field 5567 5750 53H10 Shop 5983 5950 Field 5600 5900 23V14 Shop 5716 5750 Field 6000 5867 45V16 Shop 5667 5700 Field *

• 61V16 Shop 5800 5675 Field 5966' 5667

• The field end of tendon 45V16 is a dead-end plate and was inaccessible for taking lift-off readings.

e Table 4 i

ULTIMATE STRENGTH OF TENDON SPECIMENS F

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

P 12500 0.25 0.0491 2D28 25458 i Center 14450 0.25 0.0491 253564 Field 12600, 0.266 0.0554 227436 Shop 13100 0.25 51H9 0.0491 266802 Center 13100 0.25 0.0491 266802 Field 13100 0.25 0.0491 266802 Shop 11950 0.25 45V16 0.0491 243380 Center 11900 0.25 0.0491 242362 Field 11850 0.25 0.0491 241344 t

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