ML18121A407

SMR DC RAI - Request for Additional Information No. 452 Erai No. 9518 (15.06.05)

ML18121A407
Person / Time
Site:	NuScale
Issue date:	05/01/2018
From:	NRC
To:	NRC/NRO/DNRL/LB1
References
Download: ML18121A407 (3)

Text

NuScaleDCRaisPEm Resource From: Chowdhury, Prosanta Sent: Tuesday, May 1, 2018 3:39 PM To: Request for Additional Information Cc: Lee, Samuel; Cranston, Gregory; Franovich, Rani; Karas, Rebecca; Thurston, Carl; NuScaleDCRaisPEm Resource

Subject:

Request for Additional Information No. 452 eRAI No. 9518 (15.06.05)

Attachments: Request for Additional Information No. 452 (eRAI No. 9518).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 within 60 days of the date of this RAI to the NRC Document Control Desk.

If you have any questions, please contact me.

Thank you.

Prosanta Chowdhury, Project Manager Licensing Branch 1 (NuScale)

Division of New Reactor Licensing Office of New Reactors U.S. Nuclear Regulatory Commission 301-415-1647 1

Hearing Identifier: NuScale_SMR_DC_RAI_Public Email Number: 483 Mail Envelope Properties (BN7PR09MB2609557254855089F29DCD7C9E810)

Subject:

Request for Additional Information No. 452 eRAI No. 9518 (15.06.05)

Sent Date: 5/1/2018 3:39:29 PM Received Date: 5/1/2018 3:39:34 PM From: Chowdhury, Prosanta Created By: Prosanta.Chowdhury@nrc.gov Recipients:

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

Tracking Status: None "Cranston, Gregory" <Gregory.Cranston@nrc.gov>

Tracking Status: None "Franovich, Rani" <Rani.Franovich@nrc.gov>

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

Tracking Status: None "Thurston, Carl" <Carl.Thurston@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: BN7PR09MB2609.namprd09.prod.outlook.com Files Size Date & Time MESSAGE 556 5/1/2018 3:39:34 PM Request for Additional Information No. 452 (eRAI No. 9518).pdf 74344 Options Priority: Standard Return Notification: No Reply Requested: No Sensitivity: Normal Expiration Date:

Recipients Received:

Request for Additional Information No. 452 (eRAI No. 9518)

Issue Date: 05/01/2018 Application

Title:

NuScale Standard Design Certification 048 Operating Company: NuScale Power, LLC Docket No.52-048 Review Section: 15.06.05 - Loss of Coolant Accidents Resulting From Spectrum of Postulated Piping Breaks Within the Reactor Coolant Pressure Boundary Application Section:

QUESTIONS 15.06.05-7 Title 10 of the Code of Federal Regulations (10 CFR), Part 50, Appendix A, General Design Criterion (GDC) 35, Emergency Core Cooling, requires that a system to provide abundant emergency core cooling shall be provided. The system safety function shall be to transfer heat from the reactor core following any loss of reactor coolant at a rate such that (1) fuel and clad damage that could interfere with continued effective core cooling is prevented and (2) clad metal-water reaction is limited to negligible amounts. DSRS Section 15.6.5 provides guidance for complying with GDC 35. It requires that evaluation models meet the requirements of 10 CFR 50.46, which states that the evaluation model must include sufficient supporting justification to show that the analytical technique realistically describes the behavior of the reactor system during a loss-of-coolant accident.

FSAR Chapter 15.6.5 and Section 9 of the Loss-of-Coolant Accident Evaluation Model, TR-0516-49422-P, Rev. 0, a topical report supporting the DCD Chapter 15 analyses, indicates that a stable natural recirculation flow pattern with the reactor recirculation valves and steam venting through the reactor vent valves (RVVs) is relied upon to remove decay heat passively via boiling in the core. The staff noted that the applicant did not evaluate the flows in the RRVs for potential vortex forces in the flow during this recirculation phase. Further, in RAI 9486, Question 31454, the staff noted a similar issue relative to the Station Blackout calculation.

Please provide an evaluation of the occurrence of vortex forces in the valves nozzles, such as through analysis, and show that adverse effects are precluded in the NPM design.