ML20059H793
| ML20059H793 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 11/02/1993 |
| From: | Denton R BALTIMORE GAS & ELECTRIC CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20059H796 | List: |
| References | |
| NUDOCS 9311100217 | |
| Download: ML20059H793 (8) | |
Text
E BALTIMORE t.
GAS AND g ELECTRIC 1650 CALVERT CLIFFS PARKWAY. LUSBY, MARYLAND 20657-4702 ROBERT C. DENTON VICE PRESIDENT NUCLEAR cNE30Y (480) 260 USE U. S. Nuclear Regulatory Commission ,
Washington,DC 20555 ATTENTION: Document Control Desk
SUBJECT:
Calvert Cliffs Nuclear Power Plant Unit Nos.1 & 2; Docket Nos. 50-317 & 50-318 License Amendment Reouest: Emercency Diesel Generator Testine Pursuant to 10 CFR 50.90, the Baltimore Gas and Electric Company (BG&E) hereby requests an Amendment to Operating License Nos. DPR-53 and DPR-69 by the incorporation of the changes described below into the Technical Specifications for Calvert Cliffs Unit Nos. I and 2.
DESCRIPTION The proposed amendment would revise the Technical Specifications for both Units 1 and 2 regarding surveillances associated with the Emergency Diesel Generators (EDGs).
BACKGROUND There are three 4160 volt,3-phase,60 cycle EDGs in use at Calvert Cliffs. The EDGs are designed to provide reliable in-plant AC power to facilitate safe plant shutdown in the event of a loss of offsite power. Each EDG is physically separated and electrically isolated from the others and has a continuous rating of 2500 kW.
Normally, one EDG is dedicated to each unit and supplies power to one of the unit's 4160 volt >
Engineered Safety Features (ESF) busses. The third " swing" EDG is capable of being aligned to either unit to supply power to the second ESF bus. Should a loss of power to an ESF bus be sensed by the loss of voltage instrumentation, the EDGs will start and a sequencer will load appropriate accident or shutdown equipment on to the EDG. If accident conditions are present concurrent with the loss of voltage, the loss-of-coolant-incident sequencer actuates to load ESF componcnts.
The EDGs are maintained in reliable condition by performing monthly surveillance testing, minimizing the number of performance-degrading starts, periodically performing a complete maintenance inspection, and by maintaining a comprehensive Preventive Maintenance Program. Te further enhance EDG performance and reliability, several changes to the EDG surveillances are being requested. '
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Document Control Desk November 2,1993 Page.2 A. As required by Technical Specification 4.8.1.1.2.d.1, every 18 months the EDGs are inspected in accordance with the vendor's recommendations. Additionally, testing is conducted to i
verify start logic and performance. The frequency for this specification is consistent with the former refueling interval for Calvert Cliffs. However, the current refueling interval at Calvert Cliffs is 24 months. As a result, a special surveillance outage is sometimes required prior to the end of the fuel cycle. This special outage forces the plant through additional shutdown and startup tra isients and negatively impacts the economic benefits gained from the 24. month fuel cycle. To schedule surveillances and testing consistent with the refueling interval, an extension of the surveillance interval to the current refueling inteaval is desired.
B. EDG surveillances are performed on monthly, semi-annual, and 18-month intervals to ensure EDG operability. As part of the monthly testing, the EDG is started and verified to reach the required voltage, frequency, and speed.
The frequency listed in Technical Specification 4.8.1.1.2.a.4 is 60 i 1.2 IIz. Frequency and speed are related and the proper speed will be achieved if the frequency is verified to be within the specific range. Therefore, we believe the requirement to measure engine speed can be removed from this surveillance.
C. The surveillances for testing the EDGs in Modes 5 and 6 are identical to the surveillances required in Modes 1-4 (with the exception of Surveillance 4.8.1.1.2.a.5). These surveillances include verifying the loss-of-coolant incident sequencer is operable by starting the EDG and loading it with the accident loads. Sequencer initiation occurs when a loss of offsite power is sensed by undervoltage instrumentation and a safety injection actuation system actuation signal is present. This undervoltage instrumentation is only required to be operabic in Modes 1-3, and most of the safety injection actuation system loads are only required in Modes 1-4. The sequencer, with required loads, is verified to be operable prior to exiting Mode 5 and entering Mode 4. To climinate unnecessary testing. it is proposed to modify Technical Specification 4.8.1.2 to exclude sequencer testing in Modes 5 and 6.
D. In the spring of 1992, an Electrical Distribution Safety System Functional Inspection was performed at Calvert Cliffs. Due to issues raised in the inspection regarding the ability of the :
EDGs to provide adequate electrical capacity for accident loads, additional calculations were l performed by our design organization to determine the actual load margin. It was !
determined the margin has decreased to a minimal value. In response to this concern we are i upgrading the EDGs to increase their capacities. Each of the three diesels will be upgraded during separate refueling outages. l l
Technical Specification 4.8.1.1.2.d.5 verifies the auto-ccmnected loads to each EDG do not exceed the current 2(XX) hour rating of 2700 kW. To support the EDG upgrades, and the associated capacity increases, it is desired to modify this specification by removing the reference to 2700 kW and to simply state the 2000 hour0.0231 days <br />0.556 hours <br />0.00331 weeks <br />7.61e-4 months <br /> rating of the specific EDG being tested is not to be exceeded.
E. Emergency Diesel Generator reliability is maintained at Calvert Cliffs with a comprehensive monitoring and test program. Currently, Technical Specification 4.8.1.1.2.a.4 verifies the EDGs are pre-lubricated and slow started once per 31 days. Non-pre-lubricated fast starts are conducted every 184 days and 18 months per Technical Specification 4.8.1.1.2.e and 4.8.1.1.2.d.3.b.
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Document Control Desk '
November 2,1993 Page 3 ~t Reliability of the EDGs is enhanced by pre-lubrication pnor to every planned start of the EDG. Pre-lubrication minimizes wear on the EDG and is recommended by the vendor. -i Therefore, we propose to modify Technical Specifications 4.8.1.1.2.c and 4.8.1.1.2.d.3.b to '
eliminate non-pre-lubricated starts and allow all planned EDG starts to be pre-lubricated in ,
accordance with vendor recommendations.
REOUESTED CIIANGES f
Change various Technical Specifications associated with EDG testing, including: l A. Specification 4.8.1.1.2.d of the Unit 1 and Unit 2 Technical Specifications as shown on the marked-up pages attached to this transmittal. This change to the Technical Specifications >
extends the inteaval from 18 months to the current refueling interval of 24 months for the ,
surveillances listed under 4.8.1.1.2.d. The provisions of Specification 4.0.2 would continue to :
apply to this specification. ;
B. Specification 4.8.1.1.2.a.4 as shown on the marked-up pages attached to this transmittal. This change to the Technical Specifications removes the requirement to verify a specific EDG speed of 900 rpm. ;
C. Specification 4.8.1.2 as shown on the marked-up pages attached to this transmittal. This change adds the EDG surveillances dealing with sequencer testing to the list of those -
surveillances that can be exempted in Modes 5 and 6. l D. Specification 4.8.1.1.2.d.5 as shown on the marked-up pages attached to this transmittal. This change eliminates the specific numerical reference (2700 kW) associated with the 2000 hour0.0231 days <br />0.556 hours <br />0.00331 weeks <br />7.61e-4 months <br /> _ ;
rating of the EDG being tested. l E. Specifications 4.8.1.1.2.c and 4.8.1.1.2.d.3.b as shown on the marked-up pages attached to this transmittal. This change will allow the EDGs to be pre-lubricated prior to being started, in accordance with vendor recommendations.
SAFETY ANALYSIS t
The safety function of the EDGs is to provide electrical power for the operation of ESF and safe ,
shutdown equipment during and following the shutdown of the unit when the offsite normal Class 1E l power supply is not available.
The EDGs must have the capability to (1) start and accelerate a number oflarge motor loads in rapid succession and (2) supply power continuously to the equipment needed to maintain the plant in a safe condition if an extended loss of offsite power occurs.
The following proposed changes will not affect the above required capabilities of the EDGs. 1 A. Technical Specification 4.8.1.1.2.d requires we that periodically perform a major maintenance inspection on the EDGs. Additionally, other tests involving the EDGs' ability to start and -
load under simulated accident conditions are conducted at this time. The proposed change ' !
extends the surveillance interval for these tests and inspections from 18 months to the current refueling interval of 24 months.
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Document ControlDesk November 2,1993 Page 4 The major maintenance inspection involves all major EDG components and is performed in accordance with procedures prepared in conjunction with the vendor's recommendations.
Examples of components inspected include the bearings, injection nozzles, timing chain, vertical drive assembly, exhaust manifold, crankshaft, and blower. Inspection results to date indicate there is very little wear on these components; repetitive repair or replacement of parts has not been required, and minimal signs of degradation have been observed that can be associated with the duration of the surveillance interval.
Supporting the maintenance inspection is a comprehensive preventive and predictive maintenance program that detects and prevents EDG problems. This program involves inspections, collection of oil samples, and analysis of operational data. Collected information is used to determine the overall condition of the diesel to ensure a high level of performance is maintained. If program results indicate a degrading trend or declining performance, corrective action is taken to ensure operability and reliability. ,
Performance and reliability has been improved through a concentrated effort to reduce EDG fast cold starts. In response to Generic Letter (GL) 84-15; " Proposed Staff Actions to-
- Implement and Maintain Diesel Generator Reliability," Calvert Cliffs implemented-recommendations that reduced the average starts for each diesel per year from approximately 100 to 43. Over the past four quarters, EDG reliability as measured by INPO, has been 100 E F
Additionally we have conferred with the vendor, Fairbanks Morse, on this issue. We have evaluated their recommendations and have decided to temporarily implement a mid-cycle EDG maintenance inspection. The inspection will be scheduled for periods in which the EDG is expected to be out of service for other preventive maintenance thus EDG availability should not be affected. This 1-2 day inspection will cover many of the same components inspected during the major maintenance inspection, such as the main bearings, fuel linkage, blower, and vertical drive. Results from this inspection will be reviewed, along with other surveillance and preventive maintenance data to ensure EDG performance and availability '
remains high. We believe the major maintenance inspection conducted during refueling outages, coupled with the mid-cycle maintenance inspection, will provide sufficient ,
opportunity to detect any EDG degradation. Depending on inspection results, the mid-cycle - -
inspection may be discontinued in the future. in summary, we believe an extension of the interval between inspections from 18 months to 24 months will not adversely impact EDG reliability.
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In atm.Jon to the major maintenance inspection, EDG tests are performed, including the EDGr' ability to start and load ESF components under simulated accident conditions, every 18 months. There is no evidence to suggest time dependent problems are associated with these tests or that extending the interval for these tests would reduce EDG reliability or performance.
Reliability statistics and results from the 18-month EDG maintenance inspections and tests ;
demonstrate the EDGs have not been subjected to significant wear and tear. The EDGs have ,
been found to be in excellent condition after 18-months and the surveillance results indicate '
similar conditions would be observed for longer surveillance intervals. Therefore, an increase in the surveillance interval from 18 months to the current refueling interval of 24 months is ,
warranted.
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Document Control Desk i November 2,1993 ,
Page5 B. Technical Specification 4.8.1.1.2.a.4 requires the EDG starts and accelerates to a speed of a ,
least 900 rpm with a generator voltage and frequency of 4160 + 420 volts and 60 + 1.2 Hz, i respectively. This start, conducted every 31 days, is a pre-lubricated start. After receising a !
start signal, the EDG speed is accelerated steadily to approximately 945 rpm. During the start, the field is manually flashed and fregoency and voltage are then verified after the engine stabilizes. At this point in the surveillance, speed may actually dip below 900 rpm when h wency is slightly below 60 Hz. Since generator frequency and engine speed are !
direch : . t, these surveillance parameters are redundant. Frequency and voltage are the ;
critical pa. ters for EDG performance that must be verified in this particular surveillance, not acceleution and speed. Therefore, we believe the requirement to measure engine speed !
can be dropped from this specification. !
l This position is consistent with guidance on EDG testing provided in Regulatory Guide 1.9, ;
Revision 3, and with NUREG-1432. 1 C. An EDG is required during shutdown and refueling to ensure adequate AC electrical power is available to mitigate postulated events such as a fuel handling incident or loss of shutdown cooling. Due to the reduced pressure and temperature conditions of the reactor coolant ;
system during shutdown conditions, these events develop more slowly and the results are less !
severe than the events which occur at full power. Thus, additional time is available for the i operator to evaluate plant conditions and respond by manually operating the engineered 1 safety feature components as required to successfully mitigate the consequences of the event. I Technical Specification 4.8.1.2 ensures various EDG surveillances are performed in Modes 5 l and 6. These surveillances are identical to those performed in Modes 1-4 (with the exception of Surveillance 4.8.1.1.2.a.5). Surveillances 4.8.1.1.2.a.7,4.8.1.1.2.d.3, and 4.8.1.1.2.d.5 verify the EDG's automatic load sequencer is operable and performs properly. The load sequencer ,
must be operable in Modes 1-4 to properly load accident equipment onto the diesel in the -i event of an ESF actuation with a loss of 4 kv offsite power. Sequencer initiation requires ,
input from 4 kv bus undervoltage instrumentation. In accordance with the Technical Specifications, this undervoltage instrumentation is only required to be operable in !
Modes 1-3 and most of the equipment started by the sequencer is only required to be i operable ix Modes 14 This is consistent with the Updated Final Safety Analysis Report ;
(UFSAR) which only assumes accident laads in the operating modes. As part of the testing .
required prior to entering Mode 4 from Mode 5, the automatic loading features are required t to be operable along with ESF equipment. Sequencer testing in Modes 5 and 6 serves no ;
safety function, thus, this specification should be modified.
D. The EDGs at Calvert Cliffs have rated capacities that ensure each EDG is capable of l supplying power to accident loads over extended periods of time. The margin between EDG l capacity and the required accident loads has decreased over the years due to the addition of new accident loads through plant modifications. Although this decrease in margin does not represent a decline in the ability of the EDG to currently perform its safety function, we desire to restore the margin of safety. To improve this margin, each EDG will be upgraded ;
during future outages to increase its capacity. !
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i Document Control Desk ' i November 2,1993 j Page 6 l l
Currently, we verify every 18 months the auto-connected loads powered by the EDG do not l exceed the machine's 2000 hour0.0231 days <br />0.556 hours <br />0.00331 weeks <br />7.61e-4 months <br /> capacity. The upgrades to the EDGs will increase the 2000 hour0.0231 days <br />0.556 hours <br />0.00331 weeks <br />7.61e-4 months <br /> capacity from 2700 kW to approximately 3300 kW. The requested change will ,
remove the reference to the numerical value of the 2000 hour0.0231 days <br />0.556 hours <br />0.00331 weeks <br />7.61e-4 months <br /> capacity, but will continue to ensure the 2000 hour0.0231 days <br />0.556 hours <br />0.00331 weeks <br />7.61e-4 months <br /> capacity of the machine being tested is not exceeded. The intent of this surveillance is not affected by this proposed change.
E. Generic Ixtter 84-15 was issued to improve EDG reliability. The letter acknowledged the potential for inducing undue wear and stress on EDGs through cold fast starts. It was also recognized that manufacturer recommended preparatory actions such as pre-lubrication of all moving parts would help to reduce engine wear, extend life, and improve availability.
- Pre-lubrication eliminates the delay during the starting sequence of supplying oil to all moving parts as the engine-driven tube oil pump comes up to speed and rills voids in the ;
system. Pre-lubrication significantly reduces wear and stress on the EDGs by reducing metal i to metal contact on EDG bearings during the starting sequence. A review of past EDG start i times concluded there was no significant difference in start time between pre-lubricated and non-pre-lubricated engines.
Allowing pre-lubrication for all planned starts is explicit recognition that the periodic occurrence of unplanned starts from loss of power situations or safety injection actuation -
system actuations are sufficient to demonstrate that an EDG will perform adequately during starts which are not preceded by pre-lubrication.
The conclusion that the advantages of pre-lubrication outweigh the advantages of routine verification that an EDO will start successfully without pre-lubrication are documented in Nuclear Regulatory Commission Safety Evaluations for North Anna Power Station-(April 25,1985), Limerick Generating Station (September 28, 1989), and Peach Bottom Atomic Power Station (March 25,1993). ,
DETERMINATION OF SIGNIFICANT IIAZARDS i The proposed change has been evaluated against the standards in 10 CFR 50.92 and has been determined to not involve a significant hazards consideration, in that operation of the facility in accordance with the proposed amendments:
- 1. Would not involve a significant increase in the probability or consequences of an accident 1 previouslyevaluated. l The Calvert Cliffs Emergency Diesel Generators (EDGs) are used to provide electrical power for the operation of Engineered Safety Features (ESF) and safe shutdown equipment for events involving a loss of offsite power. Should a loss of power be sensed on one of the 4160 volt ESF busses, the EDGs will automatically start and power equipment needed to-safely shut the ~ Unit down. If an accident condition is present, the EDG will start, but will only supply power to the ESF busses if offsite power is lost.
The proposed changes will modify several Technical Specification Surveillances associated ,
with testing of the EDGs.
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Document Control Desk November 2,1993 ;
Page.7 Technical Specification 4.8.1.1.2.d verifies the overall condition of the EDG is acceptable. A major maintenance inspection and several tests invohing starting and loading the EDG are pedormed every 18 months (old refueling interval) in accordance with the surveillance. An i evaluation was conducted to determine if the surveillance interval could be extended from :
18 months to 24 months (current refueling interval). The evaluation concluded there were no problems attributed to time dependence. Extending the interval to 24 months will ,
eliminate the need for a special outage after 18 months, thus eliminating the possibility of ;
encountering plant transients associated with a plant shutdown and startup. Extending the t surveillance interval to 24 months will not significantly increase the probability of the EDG failing to operate as assumed in previously evaluated accidents.
Additionally the EDGs are not initiators to any previously evaluated accident. Therefore, extending the surveillance interval will not increase the consequences of an accident i previously identified. .
Two of the requested surveillance changes remove specific values and do not alter the intent of the surveillances. Technical Specification 4.8.1.1.2.a.4 verifies the EDG reaches 900 rpm ,
rated speed after being started. Speed and frequency are directly related and the critical parameters that should be monitored closely are frequency and voltage. Removal of the specific value for speed will have no effect on surveillance results. Technical ;
Specification 4.8.1.1.2.d.5 verifies the auto-connected accident loads powered by the EDG do l not exceed the EDGs' 2000 hour0.0231 days <br />0.556 hours <br />0.00331 weeks <br />7.61e-4 months <br /> capacity rating. Modifications to increase the EDGs' capacity will be performed in future outages. To reflect this capacity change, the current value of 2700 kW listed in the Technical Specification should be removed. The actual ;
surveillance steps and intent will remain unchanged. Therefore, these changes would have '
no effect on the probability or consequences of an accident previously evaluated.
The Technical Specifications require two EDGs to be operable in Modes 1-4, and one EDG - ,
in Modes 5 and 6. The EDG surveillances performed in Modes 5 and 6 are identical to those performed in Modes 1-4, yet plant conditions are quite different. The instrumentation that detects a loss of voltage on the 4160 volt busses is not required in Modes 5 and 6 and much of 4 the ESF equipment is not required to be operable. The proposed change would modify i Technical Specification 4.8.1.2 to reflect the status of plant conditions and equipment when l the unit is shutdown. The EDG loss-of-coolant incident sequencer which is designed to load .
ESF and equipment needed to safely shutdown the plant do not need to be tested when the ;
unit is already shutdown. The undervoltage instrumentation signals required to initiate sequencer action are not credited in the Updated Final Safety Analysis Report (UFSAR) for events which occur during shutdown modes. Therefore, eliminating sequencer testing for i operability in the shutdown modes will have no effect on the probability or consequences of - j accidents previously evaluated. ,
Emergency Diesel Generator reliability and availability will be maintained if wear and stress ;
are reduced when the EDGs are started. Proper warm-up and pre-lubrication techniques, as j recommended by the vendor, will help minimize the potential for degradation. Reliable -
EDG starts due to actual losses of power on 4160 volt busses prove their capability to perform their required safety function.
Therefore, the above proposed changes do not involve a significant increase in the probability or consequences of an accident previously evaluated.
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Document Control Desk November 2,1993 l Page 8 )
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- 2. Would not create the possibility of a new or different type of accident from any accident <
previoasly evaluated.
The proposed changes do not represent a significant change in the configuration or l operation of the plant. ,
These changes represent clarifications and improvements to the Technical Specification surveillances only and do not affect assumptions associated with the EDGs in the UFSAR. ;
The changes will modify surveillance requirements such as the verifk.ation of a specific value (900 rpm,2700 kW) and frequency of the surveillance (18 to 24 months, Modes ~5 and 6 testing). The changes will not alter the intent or method in which the surveillance is conducted. l Allowing pre-lubrication for planned fast starts does change the current test method, but will help maintain EDG reliability. ,
Therefore, the proposed changes do not create the possibility of a new or difference type of {
accident from any accident previously evaluated. ;
- 3. Would not im'olve a significant reduction in a margin ofsafety.
The proposed changes do not affect the margin of safety credited to the EDG function. The EDG will continue to provide power to ESF and safe shutdown components as stated in the ';
UFSAR. The availability of the EDGs will not be reduced by these changes and the intent of the surveillances will be preserved.
Therefore, the proposed change does not involve a significant reduction in a margin of safety. .
ENVIRONMENTAL ASSESSMENT -
r The proposed amendment changes requirements with respect to the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 or changes to an inspection or surveillance requirement. We have determined that the proposed amendment involves no significant hazards consideration, and that operation with the proposed amendment would result in no significant change in the types or significant increases in the amounts of any effluents that may be released offsite, and in no significant increase in individual or cumulative occupational radiation .
exposure. Therefore, the proposed amendment is eligible for categorical exclusion as set forth in ?
10 CFR Part 51.22(c)(9). Pursuant to 10 CFR 51.22(b) no environmental impact statement or environmental assessment is needed in connection with the approval of the proposed amendment.
SCIIEDULE This change is requested to be approved and issued by April 1,1994. However, issuance of this amendment is not currently identified as having an impact on outage completion or continued plant operation.
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Document Control Desk November 2,1993.
Page 9 SAFETY COMMITTEE REVIEW These proposed changes to the Technical Specifications and our determination of significant hazards have been reviewed by our Plant Operations and Safety Review Committee and Offsite Safety Review Committee. They have concluded that implementation of these changes will not result in an undue risk to the health and safety of the public.
Very truly yours, N _
STATE OF MARYLAND :
- TO WIT :
COUNTY OF CALVERT : l I hereby certify that on the 2 day or riovem h ,1993, before me, the subscriber, a Notary Public of the State of Maryland in and for C#19ect Cottn+V ,
personally appeared Robert E. Denton, being duly sworn, and states that he is Vice Idresident of the Baltimore Gas and Electric Company, a corporation of the State of Maryland; that he provides the foregoing response for the purposes therein set forth; that the statements made are true and correct to the best of his knowledge, information, and belief; and that he was authorized to provide the response on behalf of said Corporation.
WITNESS my Hand and Notarial Scal: "N Notary Public ,
t My Commission Expires: 8 '
I)fite RED /MDM/mdm/bjd Attachments: (1) Unit 1 Technical Specification Revised Pages 1 (2) Unit 2 Technical Specification Revised Pages cc: D. A. Brune, Esquire J. E. Silberg, Esquire R. A. Capra, NRC D. G. Mcdonald, Jr., NRC T. T. Martin, NRC i P. R. Wilson, NRC ]
R. I. McIzan, DNR i J. H. Walter, PSC )
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