ML20086K377

AO 74-40:on 740821,static Inverter Power Supply in RCIC Tripped During Start of Recirculation Pump.Cause Unknown. Mod Being Designed to Reduce or Eliminate Input Spikes Causing Inverter Trip

ML20086K377
Person / Time
Site:	Peach Bottom
Issue date:	08/31/1974
From:	Cooney M PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	Giambusso A US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20086K380	List: ML20086K377 ML20086K387
References
AO-74-40, NUDOCS 8401270052
Download: ML20086K377 (2)

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PHILADELPHIA ELECTRIC' COMPANY -[ ^ q ,s 2301 MARKET STREET PHILADELPHI A. PA.19101 (215 8414ooo

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August 31, 1974 '

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Mr. A. Giambusso Deputy Director of Reactor Projects United States Atomic Energy Commission Directorate of Licensing 50.-277 Washington, DC 20545

Subject:

Abnormal Occurrence The following occurrence was reported to Mr. W. Baunack, A.E.C.

Region 1 Regulatory Operations Office on August 22, 1974.' Wri tten noti-fication was made to Mr. James P. O'Reilly, Region 1 Regulatory Opera-tions Office on August 22, 1974. In accordance wi th Section 6.7.2.A of the Technical Specifications, Appendix A of DPR-44 for Unit 2 Peach Bottom Atomic Power Station, the following report is being submitted to the Directorate of Licensing as an Abnormal Occurrence.

Reference:

License Number DPR-44, Amendment Number 1 Technical Specification Table 3.2.8 Report No.: 50-277-74-40 Report Date: August 31, 1974 Occurrence Date: August 21, 1974 Facility: Peach Bottom Atomic Power Station R.D. 1, Delta, Pennsylvania 17314 Identi fication of Occurrence:

, Static inverter power supply in the Unit 2 Reactor Core Iso-lation Cooling System (RCIC) tripped during the start of a Unit 3 re-ci rcula tion pump.

Conditions Prior to Occurrence:

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t n 'f 1 The reactor was operating at 100% power. /

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Description of Occurrence:

During a restart of a Unit 3 recirculation pump following a surveillance test, the Uni t 2 RCIC inverter failure alarm annuncia ted in the main control room. The inverter was immediately reset.

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p - R Mr. A. Giambusso August 31, 1974 Page 2 Designation of Apparent Cause of Occurrence:

The cause of the trippings of the static inverter has not been found. A high speed memory type recorder connected to the inverter input displayed a negative going spike just prior to the inverter tripping. An analysis of this transient is now in progress.

Analysis of Occurrence:

At the time of the inverter tripping, all other Unit 2 Emergency Core Cooling Systems were operable. Due to this and the short time that the inverter was tripped, this occurrence has minimal safety significance.

Corrective Action:

l Philadelphia Electric Company, Engineering and Research De-partment, in conjunction with General Electrf c Company, has designed an input filter network to reduce or eliminate the input spikes causing

the inverter trippings. The modification is presently in the last stages of review at General Electric. The modification instructions, with the parts necessary for implementation are expected on site during the first

week of September. The modification will be implemented as soon as possible.

Additionally,- the Unit 2 inverters will be modified for auto-matic trip reset as soon as the parts are available. The Unit 3 in-verters already have this feature.

Failure Data:

Four other trippings of the RCIC inverter have been reported as A0-50-277-74-14, A0-50-277-74-20, A0-50-277-74-37 and A0-50-277-74-39 Very truly yours, M h bL-R. D. Meyer General Superintendent Generation Division cc: J. P. O'Reilly Director, Region i United States Atomic Energy Commission 631 Park Avenue King of Prussia, PA 19406 fs *

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