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| issue date = 03/11/1994
| issue date = 03/11/1994
| title = LER 94-005-00:on 940210,turbine Trip Occurred Due to Loss of Direct Current Control Power to electro-hydraulic Control Sys.Caused by Error in Design,Mfg,Const & Installation. EHC Power Supplies Monitored for stability.W/940311 Ltr
| title = LER 94-005-00:on 940210,turbine Trip Occurred Due to Loss of Direct Current Control Power to electro-hydraulic Control Sys.Caused by Error in Design,Mfg,Const & Installation. EHC Power Supplies Monitored for stability.W/940311 Ltr
| author name = HAGAN J J, PASTVA M J
| author name = Hagan J, Pastva M
| author affiliation = PUBLIC SERVICE ELECTRIC & GAS CO. OF NEW JERSEY
| author affiliation = PUBLIC SERVICE ELECTRIC & GAS CO. OF NEW JERSEY
| addressee name =  
| addressee name =  
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=Text=
=Text=
{{#Wiki_filter:e Public Service Electric and Gas Company P.O. Box 236 Hancocks Bridge, New Jersey 08038 Salem Generating Station U. s. Nuclear Regulatory Commission Document Control Desk Washington, DC 20555  
{{#Wiki_filter:e OPS~G Public Service Electric and Gas Company P.O. Box 236 Hancocks Bridge, New Jersey 08038 Salem Generating Station March 11, 1994 U. s. Nuclear Regulatory Commission Document Control Desk Washington, DC               20555


==Dear Sir:==
==Dear Sir:==
SALEM GENERATING STATION LICENSE NO. DPR-70 DOCKET NO. 50-272 UNIT NO. 1 LICENSEE EVENT REPORT 94-005-00 March 11, 1994 This Licensee Event Report is being submitted pursuant to the requirements of Code of Federal Regulation 10CFR50.73(a)
 
(2) (iv). Issuance of this report is required within thirty (30) days of event discovery.
SALEM GENERATING STATION LICENSE NO. DPR-70 DOCKET NO. 50-272 UNIT NO. 1 LICENSEE EVENT REPORT 94-005-00 This Licensee Event Report is being submitted pursuant to the requirements of Code of Federal Regulation 10CFR50.73(a) (2) (iv).
Sincerely yours, MJPJ:pc Distribution  
Issuance of this report is required within thirty (30) days of event discovery.
.,r.f"lr-.rn 94031eAonootR PDR PDR . S t'"'""1i;i11L your hands. 95-2189 REV 7-92 NRC FORM 366 (5-92) .* NUCLEAR REGULATORY COMMISSION PPROVED BY OMB NO. 3150-0104 EXPIRES 5/31 /95 LICENSEE EVENT REPORT (LER) (See reverse for required number of digits/characters for each block) ESTIMATED BURDEN PER RESPONSE TO COMPLY WITH THIS INFORMATION COLLECTION REQUEST: 50.0 HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE INFORMATION AND RECORDS MANAGEMENT BRANCH (MNBB 7714), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555-0001, AND TO THE PAPERWORK REDUCTION PROJECT (3150-0104), OFFICE OF MANAGEMENT AND BUDGET, WASHINGTON, DC 20503. FACILITY NAME (1) DOCKET NUMBER (2) PAGE (3) 1OF05 Salem Generating Station -Unit 1 05000 272 TITLE (4) Turbine Trip Due To Loss of Direct Current Control Power To Electro-Hydraulic Control Syst. EVENT DATE (5) LER NUMBER (6 REPORT NUMBER (7) OTHER FACILITIES INVOLVED (8\ FACILITY NAME DOCKET NUMBER NUMBER MONTH DAY
Sincerely yours, MJPJ:pc Distribution
* SEQUENTIAL YEAR YEAR REVISION NUMBER MONTH DAY YEAR *05000 FACILITY NAME DOCKET NUMBER 02 10 94 94 005 00 03 11 94 05000 OPERATING THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check one or more (11) MODE (9) 1 20.402(b) 20.405(c) x 50.73(a)(2)(iv) 73.71 (b) I POWER I I 20.405(a)(1)(i) 50.36(c)(1) 50.73(a)(2)(v) 73.71 (c) LEVEL (10) 99 20.405(a)(1)(ii) 50.36(c)(2) 50.73(a)(2)(vii)
              .,r.f"lr-.rn 94031eAonootR 6~8E6~12 PDR                         PDR
OTHER -20.405(a)(1  
. S t'"'""1i;i11L your hands.
)(iii) 50.73(a) (2)(i) 50.73(a)(2)(viii)(A) (Specify in Abstract U--J--........:....:....:....:....:......:.._
95-2189 REV 7-92
____
 
_____ 1--4--_;_;;__;___;_;;___--I below and in Te>d, NRC 20.405(a)(1  
NRC     FORM 366                                                           .* NUCLEAR REGULATORY COMMISSION                                 PPROVED BY OMB NO. 3150-0104 (5-92)                                                                                                                                                EXPIRES 5/31 /95 ESTIMATED BURDEN PER RESPONSE TO COMPLY WITH THIS INFORMATION COLLECTION REQUEST: 50.0 HRS.             FORWARD LICENSEE EVENT REPORT (LER)                                                                            COMMENTS REGARDING BURDEN ESTIMATE TO THE INFORMATION AND RECORDS MANAGEMENT BRANCH (MNBB 7714), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555-0001, AND TO THE PAPERWORK REDUCTION PROJECT (3150-0104), OFFICE OF (See reverse for required number of digits/characters for each block)                                            MANAGEMENT AND BUDGET, WASHINGTON, DC 20503.
)(iv) 50.73(a)(2)(ii) 50.73(a)(2) (viii)(B)
FACILITY NAME (1)                                                                                                                 DOCKET NUMBER (2)                                   PAGE (3)
Form 366A) 20.405(a)(1  
Salem Generating Station - Unit 1                                                                                                               05000 272                           1OF05 TITLE (4)
)(v) 50.73(a)(2)(iii) 50.73(a)(2)(x)
Turbine Trip Due To Loss of Direct Current Control Power To Electro-Hydraulic Control Syst.
LICENSEE CONTACT FOR THIS LEA 12) NAME TELEPHONE NUMBER (Include Area Code) M. J. Pastva, Jr. -LER Coordinator (609) 339-5165 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13) CAUSE SYSTEM COMPONENT MANUFACTURER REPORTABLE TONPRDS CAUSE SYSTEM COMPONENT MANUFACTURER REPORTABLE TONPRDS SUPPLEMENTAL REPORT EXPECTED (14) EXPECTED MONTH DAY YEAR l YES SUBMISSION DATE (15) j (If yes, complete EXPECTED SUBMISSION DATE) NO x ABSTRACT (Limit to 1400 spaces, i.e., ai:iRroximately 15 single-spaced typewritten lines) (16) On 2/10/94, at 1258 hours, a control power failure of the turbine Electro-Hydraulic Control (EHC) system occurred causing a turbine/reactor trip. The Unit was stabilized in Mode 3, at approximately 1315 hours (same day). Insufficient margin between the EHC.overvoltage protection*
EVENT DATE (5)                                     LER NUMBER (6                               REPORT NUMBER (7)                       OTHER FACILITIES INVOLVED (8\
setpoints and normal EHC power supply voltage allowed a variation in voltage to actuate the overvoltage protection circuitry.
FACILITY NAME                           DOCKET NUMBER
The margin resulted from design/installation of the EHC power supplies and use of a 17.3VDC setpoint.
* SEQUENTIAL               REVISION MONTH          DAY      YEAR     YEAR                                                             MONTH         DAY     YEAR NUMBER              NUMBER                                                                                *05000 FACILITY NAME                           DOCKET NUMBER 02             10         94       94                           005                   00             03         11       94                                               05000 OPERATING                     THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check one or more (11)
A contributor was EHC procedures that did not record power supply voltages in a manner that would reveal a reduced margin to trip. No component failures were identified as contributors to this event. EHC power supplies were monitored and no problems or transients/pulses were recorded.
MODE (9)               1         20.402(b)                                                   20.405(c)                           x 50.73(a)(2)(iv)                     73.71 (b)
The overvoltage protection circuits were replaced and the circuits' setpoints were reset to 17.9 +/-.1 voe, and the EHC +15 voe bus wiring was reworked.
POWER           I 99 I           20.405(a)(1)(i)                                             50.36(c)(1)                             50.73(a)(2)(v)                   73.71 (c)
Procedure changes have been implemented to ensure adequate margin below the overvoltage protection setpoint.
I    LEVEL (10)                         20.405(a)(1)(ii) 20.405(a)(1 )(iii)
The A +15VDC power supply was replaced and additional testing will be conducted to evaluate transient effects. During the next Unit 2 outage, voltage readings of the Unit 2 EHC 15VDC power supply will be taken to verify adequacy of the overvoltage protection margin to trip setpoint.
U--J--........:....:....:....:....:......:..__ _ _ _
50.36(c)(2) 50.73(a) (2)(i)
                                                                                        ~...._4--....:....:..;,_:_.:..;_
50.73(a)(2)(vii) 50.73(a)(2)(viii)(A)
OTHER (Specify in Abstract
_ _ _ _ _1--4--_;_;;__;___;_;;___--I below and in Te>d, NRC 20.405(a)(1 )(iv)                                           50.73(a)(2)(ii)                         50.73(a)(2) (viii)(B)         Form 366A) 20.405(a)(1 )(v)                                           50.73(a)(2)(iii)                         50.73(a)(2)(x)
LICENSEE CONTACT FOR THIS LEA 12)
- NAME                                                                                                                                       TELEPHONE NUMBER (Include Area Code)
M. J. Pastva, Jr. - LER Coordinator                                                                                                         (609) 339-5165 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)
REPORTABLE                                                                                      REPORTABLE CAUSE       SYSTEM       COMPONENT                 MANUFACTURER                                                       CAUSE   SYSTEM     COMPONENT       MANUFACTURER TONPRDS                                                                                          TONPRDS SUPPLEMENTAL REPORT EXPECTED (14)                                                                           EXPECTED         MONTH       DAY   YEAR lj YES NO SUBMISSION (If yes, complete EXPECTED SUBMISSION DATE)                                             x                                                           DATE (15)
ABSTRACT (Limit to 1400 spaces, i.e., ai:iRroximately 15 single-spaced typewritten lines) (16)
On 2/10/94, at 1258 hours, a control power failure of the turbine Electro-Hydraulic Control (EHC) system occurred causing a turbine/reactor trip. The Unit was stabilized in Mode 3, at approximately 1315 hours (same day). Insufficient margin between the EHC.overvoltage protection* setpoints and normal EHC power supply voltage allowed a variation in voltage to actuate the overvoltage protection circuitry. The margin resulted from design/installation of the EHC power supplies and use of a 17.3VDC setpoint. A contributor was EHC procedures that did not record power supply voltages in a manner that would reveal a reduced margin to trip. No component failures were identified as contributors to this event. EHC power supplies were monitored and no problems or transients/pulses were recorded. The overvoltage protection circuits were replaced and the circuits' setpoints were reset to 17.9 +/- .1 voe, and the EHC +15 voe bus wiring was reworked. Procedure changes have been implemented to ensure adequate margin below the overvoltage protection setpoint. The A +15VDC power supply was replaced and additional testing will be conducted to evaluate transient effects. During the next Unit 2 outage, voltage readings of the Unit 2 EHC 15VDC power supply will be taken to verify adequacy of the overvoltage protection margin to trip setpoint.
NRG FORM 366 (5-92)
NRG FORM 366 (5-92)
BLOCK NUMBER 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 REQUIRED NUMBER OF DIGITS/CHARACTERS FOR EACH BLOCK NUMBER OF DIGITS/CHARACTERS TITLE UP TO 46 FACILITY NAME 8 TOTAL 3 IN ADDITION TO 05000 DOCKET NUMBER VARIES PAGE NUMBER UP TO 76 TITLE I 6 TOTAL 2 PER BLOCK EVENT DATE 7 TOTAL 2 FOR YEAR 3 FOR SEQUENTIAL NUMBER LER NUMBER 2 FOR REVISION NUMBER 6 TOTAL 2 PER BLOCK REPORT DATE UP TO 18 FACILITY NAME 8 TOTAL-DOCKET NUMBER OTHER FACILITIES INVOLVED 3 IN ADDITION TO 05000 1 OPERATING MODE 3 POWER LEVEL 1 CHECK BOX THAT APPLIES REQUIREMENTS OF 10 CFR UP TO 50 FOR NAME 14 FOR TELEPHONE LICENSEE CONTACT CAUSE VARIES 2 FOR SYSTEM 4 FOR COMPONENT EACH COMPONENT FAILURE 4 FOR MANUFACTURER NPRDS VARIES 1 CHECK BOX THAT APPLIES SUPPLEMENTAL REPORT EXPECTED 6 TOTAL 2 PER BLOCK EXPECTED SUBMISSION DATE LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station Unit 1 DOCKET NUMBER 5000272 PLANT AND SYSTEM IDENTIFICATION:
 
Westinghouse  
REQUIRED NUMBER OF DIGITS/CHARACTERS FOR EACH BLOCK BLOCK          NUMBER OF TITLE NUMBER      DIGITS/CHARACTERS 1              UP TO 46                 FACILITY NAME 8 TOTAL 2                                      DOCKET NUMBER 3 IN ADDITION TO 05000 3                VARIES                 PAGE NUMBER 4              UP TO 76                 TITLE 6 TOTAL 5    I                                  EVENT DATE 2 PER BLOCK 7 TOTAL 2 FOR YEAR 6  3 FOR SEQUENTIAL NUMBER LER NUMBER 2 FOR REVISION NUMBER 6 TOTAL 7                                        REPORT DATE 2 PER BLOCK UP TO 18 FACILITY NAME 8                                      OTHER FACILITIES INVOLVED 8 TOTAL- DOCKET NUMBER 3 IN ADDITION TO 05000 9                  1                   OPERATING MODE 10                  3                   POWER LEVEL 1
-Pressurized Water Reactor LER NUMBER 94-005-00 PAGE 2 of 5 Energy Identification System (EIIS) codes are identified in the text* as {xx} IDENTIFICATION OF OCCURRENCE:
11                                      REQUIREMENTS OF 10 CFR CHECK BOX THAT APPLIES UP TO 50 FOR NAME 12                                      LICENSEE CONTACT 14 FOR TELEPHONE CAUSE VARIES 2 FOR SYSTEM 13        4 FOR COMPONENT               EACH COMPONENT FAILURE 4 FOR MANUFACTURER NPRDS VARIES 1
Turbine/Reactor Trip Due To Loss Of Direct current Control Power To Electro-Hydraulic Control System Event Date: 2/10/94 Report Date: 3/11/94 This report was initiated by Incident Report No. 94-045. CONDITIONS PRIOR TO OCCURRENCE:
14                                      SUPPLEMENTAL REPORT EXPECTED CHECK BOX THAT APPLIES 6 TOTAL 15                                      EXPECTED SUBMISSION DATE 2 PER BLOCK
Mode 1 Reactor Power 99 % Unit Load 1136 MWe DESCRIPTION OF OCCURRENCE:
 
On February 10, 1994, at 1258 hours, a turbine/reactor trip {JC} occurred due to a turbine trip signal while above the P-9 reactor power interlock setpoint.
LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station       DOCKET NUMBER      LER NUMBER      PAGE Unit 1                           5000272         94-005-00      2 of 5 PLANT AND SYSTEM IDENTIFICATION:
The turbine trip was initiated from a direct current (DC) control power failure of the turbine Electro-Hydraulic Control (EHC) System. Emergency Operating Procedure (EOP)-TRIP-1, "Reactor Trip Or Safety Injection" and EOP-TRIP-2, "Reactor Trip Response" were entered and the Unit was stabilized in Mode 3, at approximately 1315 hours (same day). At 1403 hours (same day) the NRC was notified of this event in accordance with 10CFR50.72(b)
Westinghouse   - Pressurized Water Reactor Energy Ind~stry Identification System (EIIS) codes are identified in the text* as {xx}
(2) (ii). ANALYSIS OF OCCURRENCE:
IDENTIFICATION OF OCCURRENCE:
The turbine EHC system controls steam flow through the turbine to govern turbine speed and load during startup, normal operation and shutdown.
Turbine/Reactor Trip Due To Loss Of Direct current Control Power To Electro-Hydraulic Control System Event Date:   2/10/94 Report Date:   3/11/94 This report was initiated by Incident Report No. 94-045.
In addition, the system trips the turbine if required.
CONDITIONS PRIOR TO OCCURRENCE:
The two +15-volt DC control power supplies (A and B) to the system are utilized via an auctioneering circuit. Over-voltage protection of the EHC power supplies is provided.
Mode 1   Reactor Power 99 %     Unit Load 1136 MWe DESCRIPTION OF OCCURRENCE:
Loss of both power supplies is indicated by a Control Room overhead alarm annunciator "EH DC PWR FAIL" first out window (F-32). The turbine/reactor trip occurred due to a DC control power failure of the turbine EHC System which caused a turbine trip signal while above LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station Unit 1 DOCKET NUMBER 5000272 ANALYSIS OF OCCURRENCE: (cont'd) LER NUMBER 94-005-00 PAGE 3 of 5 the P-9 reactor power interlock setpoint (>/=50% rated thermal power). Emergency Operating Procedure (EOP)-TRIP-1, "Reactor Trip Or Safety Injection", was entered. Main Steam was isolated in accordance with EOP-TRIP-2, "Reactor Trip Response" to limit cooldown of the Reactor Coolant System {AB}. The Unit was stabilized and placed in Mode 3 and Integrated Operating Procedure IOP-8 was entered. This event resulted from insufficient margin between the overvoltage protection setpoints and normal EHC power supply voltage. Consequently, a variation in voltage actuated the overvoltage protection circuitry.
On February 10, 1994, at 1258 hours, a turbine/reactor trip {JC}
The A power supply was set at approximately 220 millivolts (mV) below the overvoltage protection setpoint of 17.3 volts and the B power supply was set at approximately 340 mV below the overvoltage protection setpoint of 17.3 volts. Guidance for the power supply, Lambda Electronics, Division of VEEC Instrument Co., recommends a setpoint of 115% of the power supply voltage plus 1.0 volt (i.e. > 18 volts). The Westinghouse EHC field calibration procedure recommends an overvoltage protection setpoint of 17.3 volts. However, Engineering  
occurred due to a turbine trip signal while above the P-9 reactor power interlock setpoint. The turbine trip was initiated from a direct current (DC) control power failure of the turbine Electro-Hydraulic Control (EHC) System. Emergency Operating Procedure (EOP)-TRIP-1, "Reactor Trip Or Safety Injection" and EOP-TRIP-2, "Reactor Trip Response" were entered and the Unit was stabilized in Mode 3, at approximately 1315 hours (same day).
& Plant Betterment analysis determined 18VDC as the maximum overvoltage protection setpoint.
At 1403 hours (same day) the NRC was notified of this event in accordance with 10CFR50.72(b) (2) (ii).
Probable contributors to the insufficient setpoint margins: The power supply bus employed 18 gauge wiring, which may contribute to high line resistance which caused voltage drops from the power supply to the bus. Encountered high line resistance has required setting the power supply voltage relatively high in order to maintain proper bus voltage. Improperly crimped and loose wiring lugs in the power distribution panel wiring, confirmed by observed voltage transients during movement of the power supply output wiring. Recommendations in the Westinghouse EHC field calibration procedure required the overvoltage protection setpoint to be 17.3 volts, which was used by PSE&G. The potentiometer used to adjust the A power supply showed erratic response/high sensitivity to adjustments.
ANALYSIS OF OCCURRENCE:
EHC calibration procedure did not record power supply voltages in a manner that would reveal a reduced margin to trip. No component failures were identified as contributors to this event. In addition, the loss of one 15 volt power supply resulting in loss
The turbine EHC system controls steam flow through the turbine to govern turbine speed and load during startup, normal operation and shutdown. In addition, the system trips the turbine if required.
' LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station Unit 1 DOCKET NUMBER 5000272 ANALYSIS OF OCCURRENCE: (cont'd) LER NUMBER 94-005-00 PAGE 4 of 5 of the other could not be duplicated.
The two +15-volt DC control power supplies (A and B) to the system are utilized via an auctioneering circuit. Over-voltage protection of the EHC power supplies is provided. Loss of both power supplies is indicated by a Control Room overhead alarm annunciator "EH DC PWR FAIL" first out window (F-32).
However, troubleshooting showed that the A power supply did not adequately control under large load transients.
The turbine/reactor trip occurred due to a DC control power failure of the turbine EHC System which caused a turbine trip signal while above
At the time of this event, efforts were in progress to develop design changes to replace and upgrade the power supplies in response to previously encountered EHC power supply and distribution chassis problems, dating back to August 1992. APPARENT CAUSE OF OCCURRENCE:
 
The cause of this event is "Design, Manufacturing, Construction/Installation", as classified in Appendix B of NUREG-1022.
LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station       DOCKET NUMBER    LER NUMBER        PAGE Unit 1                           5000272       94-005-00      3 of 5 ANALYSIS OF OCCURRENCE: (cont'd) the P-9 reactor power interlock setpoint (>/=50% rated thermal power). Emergency Operating Procedure (EOP)-TRIP-1, "Reactor Trip Or Safety Injection", was entered. Main Steam was isolated in accordance with EOP-TRIP-2, "Reactor Trip Response" to limit cooldown of the Reactor Coolant System {AB}. The Unit was stabilized and placed in Mode 3 and Integrated Operating Procedure IOP-8 was entered.
Methods used during installation and design of the EHC power supplies (i.e. wire size used) resulted in minimum margin between the overvoltage protection setpoints and normal EHC power supply voltage. In addition, EHC calibration procedures did not record power supply voltages in a manner that would reveal a reduced margin to trip. The conservative 17.3VDC setpoint contributed to the reduced margin. No component failures were identified as contributors to this event. PREVIOUS OCCURRENCES:
This event resulted from insufficient margin between the overvoltage protection setpoints and normal EHC power supply voltage.
Consequently, a variation in voltage actuated the overvoltage protection circuitry. The A power supply was set at approximately 220 millivolts (mV) below the overvoltage protection setpoint of 17.3 volts and the B power supply was set at approximately 340 mV below the overvoltage protection setpoint of 17.3 volts. Guidance for the power supply, Lambda Electronics, Division of VEEC Instrument Co.,
recommends a setpoint of 115% of the power supply voltage plus 1.0 volt (i.e. > 18 volts). The Westinghouse EHC field calibration procedure recommends an overvoltage protection setpoint of 17.3 volts. However, Engineering & Plant Betterment analysis determined 18VDC as the maximum overvoltage protection setpoint.
Probable contributors to the insufficient setpoint margins:
The power supply bus employed 18 gauge wiring, which may contribute to high line resistance which caused voltage drops from the power supply to the bus. Encountered high line resistance has required setting the power supply voltage relatively high in order to maintain proper bus voltage.
Improperly crimped and loose wiring lugs in the power distribution panel wiring, confirmed by observed voltage transients during movement of the power supply output wiring.
Recommendations in the Westinghouse EHC field calibration procedure required the overvoltage protection setpoint to be 17.3 volts, which was used by PSE&G.
The potentiometer used to adjust the A power supply showed erratic response/high sensitivity to adjustments.
EHC calibration procedure did not record power supply voltages in a manner that would reveal a reduced margin to trip.
No component failures were identified as contributors to this event.
In addition, the loss of one 15 volt power supply resulting in loss
 
LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station       DOCKET NUMBER    LER NUMBER    PAGE Unit 1                           5000272         94-005-00    4 of 5 ANALYSIS OF OCCURRENCE: (cont'd) of the other could not be duplicated. However, troubleshooting showed that the A power supply did not adequately control under large load transients.
At the time of this event, efforts were in progress to develop design changes to replace and upgrade the power supplies in response to previously encountered EHC power supply and distribution chassis problems, dating back to August 1992.
APPARENT CAUSE OF OCCURRENCE:
The cause of this event is "Design, Manufacturing, Construction/Installation", as classified in Appendix B of NUREG-1022. Methods used during installation and design of the EHC power supplies (i.e. wire size used) resulted in minimum margin between the overvoltage protection setpoints and normal EHC power supply voltage. In addition, EHC calibration procedures did not record power supply voltages in a manner that would reveal a reduced margin to trip. The conservative 17.3VDC setpoint contributed to the reduced margin. No component failures were identified as contributors to this event.
PREVIOUS OCCURRENCES:
Review of documentation showed this event to be an isolated occurrence.
Review of documentation showed this event to be an isolated occurrence.
SAFETY SIGNIFICANCE:
SAFETY SIGNIFICANCE:
This event did not affect the health and safety of the public. It is reportable as an automatic RPS actuation in accordance with 10 CFR50. 73 (a) (2) (iv). The RPS functioned as designed and the heat sink was maintained during this event. The reduction in Tav , requiring main steamline isolation, has been experienced during reactor trips (e.g.,Unit 1 LER 272/93-002-00 and Unit 2 LER 311/92-009-00).
This event did not affect the health and safety of the public. It is reportable as an automatic RPS actuation in accordance with 10 CFR50. 73 (a) (2) (iv).
Engineering is investigating Tavq reduction following trips and potential corrective actions are being assessed.
The RPS functioned as designed and the heat sink was maintained during this event. The reduction in Tav , requiring main steamline isolation, has been experienced during o~her reactor trips (e.g.,Unit 1 LER 272/93-002-00 and Unit 2 LER 311/92-009-00). Engineering is investigating Tavq reduction following trips and potential corrective actions are being assessed.
CORRECTIVE ACTION: EHC power supplies were monitored for voltage stability and no problems or transients/pulses were recorded.
CORRECTIVE ACTION:
The overvoltage protection circuits were replaced and the overvoltage
EHC power supplies were monitored for voltage stability and no problems or transients/pulses were recorded.
-----------*-===
The overvoltage protection circuits were replaced and the overvoltage
--' . LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station Unit 1 DOCKET NUMBER 5000272 LER NUMBER 94-005-00 PAGE 5 of 5 CORRECTIVE ACTION: (cont'd) protection setpoints reset to 17.9 +/-.1 voe to provide greater margin to trip. The EHC +15 voe bus wiring was reworked to reduce voltage losses in the wiring. Procedure changes have been implemented to require recording of final EHC power supply voltage values in order to ensure adequate margin below the overvoltage protection trip setpoint.
 
LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station         DOCKET NUMBER     LER NUMBER       PAGE Unit 1                              5000272        94-005-00       5 of 5 CORRECTIVE ACTION:     (cont'd) protection setpoints reset to 17.9 +/- .1   voe to provide greater margin to trip.
The EHC +15 voe bus wiring was reworked to reduce voltage losses in the wiring.
Procedure changes have been implemented to require recording of final EHC power supply voltage values in order to ensure adequate margin below the overvoltage protection trip setpoint.
The A +15VDC power supply, including its potentiometer, was replaced as a precautionary measure. The B +15VDC power supply potentiometer was cycled to assure proper performance.
The A +15VDC power supply, including its potentiometer, was replaced as a precautionary measure. The B +15VDC power supply potentiometer was cycled to assure proper performance.
Additional testing of the replaced A power supply and the overvoltage protection circuits will be conducted to evaluate transient effects. During the next Unit 2 outage, voltage readings of the Unit 2 EHC 15VDC power supply will be taken to verify adequacy of the overvoltage protection margin to trip setpoint.
Additional testing of the replaced A power supply and the overvoltage protection circuits will be conducted to evaluate transient effects.
During the next Unit 2 outage, voltage readings of the Unit 2 EHC 15VDC power supply will be taken to verify adequacy of the overvoltage protection margin to trip setpoint.
PSE&G is continuing to investigate Tavg reduction following reactor trips and potential corrective actions are being assessed.
PSE&G is continuing to investigate Tavg reduction following reactor trips and potential corrective actions are being assessed.
MJPJ:pc SORC Mtg. 94-022}}
MJPJ:pc SORC Mtg. 94-022}}

Latest revision as of 06:02, 3 February 2020

LER 94-005-00:on 940210,turbine Trip Occurred Due to Loss of Direct Current Control Power to electro-hydraulic Control Sys.Caused by Error in Design,Mfg,Const & Installation. EHC Power Supplies Monitored for stability.W/940311 Ltr
ML18100A943
Person / Time
Site: Salem PSEG icon.png
Issue date: 03/11/1994
From: Hagan J, Pastva M
Public Service Enterprise Group
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-94-005, LER-94-5, NUDOCS 9403180072
Download: ML18100A943 (7)
v • d • e


Text

e OPS~G Public Service Electric and Gas Company P.O. Box 236 Hancocks Bridge, New Jersey 08038 Salem Generating Station March 11, 1994 U. s. Nuclear Regulatory Commission Document Control Desk Washington, DC 20555

Dear Sir:

SALEM GENERATING STATION LICENSE NO. DPR-70 DOCKET NO. 50-272 UNIT NO. 1 LICENSEE EVENT REPORT 94-005-00 This Licensee Event Report is being submitted pursuant to the requirements of Code of Federal Regulation 10CFR50.73(a) (2) (iv).

Issuance of this report is required within thirty (30) days of event discovery.

Sincerely yours, MJPJ:pc Distribution

.,r.f"lr-.rn 94031eAonootR 6~8E6~12 PDR PDR

. S t'"'""1i;i11L your hands.

95-2189 REV 7-92

NRC FORM 366 .* NUCLEAR REGULATORY COMMISSION PPROVED BY OMB NO. 3150-0104 (5-92) EXPIRES 5/31 /95 ESTIMATED BURDEN PER RESPONSE TO COMPLY WITH THIS INFORMATION COLLECTION REQUEST: 50.0 HRS. FORWARD LICENSEE EVENT REPORT (LER) COMMENTS REGARDING BURDEN ESTIMATE TO THE INFORMATION AND RECORDS MANAGEMENT BRANCH (MNBB 7714), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555-0001, AND TO THE PAPERWORK REDUCTION PROJECT (3150-0104), OFFICE OF (See reverse for required number of digits/characters for each block) MANAGEMENT AND BUDGET, WASHINGTON, DC 20503.

FACILITY NAME (1) DOCKET NUMBER (2) PAGE (3)

Salem Generating Station - Unit 1 05000 272 1OF05 TITLE (4)

Turbine Trip Due To Loss of Direct Current Control Power To Electro-Hydraulic Control Syst.

EVENT DATE (5) LER NUMBER (6 REPORT NUMBER (7) OTHER FACILITIES INVOLVED (8\

FACILITY NAME DOCKET NUMBER

  • SEQUENTIAL REVISION MONTH DAY YEAR YEAR MONTH DAY YEAR NUMBER NUMBER *05000 FACILITY NAME DOCKET NUMBER 02 10 94 94 005 00 03 11 94 05000 OPERATING THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check one or more (11)

MODE (9) 1 20.402(b) 20.405(c) x 50.73(a)(2)(iv) 73.71 (b)

POWER I 99 I 20.405(a)(1)(i) 50.36(c)(1) 50.73(a)(2)(v) 73.71 (c)

I LEVEL (10) 20.405(a)(1)(ii) 20.405(a)(1 )(iii)

U--J--........:....:....:....:....:......:..__ _ _ _

50.36(c)(2) 50.73(a) (2)(i)

~...._4--....:....:..;,_:_.:..;_

50.73(a)(2)(vii) 50.73(a)(2)(viii)(A)

OTHER (Specify in Abstract

_ _ _ _ _1--4--_;_;;__;___;_;;___--I below and in Te>d, NRC 20.405(a)(1 )(iv) 50.73(a)(2)(ii) 50.73(a)(2) (viii)(B) Form 366A) 20.405(a)(1 )(v) 50.73(a)(2)(iii) 50.73(a)(2)(x)

LICENSEE CONTACT FOR THIS LEA 12)

- NAME TELEPHONE NUMBER (Include Area Code)

M. J. Pastva, Jr. - LER Coordinator (609) 339-5165 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)

REPORTABLE REPORTABLE CAUSE SYSTEM COMPONENT MANUFACTURER CAUSE SYSTEM COMPONENT MANUFACTURER TONPRDS TONPRDS SUPPLEMENTAL REPORT EXPECTED (14) EXPECTED MONTH DAY YEAR lj YES NO SUBMISSION (If yes, complete EXPECTED SUBMISSION DATE) x DATE (15)

ABSTRACT (Limit to 1400 spaces, i.e., ai:iRroximately 15 single-spaced typewritten lines) (16)

On 2/10/94, at 1258 hours0.0146 days <br />0.349 hours <br />0.00208 weeks <br />4.78669e-4 months <br />, a control power failure of the turbine Electro-Hydraulic Control (EHC) system occurred causing a turbine/reactor trip. The Unit was stabilized in Mode 3, at approximately 1315 hours0.0152 days <br />0.365 hours <br />0.00217 weeks <br />5.003575e-4 months <br /> (same day). Insufficient margin between the EHC.overvoltage protection* setpoints and normal EHC power supply voltage allowed a variation in voltage to actuate the overvoltage protection circuitry. The margin resulted from design/installation of the EHC power supplies and use of a 17.3VDC setpoint. A contributor was EHC procedures that did not record power supply voltages in a manner that would reveal a reduced margin to trip. No component failures were identified as contributors to this event. EHC power supplies were monitored and no problems or transients/pulses were recorded. The overvoltage protection circuits were replaced and the circuits' setpoints were reset to 17.9 +/- .1 voe, and the EHC +15 voe bus wiring was reworked. Procedure changes have been implemented to ensure adequate margin below the overvoltage protection setpoint. The A +15VDC power supply was replaced and additional testing will be conducted to evaluate transient effects. During the next Unit 2 outage, voltage readings of the Unit 2 EHC 15VDC power supply will be taken to verify adequacy of the overvoltage protection margin to trip setpoint.

NRG FORM 366 (5-92)

REQUIRED NUMBER OF DIGITS/CHARACTERS FOR EACH BLOCK BLOCK NUMBER OF TITLE NUMBER DIGITS/CHARACTERS 1 UP TO 46 FACILITY NAME 8 TOTAL 2 DOCKET NUMBER 3 IN ADDITION TO 05000 3 VARIES PAGE NUMBER 4 UP TO 76 TITLE 6 TOTAL 5 I EVENT DATE 2 PER BLOCK 7 TOTAL 2 FOR YEAR 6 3 FOR SEQUENTIAL NUMBER LER NUMBER 2 FOR REVISION NUMBER 6 TOTAL 7 REPORT DATE 2 PER BLOCK UP TO 18 FACILITY NAME 8 OTHER FACILITIES INVOLVED 8 TOTAL- DOCKET NUMBER 3 IN ADDITION TO 05000 9 1 OPERATING MODE 10 3 POWER LEVEL 1

11 REQUIREMENTS OF 10 CFR CHECK BOX THAT APPLIES UP TO 50 FOR NAME 12 LICENSEE CONTACT 14 FOR TELEPHONE CAUSE VARIES 2 FOR SYSTEM 13 4 FOR COMPONENT EACH COMPONENT FAILURE 4 FOR MANUFACTURER NPRDS VARIES 1

14 SUPPLEMENTAL REPORT EXPECTED CHECK BOX THAT APPLIES 6 TOTAL 15 EXPECTED SUBMISSION DATE 2 PER BLOCK

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station DOCKET NUMBER LER NUMBER PAGE Unit 1 5000272 94-005-00 2 of 5 PLANT AND SYSTEM IDENTIFICATION:

Westinghouse - Pressurized Water Reactor Energy Ind~stry Identification System (EIIS) codes are identified in the text* as {xx}

IDENTIFICATION OF OCCURRENCE:

Turbine/Reactor Trip Due To Loss Of Direct current Control Power To Electro-Hydraulic Control System Event Date: 2/10/94 Report Date: 3/11/94 This report was initiated by Incident Report No.94-045.

CONDITIONS PRIOR TO OCCURRENCE:

Mode 1 Reactor Power 99 % Unit Load 1136 MWe DESCRIPTION OF OCCURRENCE:

On February 10, 1994, at 1258 hours0.0146 days <br />0.349 hours <br />0.00208 weeks <br />4.78669e-4 months <br />, a turbine/reactor trip {JC}

occurred due to a turbine trip signal while above the P-9 reactor power interlock setpoint. The turbine trip was initiated from a direct current (DC) control power failure of the turbine Electro-Hydraulic Control (EHC) System. Emergency Operating Procedure (EOP)-TRIP-1, "Reactor Trip Or Safety Injection" and EOP-TRIP-2, "Reactor Trip Response" were entered and the Unit was stabilized in Mode 3, at approximately 1315 hours0.0152 days <br />0.365 hours <br />0.00217 weeks <br />5.003575e-4 months <br /> (same day).

At 1403 hours0.0162 days <br />0.39 hours <br />0.00232 weeks <br />5.338415e-4 months <br /> (same day) the NRC was notified of this event in accordance with 10CFR50.72(b) (2) (ii).

ANALYSIS OF OCCURRENCE:

The turbine EHC system controls steam flow through the turbine to govern turbine speed and load during startup, normal operation and shutdown. In addition, the system trips the turbine if required.

The two +15-volt DC control power supplies (A and B) to the system are utilized via an auctioneering circuit. Over-voltage protection of the EHC power supplies is provided. Loss of both power supplies is indicated by a Control Room overhead alarm annunciator "EH DC PWR FAIL" first out window (F-32).

The turbine/reactor trip occurred due to a DC control power failure of the turbine EHC System which caused a turbine trip signal while above

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station DOCKET NUMBER LER NUMBER PAGE Unit 1 5000272 94-005-00 3 of 5 ANALYSIS OF OCCURRENCE: (cont'd) the P-9 reactor power interlock setpoint (>/=50% rated thermal power). Emergency Operating Procedure (EOP)-TRIP-1, "Reactor Trip Or Safety Injection", was entered. Main Steam was isolated in accordance with EOP-TRIP-2, "Reactor Trip Response" to limit cooldown of the Reactor Coolant System {AB}. The Unit was stabilized and placed in Mode 3 and Integrated Operating Procedure IOP-8 was entered.

This event resulted from insufficient margin between the overvoltage protection setpoints and normal EHC power supply voltage.

Consequently, a variation in voltage actuated the overvoltage protection circuitry. The A power supply was set at approximately 220 millivolts (mV) below the overvoltage protection setpoint of 17.3 volts and the B power supply was set at approximately 340 mV below the overvoltage protection setpoint of 17.3 volts. Guidance for the power supply, Lambda Electronics, Division of VEEC Instrument Co.,

recommends a setpoint of 115% of the power supply voltage plus 1.0 volt (i.e. > 18 volts). The Westinghouse EHC field calibration procedure recommends an overvoltage protection setpoint of 17.3 volts. However, Engineering & Plant Betterment analysis determined 18VDC as the maximum overvoltage protection setpoint.

Probable contributors to the insufficient setpoint margins:

The power supply bus employed 18 gauge wiring, which may contribute to high line resistance which caused voltage drops from the power supply to the bus. Encountered high line resistance has required setting the power supply voltage relatively high in order to maintain proper bus voltage.

Improperly crimped and loose wiring lugs in the power distribution panel wiring, confirmed by observed voltage transients during movement of the power supply output wiring.

Recommendations in the Westinghouse EHC field calibration procedure required the overvoltage protection setpoint to be 17.3 volts, which was used by PSE&G.

The potentiometer used to adjust the A power supply showed erratic response/high sensitivity to adjustments.

EHC calibration procedure did not record power supply voltages in a manner that would reveal a reduced margin to trip.

No component failures were identified as contributors to this event.

In addition, the loss of one 15 volt power supply resulting in loss

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station DOCKET NUMBER LER NUMBER PAGE Unit 1 5000272 94-005-00 4 of 5 ANALYSIS OF OCCURRENCE: (cont'd) of the other could not be duplicated. However, troubleshooting showed that the A power supply did not adequately control under large load transients.

At the time of this event, efforts were in progress to develop design changes to replace and upgrade the power supplies in response to previously encountered EHC power supply and distribution chassis problems, dating back to August 1992.

APPARENT CAUSE OF OCCURRENCE:

The cause of this event is "Design, Manufacturing, Construction/Installation", as classified in Appendix B of NUREG-1022. Methods used during installation and design of the EHC power supplies (i.e. wire size used) resulted in minimum margin between the overvoltage protection setpoints and normal EHC power supply voltage. In addition, EHC calibration procedures did not record power supply voltages in a manner that would reveal a reduced margin to trip. The conservative 17.3VDC setpoint contributed to the reduced margin. No component failures were identified as contributors to this event.

PREVIOUS OCCURRENCES:

Review of documentation showed this event to be an isolated occurrence.

SAFETY SIGNIFICANCE:

This event did not affect the health and safety of the public. It is reportable as an automatic RPS actuation in accordance with 10 CFR50. 73 (a) (2) (iv).

The RPS functioned as designed and the heat sink was maintained during this event. The reduction in Tav , requiring main steamline isolation, has been experienced during o~her reactor trips (e.g.,Unit 1 LER 272/93-002-00 and Unit 2 LER 311/92-009-00). Engineering is investigating Tavq reduction following trips and potential corrective actions are being assessed.

CORRECTIVE ACTION:

EHC power supplies were monitored for voltage stability and no problems or transients/pulses were recorded.

The overvoltage protection circuits were replaced and the overvoltage

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station DOCKET NUMBER LER NUMBER PAGE Unit 1 5000272 94-005-00 5 of 5 CORRECTIVE ACTION: (cont'd) protection setpoints reset to 17.9 +/- .1 voe to provide greater margin to trip.

The EHC +15 voe bus wiring was reworked to reduce voltage losses in the wiring.

Procedure changes have been implemented to require recording of final EHC power supply voltage values in order to ensure adequate margin below the overvoltage protection trip setpoint.

The A +15VDC power supply, including its potentiometer, was replaced as a precautionary measure. The B +15VDC power supply potentiometer was cycled to assure proper performance.

Additional testing of the replaced A power supply and the overvoltage protection circuits will be conducted to evaluate transient effects.

During the next Unit 2 outage, voltage readings of the Unit 2 EHC 15VDC power supply will be taken to verify adequacy of the overvoltage protection margin to trip setpoint.

PSE&G is continuing to investigate Tavg reduction following reactor trips and potential corrective actions are being assessed.

MJPJ:pc SORC Mtg.94-022

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