ML20198N247

License Change Application ECR 96-01511,revising Setpoints & Limits of Allowable Values for LOP Instrumentation for 4kV Emergency Buses Contained in TS Table 3.3.8.1-1, LOP Instrumentation

ML20198N247
Person / Time
Site:	Peach Bottom
Issue date:	12/24/1998
From:	Geoffrey Edwards PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20198N250	List: ML20198N247 ML20198N253
References
NUDOCS 9901060065
Download: ML20198N247 (10)

Text

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10 CFR 50.90

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lPECOLNUCLEAR

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A Unit of PECO Energy:

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ou sL Wayne. PA 19087 5691 December 24,1998 i

Docket Nos. 50-277 50-278 License Nos. DPR-44

~ DPR-56 1-5 I

U.S. Nuclear Regulatory Commission

. Attn: Document Control Desk -

Washington, DC 20555 l'

Peach Bottom Atomic Power Station, Units 2 and 3 Subjecti License Change Application ECR 96-01511

Dear Sir:

PECO Energy Company (PECO Energy) hereby submits License Change Application ECR 96-01511, in accordance with 10 CFR 50.90, requestin changes to the Peach

Bottom Atomic Power Station (PBAPS), Units 2 and 3 Facility perating Licenses. The l

O proposed changes will revise the setpoints and limits of allowa le values for the Loss of Power (LOP) Instrumentation for the._4kV emergency buses contained in Technical i

Specification (TS) Table 3.3.8.1-1 (" Loss of Power Instrumentation").

~ Attachment 1 to this letter describes the proposed changes and provides justification for the changes including the basis for PECO Energy's determination that the proposed

o changes do not involve a significant hazards consideration. Attachments 2 and 3 provides marked-up TS pages indicating the proposed changes.

PECO Energy requests that, if approved, this amendment to the PBAPS, Units 2 and 3

- TS be implemented in two phases as discussed in Attachment 1. As a part of the first 3hase approval, we request that the " interim" pages contained in Attachment 2 be mplemented within 30 days of approval of this TS change. As a part of the second phase, we request that the'" final" pages contained in Attachment 3 be implemented swithin 90 days of approval of this'TS change. This two-phase change to the TS pages s

i will permit relay setpoint and allowable value modification on a relay by relay basis

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. without the need for a plant shutdown, which would be required if the modifications were l

t performed on all relays at one time. We request that this change be approved by June 30,1999.

.lf you have any questions conceming this matter, please do not hesitate to contact us.

Ve ruly y u i, Z.

A I

darrett D. Edwards Director-Licensing i

Enclosures:

Affidavit, Attachment 1,- Attachment 2, Attachment 3 cc:

= H. J. Miller, Administrator,~ Region I, USNRC

' A. C.' McMurtray, USNRC Senior Resident inspector, PBAPS p $)R.yanati, Commonwealth of Pennsylvania y

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COMMONWEALTH OF PENNSYLVANIA:

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1 COUNTY OF CHESTER J. J. Hagan, being fimt duly sworn, deposes and says:

That he is Vice President of PECO Energy; the Applicant herein; that he has

' read -the attached License Change Application ECR 90-01511, for Peach Bottom Atomic Power Station Licenses DPR-44 and DPR-56, and knows the contents thereof; and that the statements and matters set forth therein are true and correct to the best of his knowledge, information and belief.

Pr sident Subscribed and sworn to before me thisc[fY day of chw[4 1998.

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Notary Public NOTARIAL SEAL W

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I ATTACHMENT 1 2

PEACH BOTTOM ATOMIC POWER STATION UNITS 2 AND 3 Docket Nos. 50-277 50-278 License Nos. DPR-44 DPR-56 4

LICENSE CHANGE APPLICATION ECR 96-01511 S

" Revision of Loss of Power instrumentation Setpoints

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for 4kV Emergency Buses" Supporting information - 7 Pages i

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o Dockst Nos. 50-277 i

j 50-278

' License Nos. DPR-44 DPR-56

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. introduction' 2

PECO. Energy 1 Company, Licensee under Facility Operating Licenses DPR-44 and D_PR-56 for the Peach Bottom Atomic Power Station (PBAPS), Units 2 and 3, requests -

that the Technical Specifications. (TS) contained in Appendix A to the Operating -

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Licenses be amended to revise the Loss of Power instrumentation (degraded voltage 1

relays) allowable values as provided in Table 3.3.8.1-1, Loss of Power-l

' Instrumentation". The marked-up pages indicating the proposed changes are provided '

in Attachments 2 and 3. This License Change Application provides a discussion and description of the proposed changes, a safety assessment, information supporting a l

finding. of No Significant Hazards Consideration, and information supporting an Environmental Assessment.-

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' Discussion and Description of the Proposed Chanaes t

The following are proposed changes to TS Table 3.3.8.1-1 for PBAPS, Units 2 and 3:

1. Loss of Voltage (Function 1) relay: No setpoint changes are involved.

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Degrade' Voltage Low Setting (Function 2) relay: The associated allowable value -

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!i limits are widened for both voltage and time. The current rllowable value for voltage

is 2 2288 volts and $ 2704 volts. The proposed allowable value is 2 2286 volts and 5 2706. volts. The current allowable value for. time is 2.1.6 seconds and 5 2.0 o

. The proposed allowable value for time is 21.5 seconds and 5 2.1 seconds.

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seconds.

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Degraded Voltage High Setting (Function 3) relay: The associated allowable value i

limits are widened for both voltage and time. The curreni allowable value for voltage 4

is 2 3411 volts and 5 3827 volts. The proposed allowable value is 2 3409 volts and 5 3829 volts. The current allowable value for time is 2 27.0 seconds and 5 33.0 seconds. The proposed allowable value for time is 2 23.0 seconds and 5 37.0 seconds.

4. Degraded Voltage - LOCA (Function 4) relay: The relay setpoint is changed from i'

3702 volts (89%) to 3801 volts (91.4%) of rated 4kV Emergency bus voltage. The associated allowable value limits are widened for both voltage and time.

The i

current allowable value for voltage is 2 3691 volts and 5 3713 volts. The proposed q

allowable value is 2 3766 volts and 5 3836 volts. The current allowable value for L

time is~2 9.3 seconds (0.9 seconds intemal plus 8.4 seconds external) and 510.7 seconds (1.1 seconds intemal plus 9.6 seconds external). The proposed allowable

~ value for time is 2 9.2 seconds and 510.8 seconds.

. 5. Degraded Voltage - Non-LOCA (Function 5) relay: The relay setpoint is changed from 4077 volts (98%) to 4151 volts (99.8%) of rated 4kV Emergency bus voltage.

1The associated allowable value limits are widened for both voltage and time. Tha -

current allowable value for voltage is 2 4065 volts and 5 4089 volts. The proposed allowable value is 2'4116 volts and 5 4186 volts. The current allowable value for i time is 2 57.9 seconds (0.9 seconds internal plus 57 seconds external) and 5 64.1 m'

seconds (1.1 second intemal plus 63 seconds external). The proposed allowable value for time is 2 57.8 seconds and 5 64.2 seconds.

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Dockst Nos. 50-277

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6. ' Modifying' all the relays associated with this modification at one time would require a plant shutdown to change the relay settings which would result in undue hardship.

j Rather than enter a plant shutdown, the relay settings associated with modification 96-01511 will be implemented on a relay by relay bas:s. A note is being temporarily added to Table 3.3.8.1-1 to identify that modification 96-01511.is being implemented

. In two phases. In the first phase, the Function 2 and 3 changes will be implemented l

within.30 days from the' approval of the TS change. At the completion of the first phase, the "intorim" Attachment 2-pages;will be implemented which contain the i

temporary Noto (a). During the second phase (not to exceed 90 days from the date.

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of approval of the TS change), the allowable value limits for the Function 4 and 5 relays will be modified on a relay by relay basis to the final allowable value limits contained in Attachments _2 and 3.

As phase two of modification 96-01511. is implemented, the Function 4 and 5 allowable value limits will be changed on a relay

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by relay basis from the values contained in Note (a) to the new allowable value i

. limits. During this implementation, both values are acceptable for the relay settings.

t Upon completion of all the relay setting and allowable value changes, the " final""S pages contained in Attachment 3 will be implemented. This final configuration will be achieved within 90 days of the date of approval of the TS change. The TS pages contained in Attachment 3 contain the " final" pages without Note (a).

l Safety Assessment l

The Loss of Power (LOP) Instrumentation monitors the voltage of the 4kV emergency buses. The rated 4 kV bus voltage is 4160 volts. Offsite power is the preferred source i

of power for the 4kV emergency buses. If the LOP instrumentation detects low voltage

. levels on one offsite source, the 4kV buses are disconnected end transferred to the

. other offsite source, or to theY emergency diesel generators, if the second offsite source is unavailable. The volbge for each 4kV emergency bus is monitored at five

. levels, which can be considered as two different undervoltage functions: one level of I

i loss of voltage and four levels of degraded voltage. The degraded voltage function is

. monitored by four (Functions 2 through 5) undervoltage relays per source, and loss of

- voltage is monitored by one (Function 1) undervoltage relay for each 4kV emergency bus. The combination of the loss of voltage relaying and degraded grid relaying provides protection to the Class 1E distribution system for all credible conditions of

. vo!tage collapse ~or sustained voltage degradation.

The current TS allowable value limits in Table 3.3.8.1-1 for the LOP instrumentation are j

not adequate to implement the precent plant setpoint methodology. In-process testing has identified potential instances where there was a deviation between the actual trip

?setpoints.- and the TS allowable values in Table 3.3.8.1-1.

The existing LOP instrumentation setpoints in TS Table 3.3.8.1-1 were based on the Voltage Regulation j

Study performed in;1989. The proposed relay setpoints are calculated in accordance

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- with the improved Instrument Setpoint Control Program (llSCP) methodology. Since the y

. implementation of thel current TS Table 3.3.8.1-1 LOP instrumentation setpoints, all L

eight Class _1E 500kVA load center transformers have been replaced with 1000kVA load; center transformers.

Further, as part of the system design improvements J

, documented in.the. current licensing and design bases, a third viable offsite source l

1 conforming to the guidance of General Design Criterion 17 of 10 CFR 50, Appendix A, h

has been added. : A significant portion of the non-critical plant loads have been L~

s transferred from the plant auxiliary buses to the third offsite source (3 startup). If less J,

.;than'.three offsite sources are available when a LOCA signal occurs, the non-critical 2:

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Docket Nos.' 50-277 c

50-278 License Noc. DPR-44 DPR ~

t plant loads are shed to support the LOCA loading of one. Unit and the long term shutdown loading of the other Unit (worst case).

I Based ~ on the revised PJM grid load flow analysis, the 2'startup source has been -

determined to be the single limiting offsite source instead of the 343 startup source.

The Plant Electrical Load Study has been updated to incorporate all the load changes j

'. from 1989 through present. Using the updated load. data and the 2 startup offsite

, source, the Voltage Regulation Study has been revised to establish-the proposed voltage setpoints for the LOP Instrumentation (degraded voltage relays) in accordance

'with IISCP methodology.

The proposed LOP instrumentation setpoint changes have been evaluated for their

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imaact on the Class 1E power distribution system's intended design function. The

- ex sting allowable values and the proposed allowable values for Functions 2, 3,4, anc

. 5 have been analyzed, and both values are acceptable for operation. During i

implementation of modification 96-01511 (changing of the relay setpoints), the 4kV l

buses could be in one of the three configurations: a) both sources have relays set at tha existing setpoints, b) one set of source relays with the existing old setpoints and ti e other set with.the proposed revised setpoints, or c) both sources have relays set at the l

proposed revised setpoints. Each of these configurations is acceptable, because the existing. and proposed values satisfy the design limits established in the setpoint calculation and Voltage Regulation Study. The evaluation results are summarized as i

follows:

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1. Loss of Voltage (Function 1) relay: No setpoint changes are involved; therefore, there is no impact on the c! ass 1E distribution system function.

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2. Degraded Voltage Low Setting (Function 2) relay: No change to the vo'tage L

setpoint. The' associated allowable value limits are widened for both voltage and

. time. The relay operates on a repeatable characteristic curve. The proposed wider

' allowable value limits will accommodate the incremental change in relay operation, n

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-depending on variability of the test point selected on the relay's repeatable characteristic curve. The effect of these incremental changes in allowable value limits of voltage and time' on relay operation is minimal, and it is bounded by the assumptions of the current accident analyses. The overall impact on the required

. relay function is minimal, and there will be no impact on the Class 1E power distribution system to perform its intended design function.

Since the existing allowable values for Function 2 are within the band established by the proposed allowable values, both values are acceptable for operation during the implementation of modification 96-01511.

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3. : Degraded 3 Voltage i-ligh Setting (Function 3) relay: No change to th9 voltage i

i setpoint. The associated allowable value limits are widened for both voltage and

'. time. The relay operates on a repeatable characteristic curve.- The proposed wider

allowable value limits will accommodate the incremental change in relay operation,

depending onJ variability of the~ test point.' selected on the relay's repeatable charactenstic~ curve. The effect of these incremental changes in allowable value i

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nits of voltage and time on relay operation is minimal, and it is. bounded by, ired the assumptions of the current accident analyses. The overall impact on the requ relay function is: minimal, and there:will be no' impact on the Clasi 1E power 1

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Docket Nos. 50-277-

'50-278 j

License Nos. DPR-44 j

DPR-56 l

distribution system to perform its intended design function.'

~ The allowable time delay range of 27 to 33 seconds is widened to 23 to 37_ seconds.

l Analysis of 36 test data points of the characteristic curve for this relay indicates a.

j standard deviation of 3.12 seconds. Achieving a 95% confidence level for a double

. sided distribution requires 2 standard deviations or 6.24 seconds, which rounds up to 7 seconds.. None of the above 36 analyzed test data points fall outside of the proposed 23 to 37. seconds allowable value range. Tnis represents a 20% time accuracy for this relay which is appropriate based on the test data. The affect of 1

these proposed incremental changes in allowable value limits of voltage and time on relay operation is minimal, and it:is bounded by the assumptions of the current accident analyses.' The overall impact on the required relay function is minimal, and

there will be no impact on the Class 1E power distribution system to perform its intended design function.

1 Since the existing allowable values for Function 3 are within the band established by l

the proposed allowable values, both values are acceptable for operation during the implementation of modification 96-01511.

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'4. Degraded Voltage LOCA (Function 4) relay: The voltage setpoint is changed and the associated allowable value limits are widened for both voltage and time. The i

potential that the higher allowable setpoint limit of 3836V could theoretically allow the transfer of the 4kV emergency bus to the other offsite source or to the diesel

! enerators during 'a DBA has been reviewed.

Based. on the revised Voltage i egulation Study, sufficient margin exists to prevent this event from occurring. The relay time delay settings are such that the relays will detect and respond to an actual sustained degradation of voltage, but will not actuate in response to normal i

operational voltage fluctuations. Based on the identified system design improvements and proper operation of the startup transformer Load Tap Changer

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(LTC), the degraded voltage LOCA relay will reset within its allowable time delay of 9.2 seconds to 10.8 seconds as documented in the Plant Electrical Load Study. The lower allowable setpoint limit of 3766V ensures the minimum required voltage of at the worst case class 1E 480V MCC bus is maintained per the 405V (84.4%) basis. Since the Voltage Regulation Study is performed utilizing the current design name plate load data as documented in the Plant Electrical Load Study, sufficient design margin exists between the actual and proposed setpoint values. Thus, the i

proposed setpoint allowable value limits are conservative.

Since the existing and proposed allowable value limits are within the band l

established by the Voltage Regulation Study, both values are acceptable for operation during the implementation of modification 96-01511. While the voltage setpoints are moved up within the band established by the Voltage Regulation

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- Study, the range of acceptable values still bounds the old and new setpoints.

L 5.' : Degraded Voltage. Non-LOCA (Function 5) relay: The voltage setpoint is changed -

i mI-and the associated allowable values ere widened for both voltage and time. The potential that the higher allowable setpoint limit of 4186V could theoretically allow the _ transfer of the 4kV emergency bus to the other offsite source or to the diesel 1

g generators-during normal non-LOCA. operating conditions has been reviewed.

Based on the' revised Voltage Regulation Study, sufficient margin exists to prevent

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Lthis event from occurring The relay time delay settings are such that the relays will 4

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x Docket Nos. 50-277 50-278 License Nos. DPR-44 DPR-56

' detect and respond to'an actual sustained degradation of voltage, but will not

~ actuate 'in response, to normal operational voltage fluctuations. Based on the Identified system design improvements and proper operation' of-the scartup transformer LTC, the degraded voltage Non-LOCA relay will reset within its allowable time delay of 57.8 seconds to 64.2 seconds. The lower allowable setpoint

' limit of 4116V ensures the minimum recuired voltage of 108V (90%) at the worst case downstream bus is maintained per t1e current design basis. Since the Voltage j

Regulation Study is performed utilizing the name plate load data as documented in l

i the Plant Electrical Load Study, sufficient design margin exists between the actual 1

- and proposed setpoint values..Thus, the proposed setpoint allowable values are.

a conservative.

Since the existing and proposed allowable values are within the band established by.

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= the Voltage Regulation Study, both values are acceptable for operation during the 1

-implementation of modification 96-01511. While the voltage setpoints are moved up 1

Ewithin the band ' established by the Voltage Regulation Study, the range of i

! acceptable values still bounds the old and new setpoints.

5 For Function 4 and 5, the present TS has seaarate entries in Table '3.3.8.1-1 for the intemal and extemal time delay. This submitta proposes to combine these intemal and L

extemal time delays for simplicity. The aggregate time delay is the important parameter and it.is the only time delay that is analyzed. ~ he internal time delay minimizes the relay 1

contact wear and reduces the number of extemal time delay relay _ actuations due to transient voltage-dips. The intemal time delay provides no other output functions.

Therefore, there will be no impact on the Class 1E power distribution system to perform

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its intended design function.

Information Suooortina a Findina of No Sianificant Hazards Consideration I

We have concluded that the proposed changes to the PBAPS, Units 2 and 3 TS do not involve a Significant Hazards Consideration.

In support of this determination, an evaluation of each of the three (3) standards set forth in 10 CFR 50.92 is provided

. below:

'1.

The orooosed changg;s do not involve a sianificant increase in the probability or

. consecuences of an accident oreviousiv evaluated.

L The LOP instrumentation provides safety-related electrical equipment protection.

No new equipment is added to the plant as a result of the proposed changes.

p Separation'of the 4kV emergency buses from the grid is the only potential transient that previously existed based on operation of these relays. Based on the revised Voltage Regulation Study, which incorporates the effects of system improvements and additional conservatisms, there is no significant increase in the probability'of this separation. The relay time delay settings are such that the relays.will detect and respond to an actual sustained degradation of voltage, but will not' actuate ~1n response to normal operational voltage fluctuations.

No accident initiators will be impacted by the proposed setpoint changes. All' safety w

p' systems will be able to perform their safety functions. Accident mitigation is achieved by these relays by onsuring adequate voltage is maintained throughout

= the Class 1E electrical distribution system.

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License Nos. DPR-44 DPR-56 The existing allowable values and the proposed allowable values for Functions 2, 3,4, and 5 have been analyzed and both values are acceptable for operation.

7 During implementation-of modification 96-01511. (changing of the relay setpoints), the 4kV buses could be in one of the three configurations: a) both 1

sources have relays set at the existing setpoints, b) one set of source relays with j.

the existing old setpoints and the other set with the proposed revised setpoints, or c) both sources have relays set at the proposed revised setpoints. Each of these configurations is acceptable, because the existing and proposed values

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satisfy the design limits established within the setpoint calculation and the Voltage Regulation Study.

For Function 4 and 5, the present TS has separate entries in Table 3.3.8.1-1 for the intemal and external time delay. This proposed change will combine these internal and extemal time delays for simplicity. The aggregate time delay is the important parameter and it is the only time delay that is analyzed. The internal d'

time delay minimizes the relay contact wear and reduces the number of external time delay relay actuations due to transient voltage dips. The internal time delay..

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provides no other output functions. Therefore, there will be no impact on the Class 1E power distribution system to perform its intended design function.

Therefore, the proposed changes described above, or operation while i

modification 96-01511 is being implemented, does not involve a significant

. Increase in the probability or consequences of an accident previously evaluated.

2.

The orooosed chanaes do not create the nossibility of a new or different kind of accident from any accident Dre-@usiv evaluated.

The aroposed LOP instrumentation setpoint changes will not result in any new accicents or operational transients. Separation of the 4kV emergency buses from the grid is the only potential transient that previously existed based on operation of these relays. Based on the revised Voltage Regulation Study, which Incorporates the effects of system improvements and additional conservatisms, there is no significant increase in the probability of this separation, and the proposed setpoint changes would not create the possibility of a new or different kind of accident from any previously evaluated. The relay time delay settings are such that the relays will detect and respond to an actual sustained degradation of voltage, but will not actuate in response to normal operational voltage fluctuations. The proposed setpoint changes for these relays and the proposed combining of the internal and external time delays will not become initiators of different types of accidents or transients. Additionally, since the existing and proposed allowable values for the LOP instrumentation functions are within the band established by the Voltage Regulation Study, both values are acceptable for operation during the implementation of modification 96-01511. Therefore, the possibility of a new or different kind of accident than previously evaluated is not

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3,1 The orooosed chanaes do not. involve a slanificant reduction in a marain of

. safety.

. All LOP Instrumentation functions will continue to be carried out. The proposed P

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Dockct Nos. 50-277 50-278 License Nos. DPR-44 DPR-56 setpoint and allowable value changes have been evaluated within the Voltage Regulation Study and the Plant Electrical Load Study. The relay setpoints have been established using ilSCP setpoint methodology. The setpoint determination accounts for relay accuracy, potential transformer accuracy, measurement and -

~ test equipment accuracy, and margin above the design limit established within the Voltage Regulation Study. The proposed setpoint changes for these relays and-the proposed combining of the intemal and extemal time delays will not involve a significant reduction in a margin of safety. Additionally, since the existing and proposed allowable values for the LOP instrumentation functions

, are within the band established by the Voltage Regulation Study, both values are acceptable for operation during the implementation of modification 96-01511.

Therefore, having both values during the implementation of' modification 96-01511 does not involve a significant reduction in a margin of safety.-

Information Supportina an Environmental Assessment An environmental assessment is not required for the changes proposed by this License Change Application because the changes conform to the criteria for " actions eligible for categorical. exclusion," as specified in 10 CFR 51.22(c)(9). The proposed changes will

- have no impact on the environment. The proposed changes do not involve a significant hazards consideration as discussed in the preceding section. The proposed changes do not involve a change in the types or amounts of any effluents that may be released offsite. The proposed changes do not authorize any change in the authorized power level of the facility, in addition, the proposed changes do not involve an increase in individual or cumulative occupational radiation exposure.

l Conclusion The Plant Operations Review Committee and the Nuclear Review Board have reviewed i

the' proposed changes and have concluded that the changes do not involve an unreviewed safety question and will not endanger the public health and safety.

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