ML24093A319

LLC - Supplemental Response to NRC Request for Additional Information No. 10083 (RAI-10083) on the NuScale Standard Design Approval Application

ML24093A319
Person / Time
Site:	05200050, 99902078
Issue date:	04/02/2024
From:	Fosaaen C NuScale
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
RAIO-162019
Download: ML24093A319 (1)

Text

RAIO-162019 NuScale Power, LLC 1100 NE Circle Blvd., Suite 200 Corvallis, Oregon 97330 Office 541.360.0500 Fax 541.207.3928 www.nuscalepower.com April 2, 2024 Docket No. 052-050 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. 10083 (RAI-10083) on the NuScale Standard Design Approval Application

REFERENCES:

1. U.S. Nuclear Regulatory Commission, Request for Additional Information No. 10083 (RAI-10083), dated October 11, 2023 The purpose of this letter is to provide the NuScale Power, LLC (NuScale) 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 RAI-10083:

10.1-1S1 This letter makes no regulatory commitments and no revisions to any existing regulatory commitments.

If you have any questions, please contact Thomas Griffith at 541-452-7813 or at tgriffith@nuscalepower.com.

I declare under penalty of perjury that the foregoing is true and correct. Executed on April 2, 2024.

Sincerely, Carrie Fosaaen Vice President, Regulatory Affairs NuScale Power, LLC Distribution:

Mahmoud Jardaneh, NRC Getachew Tesfaye, NRC Tommy Hayden, NRC : NuScale Response to NRC Request for Additional Information RAI-10083, nonproprietary

RAIO-162019 NuScale Power, LLC 1100 NE Circle Blvd., Suite 200 Corvallis, Oregon 97330 Office 541.360.0500 Fax 541.207.3928 www.nuscalepower.com :

NuScale Response to NRC Request for Additional Information RAI-10083, nonproprietary

NuScale Nonproprietary Response to Request for Additional Information Docket: 052000050 RAI No.: 10083 Date of RAI Issue:10/11/2023 NRC Question No.: 10.1-1S1 Supplemental Response: NuScale is including a supplemental response to the original RAI 10.1-1. The original RAI is as follows:

Regulatory Basis Title 10 of the Code of Federal Regulations (10 CFR), Section 52.137(a)(2) requires an applicant for an SDA to provide a final safety analysis report (FSAR) that that describes the facility, presents the design bases and the limits on its operation, and presents a safety analysis of the structures, systems, and components and of the facility, or major portion thereof. Section 52.137(a)(2) requires that the applicant include:

a description and analysis of the SSCs of the facility, with emphasis upon performance requirements, the bases, with technical justification, upon which the requirements have been established, and the evaluations required to show that safety functions will be accomplished. It is expected that the standard plant will reflect through its design, construction, and operation an extremely low probability for accidents that could result in the release of significant quantities of radioactive fission products. The description shall be sufficient to permit understanding of the system designs and their relationship to the safety evaluations. Items such as the reactor core, reactor coolant system, instrumentation and control systems, electrical systems, containment system, other engineered safety features, auxiliary and emergency systems, power conversion systems, radioactive waste handling systems, and fuel handling systems shall be discussed insofar as they are pertinent.

Issue FSAR Chapter 10 describes the steam and power conversion systems. For the staff to NuScale Nonproprietary

NuScale Nonproprietary understand the system design and its relationship to plant safety, the descriptions in Chapter 10 should include the systems design and performance characteristics and a reference heat balance diagram based on the normal plant operation at rated power. In general, the balance of plant (BOP) secondary plant system components and parameters are developed from the heat balance mass flow, temperatures, and steam system pressures which are used. If these are not used, a description of the bases for BOP system calculations and evaluations is needed. Power conversion system and component design must take into account the conditions established by the secondary side heat balance in order to ensure safety related components can perform their functions. For example, the main steam isolation valves (MSIVs) which will be required to close against system flow and pressure associated with the plant operating at rated power. In addition, the information provided in the heat balance allows the staff to confirm that analyses performed in Chapter 15 adequately reflect the design and use appropriate initial conditions reflective of the plants normal operation at rated power.

The heat balance also provides information on the turbine bypass and main condenser heat removal capacity.

Requested Information Based on its review of Chapter 10, the staff has determined that additional information is required to fully satisfy 10 CFR 52.137(a)(2) requirements. The staff requests that NuScale include in Section 10.1 of the FSAR a reference heat balance diagram and associated table based on normal plant operation at rated power.

NuScale Response:

The staff has stated the safety finding cannot be completed without inclusion of the secondary side heat balance data directly in the FSAR. NuScale maintains the position that this information is beyond the level of detail necessary in the FSAR as documented in the original docketed response to RAI 10.1-1 (ML23361A099), providing justification for omission based on regulatory requirements, the lack of associated SRP acceptance criteria, overall safety-significance, graded approach to review, and NEI 98-03. However, due to the staffs official position that the nominal and representative heat balance must be included in the FSAR, NuScale is including this representative heat balance within the FSAR, as shown below.

NuScale Nonproprietary

NuScale Nonproprietary Impact on US460 SDA:

FSAR Section 10.1 has been revised as described in the response above and as shown in the markup provided in this response.

NuScale Nonproprietary

NuScale Final Safety Analysis Report Summary Description NuScale US460 SDAA 10.1-1 Draft Revision 2 CHAPTER 10 STEAM AND POWER CONVERSION SYSTEM 10.1 Summary Description The steam and power conversion system removes and directs heat energy from the reactor coolant system. Heat energy from the NuScale Power Module (NPM) is transferred from the primary coolant by helical-coil steam generators to convert secondary coolant to steam. Turbine generators convert this steam energy to electrical power. The steam and power conversion system has no safety-related or risk-significant function.

The steam and power conversion system includes pipes, fittings, valves, and instruments from (and including) removable pipe spools at the containment system main steam isolation valves (MSIVs), to (and including) removable pipe spools at the containment system feedwater isolation valves. The steam and power conversion system comprises the following components and process systems:

turbine generator system (TGS) (Section 10.2) main steam system (MSS) (Section 10.3) air cooled condenser system (ACCS) (Section 10.4.1) condenser air removal system (CARS) (Section 10.4.2) turbine gland sealing system (TGSS) (Section 10.4.3) turbine bypass system (TBS) (Section 10.4.4) condensate polisher skid and resin regeneration system (CPS) (Section 10.4.5) condensate and feedwater system (FWS) (Section 10.4.6) auxiliary boiler system (ABS) (Section 10.4.7) feedwater treatment system (FWTS) (Section 10.4.8)

Table 10.3-1 shows major system operating parameters at rated thermal power.

Table 10.2-1 provides turbine generator design parameters.

Figure 10.1-1 provides a power conversion system simplified diagram of an NPM.

10.1.1 Protective Features Section 10.3 and Section 10.4 describe load rejection capabilities of the steam and power conversion system.

Main steam safety valves provide overpressure protection of the steam and power conversion system as described in Section 10.3.

Plant accidents and transient events that result in a loss of feedwater are addressed in Section 10.4.6 and Section 15.2.7.

NuScale Final Safety Analysis Report Summary Description NuScale US460 SDAA 10.1-2 Draft Revision 2 The turbine overspeed protection provides protection from exceeding overspeed limits as discussed in Section 10.2.

Turbine missiles are discussed in Section 3.5.

Under normal operating conditions, radioactive contaminants are not expected in the steam and power conversion system. However, it is possible for the system to become contaminated. Implications of detecting radioactivity in the secondary side are addressed in Section 11.5.

Audit Question A-10.1-1 RAI 10.1-1S1 The design of nonsafety-related portions of steam and power conversion systems that could adversely impact safety-related systems incorporate considerations to prevent erosion, corrosion, and flow-accelerated corrosion. Design implementations are further addressed in Section 10.3.5 and Section 10.3.6. Table 10.1-1 includes a nominal set of conditions for the representative heat balance values provided in Table 10.1-2. Figure 10.1-2 provides a heat balance diagram. The numbers for each stage in Figure 10.1-2 correspond to those in Table 10.1-2. As noted, these results are representative in nature.

Table 5.4-1 includes full-load thermal-hydraulic operating conditions, including steam generator inlet temperature, steam pressure, steam temperature, and steam flow.

Table 15.0-6 provides the initial conditions for accident analysis, including the initial conditions for feedwater temperature and steam pressure. Steam and power conversion system conditions are within the bounding assumptions of Table 15.0-6.

NuScale Final Safety Analysis Report Summary Description NuScale US460 SDAA 10.1-3 Draft Revision 2 Audit Question A-10.1-1 RAI 10.1-1S1 Table 10.1-1: Nominal Conditions for Representative Heat Balance Case Description Units Value Feedwater Heaters 3 FWHs Total Number of ACC Cells 14 Ambient Pressure psia 12.0 Ambiant Temperature F

59.0 Ambient Relative Humidity 60.0 Wet Bulb Temperature F

50.8 Heat Input BTU/sec 236,305 Heat Input MWt 249.3 Gross Power kW 79,993 Net Power kW 74,312 Steam Turbine Auxiliary kW 186 Transformer Losses kW 200 Gross Heat Rate Btu/kWh 10,643 Net Heat Rate Btu/kWh 11,448 Turbine Cycle Heat Rate Btu/kWh 10,667 Feedwater Temperature F

250

NuScale Final Safety Analysis Report Summary Description NuScale US460 SDAA 10.1-4 Draft Revision 2 Audit Question A-10.1-1 RAI 10.1-1S1 Table 10.1-2: Nominal Values for Representative Heat Balance Case Stream No.

Description Parameter Units Value 1

Steam Generator Outlet Flow lb/h 814,046 Pressure psia 475.0 Temperature F

542.2 Enthalpy BTU/lb 1264.6 2

Steam Turbine Inlet Steam Flow lb/h 812,766 Pressure psia 432.0 Temperature F

534.9 Enthalpy BTU/lb 1264.6 3

Extraction Steam to Feedwater Heater 1

Flow lb/h 59,293 Pressure psia 8.5 Temperature F

185.5 Enthalpy BTU/lb 1,027.20 4

Extraction Steam to Feedwater Heater 2

Flow lb/h 32,023 Pressure psia 17.7 Temperature F

221.5 Enthalpy BTU/lb 1,058.10 5

Extraction Steam to Feedwater Heater 3

Flow lb/h 31,550 Pressure psia 33.8 Temperature F

257.1 Enthalpy BTU/lb 1,087.0 6

Turbine Exhaust Steam Flow lb/h 635,522 Pressure psia 0.950 Temperature F

100.0 Enthalpy BTU/lb 960.9 7

Turbine Bypass Steam Flow lb/h 0

Pressure psia 432.0 Temperature F

534.9 Enthalpy BTU/lb 1,264.60 8

Turbine Bypass Desuperheating Water Flow lb/h 0

Pressure psia 200.0 Temperature F

100.3 Enthalpy BTU/lb 68.8 9

Combined Turbine Bypass Steam Flow lb/h 0

Pressure psia 0.95 Temperature F

448.8 Enthalpy BTU/lb 1,264.60 10 From Condensate Collections Tank Flow lb/h 813,701 Pressure psia 5.29 Temperature F

100.0 Enthalpy BTU/lb 68.0 11 FWH 1 Tube Side Inlet Flow lb/hr 814,046 Temperature F

102.8 12 FWH 2 Tube Side Inlet Flow lb/hr 814,046 Temperature F

177.7

NuScale Final Safety Analysis Report Summary Description NuScale US460 SDAA 10.1-5 Draft Revision 2 13 FWH 3 Tube Side Inlet Flow lb/hr 814,046 Temperature F

214.5 14 FWH 3 Tube Side Outlet Flow lb/hr 814,046 Temperature F

248.9 15 From Feedwater Pump to Steam Generators Flow lb/h 814,046 Pressure psia 527.3 Temperature F

249.9 Enthalpy BTU/lb 219.6 16 Feedwater Heater 3 Cascading Drain Flow lb/h 31,550 Pressure psia 31.9 Temperature F

224.1 Enthalpy BTU/lb 192.4 17 Feedwater Heater 2 Cascading Drain Flow lb/h 63,573 Pressure psia 17.1 Temperature F

188.0 Enthalpy BTU/lb 156.1 18 Feedwater Heater 1 Drain Flow lb/h 122,865 Pressure psia 7.963 Temperature F

112.2 Enthalpy BTU/lb 80.2 Table 10.1-2: Nominal Values for Representative Heat Balance Case (Continued)

Stream No.

Description Parameter Units Value

NuScale Final Safety Analysis Report Summary Description NuScale US460 SDAA 10.1-6 Draft Revision 2 Audit Question A-10.1-1 RAI 10.1-1S1 Figure 10.1-1: Power Conversion System Block Flow Diagram CNTS TGS FWS TG FWS MSS ABS MSS MSS Desuperheater CNTS SR NS Air Intake Air Cooled Condenser Duct ACCS FWS ACCS FWS ACCS Feedwater Regulating Valves FWS Feedwater Isolation Valves SG CNTS CNTS SG Safety Seismic Anchor Located at Exit From RXB TGS To Cond To Cond Safety NS Aux Steam Header Main Steam Isolation Valves MSSVs Secondary Main Steam Isolation Valves Removable Spool Pieces Turbine To Atm Turbine Bypass Valve Turbine Stop/

Control Valves LP Heater LP Heater LP Heater Removable Spool Pieces Condensate Pumps Condensate Polisher Skid Gland Steam Condenser Feedwater Pumps Steam Generators TGS Feedwater To Atm FWS Gland Steam Extraction Blowers From Other Units Condenser Air Removal System To Atm SR Seismic Anchor Located at Entrance to RXB Condensate Polisher Resin Regeneration Generator Chemical Injection from FWTS Deaerator Condensate Collection Tank Condensate Storage Tank 1

2 3

4 5

6 7

8 9

10 11 12 13 14 15 16 17 18

NuScale Final Safety Analysis Report Summary Description NuScale US460 SDAA 10.1-7 Draft Revision 2 Audit Question A-10.1-1 RAI 10.1-1S1 Figure 10.1-2: Heat Balance Diagram

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