ML18352B085

SMR DC RAI - Request for Additional Information No. 514 Erai No. 9645 (4.04)

ML18352B085
Person / Time
Site:	NuScale
Issue date:	12/18/2018
From:	NRC
To:	NRC/NRO/DLSE/LB1
References
Download: ML18352B085 (3)

Text

NuScaleDCRaisPEm Resource From: Cranston, Gregory Sent: Tuesday, December 18, 2018 2:35 PM To: Request for Additional Information Cc: Lee, Samuel; Karas, Rebecca; Drzewiecki, Timothy; Bavol, Bruce; Chowdhury, Prosanta; NuScaleDCRaisPEm Resource

Subject:

Request for Additional Information No. 514 eRAI No. 9645 (4.04)

Attachments: Request for Additional Information No. 514 (eRAI No. 9645).pdf Attached please find NRC staffs request for additional information (RAI) concerning review of the NuScale Design Certification Application.

Please submit your technically correct and complete response by February 11, 2019, to the RAI to the NRC Document Control Desk. It is noted that you currently cannot meet February 11, 2019 date, so please provide your revised submittal date once determined.

If you have any questions, please contact me.

Thank you.

1

Hearing Identifier: NuScale_SMR_DC_RAI_Public Email Number: 554 Mail Envelope Properties (DM2PR09MB0779BA6E59AC91157C10623890BD0)

Subject:

Request for Additional Information No. 514 eRAI No. 9645 (4.04)

Sent Date: 12/18/2018 2:34:42 PM Received Date: 12/18/2018 2:34:53 PM From: Cranston, Gregory Created By: Gregory.Cranston@nrc.gov Recipients:

"Lee, Samuel" <Samuel.Lee@nrc.gov>

Tracking Status: None "Karas, Rebecca" <Rebecca.Karas@nrc.gov>

Tracking Status: None "Drzewiecki, Timothy" <Timothy.Drzewiecki@nrc.gov>

Tracking Status: None "Bavol, Bruce" <Bruce.Bavol@nrc.gov>

Tracking Status: None "Chowdhury, Prosanta" <Prosanta.Chowdhury@nrc.gov>

Tracking Status: None "NuScaleDCRaisPEm Resource" <NuScaleDCRaisPEm.Resource@nrc.gov>

Tracking Status: None "Request for Additional Information" <RAI@nuscalepower.com>

Tracking Status: None Post Office: DM2PR09MB0779.namprd09.prod.outlook.com Files Size Date & Time MESSAGE 493 12/18/2018 2:34:53 PM Request for Additional Information No. 514 (eRAI No. 9645).pdf 260055 Options Priority: Standard Return Notification: No Reply Requested: No Sensitivity: Normal Expiration Date:

Recipients Received:

Request for Additional Information No. 514 (eRAI No. 9645)

Issue Date: 12/18/2018 Application

Title:

NuScale Standard Design Certification 048 Operating Company: NuScale Power, LLC Docket No.52-048 Review Section: 04.04 - Thermal and Hydraulic Design Application Section: 4.04 QUESTIONS 04.04-6 GDC 10 requires that the reactor core and associated coolant, control, and protection systems be designed with sufficient margin to assure that specified acceptable fuel design limits are not exceeded during any condition of normal operation, including the effect of anticipated operational occurrences. Compliance with GDC 10 requires, in part, a demonstration of thermal-margin by appropriate safety analyses. As described in Section 4.4.3.1.1 of the Final Safety Analysis Report (FSAR), these safety analyses include subchannel analyses that consider flow through the heated core and does not consider the flow that effectively bypasses the fuel rods.

During an audit, NRC staff observed that minimum and maximum bypass flow rates were calculated using computational fluid dynamics (CFD) analysis. Additionally, TR-0176-50439, "NuScale Comprehensive Vibration Assessment Program Technical Report," provides maximum design flow velocities, based on CFD analysis, for components that impact core bypass flow (i.e., the control rod assembly guide tubes). TR-0716-50439 further states, in Section 3.1.2.1, that, "[thermal-hydraulic] TH analysis provides validated maximum design flow rate results based on testing."

NRC staff needs to establish a finding that the design basis flow rate, used in the subchannel analyses, provides adequate margin to account for analysis uncertainties (e.g., manufacturing tolerances, boundary conditions, modeling simplifiaitons, etc.). Accordingly, NRC staff requests that NuScale provide one of the following :

(1) Justificaiton to demonstrate that the CFD analysis provides adequate margin to the design basis bypass flow limit such that testing is not needed, or (2) Evidence of sepearate effects testing that has been done to validate the CFD analysis as it pertains to core bypass flow, or (3) Propose a startup test to validate the design basis bypass flow