ML24215A089
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Response to SDAA Audit Question Question Number: A-4.5.1-3 Receipt Date: 10/02/2023 Question:
Clarify what the weld filler metal in the proposed Table 1 in the response to question A-4.5.1-1 is used for since most of the welds have been removed from the CRD.
Response
Initial Response:
The weld filler metals identified in Table 1 of the response to question A-4.5.1-1 are for non-reactor coolant pressure boundary (RCPB) welds of the control rod drive mechanism (CRDM).
Plug welds are on the control rod drive shaft contained within the RCPB. Additionally, the cooling jacket assembly and the rod position indication assembly are welded construction and external to the RCPB.
The weld filler metals for the CRDM are removed from Table 5.2-3 in the attached FSAR markup because the CRDM is a single-piece design without RCPB welds. Table 1 from the response to question A-4.5.1-1 is incorporated into FSAR Section 4.5.1 in the attached markup.
The markup to FSAR Section 4.5.1 clarifies the materials of the CRDM and their application.
Updated Response:
In response to feedback received by the NRC on 11/6/2023, the NRC requested the following clarifications:
Please clarify in proposed Table 4.5-1 which material are used for the bolting that connects the CRDM housing to the reactor pressure vessel head. Per paragraph NuScale Nonproprietary NuScale Nonproprietary
3.9.4.1.1 of SDA460 the CRDM pressure housing is bolted to the reactor vessel head. In addition, clarify the preservice and inservice inspections that will be applied to the bolting (for CRDM pressure housing to the reactor vessel head), noting that paragraph 3.6.2.7 of SDA460 provides augmented volumetric inspection for preservice and inservice inspections of similar small diameter bolting used on the reactor pressure vessel head.
None of the items in Table 4.5-1 provided are used for the bolting that connects the CRDM housing to the RPV head. The fasteners for CRDM components external to the RCPB included in Table 4.5-1 are referring to items such as bolts in the coil assemblies and the nuts and threaded rods that join together the external assembly.
The bolting that connects the CRDM housing to the RPV is the scope of the RPV and falls under Table 5.2-3 as RPV Bolting Other Than Main Closure Flange (SA-193 Grade B8 Class 1, SA-194 Grade 8, or SB-637 UNSN07718). This joint also implements Threaded Inserts from Table 5.2-3.
The bolting that connects the CRDM housing to the reactor pressure vessel head is subject to VT-1 visual inspection in accordance with Table IWB-2500-1 (B-G-2) for pressure-retaining bolting 2 inches and less in diameter. There are no augmented inspections for this bolting. The augmented inspection described in SDAA Section 3.6.2.7 is only applicable to the RRV and RVV, as they are a break exclusion zone for piping area.
This response includes FSAR Table 4.5-2 in the markup of Section 4.5 to incorporate Table 1 from audit response A-4.5.2-1.
Markups of the affected changes, as described in the response, are provided below:
NuScale Nonproprietary NuScale Nonproprietary
NuScale Final Safety Analysis Report Reactor Materials NuScale US460 SDAA 4.5-2 Draft Revision 2 Non-RCPB portions of the CRDM contained within the pressure housing are not categorized as ASME Code components. They are constructed to not adversely affect the integrity of the core support structures, and use materials that conform to either an ASME, Aerospace Material, or American Society for Testing and Materials (ASTM) material specification.
Audit Question A-4.5.1-3 Non-RCPB CRDM component materials are listed in Table 4.5-1.include Types 304, 316, 410, 410T, 440C, 630 H1100, AMS 5662, AMS 5698, AMS 5699, AMS 5662, AMS 5759, AMS 5894 or a low-cobalt alternative, UNS N07750, UNS N07718 (AMS 5662), and UNS N06625. Materials exposed to borated pool water, primary reactor coolant, saturated steam and non-condensable gases, or component cooling water are corrosion-resistant stainless steels, nickel-based alloys, and, to a limited extent, cobalt-based alloys. These materials are selected from those proven in light-water reactor operation and for their compatibility with the reactor coolant as specified in ASME BPVC, 2017 Edition,Section III, Paragraph NB-2160 and Subsubarticle NB-3120.
The CRDS pressure-retaining components are not fabricated or manufactured from cast austenitic stainless steel. Use of cold-worked austenitic stainless steel is avoided to the extent practicable during fabrication of CRDS structural components. Austenitic stainless steel with yield strength greater than 90,000 psi, as determined by the 0.2 percent offset method, is not used in fabricating CRDS structural components.
4.5.1.2 Austenitic Stainless Steel Components Processing and welding unstablized American Iron and Steel Institute (AISI)
Type 3XX series austenitic stainless steels for pressure-retaining parts comply with Regulatory Guide (RG) 1.44, Revision 1, to prevent sensitization and stress corrosion cracking. Austenitic stainless steel is procured in the solution-annealed condition. When rapidly cooled by means other than water quenching, non-sensitization of base materials is verified by test in accordance with Practice A or Practice E of ASTM A262 (Reference 4.5-1).
Unstabilized AISI Type 3XX series austenitic stainless steel base metals and weld filler metals have a maximum carbon content of 0.03 weight percent. This specification excludes base metals that are not welded or exposed to sensitizing temperatures in the range of 800 degrees F to 1500 degrees F subsequent to solution annealing.
The CRDM weld filler metals are in accordance, as applicable, with SFA-5.4 and SFA-5.9 of ASME BPVC, 2017 Edition,Section II, Part C. These include E308, E308L, E309, E309L, E316, E316L, ER308, ER308L, ER309, ER309L, ER316, and ER316L. They are analyzed for delta ferrite content and limited to a ferrite number (FN) of 5FN to 20FN in accordance with RG 1.31, Revision 4, and ASME BPVC, 2017 Edition,Section III, Paragraph NB-2433, except for Types 316 and 316L, which are limited to the range of 5FN to 16FN.
NuScale Final Safety Analysis Report Reactor Materials NuScale US460 SDAA 4.5-3 Draft Revision 2 Section 5.2.3 describes the controls used to minimize the introduction of potentially harmful contaminants including chlorides, fluorides, and low-melting point alloys on the surface of austenitic stainless steel components that are part of the RCPB, including the CRDM reactor coolant pressure boundary components.
Cleaning solutions, processing equipment, degreasing agents, and other foreign materials are removed during processing before elevated temperature treatments.
Acid pickling is avoided on stainless steel and not used on sensitized austenitic stainless steel.
4.5.1.3 Other Materials Audit Question A-4.5.1-3 The use of martensitic stainless steel is limited to Types 410 and 440C. Type 410 is tempered at not less than 1050 degrees F to prevent temper embrittlement and stress-corrosion cracking. Weld filler materials for martensitic stainless steels include E410, E430, ER410, and ER430.
Audit Question A-4.5.1-3 Nickel-chromium-based alloy X-750 is used for the CRDM springs and cobalt-based-alloys Haynes 25 and Stellite 6 or 6B are used for wear-resistant parts. These materials have been used in existing pressurized water reactor CRDMs for the same function with satisfactory performance. The material of the pins associated with gripper components is Haynes 25. Stellite 6 or 6B material is limited to the CRDM gripper latch arms. To minimize the possibility of stress-corrosion cracking failures, the CRDM springs and wear-resistant parts are procured in the same heat treatment condition as previously used in the industry.
Alloy X-750 spring material and heat treatment conform to the requirements of AMS 5698 or AMS 5699. There have been no operating experience reports of stress-corrosion cracking of Alloy X-750 CRDM springs fabricated from AMS 5698 and AMS 5699. For Alloy X-750, the cobalt impurity does not exceed 1 percent. To minimize cobalt intrusion into the reactor coolant, low-cobalt or cobalt-free alloys may be used for wear-resistant CRDM parts if their wear and corrosion resistance are qualified by testing. Alloy 625, Alloy 718, and Type 440C are used for improved strength in select CRDM components. Grades 8, B6, B8, and B8M are used for some screws and bolts. Type 630 H1100 is used for some fasteners and threaded rods. These materials have satisfactory performance in existing light-water reactors.
4.5.1.4 Material Cleaning and Cleanliness Control Cleaning and cleanliness controls of CRDMs comply with the quality assurance requirements in Subpart 2.1 of ASME NQA-1 (Reference 4.5-2).
4.5.2 Reactor Internals and Core Support Structure Materials Audit Question A-4.5.1-3 Figure 3.9-1 through Figure 3.9-4 show the reactor vessel internals (RVI) subassemblies with components that comprise the RVI. The RVI do not contain any
NuScale Final Safety Analysis Report Reactor Materials NuScale US460 SDAA 4.5-4 Draft Revision 2 cast austenitic stainless steel components. The RVI component materials are listed in Table 4.5-2.
4.5.2.1 Materials Specifications Materials that may be used for the RVI consist of austenitic stainless steels including, but not limited to, Type 304, F304, TP304, TP304 SMLS, TP321, XM-19, and UNS S21800, and strain-hardened Type 316 [Code Case N-60-6 (Reference 4.5-3)] in forms including, but not limited to,: SA-182, SA-213, SA-240, SA-249, SA-312, SA-403, SA-479, SA-965, A-240, A-249, A-580, and WP304.
Allowable weld materials are described in Section 4.5.2.4. The portions of the RVI performing a core support function are designed and fabricated as Class CS in accordance with ASME BPVC, 2017 Edition,Section III, Subsection NG. The materials for core support structures and threaded structural fasteners conform to the requirements of ASME BPVC, 2017 Edition,Section III, Subsubarticle NG-2120 and the applicable requirements of ASME BPVC, 2017 Edition,Section II, Part D, Tables 2A and 2B and Code Case N-60-6. The remaining portions of the RVI are designated as internal structures and are designed to conform to ASME BPVC, 2017 Edition,Section III, Paragraph NG-1122.
4.5.2.2 Control on Welding The welding of RVI materials conforms to the applicable requirements of ASME BPVC, 2017 Edition,Section III, Articles NG-2000, NG-4000, and NG-5000.
Welding is conducted using procedures qualified according to the rules of ASME BPVC, 2017 Edition,Section III, Subarticle NG-4300 and Section IX of the latest edition. Welders and welding operators are qualified in accordance with ASME BPVC Section IX of the latest edition and RG 1.71, Revision 1.
Electroslag welding is not permitted on RVI and core structural supports.
Alloy 600 (UNS N06600) and associated weld filler materials are not used in the RVI.
4.5.2.3 Nondestructive Examination Nondestructive examinations of core support structure materials, including tubular products, conform to the requirements of ASME BPVC, 2017 Edition,Section III, Subarticle NG-2500 using the methods of ASME BPVC, 2017 Edition,Section V and acceptance standards of Subarticle NG-5300.
4.5.2.4 Fabrication and Processing of Austenitic Stainless Steel Components Austenitic stainless steel parts are fabricated from materials procured in the solution-annealed condition. Use of cold-worked austenitic stainless steel is avoided to the extent practicable during fabrication of the RVI and core support structures. Cold-worked austenitic stainless steel used in the RVI and core support components does not exceed a yield strength of 90,000 psi as determined by the 0.2 percent offset method.
NuScale Final Safety Analysis Report Reactor Materials NuScale US460 SDAA 4.5-6 Draft Revision 2 Audit Question A-4.5.1-3 Table 4.5-1: Acceptable Control Rod Drive Mechanism Materials Item Material Designation (Grade, Class, or Type)
Latch Mechanism (contained within RCPB)
Magnetic parts: poles, supports, and spacers Type 410 (annealed or tempered)
Springs Alloy X-750 (UNS N07750) AMS 5698 or AMS 5699 Wear Parts: Pins Haynes Alloy 25 (AMS 5759)
Wear Parts: Grip arms and links Stellite 6 or 6B (AMS 5894)
Guide tube, Shims (gap spacers)
Type 304 or Inconel Alloy 625 (UNS N06625)
Locking nut and locking cup, Grip arm housing Type 304 MJA support items UNS N07718 (AMS 5662 or AMS 5663), Type 304 Fasteners Grade B6 Anti-rotation key Type 440C Items External to Reactor Coolant Pressure Boundary (RCPB)
Support Rings, Coil housing spacers, Power cable tube, RPI bobbin, Cooling jacket and piping, RPI seismic support plates, RPI outer housing tube Type 304 Coil Housings: Drive Coils, RDM, RHO Type 410 Fasteners Grade B8 and B8M, Type 630 H1100 Miscellaneous items UNS N07718 (AMS 5662 or AMS 5663), Type 630 H1100, Type 304, Type 316 CRD Shaft Assembly (contained within RCPB)
Tube Connector, Coupling Retainer and Connector, Dowl Pins, Manual Operating Rod, Spacers Type 304 Magnetic parts: poles, supports, upper shaft section Taper Key, Connecting Rod pieces, Retaining Ring, Extension Tubes, Protective Sleeve Type 410 (annealed or tempered)
Springs Alloy X-750 (UNS N07750) AMS 5698 or AMS 5699 CRD Shaft Coupling UNS N06625 Push Button, Button Ring, Extension Tube Adapter, Connector Tube UNS N07718 (AMS 5662 or AMS 5663)
Coupling Nut, Spring Bushing Type 440C Shims (gap spacers)
Type 304 or Inconel Alloy 625 (UNS N06625)
Fasteners Grade B8 RHO Ball Grip Assembly (contained within RCPB)
Magnetic parts: poles and grips Type 410 (annealed or tempered)
Springs Alloy X-750 (UNS N07750) AMS 5698 or AMS 5699 Ball Grip Inner, Steel Ball Type 440C Fasteners Grade 8 or B8 Dowel Pin Type 304 Weld Filler Metals for Non-RCPB Items (may be used for items both external to or contained within the RCPB)
Ferritic Stainless Steel Weld Filler Metals E410, E430 ER410, ER430 Austenitic Stainless Steel Weld Filler Metals1 E308, E308L, E309, E309L, E316, E316L ER308, ER308L, ER309, ER309L, ER316, ER316L
NuScale Final Safety Analysis Report Reactor Materials NuScale US460 SDAA 4.5-7 Draft Revision 2 CRDM RCPB Items Table 5.2-3 Notes:
(1) 0.03 percent maximum carbon for unstabilized AISI Type 3XX weld filler metals with ferrite number in the range of 5FN to 20FN, except 5FN to 16FN for Type 316 and Type 316L.
Table 4.5-1: Acceptable Control Rod Drive Mechanism Materials (Continued)
Item Material Designation (Grade, Class, or Type)
NuScale Final Safety Analysis Report Reactor Materials NuScale US460 SDAA 4.5-8 Draft Revision 2 Audit Question A-4.5.1-3 Table 4.5-2: Acceptable Reactor Vessel Internals Materials Component Material (Grade, Class, or Type)
Upper riser assembly Type 304 Lower riser assembly Type 304, Type XM-19, UNS S21800 Core support assembly Type 304, Type 316, UNS S21800 Flow diverter Type 304 In-core instrumentation guide tube (ICIGT)
Type 304 Hanger plate Type 304 Upper control rod drive shaft (CRDS) support plate Type 304 Intermediate CRDS support plate Type 304 Bellows In accordance with ASME B&PV Code, 2017 Edition,Section III, Division I, Subsection NG, Paragraph NG-2121, or Code Case N-60-6 Transition shell Type 304 Control rod assembly guide tube (CRAGT) assembly Type 304 ICIGT assembly Type 304 Upper core plate Type 304 CRAGT support plate Type 304 Fuel pin Type 304 Upper support block Type 304 Reflector blocks Type 304 Core barrel Type 304 Lower core plate Type 304 Core support assembly mounting brackets Type 304, Type 316, Type XM-19, UNS S21800
NuScale Final Safety Analysis Report Integrity of Reactor Coolant Boundary NuScale US460 SDAA 5.2-31 Draft Revision 2 Audit Question A-4.5.1-3, Audit Question A-5.4-1 Table 5.2-3: Reactor Coolant Pressure Boundary Component and Support Materials Including Reactor Vessel, Attachments, and Appurtenances Component Specification Grade, Class, or Type Reactor Pressure Vessel Lower Vessel (Lower Head, Shell and Flange)
SA-965 FXM-191 Upper Vessel (Flange, Shells including PZRIntegral Steam Plenum Baffle Plate, Upper Head, Steam Plenum and Feed Plenum Access Ports)
SA-508 Grade 3 Class 2 SG Tubes SB-163 UNS N06690 Nozzles (Thermowells, Level Sensors, Pressure Taps); Steam Plenum Caps SB-166 UNS N06690 CNV-RPV Lateral Support Lugs; RPV-CNV Support Ledges SB-168 UNS N06690 Safe-Ends SA-182 F3042 Integral Steam Plenum Bore Sleeves SA-240 Type 3042 Covers for Steam Plenum Access Ports Covers for Feed Plenum Access Ports SA-182 F3042 FXM-19 SA-240 Type 3042 FXM-191 Leak Test Ports SA-312 TP316 SMLS2 PZR Heater Bundle Flange SB-168 UNS N06690 PZR Heater Element End Plug SA-479 Type 3042 PZR Heater Element Sheath SA-213 TP3162 Threaded Inserts; Pipe Reducers; PZR Spray Nozzles SA-479 Type 3042 SA-193 Grade 8 Class 1 Grade B8M Class 1 Grade B8R Grade B8S Carbide Solution Treated RPV Bolting Main Flange Closure SB-637 UNS N077183 Other Than Main Flange Closure SA-193 Grade B8 Class 1, Grade B8R, Grade B8M Class 1 SA-194 Grade 8 SB-637 UNS N077183 SA-564 Type 630, H1100 CRDM Support Structure Supports SA-240 Type 3042 SA-479 Type 3042 Bolting SA-564 Type 630, H1100 CRDM Pressure Retaining Components CRDM Pressure Housing SA-182 F304 or F304LN2 SA-965 F304LN2 Top Plug Components SA-479 Type 3042 Type 410
NuScale Final Safety Analysis Report Integrity of Reactor Coolant Boundary NuScale US460 SDAA 5.2-32 Draft Revision 2 Austenitic Stainless Steel Weld Filler Metals SFA-5.4 E3084, E308L, E309L, E316, E316L SFA-5.9 ER3084, ER308L, ER309L, ER316, ER316L4 Weld Filler Metals for RPV and CRDM Support Structure Low-Alloy Steel Weld Filler Metals SFA-5.5 E90XX-X SFA-5.23 F9XX-EXX-XX or F10XX-EXX-XX SFA-5.28 ER90S-X SFA-5.29 E9XTX-XX 2XX Austenitic Stainless Steel Weld Filler Metals SFA-5.4 E209, E2401 SFA-5.9 ER209, ER2401 3XX Austenitic Stainless Steel Weld Filler Metals (include filler metals for weld-overlay cladding)
SFA-5.4 E308, E308L, E309, E309L, E316, E316L4 SFA-5.9 ER308, ER308L, ER309, ER309L, ER316, ER316L, EQ308L, EQ309L4 SFA-5.22 E308, E308L, E309, E309L, E316, E316L4 Nickel-Base Alloy Weld Filler Metals SFA-5.11 ENiCrFe-7 SFA-5.14 ERNiCrFe-7, ERNiCRFE-7A, EQNiCrFe-7, EQNiCrFe-7A RCS Piping
- RCS Injection Piping Assembly
- RCS Discharge Piping Assembly
- RCS PZR Spray Piping Assembly
- RPV High Point Degasification Piping Assembly Pipe SA-312 TP304 SMLS, TP316 SMLS2 Pipe Fittings SA-182 F304. F3162 SA-403 WP304 SMLS, WP316 SMLS2 SA-479 Type 304, Type 304L, Type 316, Type 316L2 Piping Supports Supports SA-240 Type 304 and Type 3162 Type 405, Type 410S SA-479 Type 304, Type 3162 Type 405, Type 410 Annealed or Class 1 SA-312 TP304, TP304L, TP316, TP316L2 Bolting SA-193 Grade B8, Grade B8M SA-194 Grade 8, Grade 8M SA-564 Type 630 H1100 Weld Filler Metals for Piping and Their Supports 3XX Austenitic Stainless Steel Weld Filler Metals SFA-5.4 E308, E308L, E316, E316L4 SFA-5.9 ER308, ER308L, ER316, ER316L4 SFA-5.30 IN308, IN308L, IN316, IN316L4 Nickel-Base Alloy Weld Filler Metals SFA-5.11 ENiCrFe-7 SFA-5.14 ERNiCrFe-7, ERNiCRFE-7A Table 5.2-3: Reactor Coolant Pressure Boundary Component and Support Materials Including Reactor Vessel, Attachments, and Appurtenances (Continued)
Component Specification Grade, Class, or Type