ML19087A240

Summary of March 5, 2019 Public Meeting on NuScale EPZ Sizing Methodology TR

ML19087A240
Person / Time
Site:	NuScale
Issue date:	05/06/2019
From:	Prosanta Chowdhury NRC/NRO/DLSE/LB1
To:	Samson Lee NRC/NRO/DLSE/LB1
Chowdhury P 415-1674
References
Download: ML19087A240 (8)

Text

May 6, 2019 MEMORANDUM TO: Samuel S. Lee, Chief Licensing Branch 1 Division of Licensing, Siting and Environmental Analysis Office of New Reactors FROM: Prosanta Chowdhury, Project Manager /RA/

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

SUMMARY

OF THE MARCH 5, 2019, U.S. NUCLEAR REGULATORY COMMISSION CATEGORY 1 PUBLIC TELECONFERENCE WITH NUSCALE POWER, LLC, TO DISCUSS THE U.S NUCLEAR REGULATORY COMMISSION STAFFS COMMENTS AND CONCERNS ON NUSCALE TOPICAL REPORT, TR-0915-17772, REVISION 1 On March 5, 2019, the U.S. Nuclear Regulatory Commission (NRC) staff held a Category 1 teleconference public meeting with NuScale Power, LLC (NuScale), to discuss the staffs comments and concerns on NuScale Topical Report (TR), TR-0915-17772, Methodology for Establishing the Technical Basis for Plume Exposure Emergency Planning Zones at NuScale Small Modular Reactor Plant Sites, Revision 1 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML18071A354).

The public meeting notice can be found in ADAMS under Accession No. ML19028A386. This meeting notice was also posted on the NRC public website.

CONTACT: Prosanta Chowdhury, NRO/DLSE 301-415-1647

S. Lee 1 Enclosed are the Meeting Agenda (Enclosure 1), List of Attendees (Enclosure 2), and Meeting Summary (Enclosure 3).

Docket No.52-048

Enclosures:

As stated cc w/encl.: DC NuScale Power, LLC Listserv

ML19087A240 NRO-002 OFFICE NRO/DLSE/LB1: PM NRO/DLSE/LB1: LA NRO/DSRA/SPRA: BC NRO/DLSE/LB1: PM NAME PChowdhury* MMoore* MHayes* PChowdhury DATE 3/28/2019 4/29/2019 4/19/2019 5/06/2019 U.S. NUCLEAR REGULATORY COMMISSION

SUMMARY

OF THE MARCH 5, 2019, CATEGORY 1 PUBLIC TELECONFERENCE WITH NUSCALE POWER, LLC, TO DISCUSS THE U.S NUCLEAR REGULATORY COMMISSION STAFFS COMMENTS AND CONCERNS ON NUSCALE TOPICAL REPORT, TR-0915-17772, REVISION 1 MEETING AGENDA Time Topic 1:00 p.m. Introduction 1:10 p.m. Open discussion on NuScale EPZ Sizing Methodology Topical Report (TR) 1:30 p.m. Public Comments 1:45 p.m. Closed discussion on NuScale EPZ Sizing Methodology TR 3:00 p.m. Meeting adjourn Enclosure 1

U.S. NUCLEAR REGULATORY COMMISSION

SUMMARY

OF THE MARCH 5, 2019, CATEGORY 1 PUBLIC TELECONFERENCE WITH NUSCALE POWER, LLC, TO DISCUSS STAFF COMMENTS AND CONCERNS ON NUSCALE TOPICAL REPORT, TR-0915-17772, REVISION 1 LIST OF ATTENDEES Name Organization Michelle Hayes U.S. Nuclear Regulatory Commission (NRC)

Marie Pohida NRC Michelle Hart NRC Robert Taylor NRC Kevin Coyne NRC Prosanta Chowdhury NRC Joseph Anderson NRC Dan Barss NRC Kenny Thomas NRC Michael Dudek NRC Steve Mirsky NuScale Power, LLC (NuScale)

Sarah Bristol NuScale Doug Bowman NuScale Tom Bergman NuScale Luke McSweeney NuScale Bill Galyean NuScale Carrie Fosaaen NuScale Jeremiah Doyle NuScale Scott Weber NuScale Cindy Williams NuScale Sarah Fields Public Edwin Lyman Public Enclosure 2

U.S. NUCLEAR REGULATORY COMMISSION

SUMMARY

OF THE MARCH 5, 2019, CATEGORY 1 PUBLIC TELECONFERENCE WITH NUSCALE POWER, LLC, TO DISCUSS STAFF COMMENTS AND CONCERNS ON NUSCALE TOPICAL REPORT, TR-0915-17772, REVISION 1

SUMMARY

On March 5, 2019, the U.S. Nuclear Regulatory Commission (NRC or Commission) staff held a Category 1 teleconference public meeting with NuScale Power, LLC (NuScale), to discuss the NRC staffs comments and concerns on NuScale Topical Report (TR), TR-0915-17772, Revision 1, Methodology for Establishing the Technical Basis for Plume Exposure Emergency Planning Zones at NuScale Small Modular Reactor Plant Sites (Agencywide Documents Access and Management System (ADAMS) Accession No. ML18071A354).

NuScale stated their concern over the NRC staffs continued questioning of the proposed NuScale methodology, which they believe is consistent with the Tennessee Valley Authority (TVA) plume exposure pathway emergency planning zone (EPZ) sizing methodology, which the staff is recommending for Commission approval. NuScale also stated that the staff is not differentiating design versus methodology, and that Regulatory Guide 1.200, An Approach for Determining the Technical Adequacy of Probabilistic Risk Assessment Results for Risk-Informed Activities, is simply guidance and, as such, NuScale does not have to comply with it.

NuScale further stated that its EPZ methodology is not related to its design certification application (DCA), to which the NRC staff pointed out that the abstract of the TR clearly says this TR is tied to the NuScale design, therefore, use of information from the DCA is useful in evaluating the EPZ sizing methodology and any potential implementation issues.

The staff clarified that with respect to the EPZ associated with the TVA Clinch River Early Site Permit (ESP), external hazards will be evaluated by the combined license (COL) applicant referencing the Clinch River ESP. The NRC staff also mentioned that per Staff Requirements Memorandum to SECY-04-118, Plan for the Implementation of the Commission's Phased Approach to Probabilistic Risk Assessment Quality, if there is a Probabilistic Risk Assessment (PRA) standard for a hazard group, it should be used to assess risk. Staff notes there is a PRA standard for seismic hazards.

At this public teleconference meeting, the NRC staff used for discussion, the following high-level talking points (see ADAMS Accession No. ML18292A874 for the staffs initial talking points):

1. PRA Acceptability: The methodology described in this TR is based on the COL Applicants PRA, but the existing review guidance for a COL PRA (in NUREG-0800, "Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants," Chapter 19.0, Probabilistic Risk Assessment and Severe Accident Evaluation for New Reactors, and Interim Staff Guidance DC/COL-ISG-028) is not sufficient to demonstrate the PRA is acceptable for use in risk-informed applications. Using the COL PRA to size the plume exposure EPZ would be a first-of-a-kind use for a COL PRA and a first-of-a-kind review for the staff.

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Proposed Resolution: Include a condition of use in the TR or Safety Evaluation Report (SER) that the COL applicant that references this TR will demonstrate that their PRA is consistent with RG 1.200. NUREG-1855, Guidance on the Treatment of Uncertainties Associated with PRAs in Risk-Informed Decision Making, shall be used to address the impact to the screening process from the parameter and model uncertainties associated with a new, un-built design.

Discussion Summary: The staff was curious about how a COL applicant that references this TR would demonstrate that the PRA would be acceptable for its intended use. NuScale asked for clarification on what is meant by consistency with RG 1.200 for the proposed condition of use. The staff clarified that RG 1.200 is not a regulatory requirement; it provides an NRC accepted approach for determining the technical acceptability for PRA results for risk-informed activities and that NUREG-1855 provides guidance on PRA uncertainty.

2. Screening of Seismic Events: The methodology described in this TR uses a seismic screening based on 1.67 times the ground motion acceleration of the design-basis safe-shutdown earthquake while all other hazards are screened on core damage frequency (CDF). Per the TR methodology, all structures in Revision 2 of the NuScale DCA would screen out, but if the CDF screening was applied using the seismic CDFs from the NuScale Severe Accident Mitigation Design Alternatives (SAMDA) analysis, the events would screen in.

Proposed Resolution: Include a condition of use in the TR or SER requiring the COL applicant that references this EPZ sizing TR to perform a seismic PRA and screen seismic sequences with same process as for other hazards.

Discussion Summary: NuScale disagrees with requiring a seismic PRA for use of the TR methodology. NuScale maintains that information about seismic risk and assumed effects on emergency response discussed in NUREG-1738, Technical Study of Spent Fuel Pool Accident Risk at Decommissioning Nuclear Power Plants, is applicable; that NuScale ground acceleration is very high, and large seismic events have been considered. Staff agreed to review NUREG-1738 and evaluate its applicability to new reactor designs.

The staff expects NuScale to justify why a seismic PRA is not needed to determine the EPZ size for early protective actions (evacuation and sheltering) in order to provide dose savings and protect the public. Issuing an RAI for this purpose may also be an option.

3. Severe Accident Phenomena: Statements in that new reactors are an improvement over existing designs. Staff seeks to understand how the following Low values were set:

• Containment Isolation Response Low requirement of only check valves appears to be inconsistent with intersystem loss-of-coolant accident guidance in SECY 93-087, Policy, Technical, and Licensing Issues Pertaining to Evolutionary and Advanced Light-Water Reactor (ALWR) Designs.

• Sequences LRF > 1E-6 per module year is inconsistent with SECY-91-06 LRF Goals of total LRF < 1E-6.

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• Sequence CDF considering only safety-related systems (focused PRA) > 1E 3/year per module year seems inconsistent with Advanced Reactor Policy Statement.

• Safety system response to detect and control initiating event - active system with manual control seems inconsistent with Advanced Reactor Policy Statement.

• Time to the beginning of core damage less than one hour seems inconsistent with Advanced Reactor Policy Statement.

Status: This cannot be resolved with a condition of use.

Discussion summary: The staff would like for NuScale to justify how the definitions of low defense-in-depth values meet expectations for advanced LWRs. Issuing an RAI for this purpose would be an option.

Comments from members of the public included the following:

1) NRC staff taking an independent hard look at several issues involving NuScale EPZ sizing methodology is appreciated;

2) a concern that under some severe seismic events emergency preparedness infrastructure may be wiped out, incapacitating emergency response capabilities;

3) a concern was expressed at the January 23, 2019, meeting of the NRCs Advisory Committee on Reactor Safeguards (ACRS) that moving one NuScale Power Module (NPM) can have adverse impact on other neighboring operating NPMs, and the staff should review this;

4) with reference to using NUREG-1738 by the staff, the Commission did not endorse it; and

5) possibility of spent fuel pool fire exists when design basis accident for drainage of NuScale SMR spent fuel pool is eliminated.

The staff noted the above comments. The staff believes the second concern was expressed based on NuScales interpretation regarding the application of NUREG-1738 assumptions for an operating reactor in relation to a severe seismic event and its impact on offsite response capabilities. Regarding the third comment, the staff stated that its evaluation and findings regarding module (NPM) movement and module drop are documented in the safety evaluation report for DCA FSAR Chapter 19, Probabilistic Risk Assessment and Severe Accident Evaluation, and a request for additional information on module drop was issued to the applicant.

The open portion of the meeting was adjourned at 3:05 p.m. (Eastern time). The staff and NuScale then conducted a closed meeting to discuss proprietary information involving some of the aforementioned topics. The closed portion of the meeting was adjourned at 3:18 p.m.

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