ML18320A024
| ML18320A024 | |
| Person / Time | |
|---|---|
| Site: | NuScale |
| Issue date: | 11/19/2018 |
| From: | Prosanta Chowdhury NRC/NRO/DLSE/LB1 |
| To: | Samson Lee NRC/NRO/DLSE/LB1 |
| Tabatabai-Yazdi O/NRO/6616 | |
| References | |
| TR-0915-17772 Rev. 1 | |
| Download: ML18320A024 (7) | |
Text
November 19, 2018 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 Omid Tabatabai Acting for/
Licensing Branch 1 Division of Licensing, Siting and Environmental Analysis Office of New Reactors
SUBJECT:
SUMMARY
OF THE OCTOBER 25, 2018, 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 October 25, 2018, 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 number ML18071A354).
The public meeting notice can be found in ADAMS under Accession Number ML18298A074.
This meeting notice was also posted on the NRC public web site.
CONTACT: Prosanta Chowdhury, NRO/DLSE 301-415-1647
S. Lee Enclosed is 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
ML18320A024 NRO-002 OFFICE NRO/DLSE/LB1: PM NRO/DLSE/LB1: LA NRO/DLSE/LB1: PM NAME PChowdhury* CSmith PChowdhury (OTabatabai for)
DATE 11/15/2018 11/19/2018 11/19/2018
SUMMARY
OF THE OCTOBER 25, 2018, 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 MEETING AGENDA Time Topic 1:30 p.m. - 1:40 p.m. Introduction 1:40 p.m. - 2:00 p.m. Open discussion on NuScale EPZ Sizing Methodology Topical Report (TR) 2:00 p.m. - 2:15 p.m. Public Comments 2:15 p.m. - 3:30 p.m. Closed discussion on NuScale EPZ Sizing Methodology TR 3:30 p.m. Meeting adjourn Enclosure 1
SUMMARY
OF THE OCTOBER 25, 2018, U.S. NUCLEAR REGULATORY COMMISSION 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 Jason Schaperow NRC Dan Barss NRC Prosanta Chowdhury NRC Steve Mirsky NuScale Power, LLC (NuScale)
Sarah Bristol NuScale Doug Bowman NuScale Scott Weber NuScale Luke McSweeney NuScale Bill Galyean NuScale Sarah Fields Public Enclosure 2
SUMMARY
OF THE OCTOBER 25, 2018, U.S. NUCLEAR REGULATORY COMMISSION 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 October 25, 2018, the U.S. Nuclear Regulatory Commission (NRC) staff held a Category 1 teleconference public meeting with NuScale Power, LLC., (NuScale) to discuss the U.S. Nuclear Regulatory Commission (NRC) staffs staff comments and concerns on NuScale Topical Report (TR), TR-0915-17772, Revision 1 (Agencywide Documents Access and Management System (ADAMS) Accession Number ML18071A354).
At this public teleconference meeting, the staff used the following high-level talking points (ML18292A874):
- 1. Screening of Seismic Events. The staff does not support a seismic screening based on 1.67 times the ground motion acceleration of the design-basis safe-shutdown earthquake (SSE) because it was not demonstrated this value is consistent with the non-seismic screening criteria.
- 2. Probabilistic Risk Assessment (PRA) Acceptability: The staff recognizes that this topical report (TR) describes a methodology for combined license (COL) applicants to establish the design/site-specific plume exposure emergency planning zone (EPZ). As such, COL applicants will be responsible for demonstrating PRA is acceptable for this intended use, as required by Regulatory Guide (RG) 1.200, An Approach for Determining the Technical Adequacy of Probabilistic Risk Assessment Results for Risk-Informed Activities. However, the staff believes it is important to note that; should the COL applicant follow the existing guidance in Standard Review Plan (SRP) 19.0, Severe Accidents, and DC/COL interim staff guidance (ISG)-028, this would not be sufficient to demonstrate acceptability because this would be a first of a kind use of a COL PRA and a first of a kind review for the staff.
- 3. Severe Accident Phenomena. TR Sections 3.4.3 Final Classification of Accidents by Severity and 3.8.2 Severe Accident Phenomena include statements that there is no physically credible containment failure mechanism other than bypass. These statements are still under review by the staff as part of the NuScale design certification application (DCA) review.
- 4. Large release frequency (LRF) Screening. The Commission goals for advanced light water reactors (ALWR) include two risk metrics, core damage frequency (CDF) and LRF.
However, this methodology only screens for CDF. The staff would like to understand how the LRF risk metric is considered in this methodology considering RG 1.174, An Approach for Using Probabilistic Risk Assessment in Risk-Informed Decisions on Plant-Specific Changes to the Licensing Basis, Revision 3, principles to maintain multiple fission product barriers. The staff also notes that the LRF risk profile has a risk peak where 93 percent of LRF results from a break of chemical volume and control system (CVCS) charging line outside of containment/failure of containment isolation valves
(CIVs)/failure of non- safety related containment flooding and drain system (CFDS). In the current methodology, this event would be screened out.
- 5. Defense in Depth Attribute Ranking (High, Medium, and Low) and Sequence Screening Rules.
- a. The staff does not believe that the quantitative threshold definitions should be rigid dividers; rather, attributes close to thresholds should be subject to increased technical review. A safety evaluation report (SER) Limitation and Condition could be added to state that rankings should be considered on a case-by-case basis.
- b. The staff believes the definitions of Low for some of the defense in depth (DID) attributes are either not possible when evaluating sequences that screen into DID considerations (( )) or they are inconsistent with the Commissions expectations for ALWRs
- i. Criterion 1, Attribute on internal initiative event frequency defines Low as
>1/module yr ii. Criterion 2, Attribute on external hazard initiating event frequency defines Low as >1E-2/yr iii. Criterion 3, Attribute on Sequence CDF, considering only safety-related systems defines Low as > 1E-3/module yr iv. Criterion 4, Attribute on containment isolation response defines Low as only check valves
- v. Criterion 5, Attribute on Sequence LRF defines Low as LRF >1E-6/yr The staff seeks to understand how these thresholds were set.
NuScale will consider the staffs points and arguments. The staff will meet internally to discuss a path forward for SER completion.
A member of the public on the conference call meeting, Ms. Sarah Fields, stated that a smaller size EPZ may impact safety. She stated that design, fabrication, construction and testing of plants impact EPZ size determination. She asked the NRC staff if there are discussions in the TR about potential events, site hazards, etc., including release of radiation from spent-fuel storage facilities on-site. The staff responded by saying: (1) site hazards are considered and reviewed under an early site permit or combined license applications; and (2) NuScale TR Sections 3.8 and 3.9 consider spent-fuel storage and design basis threats.