ML17261B280

LLC Response to NRC Request for Additional Information No. 99 (Erai No. 8905) on the NuScale Design Certification Application

ML17261B280
Person / Time
Site:	NuScale
Issue date:	09/18/2017
From:	Rad Z NuScale
To:	Document Control Desk, Office of New Reactors
References
RAIO-0917-56027
Download: ML17261B280 (15)

Text

RAIO-0917-56027 September 18, 2017 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 Response to NRC Request for Additional Information No.

99 (eRAI No. 8905) on the NuScale Design Certification Application

REFERENCE:

U.S. Nuclear Regulatory Commission, "Request for Additional Information No.

99 (eRAI No. 8905)," dated July 21, 2017 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 response to the following RAI Questions from NRC eRAI No. 8905:

10.04.10-1 10.04.10-2 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 Darrell Gardner at 980-349-4829 or at dgardner@nuscalepower.com.

y, Sincerely, Zackary W. Rad Director Director, Regulatory Affairs NuScale Power, LLC Distribution: Gregory Cranston, NRC, OWFN-8G9A Samuel Lee, NRC, OWFN-8G9A Demetrius Murray, NRC, OWFN-8G9A : NuScale Response to NRC Request for Additional Information eRAI No. 8905 NuScale Power, LLC 1100 NE Circle Blvd., Suite 200 Corvalis, Oregon 97330, Office: 541.360.0500, Fax: 541.207.3928 www.nuscalepower.com

RAIO-0917-56027 :

NuScale Response to NRC Request for Additional Information eRAI No. 8905 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.: 8905 Date of RAI Issue: 07/21/2017 NRC Question No.: 10.04.10-1 10 CFR 52.47(c)(2) requires, in part, that a standard design certification of a nuclear power reactor design that uses simplified, inherent, passive, or other innovative means to accomplish its safety functions must provide an essentially complete nuclear power reactor design except for site-specific elements such as the service water intake structure and the ultimate heat sink, and must meet the requirements of 10 CFR 50.43(e).

GDC 4 requires, in part, that structures, systems, and components (SSCs) important to safety be appropriately protected against dynamic effects, including the effects of missiles, pipe whippingthat may result from equipment failures and from events and conditions outside the nuclear power unit. The requirements of GDC 4 are met when the auxiliary boiler system (ABS) design includes provisions to accommodate the effects of missiles and boiler explosions.

FSAR Tier 2, Table 10.4-20, Auxiliary Boiler System Component Design Parameters, indicates that the high-pressure and low-pressure auxiliary boilers are committed to piping code ASME B31.1, "Power Piping." The scope of ASME B31.1 does not include the boiler proper. No further information is provided for the remaining components of the ABS. The staff is unable to determine what code or standard is used for the boiler portions (such as vessels) and remaining components (such as piping) of the ABS. The staff is concerned that, without referencing a proper code or standard, contained steam and high pressures could leave the boiler and piping vulnerable to explosion, resulting in possible damage of nearby safety systems and components (SSCs).

The applicant is requested to provide the additional auxiliary boiler system information including any supporting figures, drawings, and a discussion of how proper codes or standards are adequately used for the design of boiler vessels and piping. The staff expects the entire auxiliary boiler system to be accounted for. The FSAR is to be modified accordingly.

NuScale Response:

As acknowledged in this RAI, the auxiliary boiler system (ABS) system piping will adhere to the requirements identified in FSAR Table 10.4-20. NuScale believes the piping codes referenced in NuScale Nonproprietary

this table are adequate for ABS piping.

All three boilers will be designed and fabricated in accordance with the ASME Boiler and Pressure Vessel Code,Section I, Power Boilers. FSAR Table 10.4-20 has been updated accordingly.

Impact on DCA:

Table 10.4-20 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 Other Features of Steam and Power Conversion System RAI 10.04.10-1 Table 10.4-20: Auxiliary Boiler System Component Design Parameters High-Pressure Auxiliary Boiler Low-Pressure Auxiliary Boiler Fuel Site-specific Site-specific Number of boilers 2 1 Steam supply pressure 1100 psig 500 psig Steam rate and temperature 18,000 lb/hr at 575°F 4,600 lb/hr at 575°F Feedwater pump rate 80 gpm 10 gpm Pipe code / material ASME B31.1 / SA-335 P11 or equivalent ASME B31.1 / SA-335 P11 or equivalent Estimated blowdown (demineralized 17.3 gpm 9.2 gpm feed, 10 cycles)

Boiler code / material ASME Boiler and Pressure Vessel Code, ASME Boiler and Pressure Vessel Code,Section I, Power Boilers Section I, Power Boilers Tier 2 10.4-91 Draft Revision 1

Response to Request for Additional Information Docket No.52-048 eRAI No.: 8905 Date of RAI Issue: 07/21/2017 NRC Question No.: 10.04.10-2 10 CFR 52.47(c)(2) requires that a standard design certification of a nuclear power reactor design that uses simplified, inherent, passive, or other innovative means to accomplish its safety functions must provide an essentially complete nuclear power reactor design except for site-specific elements such as the service water intake structure and the ultimate heat sink, and must meet the requirements of 10 CFR 50.43(e).

FSAR Tier 2, Section 10.4.10 presents the following COL Information Item 10.4-2: A COL applicant that references the NuScale Power Plant design certification will describe the site-specific auxiliary boiler system, the chemistry requirements, chemistry maintenance program, and how the system meets the design requirements.

The staff is unclear as to what specific information is part of the design certification and what will part of the COL application. The FSAR Tier 2, Section 10.4.10 appears to indicate that only the boiler skids, the boiler/fuel type, and programmatic aspects are left for the COL applicant to address.

The applicant is requested to clarify the site-specific design information that the COL will need to provide. The FSAR is to be modified accordingly.

NuScale Response:

NuScale performed a review of FSAR Section 10.4.10, "Auxiliary Boiler System (ABS)," and identified a number of instances where the language used was confusing. Section 10.4.10 was intended to describe the design for the ABS with limited additional input to be provided by the COL applicant. COL Item 10.4-2 in FSAR Section 10.4.10 and Table 1.8-2 was revised to indicate that only the type of fuel supply for the boiler will be site-specific and be identified by the COL applicant. Additional clarifications were also made in FSAR Section 10.4.10.

NuScale Nonproprietary

Impact on DCA:

FSAR Section 10.4.10 and Table 1.8-2 have 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 Interfaces with Certified Design RAI 02.04.13-1, RAI 03.04.02-1, RAI 03.04.02-2, RAI 03.04.02-3, RAI 03.05.01.04-1, RAI 03.05.02-2, RAI-03.06.02-15, RAI 03.07.01-2, RAI 03.07.01-3, RAI 03.07.02-8, RAI 03.07.02-12, RAI 03.11-14, RAI 03.11-8, RAI 10.02-1, RAI 10.02-2, RAI 10.04.10-2, RAI 13.01.01-1, RAI 13.02.02-1, RAI 13.03-4, RAI 13.05.02.01-2, RAI 13.05.02.01-3, RAI 13.05.02.01-4 Table 1.8-2: Combined License Information Items Item No. Description of COL Information Item Section COL Item 1.1-1: A COL Applicantapplicant that references the NuScale Power Plant design certification will 1.1 identify the site-specific plant location.

COL Item 1.1-2: A COL Applicantapplicant that references the NuScale Power Plant design certification will 1.1 provide the schedules for completion of construction and commercial operation of each power module.

COL Item 1.4-1: A COL Applicantapplicant that references the NuScale Power Plant design certification will 1.4 identify the prime agents or contractors for the construction and operation of the nuclear power plant.

COL Item 1.7-1: A COL Applicantapplicant that references the NuScale Power Plant design certification will 1.7 provide site-specific diagrams and legends, as applicable.

COL Item 1.7-2: A COL Applicantapplicant that references the NuScale Power Plant design certification will list 1.7 additional site-specific P&IDs and legends as applicable.

COL Item 1.8-1: A COL Applicantapplicant that references the NuScale Power Plant design certification will 1.8 provide a list of departures from the certified design.

COL Item 1.9-1: A COL Applicantapplicant that references the NuScale Power Plant design certification will 1.9 review and address the conformance with regulatory criteria in effect six months before the docket date of the COL application for the site-specific portions and operational aspects of the facility design.

COL Item 1.10-1: A COL Applicantapplicant that references the NuScale Power Plant design certification will 1.10 evaluate the potential hazards resulting from construction activities of the new NuScale facility to the safety-related and risk significant structures, systems, and components of existing operating unit(s) and newly constructed operating unit(s) at the co-located site per 10 CFR 52.79(a)(31). The evaluation will include identification of any management and administrative controls necessary to eliminate or mitigate the consequences of potential hazards and demonstration that the limiting conditions for operation of an operating unit would not be exceeded. This COL item is not applicable for construction activities (build-out of the facility) at an individual NuScale Power Plant with operating NuScale Power Modules.

COL Item 2.0-1: A COL Applicantapplicant that references the NuScale Power Plant design certification will 2.0 demonstrate that site-specific characteristics are bounded by the design parameters specified in Table 2.0-1. If site-specific values are not bounded by the values in Table 2.0-1, the COL applicant will demonstrate the acceptability of the site-specific values in the appropriate sections of its combined license application.

COL Item 2.1-1: A COL Applicantapplicant that references the NuScale Power Plant design certification will 2.1 describe the site geographic and demographic characteristics.

COL Item 2.2-1: A COL Applicantapplicant that references the NuScale Power Plant design certification will 2.2 describe nearby industrial, transportation, and military facilities. The COL applicant will demonstrate that the design is acceptable for each potential accident, or provide site-specific design alternatives.

COL Item 2.3-1: A COL Applicantapplicant that references the NuScale Power Plant design certification will 2.3 describe the site-specific meteorological characteristics for Section 2.3.1 through Section 2.3.5, as applicable.

COL Item 2.4-1: A COL Applicantapplicant that references the NuScale Power Plant design certification will 2.4 investigate and describe the site-specific hydrologic characteristics for Section 2.4.1 through Section 2.4.14, as applicable.

COL Item 2.5-1: A COL Applicantapplicant that references the NuScale Power Plant design certification will 2.5 describe the site-specific geology, seismology, and geotechnical characteristics for Section 2.5.1 through Section 2.5.5, below.

COL Item 3.2-1: A COL Applicantapplicant that references the NuScale Power Plant design certification will 3.2 update Table 3.2-1 to identify the classification of site-specific SSC.

Tier 2 1.8-3 Draft Revision 1

NuScale Final Safety Analysis Report Interfaces with Certified Design Table 1.8-2: Combined License Information Items (Continued)

Item No. Description of COL Information Item Section COL Item 10.2-3: A COL Applicantapplicant that references the NuScale Power Plant design certification will 10.2 perform an evaluation of the probability of turbine missile generation. The report provides a calculation of the probability of turbine missile generation using established methods and industry guidance applicable to the fabrication technology employed. The analysis is a comprehensive report containing a description of turbine fabrication methods, material quality and properties, and required maintenance and inspections that addresses:

a) the calculated probability of turbine missile generation from material and overspeed related failures based on as-built rotor and blade designs and asbuilt material properties (as determined in certified testing and nondestructive examination).

b) maximum anticipated speed resulting from a loss of load, assuming normal control system function without trip.

c) overspeed basis and overspeed protection trip setpoints.

d) discussion of the design and structural integrity of turbine rotors.

e) an analysis of potential degradation mechanisms (e.g., stress corrosion cracking, pitting, low-cycle fatigue, corrosion fatigue, erosion and erosioncorrosion), and any specific maintenance or operating requirements necessary for mitigation.

f) material properties (e.g., yield strength, stress-rupture properties, fracture toughness, minimum operating temperature of the high-pressure turbine rotor) and the method of determining those properties.

g) required preservice test and inspection procedures and acceptance criteria to support calculated turbine missile probability.

h) actual maximum tangential and radial stresses and their locations in the turbine rotor.

i) rotor and blade design analyses, including loading combinations, assumptions and warmup time, that demonstrate sufficient safety margin to withstand loadings from postulated overspeed events up to 120 percent of rated speed.

j) description of the required inservice inspection and testing program for valves essential to overspeed protection and any inservice tests, inspections, and maintenance activities for the turbine and valve assemblies that are required to support the calculated missile probability, including inspection and test frequencies with technical bases, type of inspection, techniques, areas to be inspected, acceptance criteria, disposition of reportable indications, and corrective actions.

COL Item 10.3-1: A COL Applicantapplicant that references the NuScale Power Plant design certification will 10.3 provide a site-specific chemistry control program based on the EPRI PWR Secondary Water Chemistry Guidelines and NEI 97-06.

COL Item 10.3-2: A COL Applicantapplicant that references the NuScale Power Plant design certification will 10.3 provide a description of the flow-accelerated corrosion monitoring program for carbon steel portions of the steam and power conversion systems that contain water or wet steam and are susceptible to erosion and corrosion damage.that meets Generic Letter 89-08 and EPRI NSAC-202L-R3 for the turbine generator system (including the turbine bypass system and the turbine gland sealing system), the main steam system (including extraction steam), the condensate and feedwater system (including the condensate polishing system), and the auxiliary boiler system.

COL Item 10.4-1: A COL Applicantapplicant that references the NuScale Power Plant design certification will 10.4 determine the size and number of new and spent resin tanks in the condensate polishing system.

COL Item 10.4-2: A COL Applicantapplicant that references the NuScale Power Plant design certification will 10.4 describe the type of fuel supply for the auxiliary boilers.site-specific auxiliary boiler system, the chemistry requirements, chemistry maintenance program, and how the system meets the design requirements.

Tier 2 1.8-12 Draft Revision 1

NuScale Final Safety Analysis Report Other Features of Steam and Power Conversion System 10.4.7.5 Instrumentation Requirements Feedwater instrumentation is designed to facilitate automatic operation, remote control, and monitoring of system parameters. Instrumentation and controls are provided in the MCS to monitor variables and control CFWS operation over its anticipated range of normal operation, AOOs, and accident conditions to ensure adequate safety. Feedwater parameters monitored and instrumentation details are listed in Table 10.4-19.

Positioning of the FWRVs and speed control of the feedwater pumps are functions of the MCS. For each SG, the feedwater control system maintains the feedwater flow supply. The MCS is able to accommodate specified step load changes without a significant deviation from the programmed control band or major effect on the feed system. See Table 10.4-17. Chapter 7 describes the MCS.

10.4.8 Steam Generator Blowdown System This section is applicable only to pressurized water reactor SG designs that incorporate a blowdown system. As described in Section 5.4.1, the NuScale Power Plant SG design does not use a blowdown system. Therefore, this section is not applicable to the NuScale design.

10.4.9 Auxiliary Feedwater System The NuScale Power Plant design neither requires nor uses an auxiliary feedwater system.

Therefore, this section is not applicable to the NuScale design.

The DHRS (Section 5.4.3) performs some functions similar to an auxiliary feedwater system.

However, as compared to an auxiliary feedwater system, the DHRS differs substantially in its design, operation, and relationship to the small break loss-of-coolant accident (LOCA) plant response.

10.4.10 Auxiliary Boiler System RAI 10.04.10-2 The ABS is a nonsafety-related non-seismic system designed to supply steam to systems where main steam is not available or not preferred. The system is supplied by the COL applicant.

10.4.10.1 Design Bases This section identifies the ABS required or credited functions, the regulatory requirements that govern the performance of those functions, and the controlling parameters and associated values that ensure that the functions are fulfilled. Together, this information represents the design bases, as defined in 10 CFR 50.2, as required by 10 CFR 52.47(a) and (a)(3)(ii).

The ABS serves no safety function, is not credited for mitigation of a DBA, and has no safe shutdown functions.

Tier 2 10.4-40 Draft Revision 1

NuScale Final Safety Analysis Report Other Features of Steam and Power Conversion System RAI 10.04.10-2 General Design Criteria 2, 4, and 5 are considered in the design of the ABS. No safety-related SSC are affected by the effects of natural phenomena such as earthquakes. The design of the ABS provides protection of safety-related SSC from the environmental conditions associated with normal operation, maintenance, testing and postulated accidents. There are no safety-related components in the ABS that are shared among NPMs; therefore, failure of the ABS does not significantly impair the ability of other NPMs to perform their safety functions.

Consistent with GDC 60, the design of the ABS ensures the capability to control releases of radioactive materials to the environment. Consistent with GDC 64, the system is monitored for radioactivity that may be released from normal operations, including anticipated operational occurrences, and from postulated accidents.

Consistent with 10 CFR 20.1101(b), the (system) design supports keeping radiation exposures as low as reasonably achievable (ALARA). Consistent with 10 CFR 20.1406, the ABS is designed to preclude contamination of connecting systems, and thus minimize contamination of the associated systems, facility, and the environment.

The ABS component design parameters are shown in Table 10.4-20.

10.4.10.2 System Description The ABS is a nonsafety-related non-seismic system designed to supply steam to systems where main steam is not available or not preferred. The ABS consists of two separate systems. The high-pressure system is dedicated to supplying steam to the MHS heat exchangers during startup and shutdown. The primary functions of the low-pressure system are to provide steam to the turbine gland seals, the MC for deaeration, and to the condensate polishing resin regeneration system.

The high-pressure and low-pressure system configurations are depicted on Figure 10.4-4a and Figure 10.4-4b and are comprised of vendor-supplied boiler skid packages. The ABS provides 18,000 lb/hr of 575-degree steam at 1100 psig and 4600 lb/

hr of 575-degree steam at 500 psig at the required chemistry quality, during all modes of plant operation including AOOs, for the following functions:

• module heatup system (MHS), described in Section 9.3.4, to heat the primary coolant to initiate natural circulation during startup and shutdown

• turbine gland sealing

• sparging steam for MC deaeration at lower loads

• resin regeneration for the CPS 10.4.10.2.1 General Description The high-pressure ABS supply header is protected by pressure relief valves and monitored by pressure and temperature transmitters. Supply lines off the header distribute the steam to the MHS. Two high-pressure boilers (one primary and one redundant) supply steam to the MHS. One boiler supports heatup of a single NPM.

Tier 2 10.4-41 Draft Revision 1

NuScale Final Safety Analysis Report Other Features of Steam and Power Conversion System The simultaneous heatup of an NPM from each group of up to six NPMs can be supported using both high-pressure auxiliary boilers.

The pressure of the returning MHS steam is reduced by a pressure control valve and a flash tank, and collected as condensate in a condensate collection tank with relief valve. Excess steam pressure is vented. The demineralized water system feeds makeup water as needed, and the outlet of the CST flows to the inlet suction of redundant boiler feedwater pumps. Upstream of the feedwater pumps, a chemical addition system injects chemicals for water quality. Feedwater pumps supply redundant ABS boilers with water at the required pressure, and check valves downstream of each pump prevent backflow through the idle pump.

Boiler blowdown is monitored with a flow meter control valve, and the common blowdown header is cooled by a heat exchanger and discharged to the BPDS. Each blowdown stream has a sampling line routed to the PSS to monitor and maintain water quality for the ABS.

A line off the high-pressure steam header is routed to the low-pressure steam header for when the low pressure boiler is out of service. Protected by double blocking valves, a pressure reducer and relief valves, the pressure and temperature downstream of the pressure reducing valve is monitored.

RAI 10.04.10-2 The ABS has provisions for chemical addition for chemistry control of the steam from the auxiliary boiler. During boiler operations, water makeup is provided from a non-radioactive demineralized water source. In order to maintain the chemistry requirements of the system, appropriate additives are used to control oxygen and pH consistent with secondary side chemistry requirements described in Section 10.3.5.1. Each boiler system (low-pressure and high-pressure) has a blowdown line connected to the BPDS. The blowdown is cooled by a heat exchanger after entering the BPDS. Each boiler system has a sample line from the steam supply and the blowdown to the PSS.

RAI 10.04.10-2 COL Item 10.4-2: A COL applicant that references the NuScale Power Plant design certification will describe the type of fuel supply for the auxiliary boilers.site-specific auxiliary boiler system, the chemistry requirements, chemistry maintenance program, and how the system meets the design requirements.

During operation, the low-pressure ABS supply header provides steam to the turbine gland seals during NPM startup, the MC, and the CPS for resin regeneration.

It is protected by triple pressure relief valves and monitored by pressure and temperature transmitters. During NPM startup, the MSS flow is not established, and thus the ABS must supply gland seal steam to the TGSS. This function is transferred to the individual NuScale Power Module MSS when sufficient supply is generated.

For the low-pressure ABS, the flow is monitored by a flow transmitter which is used to control the amount of steam fed to the gland seals. The backup steam supply from the high-pressure boiler system is isolated by double block valves and a Tier 2 10.4-42 Draft Revision 1

NuScale Final Safety Analysis Report Other Features of Steam and Power Conversion System

• associated controls The ABS component design parameters are shown in Table 10.4-20.

Material selection is compatible with operating conditions. See Table 10.4-20 for ABS material.

Boiler RAI 10.04.10-2 Each ABS boiler generates steam with a site-specific design and fuel supply.

Feedwater Pumps For each system, the ABS feedwater pumps provide sufficient capacity for the maximum expected steam makeup from the ABS boiler with sufficient reserve. A redundant pump allows for component service during operation.

Deaerator A deaerator is provided in each ABSs to remove excess gases during operation of the system.

Pressure Relief A pressure-relief valve is installed on each ABS boiler. It maintains the system pressure below the design maximum and can manage the maximum expected flow from the worst transient.

Valves The ABS valves are provided on serviced components to allow component selection and servicing during operation. Valves are also provided to seamlessly integrate the use of ABS steam with main steam as desired.

Flash Tank and Condensate Return Tank A flash tank is used to vaporize and condense hot condensate before returning the liquid to the system. A condensate return tank is provided for each boiler system. It is sized to accommodate the condensate return from the maximum expected number of simultaneous components.

10.4.10.2.3 System Operation Operations are described as those supporting a single NPM operation status, even if a single NPM is shutdown while the other NPMs are running.

During normal operation, the low-pressure ABS supplies steam to the TGSS gland seals during NPM startup, the MC, and the CPS for resin regeneration. During NPM Tier 2 10.4-44 Draft Revision 1

NuScale Final Safety Analysis Report Other Features of Steam and Power Conversion System startup and shutdown when the MSS flow is not established, the ABS supplies gland seal steam to the TGSS. This function is transferred to the MSS of the individual NPM when sufficient supply is generated. The high-pressure ABS supplies steam to the MHS for NPM heatup and shutdown. When the NPM temperature reaches a set point, the ABS supply to the heat exchangers is discontinued and the inlet valve to the MHS heat exchanger isolated. The high pressure ABS can supply steam to the low-pressure header if needed (for backup only) through a pressure-reducing valve.

The ABS does not run continuously, but is brought online when needed. The system is monitored locally and in the MCR. Pressure, temperature, level, flow, remotely-operated valve position transmitters supply the operators with necessary system information.

The ABS is equipped with protective features that activate should the pressure increase beyond allowable limits. Pressure-relief valves automatically vent steam if the pressure increases above a set point to protect the system and prevent overpressure failure. If the water level in the boiler or condensate tank is too high or too low, or if flow rates or temperatures are out of safe operating limits, alarms sound locally in the auxiliary boiler building and in the MCR to alert the operator that attention or action is required. Level transmitters monitor the condensate level inside the condensate collection tanks. If the level falls below a lower limit, the level control valve in the demineralized water supply line modulates open to add water to the tank. If the water level rises above an upper limit, the level control valve modulates closed to allow the boiler feedwater pumps to lower the level in the condensate tank. Flow transmitters on the blowdown of the boilers modulate the downstream flow control valve to regulate the volume of blowdown of the boilers.

The ABS does not need to maintain essential functions in the event of adverse environmental phenomena, pipe breaks, or loss of normal AC power. The ABS is nonsafety-related and is not needed post-DBA.

RAI 10.04.10-2 The system shutdown procedure for the ABS is provided by the equipment manufacturer. The equipment manufacturer provides the sequencing and required checks to shutdown the boiler and accessories safely.

10.4.10.3 Safety Evaluation The ABS serves no safety function, is not credited for mitigation of a DBA, and has no safe shutdown functions.

RAI 10.04.10-2 GDC 2 was considered in the design and arrangement of ABS components. The ABS is nonsafety-related, but portions of the ABS are contained in the RXB, which is a Seismic Category I structure, designed to withstand the effects of natural phenomena, such as earthquakes, tornadoes, hurricanes, floods, tsunamis and seiches. Thus the portions of the ABS inside the RXB are designed to remain functionalpreclude adverse seismic interactions during and after a safe shutdown earthquake (SSE) and meet the Tier 2 10.4-45 Draft Revision 1

NuScale Final Safety Analysis Report Other Features of Steam and Power Conversion System guidelines ofconsistent with Regulatory Guide 1.29. The RXB is designed as an engineered barrier to withstand a postulated design basis missile. Consistent with Regulatory Guide 1.117, this satisfies the criteria of GDC 2 by the proper design and use of missile barriers (i.e., the RXB) to protect essential SSC against potential missiles generated by tornado or hurricane winds.

The portions of ABS that are housed in the TGB are nonsafety-related and are not located in areas that contain safety-related components and are not required to operate during or after an accident. No safety-related SSC are affected by the effects of natural phenomena such as earthquakes on the ABS.

General Design Criterion 4 was considered in the design of the auxiliary boiler system.

The design of the ABS provides protection of safety-related SSC from the environmental conditions associated with normal operation, maintenance, testing, and postulated accidents. A failure of the ABS that releases the water inventory and the resulting flooding does not prevent the operation of safety-related SSC. The plant flooding evaluation is addressed in Section 3.4. The dynamic impacts from missiles, water and steam system failures are addressed in Sections 3.5 and 3.6, respectively.

RAI 10.04.10-2 General Design Criterion 5 was considered in the design of the auxiliary boiler system.

There are no safety-related components in the ABS that are shared among NPMs; therefore, failure of the ABS does not significantly impair the ability of other NPMs to perform their safety functions.

General Design Criteria 60 and 64 were considered in the design of the auxiliary boiler system. Consistent with GDC 60, the design of the ABS ensures the capability to control releases of radioactive materials to the environment. Consistent with GDC 64, the system is monitored for radioactivity that may be released from normal operations, including anticipated operational occurrences, and from postulated accidents.

Process radiation monitors on each high-pressure return line from the MHS heat exchangers monitor the steam or condensate exiting, and a process radiation monitor on the vent of the pressure regulating valve on the high-pressure condensate collection tank monitors the steam venting from the tank. If radiation is detected in the ABS that is greater than the high-high radiation isolation or if system power is lost, the ABS flash tank pressure regulating valve and the steam supply valves from both boilers isolate.

An adjacent-to-line radiation detector monitors the cross-tie line from the high-pressure to low-pressure ABS and isolates the high-pressure to low-pressure ABS cross-tie valve if the high-high radiation isolation setpoint is exceeded or if system power is lost.

Blowdown from the ABS is delivered to the BPDS south turbine building drain tank.

This tank provides a means to monitor for radioactive contaminants in the ABS blowdown line. If a high radiation condition is detected, an alarm is initiated in the MCR, the north waste water sump pumps and north oily waste pump automatically shut down and the discharge flow path to the balance of plant drain system collection Tier 2 10.4-46 Draft Revision 1