ML24215A066
| ML24215A066 | |
| Person / Time | |
|---|---|
| Site: | 05200050 |
| Issue date: | 08/02/2024 |
| From: | NuScale |
| To: | Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML24215A000 | List:
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| References | |
| LO-169995 | |
| Download: ML24215A066 (1) | |
Text
Response to SDAA Audit Question Question Number: A-3.9.2-33 Receipt Date: 03/18/2024 Question:
FSAR, Section 3.9.2.1, Piping Vibration, Thermal Expansion, and Dynamic Effects addresses the vibrations and thermal expansion testing performed during pre-operation and initial startup for the piping systems within the scope of Section 3.9.2.1. It states that the test program described in Section 14.2, Initial Plant Test Program, verifies that ASME Boiler and Pressure Vessel Code (BPV Code) Class 1, Class 2, Class 3, and other high-energy and Seismic Category I piping systems meet functional design requirements, and that piping vibrations and thermal expansions are within acceptable levels. The ASME BPV Code Class 1, 2, and 3 piping systems that are part of the NuScale Power Module (NPM) are included in the scope of the Comprehensive Vibration Assessment Program (CVAP).
The NRC staff understands that Section 14.2, Test #91, Thermal Expansion, is for piping system thermal expansion testing and Test #102, NuScale Power Module Vibration is for piping vibration testing inside the NPM. The NRC staff is not clear what initial startup testing addresses the piping vibration testing outside the NPM. The NRC staff also requests that NuScale identify the Section 14.2 initial startup testing that addresses the piping vibration testing outside the NPM.
To prevent the licensing basis for the NuScale plant to be misunderstood in the future, the NRC staff requests that NuScale identify in FSAR, Section 3.9.2.1, the Section 14.2 initial startup testing programs that are credited for meeting the testing discussed in Section 3.9.2.1 (including the thermal expansion and vibration testing inside and outside of the NPM).
Staff Feedback (4/15/2024):
NuScale Nonproprietary NuScale Nonproprietary
To ensure the licensing basis is clear, the NRC staff requests that NuScale add reference to Section 14.2 Test #91 Thermal Expansion and Test #94 Ramp Change in Load Demand to FSAR, Section 3.9.2.1.
NuScale should also clarify in FSAR Section 3.9.2.1 that Test #94 addresses the piping vibration testing outside the NPM.
Response
Initial test program Test 94 (FSAR Table 14.2-94) is to perform ramp changes in load demand during startup testing. The test method includes conducting piping vibration testing, as required, during power changes. Acceptance criteria 8 includes piping vibration, stating:
System specific steady state vibration testing criteria are established by the piping designer. Actual acceptance criteria depends on the selected test method, but may include:
a.
Limits for stresses calculated based on the observed/measured vibration response of the system.
b.
No permanent deformation or damage is observed in the piping system or supports.
c.
Vibration displacements are not excessive, may not potentially cause the piping to come in contact with surrounding SSC, and are such that the movement of supports and flexible joints is within their allowable limits.
Test 94 addresses the piping vibration testing outside the NPM. Coupled with COL Item 3.9-2, this test addresses the startup testing described in FSAR Section 3.9.2.1.
COL Item 3.9-2 states:
An applicant that references the NuScale Power Plant US460 standard design will complete an assessment of piping systems inside the Reactor Building to determine the portions of piping to be tested for vibration, thermal expansion, and dynamic effects.
Piping systems within the scope of this testing include American Society of Mechanical Engineers Boiler and Pressure Vessel Code Section III, Class 1, 2, and 3 piping systems, other high-energy piping systems inside Seismic Category I structures or those whose failure would reduce the functioning of any Seismic Category I plant feature to an unacceptable level, and Seismic Category I portions of moderate-energy piping systems NuScale Nonproprietary NuScale Nonproprietary
located outside of containment. The applicant may select the portions of piping in the design for which vibration testing is performed while considering the piping system design and analysis, including the vibration screening and analysis results and scope of testing as identified by the Comprehensive Vibration Assessment Program.
The FSAR addition incorporates feedback from the staff. Specifically, FSAR Section 3.9.2 references Chapter 14 startup test abstracts.
In response to feedback from the NRC on 05/08/2024 - an update is provided below:
Three startup tests described in Section 14.2 address vibrations and thermal expansion during pre-operation and initial start up. Initial test program Test 94 Ramp Change in Load Demand is discussed above. Initial test program Test 91 Thermal Expansion (Table 14.2-91) verifies that ASME Code Class 1, 2, and 3 system piping can expand without obstruction and that this expansion is within design limits. Initial test program Test 102 NuScale Power Module Vibration (Table 14.2-102) performs vibration testing per the Comprehensive Vibration Assessment Program.
The updated FSAR addition incorporates feedback from the staff.
Markups of the affected changes, as described in the response, are provided below:
NuScale Nonproprietary NuScale Nonproprietary
NuScale Final Safety Analysis Report Mechanical Systems and Components NuScale US460 SDAA 3.9-19 Draft Revision 2 Initial Startup Testing Audit Question A-3.9.2-33 Initial startup testing is performed after the reactor core is loaded into an NPM.
These tests establish that vibration levels, thermal expansions and contractions, and dynamic effects of transient conditions are acceptable and bounded by analyses. If test results are not bounded, evaluations use the results from testing as input and verify that the design is acceptable. Section 14.2 contains startup test abstracts for the following:
Audit Question A-3.9.2-33 Thermal Expansion: verifies ASME Code Class 1, 2, and 3 piping thermal expansion within design limits Ramp Change in Load Demand: includes vibration testing outside of the NPM NuScale Power Module Vibration: testing covered by Comprehensive Vibration Assessment Program (CVAP) 3.9.2.1.1 Piping Vibration Details Vibration test specifications are developed in accordance with ASME OM-2017, Division 2 (OM Standards), Part 3 (Reference 3.9-3). Piping vibration testing and assessment are performed in accordance with ASME OM-2017, Division 2 (OM Standards), Part 3 (Reference 3.9-3).
Preoperational tests and initial startup tests demonstrate that piping systems withstand vibrations resulting from normal operation, including anticipated operational occurrences. If excessive vibration is observed that is outside the bounds of the analyses, a re-analysis to determine the cause and to identify the corrective action is performed.
The Initial Test Program does not address vibrations resulting from abnormal events (e.g., accidents).
Audit Question A-3.9.2-33 Selection of portions of piping in the design for which vibration testing is performed as described in this section may consider the piping system design and analysis, including vibration screening and analysis results and scope of testing as identified by the Comprehensive Vibration Assessment Program (CVAP) (References 3.9-5 and 3.9-7). The ASME Code Class 1, 2, and 3 piping systems that are part of the NPM are included in the scope of the CVAP. Piping systems that meet screening criteria for applicable flow-induced vibration mechanisms are evaluated in the analysis program. If analysis shows less than 100 percent safety margin, validation testing is required in accordance with Reference 3.9-7 and the requirements of Part 3 of ASME OM-2017, Division 2 (OM Standards).