ML19044A356

NRR E-mail Capture - Clarification Question Associated with Staff Assessment of Fragility Portion of Peach Bottom Seismic Probabilistic Risk Assessment Report Dated August 28, 2018

ML19044A356
Person / Time
Site:	Peach Bottom
Issue date:	02/11/2019
From:	Joseph Sebrosky Division of Licensing Projects
To:	Gropp R Exelon Generation Co
References
Download: ML19044A356 (3)

Text

NRR-DMPSPEm Resource From: Sebrosky, Joseph Sent: Monday, February 11, 2019 3:07 PM To: 'Gropp Jr, Richard W:(GenCo-Nuc)'

Subject:

Clarification question associated with staff assessment of fragility portion of of Peach Bottom seismic probabilistic risk assessment report dated August 28, 2018 Mr. Gropp, By letter dated August 28, 2018 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML18240A065), Exelon Generating Company, LLC (the licensee) provided its seismic probabilistic risk assessment (SPRA) report in response to Enclosure 1, item (8) of the March 12, 2012, 10 CFR 50.54(f) letter (ADAMS Accession No. ML12053A340) for Peach Bottom Atomic Power Station, Units 2 and 3 (Peach Bottom). By letter dated July 6, 2017 (ADAMS Accession No. ML17177A446), the NRC issued a generic audit plan and entered into the audit process described in Office Instruction LIC 111, Regulatory Audits, dated December 29, 2008 (ADAMS Accession No. ML082900195), to assist in the timely and efficient closure of activities associated with the 50.54(f) letter. To support the staffs audit of the August 28, 2018, SPRA report the staff has developed the clarification questions found below. After you have time to review the clarification questions, please let me know when you could support an audit phone call to discuss these questions.

Sincerely, Joe Sebrosky Senior Project Manager Division of Licensing Projects Office of Nuclear Reactor Regulation 301-415-1132 Plant: Peach Bottom Units 2 and 3 Submittal ML#: ML18240A065 F&O#: 5-16 Team Lead: Joe Sebrosky SR: SFR-A2 and SPR-C1 Reviewer:

Proposed RAI:

In response to F&O 5-16, a bounding analysis for structural fragility of Conowingo Dam is presented in EXLNPB018-REPT-014, Attachment 5. The report addressed the structural fragility of spillway piers that can lead to failure of the gates. Table 3 in the report shows that the potential failure of Gates and Power House and Intake were screened out, however, rationale for screening of these components were not documented. Spillway gates are typically steel structural system anchored to the spillway piers. The seismic and hydrodynamic loading on the gates during earthquake can cause failure of gate structure or exceed anchorage capacity during the transfer of load to the piers. Failure of gates, as pointed out in the report, can result in uncontrolled release from the reservoir and loss of 1

cooling water. Discuss the screening approach used for the gates and power house and intake structure and confirm that the structural fragility of the spillway pier is bounding for the Conowingo Dam.

Rationale/Need for RAI:

Decision:

2

Hearing Identifier: NRR_DMPS Email Number: 795 Mail Envelope Properties (BN6PR09MB129916C175C7B4ABBE8B9525F8640)

Subject:

Clarification question associated with staff assessment of fragility portion of of Peach Bottom seismic probabilistic risk assessment report dated August 28, 2018 Sent Date: 2/11/2019 3:07:22 PM Received Date: 2/11/2019 3:07:22 PM From: Sebrosky, Joseph Created By: Joseph.Sebrosky@nrc.gov Recipients:

"'Gropp Jr, Richard W:(GenCo-Nuc)'" <Richard.Gropp@exeloncorp.com>

Tracking Status: None Post Office: BN6PR09MB1299.namprd09.prod.outlook.com Files Size Date & Time MESSAGE 2415 2/11/2019 3:07:22 PM Options Priority: Standard Return Notification: No Reply Requested: No Sensitivity: Normal Expiration Date:

Recipients Received: