ML18339A035

LLC Supplemental Response to NRC Request for Additional Information No. 314 (Erai No. 9241) on the NuScale Design Certification Application

ML18339A035
Person / Time
Site:	NuScale
Issue date:	12/05/2018
From:	Fosaaen C NuScale
To:	Document Control Desk, Office of New Reactors
References
RAIO-1218-73624
Download: ML18339A035 (6)

Text

RAIO-1218-63724 December 05, 2018 Docket No.52-048 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk One White Flint North 11555 Rockville Pike Rockville, MD 20852-2738

SUBJECT:

NuScale Power, LLC Supplemental Response to NRC Request for Additional Information No. 314 (eRAI No. 9241) on the NuScale Design Certification Application

REFERENCES:

1. U.S. Nuclear Regulatory Commission, "Request for Additional Information No. 314 (eRAI No. 9241)," dated December 26, 2017

2. NuScale Power, LLC Response to NRC "Request for Additional Information No. 314 (eRAI No.9241)," dated February 23, 2018 The purpose of this letter is to provide the NuScale Power, LLC (NuScale) supplemental response to the referenced NRC Request for Additional Information (RAI).

The Enclosure to this letter contains NuScale's supplemental response to the following RAI Question from NRC eRAI No. 9241:

19.05 Aircraft Impact Assessment (NuScale SMR design)-23 This letter and the enclosed response make no new regulatory commitments and no revisions to any existing regulatory commitments.

If you have any questions on this response, please contact Marty Bryan at 541-452-7172 or at mbryan@nuscalepower.com.

Sincerely, Carrie Fosaaen Supervisor, Licensing NuScale Power, LLC Distribution: Gregory Cranston, NRC, OWFN-8G9A Samuel Lee, NRC, OWFN-8G9A Rani Franovich, NRC, OWFN-8G9A : NuScale Supplemental Response to NRC Request for Additional Information eRAI No. 9241 NuScale Power, LLC 1100 NE Circle Blvd., Suite 200 Corvalis, Oregon 97330, Office: 541.360.0500, Fax: 541.207.3928 www.nuscalepower.com

RAIO-1218-63724 :

NuScale Supplemental Response to NRC Request for Additional Information eRAI No. 9241 NuScale Power, LLC 1100 NE Circle Blvd., Suite 200 Corvalis, Oregon 97330, Office: 541.360.0500, Fax: 541.207.3928 www.nuscalepower.com

Response to Request for Additional Information Docket No.52-048 eRAI No.: 9241 Date of RAI Issue: 12/26/2017 NRC Question No.: 19.05 Aircraft Impact Assessment (NuScale SMR design)-23 In accordance with 10 CFR 50.150(a)(1), each applicant listed in paragraph (a)(3) shall perform a design-specific assessment of the effects on the facility of the impact of a large, commercial aircraft. Using realistic analyses, the applicant shall identify and incorporate into the design those design features and functional capabilities to show that, with reduced use of operator actions: (i) The reactor core remains cooled, or the containment remains intact; and (ii) Spent fuel cooling or spent fuel pool integrity is maintained. 10 CFR 50.150(b) requires that the FSAR contain a description of the design features and functional capabilities and how the design features and functional capabilities meet the assessment requirements. In addition, NEI 07-13, Revision 8 provides guidance acceptable to staff for satisfying the requirements in 10 CFR 50.150(a) regarding the assessment of aircraft impacts for new nuclear power reactors.

FSAR Tier 2, Section 19.5, Revision 0 contained descriptive information regarding the role of the main control room (MCR) and remote shutdown station (RSS); including, the capability of the design to monitor and control the plant, separation between the MCR and RSS, and the availability of the module protection system and DC power equipment to monitor reactor and containment parameters. In response to RAI 8877 and RAI 9023 this important information was removed and replaced with a sentence that states, once the operators scram the reactors and initiate DHRS and containment isolation upon warning of a potential aircraft, no further operator actions are necessary to maintain fuel cooling.

The staff recognizes that if the key design features perform as expected there are no control or protective functions that are necessary after the aircraft impact for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, as described in the FSAR; however, monitoring of plant conditions plays a vital role in the overall success of the plants ability to cope with the impact of a large commercial aircraft. NEI 07-13 acknowledges that there are unknowns and uncertainties in performing aircraft impact assessments. Thus, 10 NuScale Nonproprietary

CFR 50.54(hh)(2) requires all plants to develop and adopt mitigation strategies to address loss of large areas of the plant due to fire or explosion from any cause, including beyond-design-basis aircraft impact. NEI 07-13 adds, the guidance and strategies required under 10 CFR 50.54(hh)(2) provide a measure of defense-in-depth should the design features identified as a result of the aircraft impact assessment not perform as expected.

Without monitoring capability operators cannot verify the plants ability to cope with the impact of a large commercial aircraft through the use of design features. Therefore, the ability for operators to monitor key plant parameters must be maintained in case the key design features credited for core cooling, intact containment, or spent fuel pool integrity are not performing as expected, and a transition to an alternate mitigation strategy is necessary.

The applicant is requested to reinsert the descriptive information (identified in the second paragraph above) regarding the monitoring and protection equipment, and related design features of the MCR and RSS. The applicant is requested to identify and describe, in the FSAR, key plant parameters and their location(s) that are available to the operators to monitor and ensure the identified design features are performing as expected following the impact of a large commercial aircraft.

NuScale Response:

Based on a follow-up public meeting with NRC on August 14, 2018, the text of FSAR Section 19.5.5.5, Plant Monitoring and Control, has been replaced in its entirety with the following:

For the postulated aircraft impact event, required operator actions occur prior to the aircraft impact, upon notification of the threat. Operators trip the individual NPMs and initiate containment isolation and decay heat removal systems. Following the aircraft impact event, monitoring functions are expected to remain available. However, in the event that post-AIA monitoring is determined to be unavailable, the mitigating strategies of FSAR Section 20.2 for the LOLA beyond-design-basis event are invoked. The actions taken by the Operators prior to the aircraft impact ensure that the reactor core and spent fuel remains cooled, containment remains intact, and spent fuel pool integrity is maintained.

NuScale Nonproprietary

Impact on DCA:

The FSAR Tier 2, Section 19.5.5.5 has been revised as described in the response above and as shown in the markup provided in this response.

NuScale Nonproprietary

Adequacy of Design Features and Functional Capabilities Identified and NuScale Final Safety Analysis Report Described for Withstanding Aircraft Impacts Section 9.1.4.2.2 and shown on Figure 9.1.4-2. The design and location of the fuel handing equipment, as described above, is a key design feature for ensuring the hoists remain intact and cannot fall into the SFP and perforate the SFP liner.

RAI 19.05 Aircraft Impact Assessment (APR1400)-1 19.5.5.4 Spent Fuel Pool Cooling RAI 19.05 Aircraft Impact Assessment (APR1400)-1 Spent fuel pool cooling is not maintained for the postulated strike locations due to shock or to loss of power. However, as described in Section 19.5.5.3, SFP integrity is maintained, and SFP cooling is not required. Although forced cooling is lost, the SFP is part of the UHS, which provides a very large water inventory and ensures an adequate water level is maintained above the spent fuel assemblies for beyond the mission time, even with the loss of forced SFP cooling, as described in Section 9.1.3.3.5.

RAI 19.05 Aircraft Impact Assessment (APR1400)-1 19.5.5.5 Plant Monitoring and Control RAI 19.05 Aircraft Impact Assessment (APR1400)-1, RAI 19.05 Aircraft Impact Assessment (NuScale SMR design)-

23RAI 19.05 Aircraft Impact Assessment (NuScale SMR design)-23S1 After the operators scram the reactors and initiate the DHRS and containment isolation upon warning of a potential aircraft impact, no further operator actions are necessary to maintain core cooling.

RAI 19.05 Aircraft Impact Assessment (NuScale SMR design)-23, RAI 19.05 Aircraft Impact Assessment (NuScale SMR design)-23S1 Mitigating strategies for a loss of large area event are described in FSAR Section 20.2.

These mitigating strategies address the requirements of 10 CFR 50.54(hh)(2) and any operator actions needed to respond to this beyond design basis event.For the postulated aircraft impact event, required operator actions occur prior to the aircraft impact, upon notification of the threat. Operators trip the individual NPMs and initiate containment isolation and decay heat removal systems. Following the aircraft impact event, monitoring functions are expected to remain available. However, in the event that post-AIA monitoring is determined to be unavailable, the mitigating strategies of FSAR Section 20.2 for the LOLA beyond-design-basis event are invoked. The actions taken by the Operators prior to the aircraft impact ensure that the reactor core and spent fuel remains cooled, containment remains intact, and spent fuel pool integrity is maintained.

19.5.6 Conclusion RAI 19.05 Aircraft Impact Assessment (APR1400)-1 The aircraft impact assessment concludes that the NuScale Power Plant design and functional capabilities provide adequate protection of public health and safety in the event of an impact of the NRC defined large commercial aircraft. Containment intact, core cooling capability, and spent fuel pool integrity are not impaired as a result of the postulated aircraft impacts.

Tier 2 19.5-7 Draft Revision 3