ML20236S018

Summarizes 871020 Telcon Between NRC & Util Re Two Broken Fillet Welds on Pole Shaft Assembly of Circuit Breaker That Energizes Emergency Fire Protection Pumps for Facility. Photographs Attached to 870710 Memo to NRC Encl

ML20236S018
Person / Time
Site:	Sequoyah
Issue date:	11/18/1987
From:	Hood D Office of Nuclear Reactor Regulation
To:	Office of Nuclear Reactor Regulation
References
TAC-65955, TAC-65956, NUDOCS 8711240172
Download: ML20236S018 (7)

Text

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Docket Nos.: E0-327 and 50-328 . gg.

LICENSEE: Tennessee Valley Authority FACILITY: Sequoyah Nuclear Plant, Units 1 and 2

SUBJECT:

SEQUOYAH 2. CIRCUIT BREAKER POLE SHAFT WELD FAILURE (TACs 65955/65956)

Reference:

' Memorandum from D. Hood dated.0ctober 23, 1987

" Record of Telephone Conversation Regarding Sequoyah.2 Circuit Breaker Pole Shaft Weld Failure," Docket Nos. 50-327 and 50-328 The above reference sumarized an October 20, 1987 telephone discussion between the NRC and Tennessee Valley Authority regarding two broken fillet-welds on the pole shaft assembly of the circuit breaker that energizes the emergency fire protection pumps for Sequoyah Unit 2. The reference acknowledged that TVA's preliminary findings from the engineering analysis by its Material Engineering Section were discussed in J. B. Hosmer's memorandum dated July 10,1987 (same as enclosure 2 of D. Hood memorandum, "Sumary of September 23, 1987 Meeting on- Westinghouse Switchgear Failures,"

dated October 2, 1987). The NRC's copy of photographs attached to Hosmer's July 10, 1987 memorandum were of poor' reproduction quality and better copies were to be forwarded to NRC.

Accordingly, the NRC has received the enclosed Technical Report No..M86-87-A216-dated October 3,1987 with attached Figures I through 4.

B Darl Hood, Project Manager Project Directorate II-3 Division of Reactor Projects, I/II-

Enclosure:

As stated cc: E. Pugh, TVA J. Hosmer, TVA J. Jelovich, W_

TI C.D. Sellers EMcKenna NRC PDR JRichardson Local PDR ccheng PRC System VHodge MRood KNaidu DHood TPeebles, RII ySH J J f4 PD#II-3/DRP-I/II PD#II-3/DRP-I/II DHood/mac DHood, Acting PD 11/ g /87 11/,y/87 hDR DOC 27 F PDR

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UNITED STATES -

NUCLEAR REGULATORY COMMISSION

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E WASHINGTON, D. C. 20555 NOV 161987 Docket Nos.: 50-327 and 50-328 i

LICENSEE: Tennessee Valley Authority FACILITY: Sequoyah Nuclear Plant, Units 1 and 2

SUBJECT:

SEQUOYAH 2 CIRCUIT BREAKER POLE SHAFT WELD FAILURE (TACs 65955/65956)

Reference:

Memorandum from D. Hood dated October 23, 1987

' " Record of Telephone Conversation Regarding Sequoyah 2 Circuit Breaker Pole Shaft Weld -

Failure," Docket Nos. 50-327 and 50-328 The above reference sumarized an October 20, 1987 telephone discussion between the NRC and Tennessee Valley Authority regarding two broken fillet i

welds on the pole shaf t assembly )f the circuit breaker that energizes the emergency fire protection pumps for Sequoyah Unit 2. The reference acknowledged that TVA's preliminary findings from the engineering analysis by its Material Engineering Section were discussed in J. B. Hosmer's memorandum dated July 10,1987 (same as enclosure 2 of D. Hood memorandum,

" Summary of September 23, 1987 Meeting on Westinghouse Switchgear Failures,"

dated October 2, 1987). The NRC's copy of photographs attached to Hosmer's July 10, 1987 memorandum were of poor reproduction quality and better copies were to be forwarded to NRC.

Accordingly, the NRC has received the enclosed Technical Report No. M86-87-A216 dated October 3, 1987 with attached Figures 1 through 4. -

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• Darl Hood, Project Manager Project Directorate II-3 Division of Reactor Projects. I/II i

Enclosure:

As stated cc: E. Pugh, TVA J. Hosmer, TVA J. Jelovich, W _

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'E 13

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. 871014 254 aggagy 30,: 336_87-A216  !

TECHNICAL REPORT

, SHEET NO.: i 1 of I sheets DATE OF REPORT: 10/3/87 LOCATION: Central Laboratories - PSC - Chattanooga

SUBJECT:

CONTROL ROD DS-15 BREAKER, SEQUOYAH NUCLEAR PLANT - CUSTOMER j SAMPLE NUMBER 87-33 x i

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-) A COPIES SENT TO: Robert L._Phillins-T2). RIMS, Lab Files; Wa-~f$d /W A AY) 0t7n PREPARED 'B?: Delsa L. Fraz3er' CHECKED BY: RebecceNUoins APPROVED BY: R.~ lb.~ Morley l l

-1 The Metallurgical Laboratory Section received the subject sample (Figure la) with a- 1 request to determine the fracture mode. Visual examination of the sample showed that the plate in Area 3 had completely separated from the rod at the weld and that cracking was observed at the weld in Area 4 (Figures Ib and 2). Porosity was also observed in the weld of Area 4.

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Cross sections through Areas 1, 3,'and 4 (Figure 3) showed porosity in-the weld'in l Area 4. 'Also, the weld in this area did not appear to penetrate into the plate and rod, resulting in a poor bond. Fracture surfaces were ductile (Figure 48) in Area 3 l I

and Area 4. Poor welding techniques were determined to be the cause of failure.

l The microstructure of the rod consisted of ferrite and pearlite, while'the microstructure of the plate consisted of ferritic grains (Figure 4b and c). l If any additional information is required, please refer to Metallurgical Laboratory Report No. M86-87-A216.

I DLF:SAV (2333)

Attachments: Figures 1 through 4 l .

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Figure 1 - Control Rod DS-15 Breaker, Seguoyah Nuclear Plant - M86-87-A216, Customer Sample No. 87-33.

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b. Photograph of the fracture in Area 4, ~3X.

Figure 2 - Control Rod DS-IS Breaker, Seguoyah Nuclear Plant - M86-87-A216, Customer Sample No. 87-33.

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a. Photomacrograpn of the we3d

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Vigure 3 - Control Rod DS-IS Breaker, Sequoyah Nuclear Plant - M86-87-A216, Customer Sample No. 87 -33.

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b. Photomicrograph of the microstructure of the~ rod, 300X.

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' Figure 4 - Control Rod DS-35 Breaker, Seguoyah Nuclear Plant - M86-87 A216.-

Customer Sample No. 87-33.

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