3F0997-26, Notifies NRC of Completion of, Failure Modes & Effects Analysis for Crystal River Unit 3 Class 1E 250/125 Vdc Electrical Distribution Sys

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Notifies NRC of Completion of, Failure Modes & Effects Analysis for Crystal River Unit 3 Class 1E 250/125 Vdc Electrical Distribution Sys
ML20211D181
Person / Time
Site: Crystal River Duke Energy icon.png
Issue date: 09/24/1997
From: Rencheck M
FLORIDA POWER CORP.
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
3F0997-26, 3F997-26, NUDOCS 9709290066
Download: ML20211D181 (4)
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September 24,1997 3F0997 26 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555-0001

Subject:

Summary Report, Failure Modes and Effects Analysis for Crystal River Unit 3 Class 1E 250/125 VDC Electrical Distribution Systems

References:

1. FPC to NRC Letter,3F1096 22, dated October 28,1996
2. NRC to FPC Confirmatory Action Letter, dated March 4,1997
3. LER 97 021-00, dated August 20,1997

Dear Sir:

The purpose of this letter is to notify the NRC of the completion of the Failure Modes and Effects Analysis (FMEA) for Crystal River Unit 3's (CR 3) Class 1E 250/125 VDC (DC) electrical distribution systems, in Reference 1, Florida Power Corporation (FPC) committed to perform a DC FMEA which includod evaluations of system interactions. FPC further committed to complete the DC FMEA review to the extent that FPC was satisfied that significant safety problems had been identified and that such problems were 6Jdressed prior to startup from the current outage.

These commitments were acknowledged by the NRC as startup requirements in Reference 2.

Although an FMEA had been performed for the CR 3 Class 1E electrical distribution systems (including DC) as part of the original plant design, FPC became concerned that the original FMEA may not have fully considered system interactions, including of fects on redundant trains and components. This concern developed because a number of CR 3 design and operating vulnerabilities had been identified on a case by case basis through design and EOP reviews postulating the effects of a loss of DC power.

The DC FME^ is tracked as Restart issue D-07 and Management Corrective Action Program (MCAP ll) ! ' C CC1-1.

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3F0997 26 Page 2 of 3 a

The FMEA was completed by Parsons Power in accordance with the " Class 1E DC Power Distribution System Failure Modes and Effects Analysis Metho<fology" procedure approved by FPC. Framatome Technologies, Inc, provided assistance to Parsons Power. FPC oversight of Parsons Power was provided by a multi-disciplinary FPC team consisting of-representativesfrom Operations, Licensing, Systems Engineering, and Design Engineering.

Potential deficiencies identified by Parsons Power were dispositioned in accordance with FPC's procedure CP-111, " Processing of Precursor Cards for Corrective A? ion Program." (

An independent, third party review was ccmpleted by FPI International to ensure that the DC FMEA was performed correctly and c.ad sufficient scope and level of detail.

The DC FMEA provides a qualitative assessment of the effecta of the loss of DC power

, concurrent with a loss of offsite AC power (LOOP) and a loss of coolant accident (LOCA).

Large break and amall break LOCAs were considered. The DC i f, LEA for the small break LOCA considered the dependencies identified in Technical Specification Change Request Notice 210, submitted June 14,1997. The DC FMEA included the effects of loss of Vital 120 VAC buses, since they are powered from the Class 1 E 250/125 VDC distribution system through inverters.

Tha objective of the DC FMEA was to determine if safety system dependencies or interactions could result in degraded performance at the piant level for mitigation of LOCA/ LOOPS concurrent with a DC failure. The DC FMEA evaluations wore performed for safety systems energized by the Class 1E 250/125 VDC distribution system. These systems are identified in Attachment A. The evaluation of the loss of Vital 120 VAC buses caused by the loss of a Class 1E battery included assessments of the Engineered Safeguards Actuation System (ESAS), Emergency Feedwater integrated Control System (EFIC), Reactor Protection System (RPS), Regulatory Guide 1.97 Category 1 instruments, and miscellaneous Class 1E control components.

Evaluations were first performed at the component level, where component failure was postulated to result from the loss of DC at the first upstream fuse. Higher level failures of feeder breakers and distribution panels were then evaluated. For each higher level failure, the resultant system and plant effects were determined from a synthesis of component level failures. Failures were considered up to and including the failure of each Class 1E battery.

As a result of the DC FMEA, FPC has identified only one reportable issue. In the event of a loss of Class 1E battery "A" during a LOCA/ LOOP, the plant receives an ESAS Train "B" actuation that cannot be bypassed. This would have presented a difficult recovery challenge to the operator following the safety systems' initial responses to the LOCA/ LOOP. This condition has been reported to the NRC in LER 97-021-00, in which FPC committed to i corrective action prior to startup from the current outage. FPC is tracking completion of the I

corrective action as Restart Issue D-07A.

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U. S. Nucle:r R:gul: tory Commission l

,3P0997 26 Page 3 of 3 If you have any questions regarding this letter, please contact Mr. David F. Kunsemiller, .,

J Manager, Nuclear Licensing, at (352) 563 4566.

Sincerely,--

/ b Michael W. Rencheck '

Director, Nuclear Engineering and Projects MWR:wjl Attachment x:: Regional Administrator, Region ll ,

Senior Resident inspector i NRR Project Manager 3

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- U.S. Nucle:r Regulatory Commission - Attachm:nt A JPO997 26- Page 1 of 1

  • t Anschment A List of Systems Evaluated by the Class 1E 250/125 VDC Electrical Distribution Systems' FMEA
1. Control Building Heating, Ventilation, and Air Conditioning
2. Chilled Water System
3. Reactor Building Spray System 4.. . Decay Heat Closed Cycle Cooling Water System
5. Nuclear Services and Decay Heat Seawater System
6. Decay Heat Removal System
7. Rod Control System
8. Makeup and Purification System
9. Retetor Coolant System-
10. Nuc' ear Services Closed Cycle Cooling Water System
11. Engioeered Safeguards Actuation System
12. Emergency Feedwater System
13. Main Feedwater System
14. Main Steam System
15. Class 1E Electrical Distribution System
16. Containment Sampling System
17. Post Accident Sampling System
18. Industrial Cooling System ,
19. Auxiliary Steam System
20. Diesel Fuel System
21. Emergency Diesel Generator

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