05000388/LER-2020-001, Manual Reactor Scram Due to Rising Main Condenser Backpressure
| ML20098F706 | |
| Person / Time | |
|---|---|
| Site: | Susquehanna  |
| Issue date: | 04/07/2020 |
| From: | Cimorelli K Susquehanna, Talen Energy |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| PLA-7849 LER 2020-001-00 | |
| Download: ML20098F706 (4) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(iv)(A), System Actuation 10 CFR 50.73(a)(2)(iv)(B), System Actuation |
| 3882020001R00 - NRC Website | |
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Kevin Cimorelli Site Vice President Attn: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001 Susquehanna Nuclear, LLC 769 Salem Boulevard Berwick, P A 18603 Tel. 570.542.3795 Fax 570.542.1504 Kevin.Cimorelli@TalenEnergy.com SUSQUEHANNA STEAM ELECTRIC STATION LICENSEE EVENT REPORT 50-388/2020-001-00 UNIT 2 LICENSE NO. NPF-22 PLA-7849 TALEN~
ENERGY 10 CPR 50.73 Docket No. 50-388 Attached is Licensee Event Report (LER) 50-388/2020-001-00. The LER reports an event involving a manual scram due to rising main condenser backpressure. The condition is being reported in accordance with 10CFR 50.73(a)(2)(iv)(A) as an event that resulted in a manual actuation of the Reactor Protection System (including a reactor scram).
There were no actual consequences to the health and safety of the public as a result of this event.
This letter contains no new or revised regulatory commitments.
Attachment: LER 50-388/2020-001-00 Copy:
NRC Region I Ms. L. H. Micewski, NRC Sr. Resident Inspector Ms. S. Goetz, NRC Project Manager Mr. M. Shields, PA DEP/BRP April 7, 2020
NRC FORM 366 (04-2020)
NRC FORM 366 (04-2020)
U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 04/30/2020 LICENSEE EVENT REPORT (LER)
(See Page 2 for required number of digits/characters for each block)
(See NUREG-1022, R.3 for instruction and guidance for completing this form http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1022/r3/)
- 1. Facility Name Susquehanna Steam Electric Station Unit 2
- 2. Docket Number 05000388
- 3. Page 1 OF 3
- 4. Title Manual Reactor Scram Due to Rising Main Condenser Backpressure
- 5. Event Date
- 6. LER Number
- 7. Report Date
- 8. Other Facilities Involved Month Day Year Year Sequential Number Rev No.
Month Day Year Facility Name Docket Number 05000 02 14 2020 2020 001 00 04 07 2020 Facility Name Docket Number 05000
- 9. Operating Mode 1
)
No 06 26 2020 Abstract (Limit to 1400 spaces, i.e., approximately 14 single-spaced typewritten lines)
On February 14, 2020 at 00:25, Susquehanna Steam Electric Station (SSES) Unit 2 reactor was manually scrammed due to rising Main Condenser backpressure caused by a loss of the Unit 2 Offgas Recombiner.
This event was reported by Notification EN 54525 in accordance with 10CFR 50.72(b)(2)(iv)(B) and (b)(3)(iv)(A). This event is also reportable in accordance with 10CFR 50.73(a)(2)(iv)(A) as an event that resulted in a manual actuation of the Reactor Protection System (RPS) (including reactor scram), as well as associated isolation and actuation of other systems listed in 10CFR 50.73(a)(2)(iv)(B), including the Reactor Core Isolation Cooling (RCIC) system.
A cause evaluation is in progress. A supplement will be issued to provide information regarding the cause of the condition and corrective actions.
There were no actual safety consequences associated with the condition.
CONDITIONS PRIOR TO EVENT
Unit 1 - Mode 1, approximately 86 percent Rated Thermal Power Unit 2 - Mode 1, approximately 98 percent Rated Thermal Power Loss of the Unit 2 Offgas Recombiner caused a loss of Main Condenser backpressure, which resulted in the need for a manual scram.
EVENT DESCRIPTION
On February 14, 2020 at 00:25, Susquehanna Steam Electric Station Unit 2 reactor was manually scrammed due to rising Main Condenser [EIIS System Code/Component Code: SG/COND] backpressure caused by a loss of the Unit 2 Offgas Recombiner [EIIS System/Component Code: WF/RCB]. Following is a timeline of the events associated with the scram:
February 14, 2020 at approximately 00:12 - Unit 2 Offgas Recombiner 0C145 Panel Trouble and 2C198 Hydrogen Water Chemistry Panel Trouble alarms were received along with indication of rising Main Condenser backpressure. Initial Main Condenser backpressure was 2.6 inches HgA (Mercury Absolute) and was rising at approximately 0.3 inches HgA/minute.
February 14, 2020 at approximately 00:15 - A Recirculation Limiter 2 runback was inserted to lower reactor power. Main Condenser backpressure continued to rise following the reduction in reactor power.
February 14, 2020 at approximately 00:25 - A manual scram was inserted by placing the Reactor Mode Switch to Shutdown when Main Condenser backpressure rose to 6 inches HgA. All control rods inserted.
Reactor water level lowered to -30 inches causing a Level 3 (+13 inches) isolation and a partial (Division 2)
Level 2 (-38 inches) isolation. The Reactor Core Isolation Cooling (RCIC) system [EIIS System Code: BN]
actuated as expected for given plant conditions. Operators subsequently maintained reactor water level at the normal operating band using the Reactor Feed Water system [EIIS System Code: SJ]. No steam relief valves [EIIS System/Component Code: SB/RV] opened. The Reactor Recirculation Pumps [EIIS System Code/Component Code: AD/P] remained in service.
This event was reported by Notification EN 54525 in accordance with 10CFR 50.72(b)(2)(iv)(B) and (b)(3)(iv)(A). This event is also reportable in accordance with 10CFR 50.73(a)(2)(iv)(A) as an event that resulted in a manual actuation of the Reactor Protection System (RPS) (including reactor scram), as well as associated isolation and actuation of other systems listed in 10CFR 50.73(a)(2)(iv)(B), including RCIC.
CAUSE OF EVENT
A cause evaluation is in progress. A supplement will be issued to provide information regarding the cause of the condition.
Page 3 of 3 (04-2020)
U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 04/30/2020 LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET (See NUREG-1022, R.3 for instruction and guidance for completing this form http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1022/r3/)
- 3. LER NUMBER Susquehanna Steam Electric Station Unit 2 05000-388 YEAR SEQUENTIAL NUMBER REV NO.
2020 001 00
ANALYSIS/SAFETY SIGNIFICANCE
Safety significance information will be provided in the supplement to this LER.
CORRECTIVE ACTIONS
Corrective actions will be provided in the supplement to this LER.
COMPONENT FAILURE INFORMATION
Component failure information, as applicable, will be provided in the supplement to this LER.
PREVIOUS OCCURRENCES
Previous occurrences, as applicable, will be provided in the supplement to this LER.