PLA-7976, Automatic Reactor Scram Due to Main Turbine Trip

Automatic Reactor Scram Due to Main Turbine Trip

ML21343A422
Person / Time
Site:	Susquehanna
Issue date:	12/09/2021
From:	Cimorelli K Susquehanna
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
PLA-7976
Download: ML21343A422 (4)

Text

Kevin Cimorelli Site Vice President December 9, 2021 Attn: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001 Susquehanna Nuclear, LLC 769 Salem Boulevard Berwick, PA 18603 Tel. 570.542.3795 Fax 570.542.1504 Kevin.Cimorelli@TalenEnergy.com SUSQUEHANNA STEAM ELECTRIC STATION LICENSEE EVENT REPORT 50-388/2021-003-00 UNIT 2 LICENSE NO. NPF-22 PLA-7976 TALEN~

ENERGY 10 CFR 50.73 Docket No. 50-388 Attached is Licensee Event Report (LER) 50-388/2021-003-00. The LER reports an event involving an automatic scram due to a main turbine trip. The condition is being reported in accordance with 10 CFR 50.73(a)(2)(iv)(A) as an event that resulted in an automatic 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 co tains no new or revised regulatory commitments.

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Attachment:

LER 50-388/2021-003-00 Copy:

NRC Region I Ms. A. Klett, NRC Project Manager Mr. C. Highley, NRC Senior Resident Inspector Mr. M. Shields, PA DEP/BRP

NRC FORM 366 (08-2020)

U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 08/31/2023 LICENSEE EVENT REPORT (LER)

(See Page 3 for required number of digits/characters for each block)

(See NUREG-1022, R.3 for instruction and guidance for completing this form https://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1022/r3/)

Estimated burden per response to comply with this mandatory collection request: 80 hours9.259259e-4 days <br />0.0222 hours <br />1.322751e-4 weeks <br />3.044e-5 months <br />. Reported lessons learned are incorporated into the licensing process and fed back to industry. Send comments regarding burden estimate to the FOIA, Library, and Information Collections Branch (T-6 A10M), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by e-mail to Infocollects.Resource@nrc.gov, and the OMB reviewer at: OMB Office of Information and Regulatory Affairs, (3150-0104), Attn: Desk ail: oira_submission@omb.eop.gov. The NRC may not conduct or sponsor, and a person is not required to respond to, a collection of information unless the document requesting or requiring the collection displays a currently valid OMB control number.

1. Facility Name

2. Docket Number

3. Page Susquehanna Steam Electric Station Unit 2 05000388 1 of 3

4. Title Automatic Reactor Scram Due to Main Turbine Trip

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 10 11 2021 2021 - 003 -

00 12 09 2021 Facility Name Docket Number 05000

9. Operating Mode

10. Power Level 1

095

11. This Report is Submitted Pursuant to the Requirements of 10 CFR §:

(Check all that apply) 10 CFR Part 20 20.2203(a)(2)(vi) 50.36(c)(2) 50.73(a)(2)(iv)(A) 50.73(a)(2)(x) 20.2201(b) 20.2203(a)(3)(i) 50.46(a)(3)(ii) 50.73(a)(2)(v)(A) 10 CFR Part 73 20.2201(d) 20.2203(a)(3)(ii) 50.69(g) 50.73(a)(2)(v)(B) 73.71(a)(4) 20.2203(a)(1) 20.2203(a)(4) 50.73(a)(2)(i)(A) 50.73(a)(2)(v)(C) 73.71(a)(5) 20.2203(a)(2)(i) 10 CFR Part 21 50.73(a)(2)(i)(B) 50.73(a)(2)(v)(D) 73.77(a)(1)(i) 20.2203(a)(2)(ii) 21.2(c) 50.73(a)(2)(i)(C) 50.73(a)(2)(vii) 73.77(a)(2)(i) 20.2203(a)(2)(iii) 10 CFR Part 50 50.73(a)(2)(ii)(A) 50.73(a)(2)(viii)(A) 73.77(a)(2)(ii) 20.2203(a)(2)(iv) 50.36(c)(1)(i)(A) 50.73(a)(2)(ii)(B) 50.73(a)(2)(viii)(B) 20.2203(a)(2)(v) 50.36(c)(1)(ii)(A) 50.73(a)(2)(iii) 50.73(a)(2)(ix)(A)

Other (Specify here, in Abstract, or in NRC 366A).

12. Licensee Contact for this LER Licensee Contact Phone Number (Include Area Code)

D. R. Smith, Senior Engineer - Nuclear Regulatory Affairs 570-542-1377

13. Complete One Line for each Component Failure Described in this Report Cause System Component Manufacturer Reportable to IRIS Cause System Component Manufacturer Reportable to IRIS

14. Supplemental Report Expected

15. Expected Submission Date Month Day Year No Yes (If yes, complete 15. Expected Submission Date) 02 28 2022

16. Abstract (Limit to 1560 spaces, i.e., approximately 15 single-spaced typewritten lines)

On October 11, 2021, at approximately 13:21, Susquehanna Steam Electric Station Unit 2 reactor automatically scrammed due to a main turbine trip. Both divisions of the Reactor Protection System (RPS) actuated and all control rods inserted. This event was reported by Event Notification 55514 in accordance with 10 CFR 50.72(b)(2)(iv)(A), (b)(2)(iv)(B) and (b)(3)(iv)(A). This event is also reportable in accordance with 10 CFR 50.73(a)(2)(iv)(A) as an event that resulted in automatic actuation of a system listed in 10 CFR 50.73(a)(2)(iv)(B).

The cause of the event is under investigation and will be provided in a supplement to this LER along with associated corrective actions.

There were no actual consequences to the health and safety of the public as a result of this event.

NRC FORM 366 (08-2020)

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NRC FORM 366A (08-2020)

Page 2 of 3.

NRC FORM 366A (08-2020)

U. S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 08/31/2023 LICENSEE EVENT REPORT (LER)

CONTINUATION SHEET Estimated burden per response to comply with this mandatory collection request: 80 hours9.259259e-4 days <br />0.0222 hours <br />1.322751e-4 weeks <br />3.044e-5 months <br />. Reported lessons learned are incorporated into the licensing process and fed back to industry. Send comments regarding burden estimate to the FOIA, Library, and Information Collections Branch (T-6 A10M), U.S.

Nuclear Regulatory Commission, Washington, DC 20555-0001, or by e-mail to Infocollects.Resource@nrc.gov, and the OMB reviewer at: OMB Office of Information and Regulatory Affairs, (3150-0104), Attn: Desk ail: oira_submission@omb.eop.gov. The NRC may not conduct or sponsor, and a person is not required to respond to, a collection of information unless the document requesting or requiring the collection displays a currently valid OMB control number.

(See NUREG-1022, R.3 for instruction and guidance for completing this form https://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1022/r3/)

1. FACILITY NAME

2. DOCKET NUMBER

3. LER NUMBER Susquehanna Steam Electric Station Unit 2 05000-388 YEAR SEQUENTIAL NUMBER REV NO.

2021 003 00 NARRATIVE CONDITIONS PRIOR TO EVENT Unit 1 - Mode 1, approximately 100 percent Rated Thermal Power Unit 2 - Mode 1, approximately 95 percent Rated Thermal Power There were no structures, systems, or components that were inoperable at the start of the event that contributed to the event.

EVENT DESCRIPTION On October 11, 2021, at approximately 13:21, Susquehanna Steam Electric Station Unit 2 reactor automatically scrammed due to a main turbine [EIIS System/Component Code: TA/TRB] trip. The Unit 2 Control Room received indication of a main turbine trip with both divisions of the Reactor Protection System (RPS) [EIIS System Code: JC] actuated and all control rods inserted. The turbine bypass valves

[EIIS System/Component Code: JI/PCV] opened automatically to control reactor pressure and subsequently remained open causing the reactor to depressurize. Operations manually closed the Main Steam Isolation Valves (MSIVs) [EIIS System/Component: SB/ISV] to stop reactor depressurization. The High Pressure Coolant Injection (HPCI) [EIIS System Code: BJ] and Reactor Core Isolation Cooling (RCIC) [EIIS System Code: BN] systems were manually initiated to control reactor water level. Operations subsequently maintained reactor water at the normal operating band using RCIC and reactor pressure was controlled with HPCI in pressure control mode and the main steam line drains. The Reactor Recirculation Pumps [EIIS System/Component Code: AD/P] tripped on End of Cycle Recirculation Pump Trip.

This event was reported by Event Notification 55514 in accordance with 10 CFR 50.72(b)(2)(iv)(A),

(b)(2)(iv)(B) and (b)(3)(iv)(A). This event is also reportable in accordance with 10 CFR 50.73(a)(2)(iv)(A) as an event that resulted in automatic actuation of a system listed in 10 CFR 50.73(a)(2)(iv)(B).

CAUSE OF EVENT The cause of the event is under investigation and will be provided in a supplement to this LER.

ANALYSIS/SAFETY SIGNIFICANCE During the reactor scram off-site power remained available to power all safety related shutdown equipment. All control rods inserted as designed and all safety related equipment operated as designed.

There was no loss of function that prevented the safe shutdown of the reactor and to maintain it in a safe shutdown condition. All safety systems were available to mitigate the consequences of an accident.

Any additional insights on safety significance identified during the cause evaluation will be provided in a supplement to this LER. There were no actual consequences to the health and safety of the public as a result of this event.

CORRECTIVE ACTIONS Corrective actions will be provided in a supplement to this LER.

NRC FORM 366A (08-2020)

Page 3 of 3.

NRC FORM 366A (08-2020)

U. S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 08/31/2023 LICENSEE EVENT REPORT (LER)

CONTINUATION SHEET Estimated burden per response to comply with this mandatory collection request: 80 hours9.259259e-4 days <br />0.0222 hours <br />1.322751e-4 weeks <br />3.044e-5 months <br />. Reported lessons learned are incorporated into the licensing process and fed back to industry. Send comments regarding burden estimate to the FOIA, Library, and Information Collections Branch (T-6 A10M), U.S.

Nuclear Regulatory Commission, Washington, DC 20555-0001, or by e-mail to Infocollects.Resource@nrc.gov, and the OMB reviewer at: OMB Office of Information and Regulatory Affairs, (3150-0104), Attn: Desk ail: oira_submission@omb.eop.gov. The NRC may not conduct or sponsor, and a person is not required to respond to, a collection of information unless the document requesting or requiring the collection displays a currently valid OMB control number.

(See NUREG-1022, R.3 for instruction and guidance for completing this form https://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1022/r3/)

1. FACILITY NAME

2. DOCKET NUMBER

3. LER NUMBER Susquehanna Steam Electric Station Unit 2 05000-388 YEAR SEQUENTIAL NUMBER REV NO.

2021 003 00 NARRATIVE COMPONENT FAILURE INFORMATION Component failure information, as applicable, will be provided in a supplement to this LER.

PREVIOUS OCCURRENCES Previous occurrences, as applicable, will be provided in the supplement to this LER.