ML20209A779

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Provides Addl Info Re Compliance w/10CFR50.62, ATWS Events, Per NRC 870123 Request.Fourteen Oversized Drawings Encl
ML20209A779
Person / Time
Site: Limerick  Constellation icon.png
Issue date: 04/23/1987
From: Kowalski S
PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To: Butler W
NRC, NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
Shared Package
ML20209A785 List:
References
CON-#287-3284 OL, NUDOCS 8704280278
Download: ML20209A779 (12)
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Text

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PHILADELPHIA ELECTRIC COMPANY 23O1 M ARKET STREET P.O. BOX 8699 PHILADELPHIA. PA.19101 (2151841 4502

. .17."." ".' . "I...

APR 33 m Mr. Walter R. Butler, Director Docket Nos. 50-352/353 BWR Project Directorate No. 4 Division of BWR Licensing Attn: Document Control Desk U.S. Nuclear Regulatory Ccnmission Washington, D.C. 20555

SUBJECT:

Compliance with 10 CFR Section 50.62 Anticipated Transients Without Scram (ATWS) Events timerick Generating Station Units 1 and 2

REFERENCE:

1) Final ATWS Rule, 10 CFR Section 50.62, published in the dme 26, 1984 Federal Register
2) Letter from J. S. Kemper to A. Schwencer of the U.S. NRC, dated December 14, 1984
3) Letter from S. L. Daltroff to Harold R. Denton of the U.S. NRC, dated October 17, 1985
4) Letter from Robert E. Martin of the U.S. NRC to Edward G. Bauer, Jr., dated January 23, 1987 Reference 3 provided a description of the ATWS Prevention and mitigation features included in the design of Limerick Generating Station Units 1 and 2 to comply with the requirements of 10 CFR Section 50.62, paragraphs (cX3), alternate rod insertion (ARI),

(cX4), standby liquid control system (SLCS) capacity and (cX5),

recirculation punp trip (RPT). Reference 4 requests additional information for the NRC use in evaluating Limerick Ge wrating Station Units 1 and 2 compliance with 10 CFR Section 50.02.

1 The purpose of this letter is to provide the requested infonnat lon. Each request is restated below followed by our response for Limerick Generating Station Units 1 and 2.

8704280278 870423 /g6 T

ADOCK 05000352 PDR P PDR Iff g. b Tg

Request 1 Provide the electrical functional diagrams to indicate the recirculation pump trip (RPT) system from sensor logic to the field breaker trip coils, including documentation that redundant trip coils were used for each pump.

Response 1 The appropriate electrical drawings illustrating the ATWS RPT from sensor, through control logic to the trip coil and the use of redundant ,

circuit breakers in the recirculation pump motor power feeds are enclosed. A brief description of the ATWS RPT is provided below.

The ATWS RPT is actuated when reactor pressure exceeds or reactor water level decreases below established setpoints. Four channels (A,B,E, and F) of both reactor pressure and water level instrumentation are provided in the Redundant Reactivity Control System (RRCS) and are dedicated for use to detect an ATWS and initiate the ATWS prevention and mitigation features, including the ATWS RPT. Channels A and E are assigned to safeguard Division I and channels B and F are assigned to safeguard Division II. Both channels of either reactor pressure or j reactor water level instrumentation in a single division must be  ;

tripped to actuate the ATWS RPT. The Division I and II logics are l treated as Class 1E and are redundant to and independent of one another. i Two redundant Class 1E circuit breakers are located in the 4 kV power feed to each of the recirculation pump motors. One circuit breaker in each power feed is assigned to safeguard Division I and the other to safeguard Division II. Each circuit breaker has two trip coils, each separated from the other. One trip coil of each circuit breaker is wired to the ATWS RPT control logic, the other trip coil is wired to the End-of Cycle (EOC) RPT control logic. Each trip coil is ,

capable of tripping the associated breaker independently of the other. I I

Request 2 Provide the drawings to indicate the interface between the end-of-cycle (EOC) RPT system and the ATWS related RPT system including documentation that the qualified isolators are used between the safety related EOC-RPT signal and the ATWS-RPT signal.

Response 2 There is no interface between the ATWS RPT and the EOC RPT except for the use of a cotanon device (i.e. , the 4 kV circuit breakers in the recirculation pump motors feeds) to interrupt power to the recirculation pump motors.

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The ATWS RPT is actuated by dedicated sensors in the RRCS which are assigned to safeguard Divisions I and II. The EOC RPT is actuated by the Reactor Protection System (RPS) cultrol logic and sensors assigned to RPS channels IA, IIA, IB, and IIB. The RPS is the reactor trip system at Limerick. The ATWS RPT sensors, logic, and cabling are separated from the EOC RPT sensors, logic, and cabling in accordance with the Limerick Generating Station separation program as discussed in FSAR Section 8.1.6.1.14. Consequently, there is no interface between the ATWS RPT and the EOC RPT for which isolation must be provided. The ATWS RPT and the EOC RPT logics terminate on separate trip coils in each circuit breaker. Each trip coil is capable of tripping the associated circuit breaker independently of the other.

Request 3 Provide the documentation to describe the analysis and/or tests to verify that the Alternate Rod Injection (ARI) system functional time will begin within 15 seconds and be completed within 25 seconds from ARI initiation.

Response 3 The times required for each control rod to begin movement and for all control rods to be fully inserted during ARI were verified and documented in the RRCS pre-operational test procedure IP-58.2, revision O. The RRCS preoperational test was performed after installation of the RRCS during Unit 1 construction. These times were obtained by videotaping the full core display panel after ARI had been manually initiated. The full core display provides indication of each rod being fully withdrawn or fully inserted. A calibrated timer was displayed in front of the full core display throughout the testing. The videotape was replayed and the times required for each control rod to begin moving (fully withdrawn indicating light de-energized) and to be folly inserted (fully inserted indicating light energized) after ARI initiation, were recorded. The test was repeated for Division I, Division II, and combined Division I/ Division II manual initiation of ARI.

The results of the preoperational testing show that upon the combined Division I/ Division II initiation of ARI, all control rods began moving within 14.5 seconds and all control rods were fully inserted within 21.1 seconds. The corresponding times for the redundant divisions, when tested individually, were slightly higher:

Division I, 15.2 and 21.9 seconds, maximum; and Division II, 15.7 and 23.0 seconds, maximum. These times reflect the results of the preoperational testing program and elaborate upon the information presented in reference 3. Neither redundant division is required by design to individually meet the 15 second time limit for initiation of rod motions therefore, the small delay (0.2 seconds for Division I, 0.7 seconds for Division II) is not relevent to system operability. In each case, the rods were fully inserted within the 25 second time limit.

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Request 4 Provide the electrical one line diagram to demonstrate the electrical independence between the ARI system and the reactor trip system (RTS).

Response 4 i There is no interface between. the ARI and RPS scram function. The l ARI is actuated by the same dedicated reactor pressure and water level sensors in the RRCS as the ATWS RPT. Control rod movement is effected by venting the scram valve pilot air header and blocking -the air header

supply. Eight dedicated solenoid valves are installed in the scram j valve pilot air header and _ air header supply to perform this function.

j The ARI solenoid valves are independent of and separate from the RPS

! scram valves. The ARI sensors, logic, and cabling are separated from the RPS sensors, logic, and cabling in accordance with the Limerick Generating Station separation program as discussed in FSAR section i 8.1.6.1.14. There is no single electrical one line diagram j demonstrating the electrial independence between the ARI system and the

RPS.

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Request 5 Provide the qualification information on isolation devices:

a. For the type of device used to accomplish electrical isolation, i describe the specific testing performed to demonstrate that l the device is acceptable for its application (s) . This descrip-tion should include elementary diagrams when necessary to 1 indicate the test configuration and how the maximum credible
faults were applied to the device. ,
b. Data to verify that the maximum credible faults applied during i the test were the maximum voltage / current to which the device '

could be exposed, and define how the maximum voltage / current l t

was determined. '

) '

l c. Data to verify that the maximum credible fault was applied to the output of the device in the traverse mode (between signal ,

l and return) and other faults were considered (i.e., open and

short circuits),

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d. Define the pass / fail acceptance criteria for each type of device.

I e. Provide a commitment that the isolation devices comply with j the environment qualifications (10 CFR 50.49) and with the seismic qualifications which were the basis for plant licensing.

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f. Provide a description of the measure taken to protect the safety systems from electrical interference (i.e., Electrostatic Coupling, EMI, Comnon Mode and Crosstalk) that may be generated by the ATWS circuits.
g. Provide information to verify that the Class lE isolator is powered from a Class lE source.

Response 5 This information, including the appropriate drawings and diagrams, has previously been transmitted to the NRC (see reference 2) . After a review of this information, the use of the GE isolators in the RRCS to maintain independence between Class lE and non-Class lE circuits was accepted by .the NRC in NUREG-0991, Supplement Two: Safety Evaluation Report related to the operation of Limerick Generating Station, Units 1 and 2, section 7.2.2.9.

Request 6 Provide the proposed plant technical specification for ARI function time and the ARI system components. (Similar to the RPT system in current Tech. Spec.)

Response 6 The proposed plant Technical Specifications for ARI are provided in Attachment I. These specifications are identical to those already in place for the ATWS RPT and will also include the ATWS RPT. This proposal is consistent with the recommendation of the BWR Owners' Group l ATWS Compliance Alternatives Committee that ARI Technical Specifications similar to current RPT Technical Specifications would be adequate.

Currently the NRC's Technical Specification Improvement Committee

is considering criteria developed by the BWR Owners' Group for determining the content of Technical Specifications. We believe that a decision to require an ARI Technical Specification, specifically for function time testing, should be assessed in accordance with the proposed criteria of the ccmmittee. Should changes to the Technical Specifications be considered necessary, we believe they should be handled as a generic issue for the industry.

Request 7 Provide the information readout to the control room operator for the ARI and the RPT systems.

i

1 Response 7 The following annunciators concerning A'IWS RPT and ARI are provided in the control room:

RRCS Potential ATWS RRCS Confirmed ATWS RRCS Channel Activated Recirculation Pump Motor Trip Recirculation Pump Motor ATWS Trip Circuit Failure The following indications concerning ATWS RPT and ARI are provided in the control rrom:

RPT Breaker Status (Tripped / Closed); also provides indication of ATWS trip circuit continuity RRCS ARI Initiated RRCS ARI Ready For Reset Reactor Power Level.

Should you require any additional information, please do not hesitate to contact us.

Very truly yours,

/

. J. Kowalski Attachments RTG/sjf/468701 Copy to: See Attached service List l

. _ . _ . e cc: Troy B. Conner, Jr., Esq. (w/ enclosure)

Benjamin H. Vogler, Esq. (w/ enclosure)

Mr. Frank R. Romano (w/ enclosure)

Mr. Robert L. Anthony (w/ enclosure)

Ms. Maureen Mulligan (w/ enclosure)

Charles W. Elliot, Esq. (w/ enclosure)

Barry M. Hartman, Esq. (w/ enclosure)

Mr. Thomas Gerusky (w/ enclosure)

Director, Penna. Emergency (w/ enclosure) 4 Management Agency j Angus R. Love, Esq. (w/ enclosure) 4 David Wersan, Esq. (w/ enclosure)

Robert J. Sugannan, Esq. (w/ enclosure)

Kathryn S. Lewis, Esq. (w/ enclosure)

Spence W. Perry, Esq. (w/ enclosure) .

Atomic Safety & Licensing (w/ enclosure)

Appeal Board Atcmic Safety S Licensing (w/ enclosure)

Board Panel Docket S Service Section (w/ enclosure)

Mr. E. M. Kelly (w/ enclosure)

Mr. Timothy R. S. Campbell (w/ enclosure) i I

J r

1

3/4.J.lu ALTtxNATE ROD INSERTION /ATWS RECIRCULATION PUMP

/* TRIP INSTRUMENTATION A t t o c.b m e k I Y

LIMITING CONDITION FOR OPERATION hy \ of %

3.3.10.1 The Alternate Rod Insertion /ATWS Recirculation Pump Trip (ARI/ATWS be OPERABLE RPT) instrumentation with channels their trip setpoints shown in Table set consistent with 3.3.10.-1 shall values shown in the Trip Setpoint column of Table 3.3.10-2.

APPLICABILITY: OPERATIONAL CONDITION 1.

ACTION:

a. With an ARI/ATWS RPT instrumentation channel trip setpoint less conservative than the value shown in the Allowable Values column of Table 3.3.10-2, declare the channel inoperable until the channel is restored to OPERABLE status with the channel trip setpoint adjusted consistent with the Trip Setpoint value.
b. With the number of OPERABLE channels one less than required by the Minimum OPERABLE Channels per Trip System requirement for one or both trip systems, place the inoperable channel (s) in the tripped condition within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />,
c. With the number of OPERABLE channels two or more less than required by the Minimum OPERABLE Channels per Trip System requirement for one trip system and:
1. If the operable channels consist of one reactor vessel water level channel and one reactor vessel pressure channel, place both inoperable channels in the tripped condition within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />, or, if this action will initiate ARI/ATWS RPT, declare the trip system inoperable.
2. If the inoperable channels include two reactor vessel water level channels or two reactor vessel pressure channels, declare the trip system inoperable.
d. With one trip system inoperable, restore the inoperable trip system to CPERABLE status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or be in at least STARTUP within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />.
e. With both trip systems inoperable, restore at least one trip system to OPERABLE status within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> or be in at least STARTUP within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />.

SURVEILLANCE REQUIREMENTS 4.3.10.1.1 Each ARI/ATWS RPT instrumentation channel shall be demonstrated OPERABLE by the performance of the CHANNEL CHECK, CHANNEL FUNCTIONAL TEST and CHANNEL CALIBRATION operations at the frequencies shown in Table 4.3.10-1.

4.3.10.1.2 LOGIC SYSTEM FUNCTIONAL TESTS and simulated automatic operation of all chaanels shall be performed at least once per 18 months.

LIMERICK - UNIT 1

6ttae.kmed T-TABLE 3.3.10.1-1 Y

, ARI/ATWS RPT INSTRUMENTATION MINIMUN OPERABLE CHANNELS PER TRIP FUNCTION TRIP SYSTEM *

>, 2 --

1. Re' actor Vessel Water Level * '

Low Low, Level 2 , ,

2. Reactor Vessel Pressure - High 4, 2

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i I *0ne channel may be placed in an inoperable status for up to 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> for required surveillance provided the other channel is OPERABLE.

LIMERICK - UNIT 1 ,

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[- TABLE 3.3.10-2 '^ Y I "# 3 r ARI/ATWS RPT INSTRUMENTATION TRIP ALLOWABLE TRIP FUNCTION SETPOINT VALUE

1. Reiactor Vessel Water Level -

Low Low, Level 2 > -38 inches * > -45 inaches

2. Reactor Vessel Pressure - High $ 1093 psig $ 1108 psig i

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  • See Bases Figure B3/4 3-1.

l LIMERICK - UNIT 1

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TABLE 4.3.10-1 E* V Mof 4 6 , ARI/ATWS RPT INSTRUMENTATION

, SURVEILLANCE REQUIREMENTS CHANNEL CHANNEL FUNCTIONAL CHANNEL CHECX TEST CALIBRATION ,

TRIP FUNCTION

1. Reactor Vessel Water Izevel - M R Low Low, Level 2 S R
2. Reactor Vessel Pressure - High S M 3

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LIMERICK - UNIT 1

OVERSIZE

DOCUMENT PAGE PULLED SEE APERTURE CARDS NUMBER OF OVERSIZE PAGES FILMED ON APERTURE CARDS 1

l APERTURE CARD /HARD OOPY AVAILABLE FROM RECORD SERVICES BRANCH,TIDC l

FTS 492 = 8989

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