ML20197D034

/01X-1 on 780322:elec Degradation Observed on a GE Terminal Block Type Eb & 25 Mounted in Aluminum Terminal Box.Failure Traced to Interfacing W/Aluminum Boxes.Aluminum Boxes Replaced W/Steel Boxes

ML20197D034
Person / Time
Site:	Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png
Issue date:	09/25/1978
From:	Fleming S CONNECTICUT YANKEE ATOMIC POWER CO.
To:
Shared Package
ML20197D021	List: ML20197D018 ML20197D034
References
LER-78-002-01X, LER-78-2-1X, NUDOCS 7811210311
Download: ML20197D034 (2)

Text

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I- e EVENT DESCRIPTION AND PROB AOLE CONSEQUENCES hDuring full s f f o 12 ( l  ;

combinations, (March 16 to 22, 1978) similar to equipment recently installed pg,3, ; j i inside containment for the electrical circuits of core deluge motor operated f f a f 4i l l i j

valves, electrical degradation was observed at one point on a General E ectr c g g ,3, ,

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Company terminal block type EB-25 mounted in an aluminum terminal box.

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block / box combination had successfully passed screening environmental l lg;,; l  ;

temperature CONTINUED ON ATTACHED gg;g; qualification tests under pressure, 60 l CoVP. VALVE I 7 8 9 CAUSE CAUSE SUSCoOE SUD,qoDE

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s3 34 a a 3/ 40 48 CAUSE D[SCRIPTION AND CORRECTIVE ACTf 0NS  ;

the failure of the General Electric terminal l li jbj ] Preliminary test results indicate No failures were l

[, g , j l block was related to its interface with the aluminum box.

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experienced with the General Electric block / steel box combination.

- , , , ., j l _j replacement of the aluminum boxes with stee'. boxes was commenced on g , ; ., j l l

CONTINUED ON ATTACHED.

March 23,1978 after appropriate review per CO j ji,4; ;

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+  ! A*17ACHMEJ1T 1 ( I'YENT' DESCRIPTION AND PROBABLE CONSEQUENCES CONTINUED

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and humidity conditions conservatively simulating the post accident

cavironment. ,

i Although it is believed that the installed General Electric terminal

blocks in aluminum boxes would have performed their intended function i based on the time that failure occurred (30 minutes into test)it was

decided to replace the aluminum boxes with steel boxes. Note that the i only General Electric block / aluminum box application was in the core deluge valve 871A and 871B circuits (located at the Reactor Pressure l Vessel Head). The General Electric block / steel box combination was

} determined to be environmentally qualified based upon the same

qualification testing. -

i Also during the testing, a Westinghouse terminal block mo~unted in an aluminum box was determined to have failed at one terminal point. l i i I ' 1 $ i ![

                                                                              .                                       i j                                CAUSS DESCRIPTION AND CORRECTIVE ACTIONS CONTINUED j

1:ortheast Utilities Quality. Assurance procedures (See D. C. Switzer l

letter to D. Zeimann, dated March 29, 1978).

I Preliminary investigation of the terminal point failure on the Uestinghouse block revealed the terminal block had a crack that l appeared to be the result of excessive torque on one of the mounting l ) screws. All safety-related terminal blocks ' have had the mounting l = screws retorqued to 25 inch-pounds, as recommended by Westinghouse. Additionally all of these blocks hav'c been visually inspected with j a strong light source to insure no cracks exist. l Additional failure mode evaluations are in progress. 5 5 e 4 1 1 e '

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