ML19322B477

Reactor Bldg Structural Instrumentation Rept. Submitted W/ Amend 25 to License Application for Unit 1

ML19322B477
Person / Time
Site:	Oconee
Issue date:	12/30/1970
From:	DUKE POWER CO.
To:
References
NUDOCS 7912030315
Download: ML19322B477 (4)

Text

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OCONEE NUCLEAR STATION UNIT 1 ONLY Regutatory Flie C. '

LICENSE APPLICATION menvet vw unte /2 y C.7g _

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REACTOR BUILDING STRUCTURAL INSTRUMENTATION REPORT i

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Submitted with Amendment No. 25 December 30, 1970

$*CT 3s120a03 #

1. Purpose of Structural Instrumentation Unit 1 Reactor Building was instrumented to verify the design by comparing the calculated behavior with measured strain data obtained during the structural test.

The following instruments were installed in Unit 1 Reactor Building as shown on Figure 5-21, Sheets 1, 2 and 3, Section 5 of FSAR:

Quantity Mark Desionation 118 SGA-1 Two element strain rosette attached to rebar.

9 SGE-2 Linear element attached to concrete surface.

6 SGC-3 Crack propagation gages attached to concrete surface.

18 SGR-4 Three element rosette attached to inside and outside face of liner and penetration nozzles.

26 S FT-5 Two element rosette attached to inside and outside face of liner and penetration nozzles.

7 LC Load cells attached to the tendons.

26 CB Calibrated deflection bars attached to concrete surface.

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Cement paint area on concrete surface.

2. Purchase and installation of Gaqes The gages were purchased by Specification OS-267A, " Specification for Reactor Building instrumentation," dated March 31, 1967. The specification listed the schedule requirements and stated that the proof test would be performed January 1, 1970. Due to unforseen circumstances, the proof test has been delayed by approximately one year.

The gages were installed in accordance with Specification 05-267B, "Specifi-cation for Reactor Building Instrumentation Installation," dated November 30, 1967, and revised April 8,1968. A conference was held with the sup-plier's representative to review the installation specification and methods of gage installation.

Prior to installing the gages, the supplier held a training session with Field Personnel on the proper methods and procedures for gage installation.

Gages mark SGA-1 were fabricated and waterproofed in the supplier's shop.

The test results were reviewed by Duke Engineering and found to be accept-able, in addition, the gages were waterproof and load tested by Duke prior to installation and found to be satisfactory. The SGA-1 gages were installed between January,1968 and January,1970.

3 Performance of Gages The gages performed satisf actorily through April 1970, with only five per-cent losses. In May 1970, a significant number of gage failures began to occur.

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The status of gages on November 28, 1970 was as follows:

Number Number Number Gage Mark inoperative O pe rat ive Being Replaced SGA-1 114 4 (See 4b below)

SGE-2 7 2 (See 4b below)

SGC-3 0 6 -

SGR-4 7 11 6 S FT-5 7 19 6 LC (Load Cell) 1 6 (See 4d below)

CB (Calibrated Bar) 0 26 -

The gage losses have been ir.vestigated by Duke, Bechtel and the Supplier.

It was concluded that the gage losses (increase in gage resistance) was .

caused by chemical etching. The waterproofing material, Epoxylite 222, has broken down and moisture mixed with concrete chemicals has penetrated into the grid area and attacked the gages.

One of the load cells is inoperative due to moisture penetrating the water-proofing and grounding the gages.

4. Proposed Instrumentation Program Since a significant number of embedded gages are inoperative, we believe it prudent to verify the design by (a) utilizing test results from Palisades and, (b) continuing with the Oconee Structural Test, as noted below:

a) The design and construction of Palisades and Oconee Reactor Buildings are very similar. The Palisedes' structural Instrumentation progro .

was successful and permitted a detailed comparison between desigr. cal-culations and observed response.

b) At Oconee, the calibrated bars (optical measurements) will permit veri-fication that the structural response is consistent with the predicted behavior. In addition, twenty-six Carlson SAIOS strain gages will be surface mounted on the Reactor Building to obtain concrete strains for comparison with Palisades and those predicted for Oconee. (See attached Figure 5-21, Sheet 4),

c) Six inoperative gages mark SGR-4 and SFT-5 are accessible and will be replaced to obtain data for comparison with Palisades and predicted strains for Oconee.

d) Load cells that are inoperative will be repaired or supplemented with prestress rams that have been modified with 20 psi division gages to measure tendon forces. Prestress rams were used at Palisades and per-formed satisfactory. Results of measured forces can then be compared with those predicted.

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5. Summary of Palisades Structural Integrity Test (Submitted to AEC by Consumers Power Company, December 1970) 1  !

The containment test provided data on structural behavior for assessment of the design methods. Test measurements included concrete, reinforcing steel and liner streins; concrete temperatures; prestressing tendon forces; overall displacements; and concrete cracking patterns.

Test measurements were made at locations where analytical predictions of the measured parameters were expected to be accurate and at locations where supplemental information on structural behavior was deemed useful. Approxi-mately 450 sensors were used to obtain the test data.

Measurement of concrete strain was the primary means of evaluating the re-sponse of the structure to dead load, prestressing and pressure loadings.

Rebar-mounted strain gages and embedded Carlson meters we,e the principal sensors used to obtain strain Information.

For the prestressing plus test pressure condition, the concrete was com-pressed showing that the pressure could have been higher without reducing the compression strain to zero. As expected, the pressurization resulted in only a 1 to 3 percent increase in the prestressing force, an amount that is considered negligible. This demonstrates that pressurization causes

negligible cycling of loads in the prestressing tendons which are an impor-tant contributor to the containment strength.

The test data showed that the containment met design criteria and shows Agreement with oredictions made with the design methods. There was no evi-dence of structural Instability or loss of equilibrium. The strains result-ing from prestr essing were within the expected range and the residual strain resulting from pressurization was negligible. There was, therefore, direct evidence that the structure can safely sustain the two largest loads, pres-  !

sure and prestressing.

i l 6. Conclusion Unit 1 Reactor Building design will be verified by: (1) comparing the cal-

culated behavior with measured strain data obtained during the structural test from operative Instruments supplemented with the replacement of access-ible Inoperative gages and the addition of 26 Carlson sal 0S strain gages and (2) utilizing the Palisades structural integrity test results since the de-

, sign and construction of Oconee Reactor Buildings and Palisades are very similar.

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