ML24215A123
| ML24215A123 | |
| Person / Time | |
|---|---|
| Site: | 05200050 |
| Issue date: | 08/02/2024 |
| From: | NuScale |
| To: | Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML24215A000 | List:
|
| References | |
| LO-169995 | |
| Download: ML24215A123 (1) | |
Text
Response to SDAA Audit Question Question Number: A-5.4.1.4-1 Receipt Date: 09/15/2023 Question:
The second sentence of the second paragraph in Section 5.4.1.4 of the Standard Design Approval Application (SDAA) states, Performance of a preservice volumetric examination on the entire length [emphasis added] of the SG [steam generator] tubing meets specifications in Table IWB-2500-1 (B-Q).
The first sentence of the fourth paragraph in Section 5.4.1.4 of the SDAA states, A preservice volumetric, full-length preservice inspection of essentially 100 percent [emphasis added] of the tubing in each SG is performed. The staff requests clarification of the word essentially in this context.
Table IWB-2500-1 (B-Q) in Section XI of the 2017 Edition of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code) states the extent and frequency of examination are governed by the program required by the plant technical specifications (TS). This table does not use the wording, essentially 100 percent, or anything similar.
Section 5.4.5 of the proposed NuScale generic technical specifications (GTS) does not use essentially when describing the extent of the inspections. The staff requests clarification on the wording essentially 100 percent in this context.
10/20/23 update:
The response to Audit Issue A-5.4.1.4-1 states that the term essentially 100 percent was used in accordance with ASME Code Section XI, Article IWA-2200, and that it was not used in Section 5.5.4 of the generic technical specifications (GTS) because the intent is to inspect 100 percent of the tubes as defined in ASME Code Section XI, Article IWA-2200. No changes to the SDAA were proposed.
NuScale Nonproprietary NuScale Nonproprietary
However, the first sentence of the fourth paragraph in SDAA Section 5.4.1.4, which states, A preservice volumetric, full-length preservice inspection of essentially 100 percent of the tubing in each SG is performed, is inconsistent with the following, which do not state essentially 100 percent of the tubing in each SG:
The last sentence in the second paragraph of SDAA Section 5.4.1.4.
ASME Code Section XI, Table IWB-2500-1 (B-Q).
NuScale GTS Section 5.5.4.
Section 3.2, Steam Generator Pre-Service Inspection Requirements, of Pressurized Water Reactor Steam Generator Examination Guidelines: Revision 7.
Therefore, based on these inconsistencies and NuScales statement that the intent is to inspect 100 percent of the tubes, it is still unclear why essentially 100 percent of the tubing in each SG is used in this one instance.
Response
Section 5.4.1.4 of the Standard Design Approval Application (SDAA) no longer contains the word essentially when referring to steam generator tube inspections. The attached markup shows the change.
Markups of the affected changes, as described in the response, are provided below:
NuScale Nonproprietary NuScale Nonproprietary
NuScale Final Safety Analysis Report Reactor Coolant System Component and Subsystem Design NuScale US460 SDAA 5.4-9 Draft Revision 2 requiring inspection or repair is in an accessible position to minimize time and radiation exposure during refueling and maintenance outages.
The SG tube inspections and testing meet requirements of the SG program.
Performance of a preservice volumetric examination on the entire length of the SG tubing meets specifications in Table IWB-2500-1 (B-Q). A preservice eddy current test meets Electric Power Research Institute (EPRI) 1013706 (Reference 5.4-2).
Preservice examinations performed in accordance with the ASME BPVC,Section III, Subsubarticle NB-5280 and Section XI, Subarticle IWB-2200 (Reference 5.4-5) use examination methods of ASME BPVC Section V, except as modified by Section III, Paragraph NB-5111. These preservice examinations include essentially 100 percent of the pressure boundary welds.
Audit Question A-5.4.1.4-1 A preservice volumetric, full-length preservice inspection of essentially 100 percent of the tubing in each SG is performed. The length of the tube extends from the tube-to-tubesheet weld at the tube inlet to the tube-to-tubesheet weld at the tube outlet. The tube-to-tubesheet welds are not part of the tube. The preservice inspection is performed after tube installation and shop or field primary-side hydrostatic testing and before initial power operation to provide a definitive baseline record, against which future ISI can be compared. Tubes with flaws that exceed 40 percent of the nominal tube wall thickness are plugged.
Tubes with flaws that could potentially compromise tube integrity before the performance of the first ISI, and tubes with indications that could affect future inspectability of the tube, are also plugged. The volumetric technique used for the preservice examination is capable of detecting the types of preservice flaws that may be present in the tubes and permits comparisons to the results of the ISI expected to be performed to satisfy the SG tube inspection requirements in accordance with the plant technical specifications.
As discussed above, the operational inservice testing and inspection programs described in Section 5.2.4, RCPB ISI and Testing, and the SG program described in Section 5.4.1.6, Steam Generator Program, provide testing and inspection requirements following initial plant startup. Inservice inspection and testing of the SGS steam and feedwater piping is described in Section 6.6.
5.4.1.5 Steam Generator Materials Selection and fabrication of pressure boundary materials used in the SGs and associated components are in accordance with the requirements of ASME BPVC Section III and Section II as described in Section 5.2.3, RCPB Materials, and the materials used in the fabrication of the SGs are in Table 5.2-3.
The RCPB materials used in the SGS are Quality Group A and their design, fabrication, construction, tests, and inspections conform to Class 1 in accordance with the ASME BPVC and the applicable conditions promulgated in 10 CFR 50.55a(b). The SGS materials forming the RCPB, including weld