ML20125A336

STP Presubmittal Meeting Exigent Accumulator LAR 2020-05-05 Presentation L-2020-LRM-0039

ML20125A336
Person / Time
Site:	South Texas
Issue date:	05/04/2020
From:	Dennis Galvin NRC/NRR/DORL/LPL4
To:
Dennis Galvin - NRR/DORL 301-415-6256
References
L-2020-LRM-0039
Download: ML20125A336 (9)

Text

Pre-Submittal Meeting on Proposed Exigent LAR Regarding Accumulator Pressures for Unit 1 Cycle 23 May 5, 2020

STP Participants

• Lance Sterling, Regulatory Affairs Manager

• Jason Tomlinson, Plant Engineering Manager

• Drew Richards, Licensing Supervisor

• Safdar Hafeez, Reactor Analysis Engineer

• Roland Dunn, Engineering General Manager

• Fatma Yilmaz, NF&A Manager

• Jeff Atkins, Operations Manager 2

Discussion Topics

• Problem Description

• Proposed License Amendment

• Preliminary Technical Evaluation

• Planned Submittal Schedule 3

Problem Description

• Leakage identified on Safety Injection (SI) Train 1A following startup from recent Unit 1 refueling outage

• Water and nitrogen leaking from Accumulator 1A to RHR/LHSI discharge header through check valve RH-0032A

• Maintaining volume and pressure requires frequent RHR venting and refilling of SI Accumulator 1A

• Challenge to safety-related components due to component cycling

• Lowering pressure of all accumulators to less than RHR relief valve pressure will eliminate need for cycling safety-related components 4

Proposed License Amendment

• Modify TS 3/4.5.1, Accumulators to allow Unit 1 to operate with all three Safety Injection (SI) System Accumulators at reduced pressure

• Add note to TS Surveillance Requirement 4.5.1.1 to reduce the lower pressure limit for the accumulator nitrogen cover-pressure from 590 psig to 500 psig through the end of the next refueling outage

• Resolves valve leakage issue while maintaining all three SI accumulators operable and having no significant adverse impact to the RHR or Low-Head Safety Injection (LHSI) systems

• One-time change would support deferral of repairs until the next Unit 1 refueling outage

• Need for exigency - necessary to avoid a reactor shutdown without a commensurate increase in safety 5

Preliminary Technical Evaluation

• Large-Break LOCA Peak Clad Temperature (PCT) impact

• Containment Analysis Peak Pressure impact

• Large Break LOCA limiting

• Containment Analysis Peak Temperature impact

• Main Steam Line Break limiting

• Containment Equipment Qualification Peak Pressure and Temperature

• Containment subcompartment analysis

• Leak-Before-Break (LBB) methodology

• Post-LOCA hot leg recirculation switchover time

• Plan to evaluate small break LOCA, post-LOCA long-term cooling and subcriticality, Main Steam Line Break Hot Zero Power DNBR analysis 6

Planned Submittal Schedule

• SI Accumulator 1A isolated on April 29, 2020

• STP will receive results of analysis from vendor on May 11, 2020

• Planned amendment request submittal on May 14, 2020

• Approval of the amendment requested by May 28, 2020

• Amendment will be implemented prior to the expiration of the Risk-Informed Completion Time on May 29, 2020 7

Questions?

8