AECM-80-297, Fifth Interim Deficiency Rept Re Defective Topaz Inverter Model Gz,Used on Equipment Supplied by Ge.Cause Associated W/Transient Signal Failure.Supplier Will Make Mods to Product.Final Rept to Be Submitted by 810325

Fifth Interim Deficiency Rept Re Defective Topaz Inverter Model Gz,Used on Equipment Supplied by Ge.Cause Associated W/Transient Signal Failure.Supplier Will Make Mods to Product.Final Rept to Be Submitted by 810325

ML20062K301
Person / Time
Site:	Grand Gulf
Issue date:	12/01/1980
From:	Mcgaughy J MISSISSIPPI POWER & LIGHT CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
10CFR-050.55E, 10CFR-50.55E, AECM-80-297, NUDOCS 8012090246
Download: ML20062K301 (4)

Text

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!: h b MISSISSIPPI POWER & LIGHT COMPANY

h. W w' ' M7 Helping Guild Mississippi.

P. O. B O X 164 0. J A C K S O N, MIS SIS SIP PI 39206 JAMES P. McCAUGHY, Jn. December 1, 1980 ass,srov vice cs.oo,1 Office of Inspection & Enforcement U. S. Nuclear Regulatory Commission ,

Region II 101 Marietta Street, N.W.

Suite 3100 Atlanta, Georgia 30303 y _j t

~

i Attention: Mr. J. P. O'Reilly, Director

SUBJECT:

Grand Gulf Nuclear Station Units 1 and 2 Docket Nos. 50-416/417 l

File 0260/15525/15526 ~

PRD-79/17, Interin Report #5, Defective Topaz Inverters

! AECM-80/297

References:

1) AECM-79/116, 10/16/79

2) AECM-80/32, 1/31/80

3) AECM-80/103, 5/15/80 l

4) AECM-80/192, 8/18/80 On September 9, 1979, Mississippi Power & Light Company noti-fled Mr. J. K. Rausch of your of fice of a Potentially Reportable Deficiency (PRD) at the Grand Gulf Nuclear Station (CGNS) construc- ,

tion site. The deficiency concerns defective inverters manufactured ,

by Topaz Electronics for equipment supplied by General Electric.

We indicated in Reference 2 that this deficiency was reportable under 10CFR50.55(e) . GE has proposed modification of the inverters by providing capacitance on the inverter input to protect the devices. ,

We are still in the process of evaluating this modification as a ,

final solution to this problem. Additional details are provided In ,

the attached interin report. We expect to provide a final report by March 25, 1981.

Yours truly

/

f,y J. P. McGaughy, Jr.

EWC:mt 1

IE DOCUMENT CONTAINS POOR QUAUTY PAGES g4/7 >

. 801209D Membec Middie South utiiities System 5if 2% -_ _ _

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i MISSISSIPPI POWE!? & LIGHT COMPANY Str. J. P. O'Reilly AEQt-SO/297 NRC Page 2 cc: Mr, N. L. Stampley .,

!r. R. B. McGehec Mr. T. B. Conner Mr. Victor Stello, Director Division of Inspection & Enforcement U. S. Nuclear Regulatory Commission b'ashington, D.C. 20555

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Attachment to MCM-HU / 29 /

l' age 1 of 2 STATUS REPORT #5 FOR PRD-79/17

1. Description of the Deficiencv On September 5, 1979, GE notified the NRC of a conditiot$ repor-taole under 10CFR21 regarding inverters manufactured by Topaz Electronics, San Diego, California. Since that time, ir has been determined that only the Topaz Inverter Model CZ is af-fccted. These devices are used to supply essential divisional power from station batteries to the ECCS transmitters / trip unit analog sensors. The technical issue is that inverter failure is associated with transient signals such as those generated en the 125 VDC bus from switching relay coils. The external line tran-sient signal can blow fuses and turn on Silicone Control Recti-fiers (SCR) in the circuit causing them to undergo possible damage. Inverter failure could prevent the initiation of the Emergency Core Cooling System. The Model CZ inverter in question .

is used on Cencral Electric supplied equipment on both Units 1 and 2.

Our Architect / Engineer has also determined that Topa inverters were used in some balance-of-plant (BOP) systems, but it has been determined that they were not used in control circuitry involved in safe shutdown or accident mitigation.

11. Resolution of Deficiency The deficiency in the inverters must be corrected hv modification, or the cause for transient signals on the circuit must be climinated.

Our NSSS Supplier has taken action to qualify another vendor source, but it is unlikely that equipment delivery can be made in a time frame acceptacle for our fuel load schedule. The NSSS Supplier has also pursued the Topa: Company to make modifications to its product, but such actions so far has been unsuccessful. In order to allow preoperational tests to proceed, our NSSS Supplier pro-posed to remedy this problem by providing kits for implementation into the circuits at Grand Gulf. These kits will provide capaci-tance on the inverter input to protect the devices fror the stated p roblem.

III. Status _

Some of the capacitor kits have been delivered and are being in-stalled at GGNS.

IV. Rensens for Delavine Final Report We have not yet received our NSSS Supplier's supporting justifica-tions and qualification that the capacitor kits will suffice for a permanent solution to the inverter failure problem. Upon receipt of this information, we must ccmplete our evaluation of this modi-fication.

i 9

Attachment to A!:CM-80/297 P. ige 2 of 2 V. Projected Final Report Submittal Date k'e expect to receive the supporting documentation from'the NSSS Supplier shortly, and expect to submit our final report by March 25, 1981.

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