05000446/LER-2020-001, Manual Reactor Trip Due to Trip of Both Main Feedwater Pumps
| ML20070H633 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 02/27/2020 |
| From: | Thomas McCool Luminant, TXU Energy, Vistra Energy, Vistra Operations Company |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| CP-202000032, TXX-20001 LER 2020-001-00 | |
| Download: ML20070H633 (6) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded 10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(viii)(B) 10 CFR 50.73(a)(2)(ix)(A) 10 CFR 50.73(a)(2)(x) 10 CFR 50.73(a)(2)(v)(A), Loss of Safety Function - Shutdown the Reactor 10 CFR 50.73(a)(2)(v)(B), Loss of Safety Function - Remove Residual Heat 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(i) |
| 4462020001R00 - NRC Website | |
text
CP-202000032 TXX-20001 U.S. Nuclear Regulatory Commission ATIN: Document Control Desk Washington, DC 20555-0001 02/27/2020 V!!.: !ti\\
ENERGY
~~TXU I I!
'f* energy Luminant
SUBJECT:
COMANCHE PEAK NUCLEAR POWER PLANT DOCKET NO. 50-446 Thomas P. McCool Site Vice President Luminant P.O. Box 1002 6322 North FM 56 Glen Rose, TX 76043 o 254.897.6042 Ref 10 CFR 50.73 MANUAL REACTOR TRIP DUE TO TRIP OF BOTH MAIN FEEDWATER PUMPS LICENSEE EVENT REPORT 446/20-001-00
Dear Sir or Madam:
Pursuant to 10CFR50. 73, Vistra Operations Company LLC (Vistra OpCo), hereby submits the enclosed Licensee Event Report 446/20-001-00, "Manual Reactor Trip Due To Trip Of Both Main Feedwater Pumps" for Comanche Peak Nuclear Power Plant (CPNPP} Unit 2.
This communication contains no new licensing basis commitments regarding CPNPP Unit 2.
6555 SIERRA DRIVE IRVING, TEXAS 75039 0214-812-4600 VISTRAENERGY.COM
TXX-20001 Page 2 of 2 If you have any questions regarding this submittal, please contact Gary L. Merka at 254-897-6613.
Enclosure c-Scott A. Morris, Region IV Dennis Galvin, NRR Resident Inspectors, Comanche Peak Sincerely, I
Thomas l'..,.)VlcCool
NRCFORM366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY 0MB: NO. 3150-0104 EXPIRES: 03/31/2020 (04-2018)
, the NRC may not conduct or sponsor, and a person is not required to respond to, the Information collection.
3.Page Comanche Peak Nuclear Power Plant 05000 446 1
OF 4
- 4. Title Manual Reactor Trip Due To Trip Of Both Main Feedwater Pumps
- 5. Event Date
- 6. LER Number
- 7. Report Date
- 8. Other Facilities Involved I
Sequential I Rev Year Facility Name Docket Number Month Day Year Year Number No.
Month Day 05000 Facility Name Docket Number 01 01 2020 2020 -
001 -
00 02 27 2020 05000
- 9. Operating Mode
- 11. This Report is Submitted Pursuant to the Requirements of 1 O CFR §: (Check all that apply)
D 20.2201(b)
D 20.2203(a)(3)(i)
D 50.73(a)(2)(ii)(A)
D 50.73(a)(2)(viii)(A)
D 20.2201(d)
D 20.2203(a)(3)(ii)
D 50.73(a)(2)(ii)(B)
D 50.73(a)(2)(viii)(B) 1 D
D D
D 20.2203(a)(1) 20.2203(a)(4)
- 50. 73(a)(2)(iii) 50.73(a)(2)(ix)(A)
D 20.2203(a)(2)(i)
D 50.36(c)(1)(i)(A) 0 50. 73(a)(2)(iv)(A)
D 50.73(a)(2)(x) 1 O. Power Level D 20.2203(a)(2)(ii)
D 50.36(c)(1)(ii)(A)
D 50.73(a)(2)(v)(A)
D 73.71(a)(4)
D 20.2203(a)(2)(iii)
D 50.36(c)(2)
D 50.73(a)(2)(v)(B)
D 73.71 (a)(5)
D 20.2203(a)(2)(iv)
D 50.46(a)(3)(ii)
D 50.73(a)(2)(v)(C)
D 73.77(a)(1) 100 D 20.2203(a)(2)(v)
D 50. 73(a)(2)(i)(A)
D 50.73(a)(2)(v)(D)
D 73.77(a)(2)(i)
D 20.2203(a)(2)(vi)
D 50.73(a)(2)(i)(B)
D 50.73(a)(2)(vii)
D 73.77(a)(2)(ii)
~Cfl\\; D 50.73(a)(2)(i)(C)
D Other (Specify in Abstract below or in SUMMARY OF THE EVENT, INCLUDING DATES AND APPROXIMATE TIMES On January 1, 2020, Operators (Utility, Licensed) were shutting down Circulating Water Pump 2-01 [EIIS:(NN)(P}], which is a normal plant activity to improve efficiency during the Winter months. The Circulating Water Pumps at CPNPP draw water from the Squaw Creek Reservoir (SCR) and, through a system of piping and valves, pass that water as a cooling medium through various components including the Main and Auxiliary Condensers, before discharging the water back into the SCR. Seasonal variation in the temperature of the SCR necessitates periodic shifting in the lineup of the Circulating Water Pumps and throttling cooling water flow to ensure maximum efficiency in plant operation.
During adjustment of the Auxiliary Condenser Outlet Valves [EIIS:(SG)(PDCV)], Operators inadvertently closed both of the outlet valves simultaneously. This caused a loss of vacuum on both Main Feedwater Pumps [EIIS:(SJ)(P)] and both pumps automatically tripped on low vacuum. At 1253, CPNPP Unit 2 was manually tripped due to the trip of both Main Feedwater Pumps. The Unit 2 Auxiliary Feedwater Pumps started as designed due to trip of both Main Feedwater Pumps. There was no impact on Unit 1.
E. THE METHOD OF DISCOVERY OF EACH COMPONENT OR SYSTEM FAILURE, OR PROCEDURAL PERSONNEL ERROR Operators (Utility, Licensed) in the Unit 2 Control Room received Feedwater Pump Turbine A and B trip alarms on the Main Control Board.
II. COMPONENT OR SYSTEM FAILURES A. CAUSE OF EACH COMPONENT OR SYSTEM FAILURE Not applicable - No component or system failures were identified during this event.
B. FALURE MODE, MECHANISM, AND EFFECTS OF EACH FAILED COMPONENT Not applicable - No component or system failures were Identified during this event.
C. SYSTEMS OR SECONDARY FUNCTIONS THAT WERE AFFECTED BY FAILURE OF COMPONENTS WITH MULTIPLE FUNCTIONS Not applicable - No component or system failures were identified during this event.
D. FAILED COMPONENT INFORMATION
Not applicable - No component or system failures were identified during this event.
Ill. ANALYSIS OF THE EVENT A. SAFETY SYSTEM RESPONSES THAT OCCURRED The Unit 2 Reactor Protection System and the Unit 2 Auxiliary Feedwater systems responded as designed.
B. DURATION OF SAFETY SYSTEM TRAIN INOPERABILITY This event did not involve the inoperability of any safety systems.
C. SAFETY CONSEQUENCES AND IMPLICATIONS
OF THE EVENT A loss of normal feedwater is an ANS Condition II event (Faults of Moderate Frequency). This event is bounded by FSAR Section 15.2, "Decrease In Heat Removal By The Secondary System." When both of the Main Feedwater Pumps tripped, the reactor was manually tripped and the Auxiliary Feedwater System automatically started to provide feedwater to the steam generators.
No automatic safety functions were exercised other than the expected automatic start of the Auxiliary Feedwater System and all plant safety systems responded as designed during the resultant transient. This event had no impact on nuclear safety, reactor safety, radiological safety, environmental safety, or the safety of the public. This event has been evaluated to not meet the definition of a safety system functional failure per 1 OCFR50.73(a)(2)(v).
IV. CAUSE OF THE EVENT
The cause of this event was neither the on-shift crew nor the leadership supporting them recognized, understood or addressed the risk prior to throttling the Auxiliary Condenser outlet valves in the closed direction. The potential risk to generation never entered the thinking of anyone involved in the task. Adjusting the CWP cooling flow was considered a routine task covered by procedure. Crew inexperience and the negative potential of that inexperience was not adequately considered or addressed.
V. CORRECTIVE ACTIONS
Immediate Corrective Actions included removal of the involved Operations personnel pending Performance Improvement plans, presentation of a case study on the preliminary causes of the event to all Operations personnel prior to assuming watch standing duties, additional around the clock field and control room oversight for two weeks with daily roll-ups, oral boards for all Operations personnel, and re-performance of Leadership and Team Effectiveness assessments for crew composition. Per the CPNPP Corrective Action Program, Behavioral Learning Activities will be developed to reinforce Operator Fundamentals, Nuclear Professional Fundamentals and Supervisory Intrusiveness. A site wide observation blitz will be conducted on challenging risk, preparation, and critical thinking in work preparation (including Pre-Job Briefs) and execution.
VI. PREVIOUS SIMILAR EVENTS
There have been other manual reactor trips in the last three years. However, the causes of those events are believed to be sufficiently different from this event such that previous corrective actions could not have prevented this event. Page 4
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