ML20154N514

Part 21 Rept Re Failure of Standby Liquid Control Sys Squib Valve to Fire.Caused by Discrepancies Identified Between Conax Corp Drawings of Trigger Assemblies & Wiring Configuration of Trigger Assemblies in Stock

ML20154N514
Person / Time
Site:	Vermont Yankee
Issue date:	03/10/1986
From:	Murphy W VERMONT YANKEE NUCLEAR POWER CORP.
To:	Murley T NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
REF-PT21-86, REF-PT21-86-089-000 FVY-86-20, IEB-86-013, IEB-86-13, PT21-86-089-000, PT21-86-89, NUDOCS 8603170342
Download: ML20154N514 (4)

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VERMONT YANKEE NUCLEAR POWER CORPORATION FVY 86-20

. , RD 5, Box 169, Ferry Road, Brattleboro. VT 05301 y,,g ,o y ENGINEERING OFFICE 1671 WOnCESTER HO AD

• FnAMINGHAM. MASSACHUSETT3 01701

. If L 8 fHONE, Gi f 4'J 4100 March 10, 1986 U.S. Nuclear Regulatory Commission Office of Inspection & Enforcement Region I 631 Park Avenue King of Prussia, PA 19406 Attention: Dr. Thomas E. Murley Regional Administrator

References:

a) License No. DPR-28 (Docket No. 50-271)

Subject:

Notification of Potential Existence of a Defect in Accordance with 10CFR21.21 In accordance with the provisions of 10CFR Part 21, Section 21, we are hereby notifying you that we have obtained information indicating that a defect may exist with respect to SLC squib valve tirgger assemblies manufactured by Conax Corporation.

Enclosure I to this letter documents the details of this notification.

Should you have any questions regarding this matter, please contact us.

Very truly yours, VERMONT YANKEE NUCLEAR POWER CORPORATION (440-- Ym Warren P. Murphy Vice President an Manager of Operations

/dm 0603170342 860310 2 1 DR ADOCK 0 6

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F -VERMONT YANKEE NUCLEAR POWEP CORPORATION g,.

3 U.S. Nuclear ' Commission s+

March 10,1986 .

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, s cc: (3) U.S. Nuclear Regulatory Commission Director, Office of Inspection ,A Enfo, rey,,.ent Washington, D.C. 20555 -

(3) Chairman, Vermont Yankee Nuclear -

Safety Audit and Review Committee .,

(1) Manager, Operational Quality Assurance Dept. i,.-

Yankee Atomic Electric Company .

(1) ' Institute of Nuclear Power Operations (INPO) '

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ENCLOSURE I f

SLC SQUIB VALVE TRIGGER ASSEMBLY PART 21 REPORT I

L COMPANY INFORMING Vermont Yankee Nuclear Power Corporation THE COMMISSION RD 5, Box 169 Ferry Road Brattleboro, Vermont 05301 FACILITY Vermont Yankee Nuclear Power Station PO Box 157 Governor Hunt Road Vernon, Vermont 05354 FIRM SUPPLYING Conax Corporation l COMo0NENT 2300 Walden Avenue Buffalo, New York 14225 g NATURE OF DEFECT Following routine surveillance testing on February 6 and 11, 1986, during which Vermont Yankee's Standby Liquid Control (SLC) System squib valve failed to fire, Vermont Yankee identified that trigger assemblics supplied by Conax Corporation had two different pin to coil con-figurations. This failure to fire occurred despite indi-cation via the continuity test circuit that continuity t was present.

Discrepancies were identified between Conax manufac-turing drawings and the wiring configuration of trigger assemblies in stock at Vermont Yankee. According to the Conax drawing, bridge wires were supposed to be wired across Pins 1 and 4 with the second bridge across Pins 2 and 3. Testing of pin assemblies of the units currently installed at Vermont Yankee determined that there was a bridge wire across Pins 1 and 2 with the second bridge across Pins 3 and 4. Testing of pin assemblies purchased before and after pin assemblies currently installed at Vermont Yankee determined that they had bridge wire con-nections across Pins 1, 4 and 2, 3.

During a meeting with Conax on February 19, 1986, it was learned that there should only be one pin configuration with the correct configuaation having bridges across Pins 1, 4 and 2,,3. Conax felt that the cause of the problem (Units with two different pin configurations) was the i

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Enclosure I Page 2 moving of their manufacturing operations to Florida.

From approximately mid-1983 to near the end of 1985,

,I Conax had primer trigger. assemblies manufactured at their Florida plant. . Conax has since moved these manufacturing operations back to Buffalo, New York.

DATE ON WHICH A potential Part 21 Report Evaluation was initiated on

. DEFECT WAS DETECTED February 14, 1986.

. NUMBER.0F' COMPONENTS Vermont Yankee had six (6) trigger assemblies with AT FACILITY incorrect pin to coil wiring configurations.

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CORRECTIVE ACTIONS Vermont Yankee is modifying its procedures to require a pin to pin continuity check for.all trigger assemblies prior to installation.

! 2. Vermont Yankee is modifying its existing procedure which tests the first primer of each batch to require the testing to be performed in the firing circuit.

3. Vermont Yankee is investigating the possibility of revising the continuity test circuit design to ensure it actually indicates ability to " fire" the squib charge.

4. . Incorrectly wired trigger assemblies are being returned to Conax Corporation for replacement.

5. The surveillance test performed which uncovered this problem will be repeated prior to declaring the system operable.

RELATED ADVICE Vermont Yankee recommends other BWR operators review in detail USNRC IE Information Notice No. 86-13, " Standby Liquid Control Squib Valves Failure to Fire" issued February 21, 1986.

Vermont Yankee also warns BWR operators that, although our wiring did not agree with our wiring diagrams, the as-found wiring was acceptable per General Electric SIL No. 186 issued July 30, 1976. Accordingly, compliance with this SIL does not alleviate the concern Vermont Yankee has identified.

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