ML19312C926

Reactor Bldg Post-Tensioning Sys Initial Surveillance.

ML19312C926
Person / Time
Site:	Oconee
Issue date:	03/20/1975
From:	DUKE POWER CO.
To:
Shared Package
ML19312C925	List: ML19312C924 ML19312C926
References
NUDOCS 8001140585
Download: ML19312C926 (12)

Text

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DUKE POWER COMPANY OCONEE NUCLEAR STATION UNIT 2 REACTOR BUILDING POST-TENSIONING SYSTEM INITIAL SURVEILLANCE s

March 20, 1975 8001340N 1

TABLE OF CONTENTS Section Pa g e_

1.0 INTRODUCTION 1

2.0

SUMMARY

AND CONCI.USIONS 2.1

SUMMARY

2 2,2 CONCLUSI0SS 2 2

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

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1. CL INTF0 DUCTION The surveillance program for the Oconee Nuclear Station, Unit 2 , reactor building post-tensioning system was defined, and.is executed, in order to' assure the continued quality of the system. 1te 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, therefoce ,

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

The requirements for the program are detailed in the Oconee Technical Specifications, Sections 4.4.2.1 and 4.4.2.2.

December 13 through December 20.

Surveillance was conducted 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 .

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- - 1: -

5

2.0

SUMMARY

Ajg) CONCLUSIONS 2.1

SUMMARY

No significant discoloration of the sheathing filler was observed.

Laboratory analysis of sheathing filler samples sho be well within acceptable limits. wed impurities _to The end anchorage components were found to be in ex cellent condition with no sign of the development of adverse conditions or excessive corrosion, or missing or deformed buttonhsuch eads.

as cracking The lif t-off forces for all surveillance tendons were of predicted values,'considering the effects of concretwithin shrinkage, e creep and the range steel relaxation and initial structural deformation .

The tendon wires were in excellent condition and corrosion nothe along length of the wires was observed.

had occurred during the interval since the initial RIt was determ Structural Integrity Test. eactor Building Mechanical tests of specimens showed no significante changes in th ultimate _ strength of the wire as compared to results obt i initial acceptance tests. a ned during

2.2 CONCLUSION

S Based on the tests and inspections described her i the post-tensioning system for Oconee Nuclear Ste n, it is concluded that excellent condition, ation, Unit 2, is'in that the functional capability of the~syst em has not diminished, and that the system shows no detectable e id j.

occurrence of any adverse deterioration. v ence of the 9

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, l

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 present on the edges and faces of shims and bearing plates. However, this condition existed at the time of installation ar.d no deterioration has occurred in the interval since installation).

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 i

of concrete creep and shrinkage, steel relaxation and initial structural deformation.

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3.4 WiltE SURVEILLANCE AND TESTING One survefilance tendon of each directional group was relaxed -'lD28 ,

13H9 and 23V14.

One wire was removed from tendons 1D28, 23V14, and 13H9.

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 _ i discoloration.

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 REPLACEMENT 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 removed during the surveillance process was replaced with new filler.

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SHEATHING FILLER INSPECTION Filler Coating Acceptable Filler Color and Button Stress. Bearing '

Tendon End Heads Washer Shims Plate Cap Acceptable 1D28 Shop Yes Yes Yes Yes Yes Ys Field Yes Yes Yes Yes Yes Y 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 tY g 13H9 Shop Yes Yes Yes Yes Yes e Yes Field Yes Yes Yes Yes Yes e Yes 51H9 Shop Yes Yes Yes Yes Yes Yes Field Yes Yes Yes Yes Yes Yes 53H10 Shop Yes Yes Yes Yes Yes Yes Field Yes Yes Yes Yes Yes

. Yes 23V14 Shop Yes Yes Yes Yec Yes Yes Field Yes Yes Yes Yes Yes Yes 45V16 Shop Yes Yes Yes Yes Yes Yes Field Yes Yes Yes Yes Yes Yes 61V16 Shop Yes Yes Yes Yes Yes Yes Field Yes Yes Yes Yes Yes Yes

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' LABORATORY ANALYSIS OF SHEATil1NC FILLER i

4 Water Soluble Water Soluble . Water Soluble CHLORIDES NITRATES SULFIDES Tendon (Limit 5.0 ppm) (Limit 5.0 ppm) (Limit 5.0 ppm) 1D28 < l.0 0.0 0.0 13H9 < l.0 0.0 0.0 23V14 2.0 0.0 0.0 1

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• . Table 2 i

d c . ~ r , ,, e - . 7.. - , ., --,

END ANCHORAGE COMPONENT INSPECTION Buttonheads Stress Washer Shims Bearing Plate Tendon 'End Corrosion Cracks Shape Corrosion Cracks Corrosior 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 e 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

@ 13H9 Shop None None Good None None None None None None f

Field None None Good None None None None None None 51H9 Shop None None Good None None None None None None Field None None Good None None None None None None 53H10 Shop None None Good None None None None None None Field None None Good None None None None None None 23Vl'4 Shop None None Good None None None None None None Field None None Good None 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

1DiDON LIFT-OFF FORCES Tendon Force (Psi) 1D28 5225 i 2D28 5700 3D28 5817 1 3119 5500 i SlH9 5700 l

53H10 5750 23V14 5714 45V16 5650 61V16 5817 i

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.: i Table 4 J

r ULTIMATE STRE!!GTH OF TENDON SPECIME ;S r

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

Shop 12,100 0.250 0.0491 246435 1D28 Center 12,100 0.250 0.0491 246435 Field 12,100 0.250 0.0491 246435 Shop 12,600 0.250 0.0491 256619 23V14 Center 12,650 0.250 0.0491 257637 Field 12,600 0.250 0.0491 256619 - '

Shop 12,350 0.250 0.0491 251527 13H9 Center 12,350 0.250 0.0491 251527 Field 12,450 0.250 0.0491 753561 I

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Table 5

TENDON SURVEILLANCE FORCE-TDE PLOT Upper Limit = 8.6 kips- f 9.0 _ __

. [_ ,

. .. :D2s a 2D28 8.0

+ 3D28 j

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7.0 Lower Limit - 7.2 kips-I DOME TENDONS l Upper Limit = 8.6 kips j 9.0 / _

e 13H9 7

• a 51H9

& 8.0

+ 53H10 25 E ra - $ -

E$: 7.0 Lower Limit = 7.22 kips \

g

. d n.

l HORIZONTAL TENDONS

! Upper Limit = 8.6 kips g -

f g 9.0

. 23V14

" = 45V16 8.0 + 61V16 4 - - -

Lower Limit = 7.34 kips d l

l VERTICAL TENDONS i

y 5 4 4 4

• I s I 5 5 , 10 20 30 40 TIME (Years)

_ - _ _ _ _ _ _ _ _ _ _ _ _ _ _ - _ _ - _ _ _ _ - - - - - _ - _ _ - _ _ - . . . _ _ _ _ - - _ _