3F0997-16, Application for Amend to License DPR-72,revising EDG Protective Relaying Scheme,As Described in FSAR Chapter 8
| ML20210T985 | |
| Person / Time | |
|---|---|
| Site: | Crystal River  |
| Issue date: | 09/12/1997 |
| From: | Cowan J FLORIDA POWER CORP. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| 3F0997-16, 3F997-16, NUDOCS 9709160218 | |
| Download: ML20210T985 (19) | |
Text
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September 12, 1997 3F0997-16 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555-0001 l
Subject:
License Amendment Request Number 219 l
Emergency Diesel Generator Protective Relays - Unreviewed Safety Question l
References:
I
- 1. NRC Special Inspection Report No. 50-302/97-09, dated July 14, 1997 l
l
Dear Sir:
Florida Power Corporation (FPC) hereby submits for NRC review a request for amendment of racility Operating License No. DPR-72 for Crystal River Unit 3 (CR-3) nuclear power plant.
This request for license amendment involves a revision to the Emerg;ency Diesel Generator (EDG) protective relaying scheme at CR-3, as described in the Final Safety Analy::is Report (FSAR)
Chapter 8. FPC has evaluated the proposed modifications pursuant to 10 CFR 50.59 and has determined that these modifications constitute an umeviewed safety question (USQ) based on a resulting increase in the probability of a malfunction of equipment important to safety.
Accordingly, FPC is requesting amendment of the CR-3 license to resolve that USQ.
In Reference 1, the NRC cited an apparent violation that the modifications made to the EDG engine relaying in 1987 constituted an USQ, stating that this was based on the fact that a single failure of any one of the added protective relays for an EDG could result in an inappropriate failure of the EDG, and that this modification increased the probability of failure of the EDGs.
In Reference 2, FPC agreed that the 1987 modifications involved an USQ and stated that additional modifications would be made to the EDG relaying. In that response, FPC committed to submit a request for license amendment t'o resolve the USQ related to the final configuration. hjM The proposed modification will add new protective relays to each EDG generator output breaker to provide additional protection for a potential electrical fault or overpower conditio ofincreased EDG reliability resulting from these modifications outweighs the small increase in the I probability of malfunction of equipment identified in the 10CFR50.59 evaluation performed by FPC. 9709160218 970912 PDR P
ADOCK 05000302 PDR '
ll ll[llhllh)hlhlll CRYSTAL RIVER ENERGY COMPLEX: 1s7so W. Power une street crystai River, Florida 344284704 * (352) 795-4436 A Florida Progress Cornpany
'1 ' U.S. Nuclear Regulatory Commission-1.4 l3F0997 16 -
Page 2 of 3;
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The current schedule for performing.the relay modifications is' to modify the 'B' EDG first and then the 'A' EDO. The 'B' EDO outage is to begin September 20,1997, with completion of the' work projected for October 22,-1997.' The 'A' EDG outage is to begin October 27,1997,' with
^ i completin projected for November 16, 1997. ,
FPC respectfully requests NRC Staff review and approval of the requested license amendment by
- . October 22; 1997, _ Approval by that date is needed to allow FPC to close out the modifications
- to the 'B' EDG with the modified rela'y configuration and to complete the modifications on the 'A'
- EDO.
J Attachment A provides the description of the proposed modifications and the basis for the USQ, the reason for the modifications, and the evaluation of the request. Attachment B provides the
-Determination of No:Significant Hazards Consideration pursuant to' 10 CFR150.92 and the
- Environmental Impact Evaluation. ; Att::chment C contains proposed revisions to the CR-3 FSAR.
No revisions to'the Improved Technical Specifications (ITS) or Bases are proposed as part of this l requested license amendment.
[
l-To facilitate the NRC review of this issue, FPC recommends a meeting be conducted as quickly as possible to explain the proposed modification. FPC requests that the license amendment be
' made effective on issuance with no implementation period.
-If you have any questions regarding this submittal or the. schedule, please contact David F.
Kunsemiller, Manager, Nuclear Licensing, at (352) 563-4566.
Sincerely,,
hbCi 4 John Paul Cowan:
Vice President Nuclear Production-a JPC/rer t j
- xc: ; Regional l Administrator, Region II
- Senior Resident Inspector .
NRR Project Manager.
{ Attachments:
LA.1 Description of Changes; Reason For Request, and Evaluation of Request
- B. .. Determination of No Significant Hazards Pursuant to 10 CFR 50.92 and Envirotunental Impact Evaluation -
C.-. - Proposed Revisions to CR-3 Final Safety Analysis Report w
U.S. Nuclear Rigul: tory Commissioni
.- 3F0997 : Page 3. of 3 -'
STATE OF FLORIDA '
. COUNTY OF CITRUS l
)
E-Johti Paul Cowan states that he is the Vice President, Nuclear Production for Florida Power Corporation; that he is authorized on the part of said company to sign and file with the Nuclear Regulatory Commission the information attached hereto; and that all such statements l
made and matters set forth therein are tnie and correct to the best of his knowledge,- information, and belief.
hlm John Paul Cowan Vice President Nuclear Production Sworn to and subscribed before me this />M day of S M/f/a Ire ,1997,by _
John Paul Cowan.
Signature of Notary Public -
State of Florida USA ANN MCBRIDE I ' Netary Public. State of Floride My comm. Exp. 0ct. 25,1999 Jo [gg /)/ C h , Y g
- comm. No. cc sos 4ss (Print, type, or stamp Commissioned Name of Notary Public)
Personally Produced
-OR-Known - V Identification
U.S. Nuclear Regulatory Commission Attachment A Page 1 of 12 3F0997-16
. 8 i
ATTACllMENT A DESCRIPTION OF CIIANGES, REASON FOR REQUEST, AND EVALUATION OF REQUEST LICENSEE DOCUMENT INVOLNED: Final Safety Analysis Report '
' PORTIONS: Section 8.2.3.1.3, Emergency Diesel Generators DESCRIPTION OF CIIANGES:
A summary dise.mssion of the proposed protective relaying on the emergency diesel generators is added to the FSAR. Included is a discussion of the actions taken by the protective relaying
-if an unacceptable operating condition is detected. The actions discussed include tripping and lock-out of the EDG engine and associated output breaker. The relaying is stated to be single channel and not bypassed during an accident condition.
BACKGROUND Crystal River Unit 3 (CR-3) has two trains of Engineered Safeguards (ES) loads for Design Basis Accident (DBA) mitigation and safe shutdown of the plant. Each train of ES loads is powered from an associated 4160V ES bus. Each 4160V ES bus is normally powered from one of two offsite power circuits from the Crystal River 230 kV Switchyard. Each 4160V Es bus can also be powered from the CR-3 main generator or 500 kV Switchyard. - However, the CR-3 generator is not the normal power source during plant power operations. The 500 kV backfeed can only be utilized when shut down. Each '4160V ES bus can also be supplied from an associated standby Emergency Diesel Generator (EDG). ~ Following a Loss-of-Offsite-Power (LOOP) or degraded voltage condition, each EDG automatically starts and energizes the associated 4160V ES. bus and previously running Block i loads. If a Design Basis Accident is also occurring, the Engineered Safeguards Actuation System (ESAS) will apply the balance of the required ES loads to the 4160V ES bus and EDG by way of block load sequencing circuitry.
In Inspection Report 50-302/97-09, dated July 14,1997, the NRC stated that modifications made
.to the EDG relaying scheme constituted an Unreviewed Safety Question (USQ) and that those modifications should not have been made without NRC review and approval. In the response dated 8/l1/97, FPC agreed that an USQ existed and stated that the issue would be resolved by additional modifications to the EDO relay scheme. FPC stated that the additional modifications
- were expected to also involve a USQ. The following is a description of those changes planned to be made, e
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U.S. Nuclear Regulatory Commission Attachment A Page 2 of 12 3F0997-16 The following figures are provided to facilitate NRC staff review. They are Figure 1, which shows the relaying configuration prior to Modification 80 09-13-01; Figure 2, which shows the relaying configuration after Modification 80-09-13-01; and Figure 3, which shows the relaying configuration aller Modification 97-08-01-01. Figure 4 reflects the information regarding EDO engine protective trips from the current FSAR Figure 8-9 (Revision 14), with some editorial clarifications not related to the proposed EDG relay modifications.
Modification 80-09-13-01 added new relaying to each EDG and rewired some of the existing relaying. The changes were made to add more protection for eaQ EDG in an effort to improve EDG availability after a fault or overpower condition had occurred. Some of the new relaying was added to the EDG engine device-86 lock-out relay. The EDG engine _ device 86 lock-out relay hips the EDG output breaker and prevents its subsequent closure. Tl:e EDG engine device-86 lock-out relay also isolates the fuel to the EDG engine, shutting the engine down.
Modification 97-08-01-01 will install a new device-86 EDG breaker lock-out relay for each EDG.
- l. The device-86 EDG breaker lock-out relay trips and prevents subsequent closure of the EDG output breaker. Modification 97-08-01-01 will return each EDG engine device-86 lock-out relay circuits to the pre-modification 80-09-13-01 configuration by moving the overcurrent relaying from the EDG engine device-86 lock-out relay to the new device 86 EDG breaker lock-out relay.
The changes by Modification 97-08-01-01 will allow the EDG to operate in stand by for fault or overcurrent conditions caused by a 4160V ES bus problem or for a false protective relay actuation.
The changes implemented by Modification 80-09-13-01 and Modification 97-08 01-01 involve adding protective relaying to each EDG and 4160V ES bus, Adding protective relaying to each EDG and 4160V ES bus involves both benefits and negative impacts compared to the pre-modification 80-09-13-01 configuration. The pre-modification 80-09-13-01 configuration had some protective relaying for each EDG. However, this protective relaying did not provide
- adequate protection creating the potential for damaging the EDG ifit was subjected to a fault or overcurrent condition that was the result of a degraded 4160V ES bus. The changes of Modification 80-09-13-01 and Modification 97-08-01-01 will provide more complete protection for each EDG and 4160V ES bus. The modifications have the benefit of preventing damage to the EDG and possibly limiting the damage to the 4160V ES bus. Protecting the EDG and limiting the _ damage to the 4160V ES bus improves the probability of restoring the EDG and 4160V ES bus, thereby reducing the sole dependency on the unaffected EDG and 4160V ES bus.
The modifications have the negative impact of increasing the probability of a spurious relay operation disabling the on-site emergency AC source when a true 4160V ES bus problem does not exist. However, protective relaying is very reliable and spurious operation is rare. In addition, recovering from a spurious protective relay operation is much simpler and quicker than recovering a damaged EDG and 4160V ES bus.
U.S. Nuclear Regulatory Commission Attachment A Page 3 of 12 3F0997-16 DESCRIPTION OF PREVIOUS MODIFICATION i
Modification 80-09-13 01 added new protective relaying to each EDG as described in detail I below (See Figure 2). !
Device-51V AC time overcurrent relavs with voltage restraint. These relays protected the EDG i from damage by tripping the EDG engine device-86 lock-out relay if a fault or prolonged (
overcurrent condition is detected. These relays provide new protection for 4160V ES bus phase to phase and three phase faults and backup protection to the device-87 generator differential relaying for faults in the EDG generator or in the power cables between the generator and EDG !
breaker. The voltage restraint feature of these relays prevents the EDG from tripping during overcurrent excursions resulting from block loading. The device-51V AC time overcurrent relays are self powered from the EDG current transformers (cts) and potential transformers (pts). The device-51V AC time overcurrent relays are arranged with one relay per phase. Each relay trips the EDG engine device-86 lock-out relay (single-channel trip). The device-51V AC time overcurrent relaying is coordinated with the associated 4160V ES bus load breaker device-50/51 l AC instantaneous and time overcurrent ielaying and device-50/51/83 selective / C instantaneous and time overcurrent relaying. The device-51V AC time overcurrent relays ore electro-mechanical induction disk relays.
Device-32 directional nower relay. This relay prevents an EDG overload only when the EDG and 4160V ES bus are paralleled with offsite power sources. This relay sends a trip signal to each of the three bus offsite power source breakers if the EDG is called upon to deliver real power greater than 3498 KW to the 4160V ES bus. An EDG that is paralleled with the offsite power switchyard is considered " inoperable." There is one device-32 directional power relay for each EDG. The device-32 directional power relays are solidstate and require DC power to operate.
Modification 80-09-13-01 wired each of the three previously existing 4160V ES bus offsite power source breaker device-86B lock-out relays to the EDG engine device-86DG lock-out relay. This relaying prevents the EDG from running and attempting to energize the associated 4160V ES bus after the 4160V bus has been de-energized due to an overcurrent or fault condition (sensed by the bus source breaker device-51B or device-51BN AC time overcurrent relays). The 4160V ES bus source breaker device-51B overcurrent relaying is one relay per phase for each of the three bus source breakers. There is one device-51BN AC time overcurrent relay for each of the three bus ~ source breakers. Each device-51BN relay monitors the current imbalance of the three source breaker phases. All of the bus source breaker overcurrent relaying is single channel trip.
The previously existing-86B lock-out relays from each of the three bus offsite power source breakers are located on the rear of the Main Control Board (MCB) and would be isolated upon transfer to the Remote Shutdown Panel (RSP) due to a fire in the Main Control Roc- or Cable Spreading Room. Modification 80-09-13-01 installed additional device-86BI lock-ou: .ays from two of the three 4160V bus offsite power source breakers (230 kV switchyard) device SIB and device-51BN AC time overcurrent relaying. The two new device-86B1 lock-out relays were
. U.S. Nuclear Regulatory Commission Attachment A Page 4 of 12 3F099716 installed on the 4160V ES bus enclosure for use after control was transferred to the Remote Shutdown Panel. The two new device-86B1 lock-out relays are only functional after control is transferred to the Remote Shutdown Panel. The device-86B lock-out relays on the Main Control Board are only functional before control is transferred to the Remote Shutdown Panel. This circuit configuration maintains the function of the 4160V ES bus offsite power source breaker
- device-86B lock-out relay trips to the EDG engine device-86DG lock-out relay for both Main Control Room or Remote Shutdown Panel operation.
Modification 80-09-13-01 wired the previously existing device-64DG generator ground relay to the EDG engine device-86DG lock-out relay. The purpose of the device-64DG generator ground relay was to protect the EDG from a 4160V ES bus ground fault. Prior to Modification 80 09-13 01, the device-64DG generator ground relay only tripped the EDG breaker. Upon detection of a 4160V ES bus ground fault condition, the device-64DG generator ground relay would trip the ElG breaker and then the device-64DG generator ground relay would reset. Next, the device-27 bus undervoltage relaying would re-close the EDG breaker (assuming the EDG had been the sole power source for the 4160V ES bus). If the ground fault condition still existed, then the cycle would repeat itself. Another reason Modification 80-09-13-01 moved the device-64DG generator ground relay to the EDG engine device-86DG lock-out relay was to act as a
- backup for the device-87DG generator differential relaying for a ground fault in the EDG generator or on the power cables between the EDG generator and the EDG breaker. A ground i fault in the EDO generator or on the power cables between the EDG generator and the EDG
[-
breaker requires the EDG generator to be shut down since tripping the breaker will not isolate the ground fault. There is one device-64DG generator ground relay per EDG, DESCRIPTION OF PROPOSED MODIFICATION Modification 97-08-01-01 will install a new EDG breaker device-86B lock-out relay on the 4160V ES bus enclosure (See Figure 3). The modification will also move the device-51V AC time overcurrent relaying with voltage restraint, device-86B/B1 lock-out relaying from each of the three bus offsite power source breakers, and the device-64DG generator ground r: lay from the EDG cngine device-86DG lock-out relay to the new EDG breaker device-86B lock out relay.
The device-51V AC time overcurrent relaying with voltage restraint and the desice-64DG generator ground relay will no longer function as backup protection to the device-87DG generator differential relaying for a ground fault in the EDG generator or on the power cables between the EDG generator and the EDG breaker. This is acceptable since the device-87DG generator differential relaying can be depended upon to protect the EDO and cabling. The zone of protection of the device-64DG generator ground relay will be the same as it was prior to Modification 80-09-13-01.
The device-46DG negative requence relay will be moved from the EDG breaker trip circuit to the new EDG breaker device-86B lock-out relay. The device-46DG negative sequence relay is being connected to the new EDG breaker device-86B lock-out relay to prevent EDG breaker cycling due to an unsymmetrical operating condition. EDG breaker cycling could occur r,ince the device 46DG negative sequence relay will reset after the EDG breaker trips. Next, the I
4
. U.S. Nuclear Regulatory Commission Attachment A
. Page 5 of 12 3F0997-16 device-27 bus undervoltage relaying would re c!ose the EDG breaker (assuming the EDG had been the sole power source for the 4160V ES bus), if the unsymmetrical operating condition still existed (example: open conductor on a large auto-connected load motor), the cycle would repeat.
Repeatedly cycling the EDG and 4160V ES bus loads challenges the integrity of the equipment due to the load starting torques and currents. In this condition, the EDG and 4160V ES bus is not able to perform its design basis function.
If actuated by one of the relays listed above, the new breaker device-86B lock-out relay will trip '
and prevent the closure of the EDG breaker. The EDG breaker device-86B lock-out will also initiate an alarm on the Main Control Board. A power available light will also be located adjacent to the new EDG breaker device-86B lock-out relay to indicate that the lockout circuit has power available and is not actuated. The new EDG breaker device-86B lock-out relay will not automatically shut the EDO engine down.
The two device-86B1 lock-out relays that were installed for Remote Shutdown Panel operation will also be connected to the new EDG breaker device-86B lock-out relay. As before, the two device-86B1 lock out relays are only functional after contrcl is transferred to the- Remote Shutdown Panel. If a Main Control Room fire / Cable Spreading Room fire occurred shorting out h conductors to the device 86B lock out relaying located on the Main Control Board and tripping l the EDG breaker device-86B lock-out relay, an operator verification action to reset the EDG breaker device-86B lock-out relay is required. This is considered acceptable since the new EDG breaker device-86B lock-out relay is located in the 4160V ES Switchgear -Room-with the associated Remote Shutdown Panel transfer switches. The need to check / reset the EDO breaker.
device-86B lock-out will be a planned verification action per AP-990 for a Main Control.
Room / Cable Spreading Room fire. This operator action is not required for mitigation of a Design Basis Accident since a concurrent fire is not postulated.
Modification 97-08-01-01 will not change the operation of the device-32 directional power relayir.g which was installed by Modification 80-09-13-01. Modification 80-09-13-01 did not, and Modification 97-08-01-01 will not, change the engine overspeed switch circuitry, crankcase pressure high circuitry (operational in test mode only), low lube oil pressure switch circuitry (2-out-of-3 logic matrix), or start failure circuitry (bypassed during an ESAS actuation) associated <
with EDG engine shutdown.
The additional current transfonner (CT) and potential transfermer (PT) burden added by the new relaying has been reviewed and is acceptable.
BASIS FOR UNREVIEWED SAFETY OUESTION Pursuant to 10 CFR 50.59 review FPC determined that an unreviewed safety question (USQ) exists based on an ine: ease in'the probability of an accident previously evaluated in the FSAR and a malfunction'of equipment important to safety. This conclusion was based on having added
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new relaying to each onsite emergency AC system which could spuriously actuate, thereby resulting in an increased probability of an EDG failing to energize the associated 4160V ES bus.
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f xU.S. Nuclear Regulitory Commission : Attachment A i : Page 6 of 12 - IF0997-16 1
1 Spurious _ actuation'of the overcurrent relaying for the load carrying 4160V ES 1.us offsite power isource breaker would cause a loss of power on the.4160V ES bus and prevent the EDG from re-4 (energizing the bus.1 Spurious actuation of the _EDG directional power relaying could cause a loss of power on the associated bus requiring the EDO to start ar.d energize the 4160V ES bus.
1
+ /
1
[ 2 REASON FOR REQUEST::
The cumulative benefits of Modification 80-09-13-01 and Modification 97-08-01-01 will be to L - protect each EDO from damage resulting from the EDG attempting to energize a faulted bus or . j
' being subjected to overcurrents for an extended period of time if a fault (or unsymmetrical d
. operating condition) occurred:- whilei tiie EDG was powering. the- 4160V- ES: bus. The modifications may also limit damage to the 4160V ES bus. 'There is no benefit to the EDG '
attempting to energize a faulted or _ degraded.4160V ET bus since the 4160V ES bus will:be L 0 unabic to perform its; design basis function.- Both protecting the EDO and limiting the damage
- to the 4160V ES bus _ increase the probability that the EDG and 4160V-ES bus can be made
', available to supply, emergency power.for long-term accident mitigation The additional relaying _ !
also reduces the probability:that an offsite power. switchyard disturbance will trip-an EDG -
paralleled for testing purposes and cause a loss of power to the associated 4160V ES bus.tThe slight increase in probability that the additional components will cause a malfunction of the EDG
. is outweighed by the 'positive benefits described above.
< EVALUATION _OF REQUEST:
(Protective relaying is used extensively throughout the power industryA Spurious actuation is-considered highly tmlikely. l An electro-inechanical induction disk relay (example: device-51B,L
- 151BN, and 51V) requires a pos.itive force to rotate'a metallic disk and contact against spring pressure to actuate. l Protective =solidstate relays (example: device-32) offer equalLor ' superior reliability, low maintenance, and flexibility;for the power industry protective relaying needs.-
D j evice-86 Block-outrelaysareofaruggedconstructionindarereliable. Conductor-to-conductor H
shorts mimicking the actuation of the protective or auxiliary relaying, open circuits on a current -
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m : transformer; secondary (circuit, short circuitsLon'a potential transformer secondary circuitLor a 4 power supply circuit are all' extremely; low probability occurrences.
7All of the~newi relaying . installed! forL Modification 80-09-13i01 and to be installed by-Modification 97-08-01-01.will be qualified for the application, environment, and will be installed -
~ ~ toLmeet' applicable electricalfdesign criteria including electrical and physical separation and-L10CFR50; Appendix "R." In addition, all components will be procured and-installed to meet iapplicable seismic criteria.
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U.S. Nucl:ar Regulatory Commission Attachment A
!= Page 7 of 12 3F0997-16 CONCLUSIO.N f
j The changes of Modification 80-09-13-01 and Modification 97-08-01-01 involve adding more l protective relsying to each EDG and 4160V ES bus. Adding more protective relaying to each
} EDG and 4160V ES bus involves both benefits and negative impacts compared to the pre-L modification 80-09-13-01 configuration. The pre-modification 80-09-13-01 configuration had
'~ some protective relaying for each EDG. However, this protective re:aying did not provide adequate protection. This created the potential for damaging the EDG ifit was subjected to fault or overcurrent condition. This would have most likely been the result of a degraded 4160V ES bus that was not capable of performing its design basis function. The changes of Modification 80-09 13-01 and Modification 97-08-01-01 will provide more complete protection for each EDG and 4160V ES bus. The modifications have the benefit of reducing the probability of damaging the EDG and limiting the damage to the 4160V ES bus. Protecting the EDG and limiting the damage to the 4160V ES bus during a Design Basis Accident coincident with a Loss-of-Offsite-Power improves the probability of restoring the failed EDO and 4160V ES bus, making them available for long-term accident mitigation. Lt.r.t term accident mitigation would not depend solely on the single unaffected EDG and 4160V ES bus. The modifications have the negative impact ofincreasing the probability of a false or spurious relay operation disabling an EDG when a true 4160V ES bus problem did not exist. However, protective relaying is very reliable and spurious operation is very unlikely. In addition, recovering from a spurious protective relay operation is much simpler and quicker than recovering a damaged EDG and 4160V ES bus. The ,
amount of protective relaying resulting from the two modifications is judged to be appropriate.
Even with the increased probability of a malfunction of equipment due to spurious relay operation, nuclear safety will not be reduced.
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U.S. Nucle:r R:gulatory Commission Attachment A Page 8 of 12 3F0997-16 FIGURES Figure 1: Relaying Prior To hiodification 80-09-13 01 Figure 2: Relaying Post-hiodification 80-09-13-01 Figure 3: Relaying Post-hiodification 97-08 01-01 Figure 4: Emergency Diesel Generator Control The following is a list of the relays used in the proposed fm' al design of the EDG protective relaying. This list is intended as supporting information to aid in the review and understanding of the figures.
Device-25Z: Generator Synchronization Check Relay: Supervises manual EDG breaker closure.
Device-27: 4160V ES Bus Undervoltage Relay: Starts EDG.
l Device-32: Generator Directional Power Relay: Trips bus source breakers.
I Device-40EG: Generator Field Failure Relay: Alarm.
Device-46DG: Generator Negative Sequence Relay: Trips ED : breaker lock-out.
Device-49G: Generator Temperature Relay: Alarm.
Device-51B & SlBN: Bus Source Breakers Overcurrent Relays: Trips bus source breaker and EDG breaker lock-out.
Device-51V: Gene'rator Overcurrent with Voltage Restraint Relays: Trips EDG breaker lock-out.
Device-59D: Generator Voltage Relays: Generator Ready hiatrix (Note 2).
Device-64DF: Generator Field Ground Relay: Alarm. i Device-64DG: Generator Ground Relay: Trips EDG breaker lock-out.
Device-67DG: Reverse Power Relay: Trips EDG breaker.
Device-76DF: Generator Field Overcurrent Relay: Trips EDG breaker and exciter (Note 1).
Device 81D: Generator Frequency Relay: Generator Ready hiatrix (Note 2).
Device-87DG: Generator Differential Relays: Trips EDG engine lock-out.
Note 1: The generator exciter must be manually reset locally at the EDG Control Room.
Note 2: There are three device-59 voltage relays (2 out of 3 logic matrix) and three device-81 frequency relays (2 out of 3 logic matrix) associated with each EDG, These relays are installed as a permissive for EDO breaker closure. There is no trip function associated with these relays.
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w E' Relaying Prior to Modification: 80--09-13-01 lW '
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. .O-Bus Source - ' Bus Scurce - ' Bus Source - - !
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,hGenerator Ground NOTES:
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- -Indicates coil to contact refetion ., - 3O-One ofWee W sh 'e3-h Negative . Sequence MAR 97-08-01-01-- USOD ~>
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- ("mplified) '
8 c' 51 51 51 51 51 51 F-B- BN i B> BN 8 BN - o .-
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' Relay Typicci for each as thre.e hGenerator Ground Bus Source Breckers Negetive Sequence
. Notes:
yp-h Directional Power '
- - Indicetes coil to contact relation y '
e One of three (3) shown g w :2 -
. Qomrcurrent w/voitoge nestrotnt MAR 97-08-01-01.- USOD
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W mo FIGURE 3 ;; :El I
c Relaying Post Modification 97-08-01-01 (Simplified)
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Brecker Brecker Breaker G'
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U . Nuclear Regulatory Commission Attachment B Page 1 of 3 3F0997-16 ATTACHMENT B DETERMINATION OF NO SIGNIFICANT IIAZARDS CONSIDERATION PURSUANT TO 10 CFR 50.92 Florida Power Corporation (FPC) has evaluated the proposed license amendment in accordance with 10 CFR 50.91(a)(1) regarding no significant hazards considerations using the standards in 10 CFR 50.92(c). Based on the evaluation FPC considers that the amendmer.t does not involve a significant hazards consideration. A discussion of these standards, as they relate to this license amendment request, follows:
- 1. Does not involve a significant increase in the probability or consequences of an
' accident previously evaluated.
The EDGs perform a support function for Design Basis Accident mitigation by providing a source of emergency AC electrical power for the Engineered Safeguards loads. For most
(_
' Design Basis Accidents,'a coincident Loss-of-Offsite-Power is postulated to occur and any single random electrical failure is considered credible including complete failure for one EDG to energize the associated 4160V ES bus. The failure of an EDG to energize the associated 4160V ES bus is not a precursor for any postulated Design Basis Accident except Station Blackout'(SBO). The failure of both EDGs concurrent with a Loss-of-Offsite-Power causes a Station Blackout. Therefore, any increase in the probability that an -
EDG will not-energize the associated 4160V ES bus will increase the probability of a Station Blackout.
The new relaying added to each EDG has a small probability of spuriously actuating, resulting in a small increase in the probability of an EDG failing to energize the associated 4160V ES bus. Spurious actuation of the overcurrent relaying for the load carrying 4160V ES bus offsite power source breaker will cause a loss of power on the 4160V ES bus and prevent the EDG from re-energizing the bus. In addition, a spurious actuation of the device-32X directional power auxiliary relay can cause a loss of offsite power for the associated 4160V ESl bus. This spurious actuation also increases the probability of a Station Blackout. The only new system interfaces :e between the EDO and 4160V ES bus systems._ The modified relaying will not directly affect the fuel cladding, the Reactor Coolant System (RCS) pressure boundary, or the containment building.
The increase in the probability of a Station Blackout is negligible. Although EDG availability is a contributor to the risk of Station Blackout, the CP-3 licensing basis asstimes this event without regard to EDG reliability. Therefore, the probability of previously evaluated accidents is not significantly increased. ' The new protective relaying could shorten the duration of an actual Station Blackout if a 4160V ES bus fault or other similar problem was a contributor to the event by limiting the damage to the station power systems.
9 d
+
U.S. Nuclear Regulatory Commission Attachment B Page 2 of 3 3F0997-16 The modified relaying will not increase the consequences of a Station Blackout since both EDGs and offsite power are assumed to be unavailable. The new protective relaying will-not create any new timing or sequencing impact to the ES loads supplied from the 4160V ES bus. The small increase in probability that an EDG will not energize the associated
{
4160V ES bus does not invalidate the Design Basis Accident assumption that one EDG j
successfully energizes the associated 4160V ES bus (single failure proof). Therefore, the conclusions conceming fission product releases in the FSAR will not be changed, l
2.. Does not create the possibility of a new or different kind of accident from any {
- accident previously evaluated. j The modified relaying will not directly affect the fuel cladding, the Reactor Coolant System (RCS) pressure boundary, or the containment building. The modifications only impact the EDGs and 4160V ES buses.
The failure of one of the EDGs to energize the associated 4160V ES bus during a Design Basis Accident is a standard " single failure" for determining the acceptability of an accident mitigation system. A standby EDG and the associated 4160V ES bus are not capable of creating an accident such as a Loss-of-Coolant Accident (LOCA) or Main Steam Line Break (MSLB).
' There is a small increase in the probability that an EDO will not successfully energize the -
- associated 4160V ES bus. However, the Design Basis Accident assumption that one EDG does successfully energize the bus remains valid. Therefore, no new accident involving the -
failure of both EDGs other than a Station Blackout needs to be postulated. -_The proposed modifications to the EDG relaying and the small increase in the probability that an EDG will not energize the associated 4160V ES bus do not introduce any new interfaces or mechanisms that could challenge any fluid system or fission product barrier in a different way than previously evaluated. . Therefore, the modifications cannot create the possibility of an accident of a different type than previously evaluated in the FSAR.
.A
- 3. Does not involve a significant reduction in the margin of safety.
The Bases of the CR-3 technical specifications do_ not identify a " margin of safety" for the EDUs or 4160V ES buses that is applicable to the proposed EDG relaying modifications.
Therefore, the plant response to Design Basis Accidents _was evaluated. _ The accident analysis assumptions remain valid with the existing and proposed changes to the EDG and
- 4160V ES bus protective relaying. Plant response will remain as evaluated in the accident analysis and the calculated primary and secondary pressures and temperatures during
. evaluated accidents will not be increased by the changes. The reliability of each EDG and .
- associated 4160V- ES bus is _ being insignificantly reduced in order to increase the
-4 U.S. Nuclear Regulatory Commission Attachment B Page 3 of 3 3F099716 occurs. A spurious actuation of one of the added relays might cause one EDG to fail to energize one 4160V ES bus but would not result in failure of the other EDG to perform its function. Therefore, the changes do not reduce the margin of safety in the bases for hay j Improved Technical Specification.
l ENVIRONMENTAL IMPACT EVALUATION l
10 CFR 51.22(c)(9) provides criteria for, and identification of, licensing and regulatory actions eligible for categorical exclusion from performing an environmental assessment. A proposed 3 amendment to an operating license for a facility requires no environmental assessment if operation of the facility in accordance with the proposed amendment would not: (1) involve a signifkant hazards consideration, (2) result in a significant change in the types or significant incre:a in the amount of any effluents that may be released offsite, or (3) result in an increase l in inditidual or cumulative occupational radiation exposure. FPC has reviewed this license amendment and concludes that it meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9). Pursuant to 10 CFR St.22(c), no environmental impact statement or environmental assessment needs to be prepared in connection with the issuance of the proposed license amendment. The basis for this determination is as follows:
- 1. The proposed modifications to the EDG protective relaying scheme do not involve significant hazards as discussed in the No Significant Hazards Consideration.
- 2. The proposed modifications to the EDG protective relaying scheme do not result in a significant change in the types or signif%t increase in the amounts of any effluents that may be released offsite. The modifie.1 relaying scheme does not result in an increase in the consequences of previously evaluated accidents. FPC has concluded that the changes do not involve irreversible environmental consequences beyond those already associated with normal operation.
- 3. The proposed modifications to the EDO protective relaying scheme do not result in a significant increase in individual or cumulative occupational radiation exposure. This conclusion is based on the facts that the modified relaying scheme does not result in any increased consequences of accidents previously evaluated and that failure of an EDG is not an initiator of a Design Basis Accident.
o.- .
U.S. Nuclear Rcgulatory Commission ; Attachment C Page 1 of 1 -
3F0997 . .
ATTACHMENT C -
PROPOSED REVISIONS TO CR-3 FINAL SAFETY ANALYSIS REPORT The following is proposed to be added as the last paragraph of FSAR section 8.2.3.1.3, Emercency Diesel Generators Each emergency diesel generator is equipped with protective relaying to prevent or limit damage resulting from an unacceptable operating condition such as a generator or 4160 volt ES bus fault. .Upon detection of an unacceptable operating condition, the emergency diesel generator differential relaying will trip and lock-out the emergency diesel generator engine - U l (reference Figure 8-9) and the associated output breaker. Upon detection of an L unacceptable-operating condition, other protective relaying will trip and lock-out:the-L emergency- diesel generator output breaker (and generator exciter in the case of the generator field overcurrent relaying). The protective trip relaying affecting each emergency diesel generator and its associated breaker is single-channel and not bypassed during an accident condition.
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