ML20113G432

Application for Amends to Licenses NPF-35 & NPF-52,revising Breaker Coordination

ML20113G432
Person / Time
Site:	Catawba
Issue date:	09/21/1996
From:	Mccollum W DUKE POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20113G434	List: ML20113G432 ML20113G443
References
NUDOCS 9609270212
Download: ML20113G432 (10)

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• (Juke {bu>er Company 3 , HhuntR % D w ri,18

. Catau ba Nuclear Gencrution ikpartment \' ice hesident

- 4800 ConcordRoad (b03)831-3200 Office nrk, SC29745 (80318313426Ihx

DUKEPOWER September 21, 1996 U.S. Nuclear Regulatory Commission Attention

Document Control Desk Washington, D.C. 20555

Subject:

Catawba Nuclear Station, Units 1 and 2 Dockets Nos. 50-413 and 50-414 Request for Facility Operating License Amendment Breaker Coordination Pursuant to 10CFR 50.90, Duke Power Company hereby requests an amendment to its Facility Operating License Nos. NPF-35 and NPF-52 for Catawba Nuclear Station, Units 1 and 2, respectively. Specifically, Duke Power requests NRC review and approval of the proposed UFSAR changes related to breaker coordination since the NRC staff has determined that these changes involve an Unreviewed Safety Question (US0).

Attachment 1 contains a description of the changes, safety analysis, and the determination of no significant hazards. ,

Attachment 2 contains marked-up UFSAR pages depicting the changes.

It is requested that this amendment be issued in a timely ,

manner to support the current startup schedule of Unit 1 j since the NRC has taken the position that, with the existing USQ, a license amendment must be obtained prior to operating Unit 1. Unit 1 is currently in Mode 5 with the schedule for startup as follows:

Enter Mode 4 September 22, 1996 @ 1500 Enter Mode 3 September 22, 1996 @ 2300 Enter Mode 2 September 28, 1996 @ 2200 Enter Mode 1 September 30, 1996 @ 0600 The need for the requested license amendment was first identified to Duke Power Company in a letter from Herbert N.

Berkow, NRC/ONRR to William R. McCollum, Duke Power Company, dated September 17, 1996. Duke Power had been working with l

the NRC staff to resolve this issue under the provisions of 10CFR 50.59 as a deviation to the USFAR until receipt of the 9609270212 960921 x I PDR ADOCK 05000413 ALOf i P PDRes w on es,nw l

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Document Control Desk Page 2 September 21, 1996 September 17, 1996 letter. This letter was the first notification that the breaker coordination issue had been identified as involving an USQ.

Any delay in approval of this amendment request would result 1 in the. prevention of a resumption of operation for Catawba l Unit 1 and subsequent increase in power output up to the I unit's licensed power level. Additionally, this situation would also apply to Catawba Unit 2 should it trip or have a forced outage.

This proposed change to the Facility Operating License has been evaluated and has been determined to involve no significant hazards considerations. This proposed change to the Facility Operating License and the determination of no significant. hazards have been reviewed by our Plant Operational Review Committee (PORC) and the Nuclear Safety Review Board (NSRB). It has been concluded that implementation of these changes will not result in an undue risk to the health and safety of the public. In addition, a copy of this amendment request and - no significant hazards consideration determination have been provided to the appropriate South Carolina state official.

Should you have any questions regarding this matter, please contact Mike Kitlan at (803)831-3205.

Very truly yours, W.R.- McCollum, Jr Attachments xc (with attachments):

S.D. Ebneter, Regional Administrator, Region II j R.J. Freudenberger, Senior Resident Inspector l

P.S. Tam, Senior Project Manager, ONRR j i

Max Batavia, Chief, Bureau of Radiological Health, SC  !

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i Document Control Desk Page 3 September 21, 1996 W. R. McCollum, Jr., being duly. sworn, states.that he is Site Vice-President, Catawba Nuclear Station, Duke Power Company; i

that he is authorized on the part of said' company to sign'and

! file with the U.S. Nuclear Regulatory Commission .these

! revisions to the Catawba Nuclear Station. License Nos. NPF-35 l and NPF-52; 'and that all statements' and matters set forth l therein are true and correct to the best of his knowledge..

[

W. R. McCollum, Jr., S Vice-President

' Catawba Nuclear Stat l

Subscribed and sworn to before me this 21st day of September, 1996

- %uo>eul nafA

Notary Public~ ,

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.My commission expires:

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ATTAC M M 1 l l

l DESCRIPTION OF CHANGE l l

Replace UFSAR section 8.3.2.2.4 with the following. j "The design of Class 1E DC power systems complies with the j requirements of IEEE 308-1974 as augmented by Regulatory -i Guide 1.32 with the following clarification:

l In general, protective devices on the 125 VDC Vital Instrumentation and Control Power System (EPL) are selected i and set so that a minimal amount of equipment is isolated )

from the system for adverse conditions such as a fault. ,

Protective devices protect cable and equipment. In the case l of DC distribution system breakers that may not fully coordinate, the resulting amount of equipment isolation is 1 acceptable, such that there is no impact on the UFSAR

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Chapter 15 safety analyses and redundant equipment is not i affected.

The Class 1E batteries are given a service' test at an interval not to exceed 18 months. Additionally, the Class 1E battery performance and acceptance tests comply with Section 5 of IEEE 450-1975 and/or section 6 of IEEE 450-1980."

Revise the indicated portions of UFSAR section 8.3.1.1.2.2 as follows:

"In general, protective devices on the 600 VAC Essential Auxiliary Power System (EPE) are selected and set so that a minimal amount of equipment is isolated from the system for adverse conditions such as a fault. Protective devices protect cable and equipment. In the case of essential motor control center equipment, incoming breakers may not fully coordinate with motor control center load breakers.

However, the resulting amount of equipment isolation is acceptable, such that there is no impact on the UFSAR ]

Chapter-15 safety analyses and redundant equipment is not affected. The load center breakers are set to protect the cable feeding the essential motor control centers and ,

coordinate with the breakers that feed motor control center j loads. The relays on the essential load center transformer i feeders are set to protect the transformers and coordinate l with the load center breakers."

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1 Revise Table 8-8 (Page 5 of 5) Item 17 as follows:

Under Safety Significance / Comments, delete existing paragraph and replace with the following:

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" Interlocked armor cable faults are unlikely; however, some i faults beyond the motor control center feeder breaker may i trip the motor control center incoming breaker also. The I loads supplied by the affected motor control center are lost, but the redundant loads of the other train remain i available."

Revise Table 8-10 (Page 1 of 3) Item 1 as follows:  !

Under Safety Significance / Comments for Internal battery charger fault, delete existing paragraph and replace with the following:

"If the battery charger output breaker does not clear the fault the battery breaker may trip also. Power is lost to the instrumentation and control channel served by the faulted charger; however, the redundant channels continue to operate unaffected."

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i SAFETY ANALYSIS l The 600V Essential Auxiliary Power System (EPE) (Reference i 4 Section 8.3.1.1.2.2) is provided to supply essential i power through' load centers to 600V essential motor control J centers. 600V essential power is supplied to nuclear ,

safety related auxiliary equipment required during normal  !'

! and accident conditions.

The 125 VDC Vital Instrumentation and Control Power System l (EPL) (Reference 4 Section 8.3.2.1.2.1) is provided to l supply power to nuclear safety related instrumentation and i control loads requiring an uninterrupted power source I during normal and accident conditions.

During the Electrical Distribution System Functional l Inspection (EDSFI), in February 1992, a deviation was cited l (Reference 1) on certain breakers in the 600 VAC Essential l Auxiliary Power System (EPE) and the 125 VDC Vital

, Instrumentation and Control Power System (EPL). The concern

! was that the incoming breakers to the essential 600 VAC l

l motor control centers are not coordinated with the outgoing I breakers from the motor control centers and the 125 VDC l vital instrumentation and control power molded-case breakers in the distribution centers are not coordinated for all faults.

l Engineering conducted a study of alternatives (Reference 3) which provided a resolution to this deviation. The study reviewed what types of faults would be required to cause a miscoordination event and how well these systems are protected against such faults. j The conclusion of the study for both the EPE and EPL Systems was that there was not sufficient justification for major system redesigns and that UFSAR changes would be pursued. l This study was reviewed by the NRC in NRC Inspection Report )

No. 50-413/93-11 and 50-414/93-11 dated April 27, 1993. '

I The justification centered on the following system design features:

• Interlocked armor cable which protects against cable faults leaving only the potential for faults at the load  !

e Conservatism in the cable rating

e The advantage afforded by the ungrounded DC system to j limit the consequence of faults by its design

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• Design of the system and its resulting protective features consistent with industry standards  ;

• Component sizing and getting such that maximum I coordination with existing equipment has been achieved The issue of breaker coordination does not change or affect any assumptions or implications in the bases to applicable l Technical Specifications. Common mode failures that result from a lack of full breaker coordination are avoided by the independence and separation afforded by the system design.  ;

Additionally, a minimal amount of equipment is isolated  !

from the system for adverse conditions such as a fault.  !

There is an acceptable amount of equipment isolation such that there is no impact on the UFSAR Chapter 15 safety analyses.

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DETERMINATION OF NO SIGNIFICANT HAZARDS This proposed change has been evaluated against the standards in 10 CFR 50.92 and has been determined to involve no significant hazards considerations, in.that operation of the facility in accordance with the proposed amendment would not:

1. involve a significant increase in the probability or consequences of an accident previously evaluated; The UFSAR change documents the level of breaker coordination to the current situation with the uncoordinated faults as identified in Reference 7. The EPE system is not identified as an accident initiator should an uncoordinated fault occur. Therefore, the level of breaker coordination in the EPE system would not significantly increase the probability of an accident previously evaluated.

Analyzing the EPL System reveals that an uncoordinated fault involving loss of Distribution Center EDA, Distribution Center EDD, Panelboard EPA or Panelboard EPD will result in a Loss of Normal Feedwater (UFSAR Section 15.2.7) and a Reactor Trip. Review of the Catawba operating experience indicates that no events requiring reactor trip have i occurred due to the level of breaker coordination in the EPL i system. Bus faults are generally considered to be '

infrequent events. Therefore, the probability of an accident previously evaluated in the UFSAR is not significantly increased due to the level of breaker coordination in the EPL system. I Further details of the evaluation of the likelihood of EPL system failures and accident sequences were submitted in l Reference 9.

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The consequences of accidents previouc.ly evaluated are not impacted by this UFSAR change. The UFSAR Chapter 15 accident analysis assumes one complete train of safety related equipment is not available for accident mitigation purposes. For example, the unavailability of one complete train of accident mitigation equipment can result from the failure of a Diesel Generator during' an accident sequence involving a " Loss of Offsite Power" (UFSAR Section 15.2. 6) .  !

The issue of breaker coordination does not change these l assumptions as common mode failures that result from a lack of full breaker coordination are avoided by the independence and separation afforded by the system design. The single

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failure analyses presented in UFSAR Table 8-8, for the "Onsite Power System", and UFSAR Table 8-10, "125 VDC Vital I & C Power System", are not compromised by this UFSAR change.

2. create the possibility of a new or different kind of accident from any previously evaluated; The concern with the existing breaker coordination is the potential tripping of the upstream breaker ~in addition to the breaker closest to the fault. Should this occur, no accidents different than those previously evaluated can occur. Since faults have already been evaluated which can make unavailable as much as one channel of the EPL System (UFSAR Table 8-10) and one entire train of the 4160 volt switchgear (USFAR Table 8-8) with bounding results,..no new accidents are created.

3. involve a significant reduction in a margin of safety.

These UFSAR changes do not affect any of the assumptions or implications in the bases to the Technical Specifications.

The potential tripping of the upstream breaker in addition to the breaker closest to the fault will not result in a cotmon mode failure. The UFSAR Chapter 15 accident analyses is satisfied regardless of whether complete or - incomplete breaker coordination exists. No safety limits, setpoints, or limiting safety system settings are affected by these UFSAR changes, and no changes are required to any Technical Specification. Therefore, the margin of safety defined in the bases to the Technical Specifications is not significantly reduced.

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5 REFERENCES

1. NRC Inspection Report NOS. 50-413/92-01 and 50-414/92-01 dated March 18, 1992.

2. Catawba Reply to a Notice of Violation and Notice of Deviation dated April 16, 1992.

l 3 Catawba Follow-up Report on Evaluation of Options to Resolve Deviation dated' October 30, 1992.

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'4. Catawba Nuclear Station UFSAR, through 1995 update. I i

5 Catawba Nuclear Station Technical Specifications, I through Amendments 149/143.

6. IEEE 308-1974 "IEEE Standard Criteria for Class IE Power Systems for Nuclear Power Generating Stations". l l

7. March-2,-1994 letter from D.L. Rehn to U.S. Nuclear Regulatory Commission summarizing February 7, 1994 I meeting between Duke Power Company and NRR. l l

8. September 14, 1994 letter from R.E. Martin to D.L. j Rehn, Request For Additional Information.

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9. December 29, 1994 Letter from D.L. Rehn to U.S. Nuclear I Regulatory Commission, Electrical Breaker Coordination FSAR Update Evaluation, Attachment 3, CNC-1535.00 0007, Breaker Coordination Evaluation for the 125 VDC Vital I&C Power System (EPL) and the 600 VAC' Essential Auxiliary Power System (EPE).

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