05000370/LER-1997-001-06, :on 970527,DG Load Sequencer 2B Inadvertent Esfa Occurred.Caused by Inadequate Development & Review of Change Made to Sequencer Timer Calibr Procedure.Review of Similar Procedures Being Conducted
| ML20141F031 | |
| Person / Time | |
|---|---|
| Site: | Mcguire |
| Issue date: | 06/25/1997 |
| From: | Pitesa J DUKE POWER CO. |
| To: | |
| Shared Package | |
| ML20141F027 | List:
|
| References | |
| LER-97-001-06, LER-97-1-6, NUDOCS 9707010315 | |
| Download: ML20141F031 (6) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(iv), System Actuation 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2) 10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2)(x) |
| 3701997001R06 - NRC Website | |
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- NRC FORM 366 U S. NUCLEAR REGULATORY COMMISSION APPROVED EY OMB NO. 31504104 EXPtRES 04t30t94 ESTIMATED BURDEN PER RESPONSE TO COMPLY WITH THIS MANDATORY INFORMATION COLL ECTION REQUEST; 50.0 HRS.
REPORTED LESSONS LEARNED ARE INCORPORATED INTO THE LICENSEE EVENT REPORT (LER) uCENSiNo PROCESS ANo RED BACK TO iNDuSTRv. FORWARD COMMENTS REGARDING BUROEN ESTIMATE TO THE INFORMATION AND RECORDS MANAGEMENT BRANCH (T 6 F33). U.S. NUCLEAR l
REGULATORY COMMISSION, WASHINGTON, DC 206554001, AND TO THE PAPERWORK REDUCTION PROJECT (3150-0104). OFFICE OF MANAGEMENT AND BUOGET, WASHINGTON. DC 20503 FACILITY NAME (1)
DOCKET NUMBER (2)
PAGE {3)
McGuire Nuclear Station, Unit 2 05000 370 1 Of 6 TITLE (4)
Diesel Generator Load Sequencer 28 Inadvertent Engineered Safety Feature Actuation EVENT DATE (5)
LER NUMBER (6)
REPORT DATE (7)
OTHER FACILITIES INVOLVED (8)
MONTH DAY YEAR YEAR SEQUENTIAL REVISION MONTH DAY YEAR FACILITV NAME DOCKEI NUMBER (S)
NUMDER
(
NUteER N/A 05000 05 27 97 97 01 00 06 25 97 05000 OPERATING THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR (Check one or more of the followrno)(11 MODE (M 1
20.402(b) 20.405(c) x 50.73(a)(2)(iv) 73.71(b)
POWEJ 20.405(a)(1)(i) 50.36(c)(1) 50.73(a)(2)(v) 73.71(c)
LEVEL (10) 100 20.405(a)(1)(ii) 50.36(c)(2) 50.73(a)(2)(vii)
OTHER (Specitin m.,
.n
- - t..
20.405(a)(1)(lii) 50.73(a)(2)(l) 50.73(a)(2)(viii)(A)
Abstract below and h j -g -b[ ;
20.40$(a)(1)(iv) 50.73(a)(2)(ll) 50.73(a)(2)(vill)(B) in Text, NRC Form W'
" xh 20 40$(a)(1)(v) 50 73(a)(2)(lii) 50.73(a)(2)(x) 366A)
LICENSEE CONTACT FOR THIS L ER (12)
NAME TELEPHONE NUMBER AREA CODE J. W. PiteSa (704) 875-4788 COMPLETE ONE LINE FOR E ACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)
CAUSE
SYSTEM COMPONENT MANUFACTURER REPORTABLE
CAUSE
SYSTEM COMPONENT MANUFACTURER REPORTABLE u
TO NPROS M
TO NPRDS N
b NO
%[
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' \\s
'*i'.
SUPPLEMENTAL REPORT EXPECTED (14)
EXPECTED MONTH DAY YEAR SUBMISSION YES (1 yes, complete EXPECTED SUBMISSION DA TE) x NO DATE (15)
ABSTRACT (Lima to 1400 spaces, Le. app,oximately fifteen single space typewritten knes)(16)
Unit Status: Unit 2 was in Mode 1 (Power Operation) at 100 percent power.
Ernt Description: On May 27, 1997, at approximately 1135, Instrument and Electrical (IAE) Technicians were performing the Train B Diesel Sequencer Timer Calibration when a partial actuation of Train B Blackout equipment occurred.
The Turbine Driven Auxiliary Feedwater Pump and the 2B Nuclear Service Water Pump auto started, and several Nuclear Service Water valves realigned.
Subsequently, when LAE Technicians were verifying a sliding link was securely open, a partial actuation of Train B Safety Injection (SI) equipment occurred. No abnormal equipment actuation was identified and opnrator actions were appropriate for the event.
The health and safety of the public and plant personnel were not affected as a result of this event.
This event is not considered significant.
Evrnt Cause The partial actuation of Blackout equipment was caused by inadequate development and review of a change made to the Sequencer Timer Calibration procedure.
The partial actuation of SI equipment could not be conclusively determined, but is believed to have been caused by IAE personnel inadvertently making contact with both sides of a sliding link while i
verifying the link was securely open.
Ccrrective Action: A review of similar procedures which test safety related logic circuits is being conducted to apply lessons learned from this event.
Additionally, a communication of lessons learned on this event will be given to appropriate IAE and Plant Engineering personnel.
"" " Wo7010315 970626 PDR ADOCK 05000370 S
eU S. NGCLEAR REGULATOHV COMMISSION (6 APPROVED BY 0808 NO. 31504104 69)
EXPIRES 04/3W98 ESitMATED BURDEN PER RESPONSE TO COMPLY WITH THIS MANDATORY INFORMATION COLLECTION REQUEST: 50.0 HRS. REPORTED LESSONS LICENSEE EVENT REPORT (LER)
LEARNED ARE iNCORPOnATED iNTO THe uCENSiNG 5 ROCESS AND RED TEXT CONTINUATION BACK TO INDUSTRY. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE INFORMATION AND RECORDS MANAGFMENT BRANCH (T4 F33) U.S. NUCLEAR REGULATOHY COMMISSION. WASHINGTON, DC 20555 0001. AND TO THE PAPERWORK REDUCTION PROJECT (3150 0104).
OFFICF OF MANAGFMFNT AND BODGFT. WASHINGTON 0C P0503 FACILITY NAME (1)
DOCKET NUMBER (2)
LER NUMBER (6 PAGE (3) g%
YEAR SEQUEN'nAL REVISION NUMBFR NUMBER e
g McGuire Nuclear Station, Unit 2 5000 370 97 M
01 R
00 2OF6 EVALUATION:
Background
Nuclear Regulatory Commission Generic Letter 96-01 was issued to request licensees evaluate the adequacy of testing safety related logic circuits.
During Generic Letter 96-01 review, it was determined that the Diesel Generator (EIIS: EK] Load Sequencer Test circuitry was not being fully tested.
Current testing did not verify that the Sequencer test circuitry would allow the Sequencer to come cut of test and begin sequencing emergency load groups if a valid Safety Injection or Blackout
'3 signal occurred while in test.
Description of Event
At the time of the event Unit 2 was in Mode 1 (Power Operation) at 100 percent power.
The Train B Emergency Diesel Generator control power had been tagged for maintenance and the sequencer timer calibration.
Additionally, the Train B Motor [EIIS: MO) Driven Auxiliary Feedwater (CA) [EIIS: BA] Pump [EIIS: P] was tagged out for maintenance.
On May 27, 1997, at approximately 1135, Instrument and Electrical l
(IAE) Technicians were performing the Train B Diesel Sequencer Timer Calibration procedure (IP/0/A/3250/012B) when a partial actuation of Train B Blackout equipment occurred.
The Turbine [EIIS: TRB] Driven CA (TDCA) Pump and the 2B Nuclear Service Water (RN) [EIIS: BI] Pump auto started, and several Nuclear Service Water valves (EIIS: V]
realigned.
I l
The Reactor Operator at the Controls (ROATC) reset and closed the Steam Generator [EIIS: SG) (S/G) CA Control Valves to terminate i
feeding the S/Gs.
Operations personnel declared the TDCA Pump inoperable due to closure of the CA Control Valves.
(Note: Technical Specifications (TS) surveillance require the CA discharge control 4
valves to be fully open at all times above 10% reactor power and these valves auto open on an automatic pump start.)
This resulted in two CA pumps being inoperable requiring the unit to be in at least HOT STANDBY within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> per TS.
1 i
Two RN valves closed which isolated cooling water to the containment e
ventilation systems and caused Unit 2 containment pressure and temperature to increase.
Operations personnel opened a discharge flow path for the Train B RN Pump to the Standby Nuclear Service
a e
.U S. NELEAR REQUI.ATORY COMMISSON(6-APPROVED BY OM8 NO. 31504104 09)
EXPIRES 04/3098 ESTIMATED BURDEN PER RESPONSE TO COMPLY WITH THl3 MANDATORY INFORMATION COLLECTION REQUEST: 50.0 HRS. REPORTED LESSONS LICENSEE EVENT REPORT (LER)
LEARNED AaE INCORPORATED iNTO THE uCENSiNo PROCESS AND RED BACK TO INDUSTRY. FORWARD COMMENTS REGARDING BURDEN 1
TEXT CONTINUATION ESWATE TO THE INFORMATON 20 RECORDS MANAGEMENT BRANCH (T4 F33), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 205$5-0001, ANO TO THE PAPERWORK REDUCTION PROJECT (3150-0104),
OFFICF OF MANAGFMENT ANO BUDGFT, WASHINGTON DC 20503 FACIUTY NAME (1)
DOCKET NUMBER (2)
LER NUMBER (6)
PAGE (3)
YEAR SEQUENTIAL j@
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e e
j McGuire Nuclear Station. Unit 2 5000 370 97 01 00 3 OF 6 i
Water Pond which re-established containment ventilation cooling water flow.
IAE personnel began investigating the cause of the partial actuation of Blackout equipment.
At this point, the investigation was limited to verifying electrical and equipment status.
No maintenance actions were to be taken until an adequate review of the event had been completed.
j At approximately 1144, a partial actuation of Train B Safety i
Injection equipment occurred while IAE Technicians were verifying that a sliding link was securely open.
This sliding link had been opened by the Sequencer Timer Calibration procedure to allow the Diesel Generator Load Sequencer Test circuitry to remain in the circuit when a simulated SI and Blackout signal was introduced.
The partial actuation of Train B Safety Injection equipment caused the Train B ECCS pumps to start and run in recirculation.
Additionally, the Train B Component Cooling Water (KC) [EIIS: CC]
Pump auto-started.
A four hour notification was made to the Nuclear Regulatory Commission, per 10CFR50.72, due to the Engineered Safety Feature actuation.
Because the TDCA auto-start signal was still present while Engineering and IAE personnel were evaluating the event, Operations personnel locally tripped the TDCA pump.
At approximately 1500, when it was determined that the event evaluation and troubleshooting would extend beyond the TS time limits for two inoperable CA Pumps, the TDCA pump was restarted, aligned to the S/Gs and declared operable.
On May 28, 1997, at approximately 0045 the 2B Load Sequencer was completely reset and the ECCS systems were returned to standby readiness.
The TDCA Pump ran until the 2B Motor Driven Auxiliary Pump was returned to an operable status at 1140 and realigned to standby readiness.
1
.U S. Nt;CLE AR REGULATORY COMMISSIONf6-APPROVED SY 048 NO. 31804104 sei ExPuws w3ame ESTIMATED BURDEN PER RESPONSE 10 COMPLY WITH THIS MANDATORY INFORMATION COLLECTION REQUEST: 50.0 HRS. REPORTED LESSONS LICENSEE EVENT REPORT (LER)
LEARNED ARE INCORPORATED INTO THE UCENSING PROCESS AND FED BACK TO INDUSTRY. FORWARD COMMENTS REGARDING BURDEN TEXT CONTINUATION ESTIMATE TO THE INFORMATION AND RECORDS MANAGEMENT BRANCH (T4 F33) U.S. NUCLEAR REGLA.ATORY COMMISSION, WASHINGTON, DC 20555-0001, AND TO THE PAPERWORK REDUCTION PROJECT (3150 0104).
OFFICE OF MANAGEMENT AND BUDGET, WASHINGTON DC 20503 FACluTY NAME (1)
DOCKET NUMBER (2)
LER NUMBER (6 PAGE (3)
YEAR
$EQUENTIAL REbSION NUMBFR NUMBER 3
P McGuire Nuclear Station Unit 2 5000 070 97 01 h 00 4 OF 6 j
Conclusion This event did not result in any uncontrolled releases of radioective i
material, personnel injuries, or radiation overexposures.
This event is not Nuclear Plant Reliability Data System (NPRDS) reportable.
This event is assigned causes of Procedure Deficiency and apparent Inadvertent Action.
The Procedure Deficiency contained in the Train B Diesel Sequencer Timer Calibration procedure (IP/0/A/3250/012B) was caused by inadequate development and review of a procedure section.
This occurred when the procedure was revised to incorporate additional testing of that portion of the Sequencer Test Circuitry which allows the Sequencer to come out of test and begin sequencing emergency load groups if a valid Safety Injection or Blackout signal occurs while in test.
Since the associated circuitry was not originally designed for this test, it was determined that sliding a link to maintain a test timer relay [EIIS: RLY] de-energized would be the best way to isolate the test circuitry from the introduced SI and Blackout signal.
The procedure writer and reviewer failed to recognize a circuit interaction.which would backfeed the test relays and maintain two of the relays energized due to an additional relay negative leg wire which bypassed the sliding link when the Blackout signal was momentarily introduced as instructed by the procedure. Five of the seven test blocking relays de-energized and prevented the test signal from being blocked which allowed partial Sequencer logic to be satisfied. This allowed the TDCA Pump and a second RN Pump to auto start and several RN valves to realign.
It appears an Inadvertent Action by IAE personnel occurred while attempting to verify that the sliding link was securely open.
While it could not be conclusively determined, it appears that the nut driver used to ensure the sliding link was open may have inadvertently contacted both sides of the terminal introducing a momentary Safety Injection signal that resulted in energizing the Sequencer loading relays.
The partial Train B Safety Injection actuation caused the Train B ECCS pumps to start and run in recirculation.
Additionally, the Train B KC Water Pumps auto-started.
The Train B Emergency Diesel Generator was not started since its control power had been tagged out for the Sequencer Timer Calibration.
NHC FORM 366A U.S. NUCLEAR REGULATORY COMMIS$10NG-APPROVO BY OM8 NO. 315&O104
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ExmEs==
ESTIMATED BURDEN PER RESPONSE TO COMPLY WITH THIS MANDATORY INFORMATION COLLECTION REQUEST 50.0 HRS. REPORTED LESSONS LICENSEE EVENT REPORT (LER)
LEARNEo ARE iNCOReORATEo iNTO TsE uCENSiNG eROCESS ANo reo BACK TO INDUSTRY. FORWARO COMMENTS REGARDING BURDEN TEXT CONTINUATION ESTiuATE TO TuE iNFORuATiON ANO RECORoS uANAoEuENT.RANCs (T 6 F33), U.S NUCLEAR REGULATORY COMMISS!ON, WASHINGTON. DC 20555401, AND TO THE PAPERWORK REDUCTION PROJECT (3150 0104),
OFFICF OF MANAGFMENT AND 000GFT WASHINGTON 00 20503 FACILITY NAME (1)
DOCKET NUMBER (2)
LFR NUMBER (6)
PAGE (3)
YEAR
',%f,
SEQUENTLAL 4
REVISION NUMBFR 4a NUMBE R
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McGuire Nuclear Station, Unit 2 5000 370 97 01 00 5OF6 All equipment operated as expected and operator actions were appropriate for this event.
A search of the Operating Experience and Problem Investigation Program Database for the previous 24 months did not render any evidence of a similar event. Therefore, this is not considered a recurring event.
CORRECTIVE ACTION
Immediate:
I 1.
OPS personnel entered appropriate procedures to control the transient.
Subsequent:
1.
Procedures IP/0/A/3250/012A and B (Train A/B Diesel Sequencer Timer Calibration) were placed on HOLD until they could be reviewed.
Planned:
- 1. A review of the procedures that were and are in the process of being modified as a result of Nuclear Regulatory Commission Generic Letter 96-01, is being conducted to apply lessons learned from this event.
- 2. Communication of lessons learned on this event will be given to appropriate IAE and Plant Engineering personnel.
SAFETY ANALYSIS
The health and safety of the public and plant personnel were not affected as a result of this event.
Therefore, this event is not 4
considered significant.
The following facts support the conclusion that this event was not safety significant:
i The Unit was always in compliance with Technical Specifications.
e The Unit was never in an unanalyzed condition or outside of its design basis.
e NRQ FQHM 306A U S. NUCLEAR REGUll. TORY COMMGS3ON(6-APPROVED AV OME NO. 3150 0104 89)
EXPtRES 04/3044 ESilMATED BURDEN PER RESPONSE TO COMFtY WITH THIS MANDATORY INFORMATION COLLECTION REQUEST: 50.0 HRS. REPORTED LESSONS LICENSEE EVENT REPORT (LER)
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ESTiuATE TO TwE iNrORuATiON AND RECORDS uANAoEuENT BRANCN (T-6 F33), U S NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 205554001, AND TO THE PAPERWORK REDUCTION PROJECT (3150 0104),
OFFICE OF MANAGFMFNT AND BUDGET. WASHINGTON DC 20503 FACluTY NAME (1)
DOCKET NUMBER (2)
L ER NUMBER (6)
PAGE (3) 4 YEAR l
SEQUENTIAL g REVISION NUMRFR M
NUMBER p
g McGuire Nuclear Station, Unit 2 5000 370 97 e
01 00 6 OF 6 The equipment necessary to mitigate the consequences of an accident was always available since the Train 2A Diesel Generator and both trains ECCS remained operable and available throughout this event.
Unit 2 did not have a transient or have any plant conditions warranting a Blackout or Safety Injection signal during this event.
Each signal associated with the event had been simulated or initiated for the test.
No ECCS Injection into the Reactor Coolant (NC) [EIIS: AB] System occurred due to this event.
1 Additionally, while portions of the Train 2B Emergency Systems were unavailable during this event, the ECCS Systems were operable.
The following facts give perspective on Train 2B equipment availability during this event:
The Train 2B Diesel Generator was inoperable and unavailable during this event due to having control power tagged to prevent auto-starting during the test.
The unavailability of the Diesel Generator concurrent with the inoperability of the TDCA Pump places Unit 2 in a Technical Specification to be in at least HOT STANDBY within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />.
The Train 2B Motor Driven CA Pump was tagged out for maintenance and was unavailable throughout this event.
i The TDCA Pump was declared inoperable for approximately 3.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> a
however, it was unavailable for only 2.45 hours5.208333e-4 days <br />0.0125 hours <br />7.440476e-5 weeks <br />1.71225e-5 months <br /> concurrent with the Motor Driven CA Pump unavailability.
With two inoperable CA pumps, Technical Specifications require the unit to be in at least HOT STANDBY within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />.
The Train 2B ECCS Pumps, the KC Pumps, and the RN Pumps auto-started e
during the event and were continuously available.
If a valid Safety Injection signal had occurred, Emergency Operating Procedure guidance would have aligned the systems appropriately to allow the systems to operate as designed.