ML18193B178
| ML18193B178 | |
| Person / Time | |
|---|---|
| Site: | NuScale |
| Issue date: | 07/12/2018 |
| From: | Rad Z NuScale |
| To: | Document Control Desk, Office of New Reactors |
| References | |
| RAIO-0718-60864 | |
| Download: ML18193B178 (10) | |
Text
RAIO-0718-60864 July 12, 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. 253 (eRAI No. 9184) on the NuScale Design Certification Application
REFERENCES:
- 1. U.S. Nuclear Regulatory Commission, "Request for Additional Information No. 253 (eRAI No. 9184)," dated October 13, 2017
- 2. NuScale Power, LLC Response to NRC "Request for Additional Information No. 253 (eRAI No.9184)," dated December 11, 2017 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 Questions from NRC eRAI No. 9184:
06.01.01-8
06.01.01-9 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, Z ckary W. Rad Za Zackary Director Regulatory Affairs
- Director, NuScale Power, LLC Distribution: Gregory Cranston, NRC, OWFN-8G9A Omid Tabatabai, NRC, OWFN-8G9A Samuel Lee, NRC, OWFN-8G9A : NuScale Supplemental Response to NRC Request for Additional Information eRAI No. 9184 NuScale Power, LLC 1100 NE Circle Blvd., Suite 200 Corvalis, Oregon 97330, Office: 541.360.0500, Fax: 541.207.3928 www.nuscalepower.com
NuScale Supplemental Response to NRC Request for Additional Information eRAI No. 9184 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.: 9184 Date of RAI Issue: 10/13/2017 NRC Question No.: 06.01.01-8 Regulatory Basis:
Appendix A, General Design Criteria for Nuclear Power Plants, to Title 10 of the Code of
Federal Regulations (10 CFR) Part 50, Domestic Licensing of Production and Utilization
Facilities, General Design Criteria (GDC) 1, requires that structures, systems, and components
(SSCs) important to safety shall be designed, fabricated, erected, and tested to quality
standards commensurate with the importance of the safety functions to be performed.
GDC 4, Environmental and dynamic effects design bases, requires that SSCs important to
safety shall be designed to accommodate the effects of and to be compatible with the
environmental conditions associated with normal operation, maintenance, testing, and
postulated accidents, including loss-of-coolant accidents (LOCAs).
GDC 14, Reactor coolant pressure boundary, requires that the reactor coolant pressure
boundary (RCPB) shall be designed, fabricated, erected, and tested so as to have an extremely
low probability of abnormal leakage, of rapidly propagating failure, and of gross rupture.
GDC 31, Fracture prevention of reactor coolant pressure boundary, requires that the RCPB
shall be designed with sufficient margin to assure that when stressed under operating,
maintenance, testing, and postulated accident conditions (1) the boundary behaves in a
nonbrittle manner and (2) the probability of rapidly propagating fracture is minimized.
Applicant PDC 35, Emergency core cooling, requires a system to provide abundant
emergency core cooling. The system safety function shall be to transfer heat from the reactor
core following any loss of reactor coolant at a rate such that (1) fuel and clad damage that could
interfere with continued effective core cooling is prevented and (2) clad metal-water reaction is
limited to negligible amounts.
10 CFR Part 50, Appendix B, Criteria IX, Control of Special Processes, and XIII, Handling,
Storage, and Shipping, require establishing measures to: (1) assure that special processes are
controlled and accomplished in accordance with applicable codes, standards, specifications,
criteria, and other special requirements; and (2) control cleaning of material and equipment in
accordance with work and inspection instructions to prevent damage or degradation.
NuScale Nonproprietary
DCD Tier 2, FSAR, Section 6.1.1.1 states that the pressure-retaining bolting and stud materials
for connection of the upper and lower containment vessel (CNV) shell flanges, top head, and
reactor pressure vessel (RPV)-to-CNV support ledge shell are fabricated out of Alloy 718.
The supplement to DCD Tier 2, FSAR, Section 3.13 dated August 10, 2017 [ADAMS
ML17222A218] states that all uses of Alloy 718 receive the same heat treatment and that this
heat treatment will mitigate stress corrosion cracking (SCC). However, DCD Tier 2, FSAR,
Section 6.1.1 does not reference Section 3.13.
Revise DCD Tier 2, FSA5, Section 6.1.1 to reference Section 3.13 related to the Alloy 718
threaded fastener design requirements for the mitigation of SCC.
NuScale Response:
NuScale updated FSAR Section 6.1.1.1 to indicate that the Alloy 718 heat treatment requirements discussed in FSAR Section 13.3.1.1 are applied to the Alloy 718 CNV main vessel closure studs.
In addition, FSAR Tables 6.1-1 and 6.1-2 are updated to add a note indicating that material designated as Type or Grade 304/304L is dual certified stainless steel material.
Impact on DCA:
FSAR Section 6.1 and Tables 6.1-1 and 6.1-2 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 Engineered Safety Feature Materials ASME Code Section III, Subsection NB-4300 and the low-alloy steel forgings that have cladding applied are manufactured to an ASTM grain size of 5 or finer. Electroslag welding is not used other than for austenitic stainless steel cladding of low-alloy steel.
Implementation of RG 1.44 guidelines minimizes the potential for stainless steel intergranular stress corrosion cracking. Prior to fabrication, unstabilized austenitic stainless steel of the AISI Type 3XX series is solution treated per the guidance of RG 1.44, which describes acceptable criteria for preventing intergranular corrosion of stainless steel components. Where austenitic stainless steel materials are subjected to sensitizing temperatures for greater than 60 minutes during post weld heat treatment, non-sensitization of the materials is verified by testing in accordance with ASTM A262, Practice A or E. Furnace-sensitized austenitic stainless steel is not used in NuScale ESF components.
Delta ferrite content of stainless steel weld filler material conforms to the guidelines stipulated in ASME BPVC,Section III, Subsections NB-2433, NC-2433 or NF-2433 and RG 1.31 to ensure sufficient ferrite content to avoid microfissures in welds, offset dilution and reduce thermal aging. The delta ferrite content in stainless steel weld metal is controlled between ferrite number 5 and 20. Ni-Cr-Fe filler metals used for Alloy 690 to low alloy material welds are made with Alloy 52/152/52M filler metal to provide a high level of corrosion resistance.
The guidelines of RG 1.31 or ASME BPVC,Section III, Subsection NB-2433 for determining the delta ferrite of stainless steel welds do not apply to the filler materials used for depositing cladding because the cladding is deposited as a corrosion resistant layer and does not have a structural function. The delta ferrite content in the austenitic stainless steel weld cladding is controlled between ferrite number 5 and 20.
The chemical composition of low-alloy steel filler metals used for the ESF components meets the requirements of the ASME BPVC,Section II material specifications. The weld metal filler metals are listed in Table 6.1-1.
RAI 06.01.01-5, RAI 06.01.01-8, RAI 06.01.01-8S1, RAI 06.01.01-9, 06.01.01-9S1 Pressure retaining bolting and stud materials (studs, nuts and flat washers) used in ESF systems are fabricated of corrosion resistant alloys; SB-637, Alloy 718 (UNS N07718) for connection of the upper and lower CNV shell flanges, top head and reactor pressure vessel (RPV) to CNV support ledge shell; and, SA-564, Grade 630, Condition H1100 for CNV appurtenance flanges, and manways and inspection or access ports. These bolting and stud materials are consistent with ASME BPVC,Section III, Subsection NB-2128 and are inspected to the requirements of NB-2580. In addition, the Alloy 718 heat treatment requirements discussed in Section 3.13.1.1 are applied to the Alloy 718 CNV main closure flange studs.
Threaded inserts for CNV bolting are fabricated of corrosion resistant alloy SA-479, Type 304/304L.
To minimize the potential for stress corrosion cracking, cold-working of austenitic stainless steel surfaces from abrasive work, such as grinding or wire brushing, is Tier 2 6.1-3 Draft Revision 2
NuScale Final Safety Analysis Report Engineered Safety Feature Materials RAI 06.01.01-1, RAI 06.01.01-1S1, RAI 06.01.01-2, RAI 06.01.01-3, RAI 06.01.01-4, RAI 06.01.01-8S1, 06.01.01-9S1 Table 6.1-1: Material Specifications for ESF Components Component Material/Grade/Type CNTS Inside Containment Piping ^'dWdW>
Supports SA-182, Grade F304/F304L CNV Lower Shell Assembly CNV Lower Flange ^&yD CNV Lower Transition Shell SA-240, Type 304/304L CNV Lower (Core Region) Shell SA-182, Grade F304/F304L CNV Bottom Head SA-479, Type 304/304L Upper/Lower Shell Flange Studs, nuts, and bolts SB-637, UNS N07718Note 2 CNV Upper Shell Assembly CNV Upper Flange SA-508, Grade 3, Class 2 CNV RPV Support Ledge Shell CNV Steam Plenum Access Shell CNV Upper Shell CNV Support Lugs Set Screws SA-193, Grade B8,Class 1 Hex Nuts Threaded Inserts SA-479 Type 304/304L SG Inspection Port (CNV27 -CNV30); PZR Heater Access Port SA-637, UNS-N07718Note 2 (CNV31 and CNV32); and Manway (CNV26) Cover studs, nuts and washers PZR Heater Access (CNV31-CNV32); Manway (CNV26) and SA-240, Type 304/304L SG Inspection Port (CNV27-CNV30) Covers Leak Port Tube SA-213, Grade TP316L CNV Upper Shell Penetrations: DHRS Nozzles (CNV22 and CNV23); SA-508, Grade 3, Class 2 Manway (CNV26); SG Inspection Port (CNV27-CNV30); PZR Heater Access Port (CNV31 and CNV32); RVV Trip/Reset Nozzles (CNV33, CNV34 and CNV40); RRV Trip/Reset Nozzles (CNV35 and CNV36) and RVV Trip Nozzle (CNV41)
Hex Head Bolts Hex Head, Flat Washers, Nuts for the RPV Support SB-637 UNS N07718Note 2 Lug Shell CNV Head Assembly CRDM Power (CNV37); Instrument Port (CNV8, CNV9, CNV17- SA-564, Grade 630, Condition H1100 CNV20, CNV38 and CNV39); PZR Heater Power (CNV15 and CNV 16); CRDM Access Opening (CNV25) and Head Manway (CNV24)
Cover studs, nuts and washers Inspection Ports and Manway Cover Threaded Inserts Vessel Alignment Pin Threaded Insert SA-479, Type 304/304L Set Screws SA-193, Grade B8, Class 1 CNV Top Head and Top Head Nozzles: SA-508, Grade 3, Class 2 FWS (CNV1 and CNV2); MSS (CNV3 and CNV4); CRDS Return and Supply (CNV5 and CNV12); CES (CNV10); CVCS (CNV6, CNV7, and CNV13); RCS High Point Degasification (CNV14) and CFDS (CNV11)
CRDM Access Opening Cover (CNV25) SA-182, Grade F304/F304L CNV Head Manway Blind Flange (CNV24) SA-240, Type 304/304L CRDM Access Opening Cover Lifting Lugs, PZR Heater Power (CNV15 and CNV16) and CRDM Power Blind Flange (CNV 37)
Division 1& 2 (CNV8 and CNV9); Group A-D (CNV17-CNV20); RPI SA-240, Type 304/304L Group 1 and Group 2 (CNV38 and CNV39) Electrical Penetration Blind Flanges Tier 2 6.1-7 Draft Revision 2
NuScale Final Safety Analysis Report Engineered Safety Feature Materials Table 6.1-1: Material Specifications for ESF Components (Continued)
Component Material/Grade/Type Weld Filler Material1 SFA-5.4: E308, E308L, E309, E309L, E316, E316L SFA-5.9: ER308, ER308L, E309, E309L, ER316, ER316L Note:
- 1) Carbon content of unstabilized Type 3XX weld-filler materials is restricted to 0.03 percent maximum.
- 2) Solution treatment temperature range prior to precipitation hardening treatment is restricted to 1800 °F to 1850 °F.
- 3) When the material is designated as Type or Grade 304/304L, this refers to dual-certified stainless steel material.
Tier 2 6.1-9 Draft Revision 2
NuScale Final Safety Analysis Report Engineered Safety Feature Materials RAI 06.01.01-1, RAI 06.01.01-2, RAI 06.01.01-3, RAI 06.01.01-4, RAI 06.01.01-6, RAI 06.01.01-8S1, 06.01.01-9S1 Table 6.1-2: Material Specifications for CNV Related non-ESF Components Component Material/Grade/Type CNTS outside containment Piping SA-312, Grade TP304/304L SA-182, Grade F304/F304L Piping Supports and Guides (flat plates, supports and rotational SA-240, Type 304/304L restraint) SA-479, Type 304/304L Coupler SA-182, Grade F304/F304L Reactor Coolant System See Table 5.2-4 Control Rod Drive System Piping SA-312, Grade TP304/304L Supports (brackets and bolts) SA-479, Type 304/304L Nozzle fittings, pipe caps, reducers, flange weld neck SA-182, Grade F304/F304L Flex hose TP316L stainless steel Steam Generator System See Table 5.2-4 Weld Filler Materials See Table 5.2-4 (stainless steel to be compatible with base material)
Instrumentation Sensor Line Tubing SA-312, Grade Type 316L SMLS Instrument Enclosure (Base and Cover) SA-182, Grade F304/F304L Swageloks SS304 Nuts and Studs A479-74, Grade XM-19 Flat Washers SA-240, Type 304 Sensor Cabling (Sheath) TP304L Stainless Steel Alignment Pins CNV Vessel Alignment Pins and Threaded Inserts SA-479, Type 304/304L Note:
- 1) When the material is designated as Type or Grade 304/304L, this refers to dual-certified stainless steel material.
Tier 2 6.1-10 Draft Revision 2
Response to Request for Additional Information Docket No.52-048 eRAI No.: 9184 Date of RAI Issue: 10/13/2017 NRC Question No.: 06.01.01-9 DCD Tier 2, FSAR, Table 1.9-2, Conformance with Regulatory Guides, states that RG 1.65,
Materials and Inspections for Reactor Vessel Closure Studs, is applicable to Section 6.1,
which describes the containment vessel (CNV). The CNV closure studs are part of the CNV and
also described in Section 6.1.
The supplement to the DCD dated July 11, 2017 [ADAMS ML17192A869] revises DCD Tier 2,
FSAR, Section 6.1.1.1 to state that the concerns addressed by RG 1.65, Revision 1, Position
2(b) do not apply to Alloy 718 due to its resistance to general corrosion. As written, this
sentence is unclear since it does not refer to the specific CNV closure studs. There are other
threaded fasteners that are manufactured out of Alloy 718 that are used within the CNV. Furthermore, the proposed wording of Section 6.1.1.1 does not address the applicability
of the remaining positions of RG 1.65 to the Alloy 718 CNV closure studs.
Revise DCD Tier 2, FSAR, Section 6.1.1 to discuss all of the applicable positions of RG 1.65,
Revision 1, for the specific CNV closure studs.
NuScale Response:
The scope of RG 1.65 is reactor pressure vessel (RPV) closure stud bolting. The statement in FSAR Section 6.2-7, discussing CNV bolting and threaded fastener integrity and fracture toughness requirements, has been clarified to indicate that alloy 718 heat treatment requirements identified in FSAR Section 3.13 are applied to the CNV main flange closure studs.
Impact on DCA:
FSAR Section 6.2 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 Containment Systems The CNV system meets the relevant requirements of GDC 1 (Section 3.1.1) with regards to quality standards for design and fabrication, GDC 16 (Section 3.1.2) related to the release of radioactivity, and GDC 51 (Section 3.1.5) related to sufficient design margin for fracture prevention. In meeting the requirements of GDC 1, 16 and 51, the ferritic containment pressure boundary materials satisfy the fracture toughness criteria for ASME Section III, Subsection NB.
The design, fabrication, and materials of construction for the CNV system includes margin to provide reasonable assurance that the CNV pressure boundary will not undergo brittle fracture, and the probability of rapidly propagating fracture will be minimized, under operating, maintenance, testing, and postulated accident conditions over its 60-year design life. Section 6.2.1 provides additional detail.
For ferritic materials classified as pressure-retaining components of the RCPB, the requirements of ASME BPVC Section XI Appendix G apply.
The NuScale ferritic containment pressure boundary conforms to ASME BPVC,Section II material specifications and meets the fracture toughness criteria and testing requirements identified in ASME BPVC Section III, Division 1, NB-2300 for containment pressure boundary components fabricated of ferritic materials. Fracture prevention of the containment pressure boundary is assured.
RAI 06.01.01-8S1, RAI 06.01.01-9S1 Information addressing the integrity and fracture toughness of CNV bolting and threaded fasteners is addressed in Section 3.13.The Alloy 718 heat treatment requirements discussed in Section 3.13.1.1 are applied to the Alloy 718 CNV main closure flange studs.
Portions of the lower CNV have 60-year design fluence in excess of 1E+17 neutrons/cm2, E > 1 MeV, with the peak fluence in the lower CNV not exceeding 5.5E+18 neutrons/cm2, E > 1 MeV. To remove neutron embrittlement concerns in the CNV, the lower CNV is made of austenitic stainless steels which are more resistant to neutron embrittlement than ferritic materials.
6.2.8 References 6.2-1 TR-0516-49084, Rev 0, Containment Response Analysis Methodology Technical Report 6.2-2 TR-0516-49422, Rev 0, "LOCA Evaluation Model," July 2016 6.2-3 TR-0716-50424, Rev 0, "Combustible Gas Control Technical Report,"
6.2-4 TR-0516-49416, Rev. 0, "Non-LOCA Transient Analysis Methodology Report,"
January 2017 6.2-5 TR-0916-51299, Rev. 0, "Long Term Core Cooling Methodology". January 2017.
6.2-6 TR-1116-51962, Rev. 0, "NuScale Containment Leakage Integrity Assurance",
December 2016.
Tier 2 6.2-57 Draft Revision 2