ML24302A030
| ML24302A030 | |
| Person / Time | |
|---|---|
| Issue date: | 10/28/2024 |
| From: | Michael Snodderly Advisory Committee on Reactor Safeguards |
| To: | |
| References | |
| Download: ML24302A030 (4) | |
Text
NuScale Nonproprietary 1
NuScale Nonproprietary Chapter 3 Significant Changes from DCA to SDA Discussion Section 3.1 - Design of Structures, Systems, Components and Equipment Changes are minimal.
Section 3.2 - Classification of Structures, Systems, and Components COL Item 3.2-1 removed.
It is not expected that an applicant would add components to these tables.
Section 3.3 - Wind and Tornado Loadings SDAA uses more conservative wind loads than required by regulatory guidance.
Conservative wind loads are chosen to bound requirements from both ASCE 7-05 and ASCE 7-16, so a single analysis demonstrates compliance to both standards.
Section 3.4 - Water Level (Flood) Design SDAA evaluates flood zones instead of rooms.
COL Items have updated or removed.
Clarification of COL applicant responsibilities.
Personnel access tunnel from RXB to CRB has been removed.
Section 3.5 - Missile Protection No turbine missile evaluation is required for Control Building.
Essential equipment, as defined by RG 1.115, has been removed from the building.
Section 3.6 - Protection against Dynamic Effects Associated with Postulated Rupture of Piping Leak Before Break (LBB) is no longer used.
The main steam and feedwater lines inside containment comply with the criteria of BTP 3-4 B.1.(ii), eliminating the need to postulate breaks and cracks for the evaluation of dynamic effects (i.e., break exclusion). Previously, LBB methodology was used to eliminate breaks in these lines.
Section 3.9 - Mechanical Systems and Components Changed CRDM connection from welded to bolted Updated the CRDM pressure housing to a bolted connection on the top head.
Connection design requirements unchanged for pressure and stress.
Updated transient definitions SDAA changed transient definitions that are described in Chapter 3.9.1
NuScale Nonproprietary 2
NuScale Nonproprietary Updated ASME BPV Code 2017 The new design was updated to ASME 2017 code to keep current with industry codes and standards.
Section 3.10 - Seismic and Dynamic Qualifications of Mechanical and Electrical Equipment Newer Versions of Regulatory Guidance and Industry Standards Adopted RG 1.100 Revision 4 IEEE 344 from 2004 to 2013 ASME QME-1 from 2007 to 2017 Three COL Items Related to Administration of Qualification Program Removed Combined License Application will incorporate the seismic and dynamic qualification program described in the SDA by reference Section 3.11 - Environmental Qualification of Mechanical and Electrical Equipment List of environmentally qualified equipment updated to reflect US460 design Table 3.11-1 Updated Maximum post-accident operating time reduced to 720 hours0.00833 days <br />0.2 hours <br />0.00119 weeks <br />2.7396e-4 months <br /> The 720 hour0.00833 days <br />0.2 hours <br />0.00119 weeks <br />2.7396e-4 months <br /> operating time aligns with the Chapter 15 safety analysis. After 30 days, the reactor vessel pressure is low and stable and the reactor core remains covered during the entire event with sufficient margin.
Appendix 3C -
Methodology for Environmental Qualification of Electrical and Mechanical Equipment Updated to reflect US460 design EQ Zones Harsh/Mild Environment Areas Post-Accident Operating Times Normal Operating Conditions DBE Environment Conditions Limiting DBA EQ Radiation Dose Temperature Profiles Section 3.12 - ASME Code Class 1, 2, and 3 Piping Systems, Piping Components and Associated Supports Alternative to NUREG-1367 functional capability guidance incorporated NUREG-1367 concerns have largely been addressed by the current ASME Code or other NRC guidance.
Section 3.13 - Threaded Fasteners (ASME Code Class 1, 2, and 3)
Containment vessel pressure retaining threaded fasteners are examined in accordance with ASME BPVC,Section XI, Subsection IWE The CNV is a Class MC vessel, constructed and stamped in accordance with Class 1 for both DCA and SDAA.
The DCA specified examination of the CNV as a Class 1 vessel. For SDA, while constructed to Class 1, the CNV is still a Class MC vessel and will be inspected as such.
NuScale Nonproprietary 3
NuScale Nonproprietary Added augmented examination requirements for ASME Class 1 threaded inserts and seal welds In response to RAI 10133 (Question 3.13-1)
Chapter 8 Significant Changes from DCA to SDA Discussion Overview of Design Changes Section 8.1 -
Updated to reflect US460 plant systems instead of US600 plant systems.
Section 8.2 -
Removal of three COL items.
With exemption for GDC 17 and GDC 18, no longer need the reliance on offsite power.
Section 8.3 Updated to reflect design of US460 electric power systems.
Removal of three COL items.
Section 8.4 No notable changes.
Chapter 14 / Part 8 Significant Changes from DCA to SDA Discussion Section 14.0 No notable changes.
Section 14.1 No notable changes.
Section 14.2 Individual test abstracts are revised to reflect the US460 standard design. However, the specific design changes are the scope of other chapters or sections (e.g., changes to the emergency core cooling system design are within the scope of Chapter 6).
Added clarification. The methodology and general content are unchanged from DCA.
Section 14.3 Removed discussion of ITAAC included in Tier 1.
No Tier 1 in the SDAA. ITAAC discussions now included in Part 8.
Part 8
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NuScale Nonproprietary Additional ITAAC included for SDAA which generally reflect design changes from the US600 to the US460.
The ITAAC selection methodology is unchanged.
Examples include addition of the passive autocatalytic recombiner and addition of the ECCS supplemental boron feature in the scope of ITAAC. However, ITAAC reflects the design. Specific discussion on design changes should be addressed in the particular FSAR section that addresses that aspect of the design.