ML20040B487

Final Deficiency Rept Re NSSS Water Level Transmitters Which May Give Erroneous Readings Due to Variations of Water Leg in Flexible Tubes Affected by Thermal Growth,Sagging or Low Points,Originally Reported 811215

ML20040B487
Person / Time
Site:	Palo Verde
Issue date:	01/05/1982
From:	Van Brunt E ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR
To:	Faulkenberry B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
References
10CFR-050.55E, 10CFR-50.55E, ANPP-19820-GHD, DER-81-49, NUDOCS 8201260104
Download: ML20040B487 (4)

Text

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Docket Nos. 50-528/529/530

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U. S. Nuclear Regulatory Commission / Y' Region V / ("s Creekside Oaks Office Park 8

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I 1450 Maria Lane - Suite 210 Walnut Creek, California 94596-5368 .'l

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Attention: Mr. B. li. Faulkenberry, Chief /

Reactor Construction and ,

Engineering Support Branch j

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Subject:

Final Report - DER 81-49 A 50.55(e) Reportable Condition Relating to NSSS Water Level Transmitters May Give Erroneous Readings Due to Variations of Water Leg in Flexible Tubes Affected by Thermal Growth, Sagging or Low Points File: 82-019-026 D.4.33.2

Reference:

Telephone Conversation between J. Eckhardt and B. Kaplan on December 15, 1981

Dear Sir:

Attached, is our final written report of the reportable deficiency, under 10CFR50.55(e), referenced above.

Very truly y r.y, -

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E. E. Van Brunt, Jr.

APS Vice President Nuclear Projects ANPP Project Director EEVBJ r/ Gild: ske Attachment 13 7

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U. S. Nuclear Regulatory Commission I Attention: Mr. B. II. Faulkenberry, Chief ANPP-19820-Gild /BSK January 5, 1982 Page 2 cc: Richard DeYoung, Director Office of Inspection and Enforcement U. S. Nuclear Regulatory Commission h'ashington, D. C. 20555 J. A. Roedel D. B. Fasnacht G. C. Andognini F. W. Ilartley J. M. Allen A. C. Rogers B. S. Kaplan W. E. Ide J. Vorees J. A. Brand A. C. Gehr W. J. Stubblefield W. G. Bingham R. L. Pattersor.

R. W. Welcher R. M. Grant D. R. 11awkinson L. E. Vorderbrueggen Ms. Patricia Lee llourihan 6413 South 26th Street Phoenix, Arizona 85040 m ,----m - ----rv - F - - - w ' e r-- -*m-=

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FINAL REPORT - DER 81-49 DEFICIENCY EVALUATION 50.55(e)

ARIZONA PUBLIC SERVICE COMPANY (APS)

PVNGS UNITS 1, 2 AND 3 I. Description of Deficiency Level transmitters require a constant water reference level for accurate instrument operation. A completely filled " leg" is essential for accurate calibration since it is the source against which the varying pressure exerted by the changing height of fluid in the vessel is measured.

A partially filled reference leg will lead to erroneous transmitter output.

As the irstrument isometric drawings were originally issued for construction, a possibility of steam condensing and remaining trapp(' in the reference leg; i.e., the flex-tube which connect the root valve to the condensate pot, can possibly exist for the following reasons:

e Radiat ion heat loss effects acting on the flexihose.

e Sagging or low points in the flex 1 hose due to installed configuration.

e rhermal growth cf the vessel could possibly raise the root valvo above the condensate pot if these were origi-nally inst alled at identical elevations.

A total of twenty-three (20 steam generator and 3 pressurizer) condensate pot installations may be subject to one or more of the above conditions and, thereby, not accept 51e for use as a reference level for the transmitters. The caase of this design error is attributed to a design oversight since the use of flexihose for this application is a new developmenc and the above ramifications were r.ot seen until the hot functional test was performed on San Onofre Unit 2 shich also used the flexihose for this installation.

II. Analysis of Safety Implications This conditior,is evaluated as Reportable since if left undetected and uncorrected this deficiency could result in ,

erroneous level indication and/or discrepancies between re- l dundant level indications causing the operator to distrust l readings and, thereby, potentially make a wrong operacing decision.

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9 Final Report - DER 81-49 Page 2 III. Corrective Action The following corrective actions will assure correct installations for the various condensate pots:

s. The flexihose specified for these installations will include a vacuum jacket insulation to mini-mize heat loss condensation effects.

b. The design of flexihose installations is being reviewed and revised to provide adequate draining under all operating conditions and all unnecessary hose length will be eliminated,

c. All condensete pots will be located a minimum of five inches (5") above the root valve elevation.

All the instrument isometric drawings containing condensate pots will be raviewed, revisa l and reissued by February 15, 1982, to preclude recurrence of this condition.

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