ML20217K659
| ML20217K659 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 10/22/1997 |
| From: | Cruse C BALTIMORE GAS & ELECTRIC CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20217K663 | List: |
| References | |
| NUDOCS 9710280365 | |
| Download: ML20217K659 (10) | |
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Cut tts 11. Catu llattimore G:5 end Eles tric Company l
Vice President Cabert Cliffs Nuclear Power Plant Nuclear Energy 1650 Cah ett Cliffs Pattu ay 1,usby. h1aryland 20657 410 493-4455 1
I October 22,1997 l
U. S. Nuclear Regulatory Commission Washington, DC 20555 NITENTION: Document Control Desk SUILIECT: Calvert Cliffs Nuclee Power Plant Unit Nos.1 & 2; Docket Nos. 50 317 & 50 318 Llegnse Amendment Rcquest -- 4 kV Undervohnge Relay Setpoints Pursuant to 10 CFR 50.90, the 11altit.4 ore Gas and Electric Company hereby requests an Amendment to Operating 1.icense Nos. DPR 33 and DPR 69 by incorporation of the changes described below into the Technical Specifications for Calven Cliffs Units I and 2. The Electrical Distributtor. System Functional Inspection conducted in 1992 identified an apparent weakness associated with the 41.V emergency bus undervoltage relay settings. %e inspection determined that 75 percent of rated equipment voltage was not always available for starting of safety related motors.
De proposed amendment incorporet:s both steady state and transient degraded voltage setpoints into Technical Specifications, as opposed to the current single degraded voltage setpoint. The proposed changes ensure adequate terminal voltage to all safety related equipment during steady state and transient voltage conditions. Additionally, the 4 kV voltage range required during testing of the emergency diesel generators will be dermsed to ensure the new steady state degraded voltage relays are not actuated during testing and to ennus the 4 kV motors are operated within their voltage rating.
Attachment (1) provides a detailed discussion of the proposed changes.
We have evaluated the significant hazards considerations associated with the changes, as required by 10 CFR 50.92, and determined that there are none (see Attachment 2 for a complete discussion).
Operation with the proposed amendment would not result in any significant chanpc in the types or significant increases in the amounts of any effluents that may be released ofTsite, and in no significant increases in individual or cumulative occupational radiation exposure. Therefore, pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment is needed in connection with the approval of the proposed amendmea'. We have evaluated the plant risk associated with the changes and determined that it is acceptable. He Plant Operations and Safety Review
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Committee and Off site Safety Review Committee have reviewed the proposed changes and concurred that the changes involve no significant haards considerations, and operation with the proposed changes 87)[
will not result in undue risk to the health and safety of the public.
9710290365 971022 PDR ADOCK 05000317 \j\\i\\,\\ 1$\$ktkikk i P PDR ., *I
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Document Control Desk October 33,1997 Page 2 in order to incorportav the changes during the Spring 1998 refueling outage, we request the proposed amendment be approved prior to April 1,1998, implementation of the Technical Specification changes will occur prior to the end of the Spring refueling outage. It should be noted that the requested approval date is after the proposed implementation date for our conversion to the improved Technical Specifications (ITS). Herefore, proposed changes to tLe ITS are also attached. If the ITS are approved prior to this propose <l change, we request that this change be applied to the appropriate sections ofITS.
Should you have questions regarding this matter, we will be pleased to discuss them with you.
Very truly yours u I iW A STATE OF MARYLAND :
- TO WIT: l COUNTY OF cal. VERT : )
! 1 Charles 11. Cruse, being duly sworn, state that I am Vice President, Nuclear Energy Division, l
' Baltimore Oas and Electric Company (BGE), and that I am duly authorized to execute and file this License Amendment Request on behalf of BOE To the best of my knowledge and belief, the statements contained in this document are true and correct. To the extent that these statements are not based on my personal knowledge, they are based upon information provided by other BGE employees and/or consultantt. Such information has been reviewed in accordance with company practice and I believe it to be reliabic.
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$ Ifb N * '" UiSIs EA "d N r* N M ,Y997, saw e MaMand and County or WITNESS my lland and Notarial Seal: (4ttdU b. dh 1L1W Notary Public My Commission Expires: A 'A 9 Date CilC/JPW/bjd Attachments: (1) Description and Justification of Proposed Change (2) Determination of Significant llazards (3)- Current Unit i Technical Specification Marked up Pages (4) Current Unit 2 Technical Specification Marked up Pages
($) Improved Technical Specification Marked up Pages
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Document Controliksk October 22,1997
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- R. S. Fleishman, Esquire 11. J. Miller, NRC J. E. Silberg, Esquire Resident inspector, NRC Director, Project Directorate 1 1, NRC R.1. McLean, DNR A. W. Dromerick, NRC J.11. Walter, PSC i , i s- ;
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ATTACilMENT (1) i DESCRIPTION AND JUSTIFICATION OF PROPOSED CIIANGE l
l Italtimore Gas & Electric Comparty Docket Nos. 50-317 and 50-318 October 22,1997
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NFTACilMENT (1)
DESCRIPTION AND JUSTIFICATION OF PROPOSED CilANGE IIACKGROUND Calvert Cliffs is a two unit site. For redundancy, each unit is equipped with two 4 kV emergency busses.
One emergency diesel generator (EDG) is dedicated to each 4 kV emergency bus. The EDGs start automatically on 4 kV bus loss of voltage,4 kV bus degraded voltage, or on actuation of safety injection.
%e preferred power source is also automatically disconnected from the 4 kV emergency busses during loss of voltare or degraded voltage conditions. Both the EDGs and the preferred power source are l equipped with voltage regulators to control bus voltage. Each 4 kV emergency bus is monitored for loss l
l of voltage and degraded voltage by eight relays. Four relays provide loss of voltage input signals to the Engineered Safety Features Actuation System (ESFAS), and the four remaining relays provide degraded voltage input signals to ESFAS.
%c safety function of the relays is to ensure the preferred power source is disconnected from the 4 kV emergency busses during loss of voltage or degraded voltage conditions. The relay inputs to ESFAS also ensure the EDGs are started and loaded. Ultimately, these actions ensure that the minimum terminal voltage necessary to surt and run all safety related electrical equipment is maintained, in 1992, Calvert Clifts underwent an Electrical Distribution System Functioral Inspection. Unresolved item No. 2 from the inspection identified an apparent weakness in the adequay of degraded grid relay settings. He inspection determined that 75 percent of rated equipment voltage was not always available for starting of safety related motors. Therefore, in accordance with 10 CFR 50.59, Calvert Clifts is modifying the 4 kV bus undervoltage relays. The existing two relays for each ESFAS channel are being replaced with a single, three-element relay. Two of the elements in each new relay monitor for loss of voltage and degraded voltage, similar to the existing scheme. The third element monitors for steady state undervoltage.
A change to the Technical Specifications is required to ,upport the relay modification. The proposed amendment incorporates a revised degraded voltage setpoint, which is referred to as the " Transient Degraded Voltage" setpoint. The change also adds a new " Steady State Degraded Voltage" setpoint and associated time delay to Technical Specifications. The existing loss of voltage relay setting and associated time delay are unalTected by this amendment request. The pennissible voltage range during EDG surveillance testing will also be decreased. By verifying the 4 kV emergency bus voltage is maintained within the new limits, the new steady state degraded voltage relays will not be actuated during testing. The revised range also ensures the 4 kV motors are operated within their voltage rating.
The above changes ensure adequate terminal voltage to all safety relcted electrical equipment during steady state and transient undervoltage conditions.
IEQUESTED CilANGES Changel- Technical Specification Table 3.3 4 will be revised to show a transient degraded voltage trip setpoint and allowable value of 3710180 Volts. The current setpoint for degraded voltage is 36281 25 Volts. The new setpoint ensures that at least 75 percent of the required terminal voltage is available to the most limiting electrical load. The time delay associated with this trip setpoint will remain unchanged.
Table 3.3 4 will slso be revised to include the new steady state degraded voltage setpoint, allowable value, and associat.d time delay De setpoint has been selected to be 3900180 Volts with a time delay 1
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A'ITACllMENT (1)
DESCRIPTION AND JUSTIFICATION OF PHOPOSED CliANGE l of 101 i 3.$ seconds. His voltage setpoint ensures that at least 90 percent of the required terminal voltage is available to the most limiting electrical load. The time delay provides adequate time for the voltage regulator to recover bus voltap following a voltage swing on the 500 kV system and time for the EDO voltage regulator to stabilize.
Chance 2. kehnical Specification Tables 3.3 3 and 4.3 2 will be revised to include the new steady state degraded voltage relays. The instrumentation and surveillance requirements identified in the tables for the existing loss of voltage and degraded (transient) voltage selays will be repeated for the new steady state degraded voltage relays. The existing degraded voltage relays will be changed to identify them as
- transient degraded voltage relays.
, Chanac 3 Surveillance Requirement 4.8.1.1.2.a.4 will be revised to stipulate that each diesel generator achieve a steady state generator voltage of 4160, +240, 100 Volts. This change is consavative since the allowable range of diesel generator voltage is less than the current permitted range of 41601420 Volts.
He new minimum voltage was chosen to be 4060 Volts to provide an acceptable margin above the steady state degraded voltage relay setting, which could have a reset voltage as high as 4020 Volts.
Because Calvert Cliffs' 4 kV motors are purchased with a rated voltage of 4000 i 10 percent, the maximum voltage will be established at 4400 Volts.
Marked up Technical Specification pages for Units 1 and 2 are attached to this transmittal as Attachments (3) and (4). Minor style and punctuation changes may be made to the final Technical Specification pages, and the pages may be .enumbered to accommodate added and/or deleted pages, lh1 PROVED TECIINICAIJPECIFICATIDES The conversion to the improved Technical Specifications (ITS) (Reference 1) may be approved by the Nuclear Regulatory Commission prior to the approval of this proposed change. The changes described above apply to the ITS. Improved Technical Specifications 3.3.6,3.8.1, and associated Bases require revisions based on this amendment request. Markups of the aff:cted ITS pages are provided in Attachment (5). The Bases will be changed in accordance with the Bases Control Program, if the conversion to ITS is complete before this proposed change is approved, we request that this change be applied to the ITS.
SAFETY ANALYSIS The 4 kV bus loss of voltage and degraded voltage relays ensure that the preferred power source is disconnected and the EDGs are started and loaded when the preferred power source voltage is lost or drops below a predetermined value. This ecures adequate terminal voltage to all safety-related electrical equipment required to support accident mitigation. The accident analysis credits the starting and loading of the EDGs based on loss of offsite power. The accident analysis also credits the ability of safety.related motors to start and continue running in order to mitigate the accident. The required voltage necessary to ensure safety related motors are capable of starting is 75 percent of nominal rated equipment voltage. The require;d voltage necessary to ensure these motors continue running for extended periods is 90 percent of nominal rated equipment voltage.
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ATTACilMENT (1)
DESCRIPTION AND JUSTIFICATION OF PROPOSED CilANGE Design requirements for safety related electrical equipment at Calven Cliffs stipulate that equipment must be capable of starting at 75 percent of nominal voltage. In general, these design requirements are tcNted in vendor supplied test data. The degraded (transient) voltage setpoint is being changed from 3628 i 25 Volts to 3710 i 80 Volts. Dased on the most recent calculations, a minimum voltage of 3630 Volts is required to ensure at least 75 percent of rated equipment voltage is available to N 13 Charging Pump, which is the most limiting electrical load.
The new steady state degraded voltage relay setpoint will be established at 3900180 Volts. The setpoint ensures that there is at least 90 percent of rated equipment voltage available to No.13 Charging Pump, ne time delay associated with this actuation is 10113.5 seconds. The time delay provides adequate time for the voL:ge regulator to recover bus voltage following a voltage swing on the 500 kV system, l and includes a two second time delay associated with ESFAS.
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The transient and steady state degraded voltage relay settings allow for calibration tolerances, potential transformer correction face test equipment uncertainties, and relay drill. The nominal settings account for the above factors, plas additional margin to the analytical limit.
Technical Speci0 cations are also being revised to require a more conservative voltage range during EDG surveillance testing. The surveillace requirement verifles that the EDG voltage regulator is maintaining an acceptable voltage. Currently, the acceptable range is 4160 i 420 Volts and was based on the recommended value listed in NU,UiG 0212, (Standard Technical Specifications for Combustion Engineering Pressurized Water 14 actors). The revised voltage range will be 4160 +240, .100 Volts. The low end value provides adequae margin to ensure the steady state degraded voltage relays do not actuate during EDG surveillance testing. The upper end value is established at 4400 Volts and ensures the 4 kV motors are operated within their voltage rating of 4 kV i 10 percent.
CONCLUSION We request that the Nuclear Regulatory Commission grant our proposed amendment to the Calvert Cliffs Technical Specifications. The transient degraded voltage setpoint and new steady state degraded voltage feature ensures adequate terminal voltage to all safetprelated electrical equipment during steady state and transient undervoltage conditions. We have determined that the proposed changes do not result in undue risk to the public health and safety, and that the plant specific risk is acceptable.
REFERENCE (1) Letter to NRC Document Control Desk from Mr. C.11. Cruse (DGE), dated December 4,1996, License Amendment Request; Conversion of the Calvert Cliffs Units I and 2 Technical Specifications to the improved Standard Technical Specifications, NUREG 1432 3
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ATTACIIMENT (2) l l
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DETERMINATION OF SIGNIFICANT IIAZARDS Baltimore Gas & Electric Company Docket Nos. 50-317 and 50-318 October 22,1997
ATTACilMENT (2)
DETERMINATION OF SIGNIFICANT llAZARDS l De proposed amendment incorporates both steady state and transient degradal voltage setpoints into Technical Specifications, as opposed to the current single degraded voltage setpoint. Additionally, the 4 kV bus voltage range required during testing of the emergency diesel generators will be decreased.
He proposed changes have been evaluated against the standards in 10 CFR 50.92 and have been determined to not involve a significant hazards consideration, in that operation of the facility in accordance with the proposed amendment:
- 1. II'ould not involve a significant increase in the probability or consequences of an accident previously evaluated.
The proposed changes revise the current degraded voltage setpoint and adds an additional steady state undervoltage requirement to Unit I and 2 Technical Specifications. The current degraded voltage relays will be referred to as " transient degraded voltage relays." The r.ew settings allow for calibration tolerances, potential transformer correction factors, test equipment uncertainties, and relay drift. The nominal settings account for the above factors, plus additional margin to the analytical limit. The acceptable voltage range during EDO surveillance testing is also being decreased. %c setpoint and time delay associated with the 4 kV bus loss of voltage relays is unaffected by this amendment request.
%c accident analyses credit the loading of the EDGs based on loss of olTsite power. The 4 kV emergency bus loss of voltage and degraded voltage relays initiate starting and loading of the emergency dicsci generators (EDGs) when the preferred power source voltage is lost or drops below a predetermined value. The relays also it. tiate disconnection of the preferred power source from the 4 kV emergency busses. These acticns ensure adequate terminal voltage to all safety related electrical equipment required to support accident mitigation. The required voltage necessary to ensure safety related motors are capable of starting is 75 percent of nominal rated equipment voltage. The required voltage necessary to ensure these moors continue running for extended periods is 90 percent of nominal rated equipment voltage.
He degraded (transient) voltage setpoint is being changed from 3628 :t 25 Volts to 3710 i 80 Volts. Ilased on the most recent calculations, a minimum voltage of 3630 Volts is required to ensure at least 75 percent of the nominal voltage is available to No.13 Charging Pump. which is the most limiting electrical load.
The new steady state degraded voltage relay setpoint will be established at 3900 i 80 Volts. The setpoint ensures that there is at least 90 percent of nominal voltage available to No.13 Charging pump. The time delay associated with this actuation is 101 i 3.5 seconds. The time delay provides adequate time for the voltage regulator to recover bus voltage following a voltage swing on the 500 kV system and time for the EDO voltage regulator to stabilize. The steady ,
state degraded voltage relays will be tested in the same manner, and at the same frequency, as the i loss of voltage and transient degraded voltage relays. I De required voltage range during EDG surveillance testing is being revised fiom 4160 i 420 Volts to 4160 +240, 100 Volts. The surveillance requirement verifies that the EDG voltage i regulator is maintaining an acceptable voltage. The new value ensures the 4 kV motors are i
-p ATTACilMENT (3)
DETERMINATION OF SIGNIFICANT IIAZARDS operated within their rated voltage and prevents actuation of the steady state degraded voltage relay during surveillance testing.
The degraded voltage relays are not initiators in any previously evaluated accidents.
Additionally, decreasing the acceptable voltage range during EDO testing does not affect the initiation of any previously analyzed accidents. Therefore, the proposed changes do not involve an increase in the probability or consequences of an accident previously analyzed.
- 2. II'ould not create the possibility of a new or different type of accident from any accident previously evaluated.
The license amendment request revises the current degraded voltage setpoint and adds an additional steady state degraded voltage requirement. Additionally, the acceptable voltage range during EDO surveillance testing is being desreased. The proposed changes ensure adequate starting and running terminal voltage to all safety related electrical equipment during steady state and transient degraded voltage conditions. The addition of the steady state degraded voltage relays provide an extra scheme of protection against sustained degraded voltage conditions. The facility currently relies upon degraded voltage relays to start and load the EDGs and to disconnect the preferred power source from the 4 kV emergency busses. Therefore, revising the relay setpoint, adding additional steady state degraded voltage protection, and decreasing the acceptable voltage range during EDO testing does not create the possibility of a new or different type of accident from any accident previously evaluated.
- 3. Would not involve a significant reduction in a margin ofsafety.
The safety function of the degraded voltage relays is to ensure that the preferred power source is disconnected from the 4 kV emergency busses during loss of voltage or degraded voltage conditions. 'the relays also ensure the EDGs are started and loaded. Ultimately, these actions ensure the minimal terminal voltage necessary to start and run all safety related electrical equipment i, maintained. The proposed changes revise the current degraded voltage setpoint and adds an addinonal steady state undervoltage requirement. Additionally, the acceptable voltage range during EDO surveillance testing is being decreased to ensure actuation of the steady state degraded voltage relays does not occur during EDG testing, and to ensure the 4 kV r.otors are operated within their rated voltage range.
Because the propo>ed changes ultimately ensure adequate terminal voltage to all safety-related electrical equipment during transient and steady state undervoltage conditions, the safety function of the degraded voltage relays, as well as the margin of safety afforded by these relays is unchanged. Therefore, the danges do not involve a significant reduction in the margin of safety.
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