ML18240A210

August 9, 2018, Summary of the Public Meeting to Discuss Accident Source Term (AST) Methodolgy Associated with the Nuscale Design Certification Application

ML18240A210
Person / Time
Site:	NuScale
Issue date:	08/31/2018
From:	Getachew Tesfaye NRC/NRO/DLSE/LB1
To:	Samson Lee NRC/NRO/DLSE/LB1
Tesfaye G / 415-8013
References
Download: ML18240A210 (6)

Text

August 31, 2018 MEMORANDUM TO: Samuel S. Lee, Chief Licensing Branch 1 Division of Licensing, Siting, and Environmental Analysis Office of New Reactors FROM: Getachew Tesfaye, Senior Project Manager /RA/

Licensing Branch 1 Division of Licensing, Siting, and Environmental Analysis Office of New Reactors

SUMMARY

OF THE AUGUST 9, 2018, CATEGORY 1 PUBLIC TELECONFERENCE TO DISCUSS ACCIDENT SOURCE TERM METHODOLOGY ASSOCIATED WITH THE NUSCALE POWER, LLC DESIGN CERTIFICATION APPLICATION The U.S. Nuclear Regulatory Commission (NRC) held a Category 1 public meeting on August 9, 2018, to discuss the NuScale Power, LLC (NuScale) accident source term methodology associated with its design certification application. This teleconference was a follow-up to the June 7, 2017 and June 27, 2018, meetings on the same subject. Participants included personnel from NuScale and members of the general public that participated in-person and via bridgeline.

The public meeting notice dated August 9, 2018, can be found in the NRCs Agencywide Documents Access and Management Systems under Accession No. ML18220B439. This meeting notice was also posted on the NRC public Website.

Enclosed is the meeting agenda (Enclosure 1), list of participants (Enclosure 2), and overview (Enclosure 3).

Docket No.52-048

Enclosures:

1. Meeting Agenda

2. List of Attendees

3. Meeting Overview cc w/encl.: DC NuScale Power, LLC Listserv CONTACT: Getachew Tesfaye, NRO/DLSE 301-415-8013

ML18240A210 NRO-002

• concurred via email OFFICE DLSE/LB1:PM DLSE/LB1:LA DLSE/RPAC:BC DSRA/SPRA:BC DLSE/LB1:PM NAME GTesfaye(c) MMoore MHart* HPhan* GTesfaye (s)

DATE 8/27/2018 8/28/2018 8/28/2018 8/29 /2018 8/31/2018 U.S. NUCLEAR REGULATORY COMMISSION CATEGORY 1 PUBLIC MEETING TO DISCUSS ACCIDENT SOURCE TERM METHODOLOGY ASSOCIATED WITH THE NUSCALE POWER, LLC DESIGN CERTIFICATION APPLICATION MEETING AGENDA August 9, 2018 11:00 - 11:15 AM Introductions and Identification of topics 11:15 - 12:20 PM Discussion of Accident Source Term Methodology 12:20 - 12:30 PM Public Comments/Questions 12:30 Meeting Closure Enclosure 1

U.S. NUCLEAR REGULATORY COMMISSION CATEGORY 1 PUBLIC MEETING TO DISCUSS ACCIDENT SOURCE TERM METHODOLOGY ASSOCIATED WITH THE NUSCALE POWER, LLC DESIGN CERTIFICATION APPLICATION LIST OF ATTENDEES August 9, 2018 Name Organization Getachew Tesfaye U.S. Nuclear Regulatory Commission (NRC)

Jason Schaperow NRC Hanh Phan NRC Michelle Hart NRC John Monninger NRC Shawn Campbell NRC James Corson NRC Michael Salay NRC Edward Stutzcage NRC Ronald LaVera NRC Robert Taylor NRC Joseph Anderson NRC Kenneth Thomas NRC Anne-Marie Grady NRC Kevin Coyne NRC Marie Pohida NRC Prosanta Chowdhury NRC Samuel Lee NRC Dan Barss NRC Amanda Marshall NRC Zackary Rad NuScale Power, LLC (NuScale)

Paul Infanger NuScale Gary Becker NuScale Cindy Williams NuScale Paul Guinn NuScale Jennie Wike NuScale Mark Shaver NuScale Scott Weber NuScale Patrick Conley NuScale Sarah Bristol NuScale Russell Goff NuScale Robert Gamble NuScale Tom Bergman NuScale Bill Galyean NuScale Dan Stout Member of the public Kati Austgen Member of the public Mark Holbrick Member of the public Wayne Moe Member of the public Enclosure 2

U.S. NUCLEAR REGULATORY COMMISSION OVERVIEW OF THE AUGUST 9, 2018, PUBLIC MEETING TO DISCUSS ACCIDENT SOURCE TERM METHODOLOGY ASSOCIATED WITH THE NUSCALE POWER, LLC DESIGN CERTIFICATION APPLICATION The purpose of this meeting was for the U.S. Nuclear Regulatory Commission (NRC) staff to continue the dialogue on NuScale Power, LLCs (NuScale) planned changes to the methodology for accident source term (AST) that was previously discussed in public meetings on June 7, 2018 (Agencywide Documents Management and Access System (ADAMS)

Accession No. ML18173A260) and June 27, 2018 (ADAMS Accession No. ML18206A933).

NuScale gave a PowerPoint presentation (ADAMS Accession No. ML18222A193) that outlined additional options to address maximum hypothetical accident (MHA) to resolve post-accident sampling (PAS) and environmental qualification (EQ) issues. NuScale stated that the original overly conservative deterministic AST Methodology assumed significant core damage that was used as the design basis for PAS doses and EQ of in-containment instruments that required possible design changes without identifiable safety benefit. The NRC staff provided its initial observation during the meeting.

A. To address the PAS and EQ issues, NuScale presented two categories of options and variations within each group:

• Group 1 options: Evaluation of design basis accidents, defense in depth, and risk insights to determine MHA source term:

o Option 1A: Use iodine spike as MHA source term if Chapter 15 design basis accidents do not result in fuel failure, design incorporates defense in depth, and Chapter 19 confirms likelihood of severe accidents is very small.

Otherwise, use core damage MHA source term.

o Option 1B: Utilize both deterministic analysis and risk insights as proposed in Accident Source Terms Regulatory Framework White Paper (ADAMS Accession No. ML18136A850)

• Group 2 options: Limit application of core damage MHA in the design basis o Option 2A: Analyze core damage MHA for offsite dose consequence purposes only.

o Option 2B: Exclude core damage MHA from design basis of PAS and EQ.

o Option 2C: Revise Post Accident Monitoring (PAM) and PAS capabilities under core damage MHA.

1 Enclosure 3

NuScale stated that under all options doses to public are shown acceptable for spectrum of postulated events, emergency preparedness remains last layer of defense in depth, and no significant differences in design.

B. The NRC staff made some observations during the meeting and NuScale provided clarification and took actions to provide additional clarifications for some of the observations. The following are summaries of the pertinent points discussed:

• The NRC staff asked what the driving force was for the challenge with core damage MHA. NuScale explained that unlike conventional light water reactors with large containments and large compartments, the containment and the area under the bioshield for the NuScale power module are substantially small. As a result, the inventory after a core melt does not disperse over a large volume resulting in a significantly higher dose for EQ. Instrument vendors and EQ experts have informed NuScale that instruments will have to be redesigned to meet the EQ requirements.

NuScale does not see any benefit for such costly modification given the unlikely scenario these instruments are currently evaluated. Regarding PAS, NuScale stated that in order to meet the regulation, shielding would have to be provided. They rely on isolation and the rad monitors under the bioshield for monitoring. If they have to take sampling, they will have to unisolate which will result in a situation that is less safe by creating pathway for radiation to escape.

• The NRC staff asked if NuScale has looked into EQ for electrical penetration and if there are challenges in meeting the requirements. NuScale responded that they are not aware of any issues with the penetrations not meeting EQ requirements and took action to look into the matter closely.

• The NRC staff cautioned on the use of DC/COL-ISG-028 guidance for other than DC and combined license (COL) applications citing a statement from the guidance which states that the staffs positions presented in DC/COL-ISG-28 should not be relied on to address other types of applications. For other applications that use probabilistic risk assessment (PRA) results and insights, the PRA acceptability should be measured on a case-by-case basis.

• The NRC staff asked if NuScale intends to provide both core melt MHA and iodine spike MHA for Options 1A and 1B in the topical report. NuScale responded that both MHAs will be provided in the topical report as viable methods, but for a specific application, only one will be used. The design certification application (DCA) final safety analysis report will only have one MHA and COL applicants who intend to use the option that is not in the DCA will have to take a departure.

• The NRC staff asked if Option 2C will be extended to other equipment other than instrumentation such as electrical penetration. NuScale stated that they have not vetted the scope of this option fully and took action to address the staffs question.

C. Next step:

The NRC staff and NuScale agreed to continue the dialgue to reach alighnment on a pathforward before the topical report revision is submitted. It was agreed to hold the next meeting the week of August 27, 2018.

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