ML20216B151
| ML20216B151 | |
| Person / Time | |
|---|---|
| Site: | Clinton  |
| Issue date: | 05/04/1998 |
| From: | ILLINOIS POWER CO. |
| To: | |
| Shared Package | |
| ML20216B123 | List: |
| References | |
| NUDOCS 9805150055 | |
| Download: ML20216B151 (14) | |
Text
SVC Protection Systems 3.8.11 3.8 ELECTRICAL POWER SYSTEMS 3.8.11- Static VAR Compensator (SVC) Protection Systems LC0 3.8.11 An-SVC Protection System consisting of two redundant protection subsystems shall be OPERABLE for each inservice SVC.
APPLICABILITY: During SVC operation ACTIONS
...._....-------------NOTE-------------------------------------
Separate Condition entry is allowed for each SVC Protection System.
CONDITION REQUIRED ACTION COMPLETION TIME A. One subsystem of an A.1 Restore SVC 30 days SVC Protection System protection subsystem inoperable. to OPERABLE status.
B. Both subsystems of an B.1 Restore one SVC 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> SVC Protection System protection subsystem incperable. to OPERABLE status.
C. Required Action and C.1 Open SVC output I hour associated Completion breaker (s) to remove Time not met. SVC from service. !
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CLINTON 3.8-44 Amendment No.
9905150055 980504 PDR ADOCK 05000461 P PDR
SVC Protection Systems 3.8.11 SURVEILLANCE REQUIREMENTS SURVEILLANCE FREQUENCY l
SR 3.8.11.1 For each required SVC Protection System, 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> perform a local, visual check of the SVC system control and status panel to confirm satisfactory operation.
I SR 3.8.11.2 Perform a system functional test of each 18 months SVC protection subsystem, including breaker actuation.
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CLINTON 3.8-45 Amendment No.
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Attachment 5 to U-602972 Page 1 of12 f
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Attached Marked-Up Pages of the Technical Specification Bases i
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AC Sources-Operating B 3.8.1 {
3.8 ELECTRICAL POWER SYSTEMS B 3.8.1 AC Sources-Operating .
BASES -
BACKGROUND The unit Class IE AC Electrical Power Distribution System AC sources consist'of ti.e offsite power sources and the onsite 4
standby power sources (diesel generators (DGs) 1A, 18, and IC). As required by 10 CFR 50, Appendix A, GDC 17 (Ref.1),
the design of the AC electrical power system provides independence and redundancy to ensure an available source of power to the Engineered Safety Feature (ESF)' systems.
I The Class IE AC distribution system supplies electrical j power to three divisional load groups, with each division I powered by an independent Class 1E 4.16 kV ESF bus (refer to LCO 3.8.9, " Distribution Systems-Operating"). Each ESF bus {
I has two separate and independent offsite sources of power.
Each ESF bus has a dedicated onsite DG. The ESF systecis of any two of the three divisions provide for the minimum safety functions necessary to shut down the unit and 4 maintainitjnasafeshutdowncondition. ~
Offsite power is supp' lied to the switchyard from the transmission network. From the switchyard one 345 kV circuit provides AC power to each 4.16 kV ESF bus. An q An ons.te, i p**4 electrically and physically independent 138 kV power source '
rovides a second completely independent circuit to each I installed dakc VA9, 4.16 kV'ESF bus. The offsite AC electrical power sources P'"'"y (gy4 are designed and located so as to minimize to the extent practical the likelihood of their simultaneous failure under I) i k*dso availah %" and postulated accident and environmental operating e3%ned' ion +o 4,e conditions. A detailed, description of the offsite power
- WSNe c'#"4 4*
network and circuits to the onsite Class IE ESF buses is found in USAR, Chapter 8 (Ref. ?';.
sopport rete. teel i y;g4.abe he fhe. An offsite circuit consists of all breakers, transformers, N b55*5- switches, interrupting devices, cabling, and controls 3 required to transmit power from the offsite transmission '
networktotheonsiteClassIEESFbus(es).j The onsite standby power source for each 4.16_kV ESF bus is a dedicated DG. A DG starts automatically on loss of coolant accident (LOCA) signal (i.e., low reactor water (continued)
CLINTON l B 3.8-1 Revision No. O J
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AC Sources-Operating B 3.8.1 BASES (continued) 1 LCO Two qualified circuits between the offsite transmission network and the onsite Class IE Distribution System and thioe separate and independent DGs (IA,18, and IC), ensure availability of the required power to shut down the reactor and maintain it in a safe shutdown condition after an -
anticipated operational occurrence (A00) or a postulated DBA.
Qualified offsite circuits are those that are described in the USAR and are part of the licensing basis for the unit.
Each offsite circuit must be capable of maintaining rated frequency and voltage, and accepting required loads during an accident, while connected to the ESF buses. Each offsite circuit consists of incoming breaker and disconnect to the respective reserve auxiliary transformer (RAT) reserve auxiliary transformer (ERAT) and the re.orspective emergency circuit path including feeder breakers to each of the 4.16 kV ESF' buses'g.
Each DG must be capable of starting, accelerating to rated speed and voltage, and connecting to its respective ESF bus on detection of bus undervoltage. This sequence must be accomplished within 12 seconds. .Each DG must also be capable of accepting required loads within the assumed loading sequence intervals, and must continue to operate-until offsite power can be restored to the ESF buses. These-capabilities are required to be met from a variety of initial conditions such as DG in standby with engine hot and DG in standby with engine at ambient conditions. Additional DG capabilities must be demonstrated to meet required Surveillances, e.g., capability of the DG to revert to standby status on an ECCS signal while operating in parallel test mode.
Proper sequencing of loads, including tripping of nonessential loads, is a required function for DG 1A and DG 1B OPERABILITY.
The AC sources in one division must be separate and independent (to the extent possible) of the AC sources in theotherdivision(s). For the DGs, the separation and independence are complete. For the offsite AC sources, the separation and independence are to the extent practical. A (continued)
CLINTON 8 3.8-3 Revision No. 0
1 Insert for Bases page B 3.8-3 An onsite, permanently installed SVC is also available for connection to each offsite circuit to support required voltage for the ESF busses. Connection of the SVCs to the offsite circuits is via circuit breakers to the secondary side of the RAT and/cr ERAT.
Connection and operation of the SVCs is dictated by the existing need for voltage support of the offsite electrical power sources based on prevailing grid conditions. Thus, OPERABILITY of the offsite electrical power sources is nor;aally supported by, but is not .
necessarily dependent on, connection and operation of the SVCs. The resultant impact on OPERABILITY of the orTsite electrical sources from disconnecting the SVCs from the offsite circuits can be determined by analysis based on use of an established model of the offsite transmission network and existing grid conditions, including available generating sources, which can be updated on a daily or more frequent basis. The model provides the capability to predict or determine what the onsite voltages would be at the RAT and/or ERAT (while connected to the offsite electrical sources) in the event of a DBA LOCA, including consideration of the loss ofgrid voltage support that would occur with a pint
. trip.
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AC Sources-Shutdown B 3.8.2 k BASES LCO electrical power support, assuming a loss of the offsite (continued) circuit. Similarly, when the high pressure core spray (HPCS) is required to be OPERABLE, a separate offsite circuit to the Division 3 Class IE onsite electrical power
- distribution subsystem, or an OPERABLE Division 3 DG,. ensure an additional source of power for the HPCS. Together, OPERABILITY of the required offsite circuit (s) and DG(s) ensure the availability of sufficient AC sources to operate the plant in a safe manner and to mitigate the consequences j of postulated events during shutdown (e.g., fuel handling i accidents, reactor vessel draindown). j 1
The qualified offsite circuit (s) must be capable of maintaining. rated frequency and voltage while connected to ,
their respective ESF bus (es), and accepting required loads 1 during an accident. Qualified offsite, circ its are those that are described in the USAR and are part of the licensing basis for the plant. The offsite circuit con *sts of incoming breaker and disconnect to the respect.ve reserve auxiliary transformer (RAT) or emergency reserve auxiliary transformer (ERAT), and the respective circuit path g including feeder breakers to all 4.16 kV ESF buses required
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by LCO 3.8.10. g INSER.T -i The required DG must be capable of starting, accelerating to rated speed and voltage, and connecting to its respective ESF bus on detection of bus undervoltage, and accepting required loads. This sequence must be accomplished within ,
, 12 seconds. Each DG must also be capable of accepting !
required loads within the assumed loading sequence '
intervals, and must continue to operate until offsite power can be restored to the ESF buses. These capabilities are required to be met from a variety of initial conditions such as: DG in standby with the engine hot and DG in standby with the engine at ambient conditions. Additional DG capabilities must be demonstrated to meet required Surveillances, e.g., capability of the DG to revert to standby status on an ECCS signs.1 while operating in parallel test mode. ,
l Proper sequencing of loads, including tripping of nonessential loads, is a required function for DG OPERABILITY.
(continuedi k,
CLINTON 8 3.8-35 Revision,No. 0
Insert for Bases page B 3.8-35 In addition, an onsite, permanently installed static VAR compensator (SVC) is available for connection to the offsite circuits to support required voltage for the ESF busses. (
Connection of the SVC to the offsite circuit is via circuit breakers to the secondary side of {
Connection and operation of the SVC(s) is dictated by the existing need for voltage support of the offsite electrical power source (s) based on prevailing grid conditions.
Thus, OPERABILITY of the offsite electrical power source (s) is normally supported by, 1 but is not necessarily dependent on, connection and operation of the SVC(s). The j resultant impact on OPERABILITY of the offsite electrical source (s) from disconnectmg l the SVC(s) from the offsite circuit (s) can be determined by analysis based on use of an established model of the offsite transmission network and existing grid conditions, including available generating sources, which can be updated on a daily or more frequent basis. The model provides the capability to predict or determine what the onsite voltages would be at the RAT and/or ERAT (while connected to the offsite electrical sour. es) under maximum postulated load conditions.
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SVC Protection Systems B 3.8.11 l B 3.8 ELECTRICAL POWER SYSTEMS B 3.8.11 Static Var Compensator (SVC) Protection Systems l
l BASES BACKGR0l ND As described in the Bases for LC0 3.8.1, "AC Sources-Operating," each Engineered Safety Feature (ESF) electrical bus within the Class IE AC Electrical Power Distribution system has two separate and independent offsite sources of power. From the plant switchyard, a 345-kV circuit provides AC power to each 4.16-kV ESF bus via the reserve auxiliary transformer (RAT). In addition, an electrically and physically independent 138-kV offsite power source provides AC power to each 4.16-kV ESF bus via the emergency reserve auxiliary transformer (ERAT). For each of these circuits, a i permanently installed static VAR compensator (SVC) is !
provided which can be connected to the secondary side of I the associated auxiliary power transformer (RAT or ERAT) via )
two (in-series) circuit breakers. The ERAT SVC and RAT SVC i provide steady state, dynamic and transient voltage support to ensure that the Class 1E loads will operate as required during anticipated or postulated events. However, as noted ,
I in the Bases for LC0 3.8.1, SVC support of the offsite power sources may not be required at all times, depending'on prevailing grid conditions relative to the requirements of the facility.
The internal control system for each SVC includes control and protective functions. However, backup protection is provided by a fully redundant and independent protection system, consisting of two redundant subsystems for each SVC, for fail safe performance of the overall SVC system. The i redundant protection subsystems are powered from independent DC supplies. Each subsystem activates separate and independent relays, which in turn will automatically open <
the two main SVC circuit breakers to automatically disconnect the SVC from the 4.16-kV circuit in response to various SVC failure conditions. The SVC main circuit breakers are redundant for increased protection against
- breaker failure.
l APPLICABLE As noted in the Bases for LC0 3.8.1, "AC Sources-0perating," f SAFETY ANALYSES the' initial conditions of DBA and transient analyses in the USAR assume ESF systems are OPERABLE. The AC electrical power sources, including the offsite electrical power (continued)
CLINTON B 3.8-93 Revision No.
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SVC Protection Systems B 3.8.11 BASES APPLICABLE sources, are designed to provide sufficient capacity, SAFETY ANALYSES capability, redundancy and reliability to ensure the (continued) availability of necessary power to ESF systems so that the fuel, reactor coolant system, and containment design limits are not exceeded. The RAT and ERAT SVCs provide voltage support, when required, from the associated offsite source circuits to the ESF busses and equipment supplied by those circuits. At the same time, failure and risk analyses performed for the SVCs demonstrate that a protection system for each SVC is necessary to protect ESF equipment from potential SVC failure modes that could damage or degrade the Class IE equipment. OPERABILITY of the SVC Protection Systems is thus consistent with minimizing the potential for SVC failures to damage or degrade required ESF equipment.
Probabilistic risk assessment has shown the SVC Protection Systems to be important for the protection of required ESF systems and equipment. Therefore, the SVC Protection Systems satisfy Criterion 4 of the NRC Policy Statement.
i LC0 Both redundant protection subsystems of a required SVC protection system are required to be OPERABLE to ensure no single failure will preclude protection on a valid signal.
Total SVC Protection System failure introduces the possibility of ESF equipment failure or degradation of ESF equipment connected or capable of being automatically connected to the busses supported by the SVC(s).
An SVC Protection System is considered OPERABLE when both SVC protection subsystems are capable of automatically opening its associated SVC main circuit breaker in response to postulated SVC failures that could potentially degrade or damage ESF equipment. OPERABILITY of an SVC protection subsystem exists when it is energized and all essential components are OPERABLE, including the associated relays and sensors (e.g., current transformers and potential transformers).
(continued)
CLINTON B 3.8-94 Revision No.
SVC Protection Systems B 3.8.11 BASES (continued)
APPLICABILITY An SVC Protection System must be OPERABLE whenever its associated SVC is in operation, i.e., whenever the SVC's associated offsite circuit is energized with the SVC connected. Although the plant ESF busses are normally aligned together and to either the RAT or ERAT, an SVC Protection System must be OPERABLE if its associated SVC is connected to the associated auxiliary transformer (RAT or j ERAT); the transformer is energized by the offsite network; l and the transformer is supplying power to at least one ESF bus, or automatic transfer capability to that transformer I
exists such that it could supply power to at least one ESF 1'
- bus.
The requirements for the offsite electrical power sources are addressed in LC0 3.8.1, "AC Sources-0perating," and LC0 3.8.2, "AC Sources-Shutdown."
! ACTIONS A.1 With one SVC protection subsystem of a required SVC Protection System inoperable, the inoperable subsystem must be restored to OPERABLE status within 30 days. With the SVC l Protection System in this condition, the remaining subsystem is adequate to provide the protection function. However, the overall reliability of the SVC Protection System is reduced because a #ailure of the OPERABLE subsystem would i result in a loss of the SVC failure protection function.
The 30-day Completion Time is based on the low probability of an SVC failure occurring during this time period, and the fact that the remaining subsystem can provide the required protection function.
B.1 If both SVC protection subsystems of a required SVC Protection System are inoperable, the backup protection system designed for the SVC is unavailable to provide its protection function. Though not all failure modes of the SVC would necessarily be unprotected or potentially damaging to ESF equipment with the required protection system unavailable, there is a significant increase in calculated risk based on conservative failure assumptions for the SVCs.
Thus, at least one subsystem must be restored to OPERABLE (continued)
CLINTON B 3.8-95 Revision No.
I SVC Protection Systems B 3.8.11-BASES .
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ACTIONS B.1 1 (continued) I status within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. The Completion Time of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> is reasonable, taking into account the low probability of an SVC failure occurring in this time period and the realistic potential for an SVC failure to adversely affect plant equipment.
l C.1 If the required SVC protection subsystems cannot be restored to OPERABLE status within the required Completion Time, the SVC must be placed in a configuration for which the SVC Protection System LCO does not apply. This is accomplished by disconnecting the associated SVC from the plant auxiliary
- power system by opening (at least one of) the SVC main circuit breakers. The Completion Time of one hour allows d
for an orderly disconnection of the SVC, including evaluation of the resultant impact on required voltage for the onsite ESF busses (i.e., for compliance with LCO 3.8.1, "AC Sources-0perating," or LC0 3.8.2, "AC Sources-Shutdown").
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SURVEILLANCE SR 3.8.11.1 REQUIREMENTS The SVC local control panel is checked to confirm satisfactory operation of the SVC Protection System (s).
This includes verifying that no warning or trouble lights that could be indicative of SVC Protection System degradation are present, and checking the overall condition i and/or status of relays to qualitatively confirm l satisfactory operation of the SVC and SVC Protection System. !
The 24-hour Frequency is based on manufacturer's recommendations.
SR 3.8.11.2 A system functional test of each SVC Protection System is performed to ensure that each SVC protection subsystem will actuate to automatically open the associated SVC's main circuit breakers in response to signals associated with SVC failure modes that could potentially damage or degrade plant (continued)
CLINTON B 3.8-96 Revision No.
SVC Protection Systems B 3.8.11 BASES SURVEILLANCE equipment. System functional testing should thus REQUIREMENTS include satisfactory operation of the associated relays and (continued) testing of the sensors for which failure modes would be undetected. As a minimum, SVC protection subsystem actuation capability should be verified for response to signals, actual or simulatod, corresponding to the following potential SVC failure modes or conditions:
(1) Overvoltage (2) Undervoltage i (3) Phase Unbalance (4) Harmonics (5) Overcurrent The 18-month Frequency is based on manufacturer's recommendations. !
REFERENCES 1. 10CFR50, Appendix A, GDC 17. ,
- 2. USAR, Chapter 8.
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t CLINTON B 3.8-97 Revision No.
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Attaclunent 6 to U-602972 LS-98-001 SVC Design Report I
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