ML22024A052

Breakout Questions - Trp 149.11 - Rvi Ductility

ML22024A052
Person / Time
Site:	Oconee
Issue date:	01/21/2022
From:	Angela Wu NRC/NRR/DNRL/NLRP
To:
Wu A, 301-415-2995
Shared Package
ML22024A002	List: ML22024A003 ML22024A004 ML22024A005 ML22024A006 ML22024A008 ML22024A009 ML22024A010 ML22024A012 ML22024A014 ML22024A015 ML22024A016 ML22024A017 ML22024A018 ML22024A020 ML22024A021 ML22024A022 ML22024A023 ML22024A029 ML22024A030 ML22024A032 ML22024A033 ML22024A034 ML22024A035 ML22024A036 ML22024A037 ML22024A038 ML22024A039 ML22024A040 ML22024A041 ML22024A042 ML22024A043 ML22024A046 ML22024A048 ML22024A049 ML22024A051 ML22024A052 ML22024A053 ML22024A055 ML22024A056 ML22024A057 ML22024A059
References
Download: ML22024A052 (2)

Text

Oconee Nuclear Station (ONS) SLRA: Breakout Topics/ Questions SLRA TLAA Section: 4.7.1, Re actor Vessel Internals, Subsection 4.7.1.1, Reduction Fracture Toughness due to Neutron Embrittlement (RVI Reduction of Ductility TLAA)

TRP: 149.11

Staff comment on RVI Reduction of Ductility TLAA: The staffs review is based on a comparison the methodology and analysis in B&W Proprietary Report No. BAW-10008, Part 1, Revision 1, and the updated TLAA in Framatome Proprietary Report No. ANP -

3899P, Rev. 0. The audit breakout discussion are oriented on the differences between the two methodologies, with a particular focus on the methodology and results for the seven components that were identified as needing reconciliation and evaluated in Section 2.3.2 of ANP-3899P, Revision 0. For these components, the staff needs to make a final determination whether thes e components are appropriately dispositioned both in the TLAA and in the gap analysis for the applicants PWR Vessel Internals Program (SLRA AMP B.2.1.7), which the applicant uses to disposition the TLAA in accordance with 10 CFR 54.21(c)(1)(iii). The seven components are: (1) the upper core barrel (UCB) bolts [ Primary category components per Item B7 in Table 4-1 of MRP -227, Rev. 1-A] ; (2) core support shield (CSS) lower flange [No Additional Measures or NAM component in MRP -227, Rev. 1-A; the CSS top flange is the Primary component per Item B1.d in Table 4-1 of the MRP report]; (3) lower grid rib sections [Expansion per B10.3 in Table 4-4 of the MRP report; elevated to Primary components in the gap analysis]; (4) lower rib grid section-to-lower grid forging joint bolts [NAM per Table 3-1 in MRP-227, Rev. 1-A, which refers to them as lower grid rib-to-shell forging cap screws]; (5) lower grid support post-to-support forging joint welds [NAM]; (6) upper grid rib section [ NAM per Table 3-1 in MRP -227, Rev. 1-A]; and (7) upper grid assembly support pads bolts [NAM per Table 3-1 in MRP -227, Rev. 1-A, which refers to the bolts as upper grid fuel assembly support pad cap screws].

Question SLRA SLRA Background / Issue Discussion Question / Request Number Section Page (As applicable/needed)

1 4.7.1.1 4 - 104 - Topic: General methodology in the TLAA used to The applicant should be prepared to discuss the re-evaluations 4 -117 update the stress intensity analyses for referenced performed in ANP -3899P, Rev. 0, especially for the seven RVI components, especially those re-evaluated in components needing reconciliation and subject to the evaluat ions in Section 2.3.2 in ANP-3899P, Rev. 0. Basis for Section 2.3.2 of the ANP report. The discussion topics may cover (but dispositioning the TLAA in accordance with are not necessarily limited to) the following areas of discussion:

10 CFR 54,21(c)(1)(iii), especially for each of the RVI components that were in need reconciliation 1) Clarifications on whether t he re-analyses for the components are per the assessment in Section 2.3.2 of the based on the assumed loading combinations defined for Case IV referenced ANP report. assessments in BAW-10008 Part 1, Revision 1 and the revised faulted conditions for the components in BAW-1621, as approved by the staff.

2) How the components were re-evaluated for appropriate stress intensity values and how appropriate LOCA and Faulted condition loads were incorporated into those values (as applicable and appropriate for the updated component -specific assessments)

3) The basis changing the stress allowable basis for the Case IV loading assessment s.

4) How the re-evaluated TLAA basis for each of the seven components relates to the final inspection category for the components, as evaluated and finalized in the gap analysis for SLRA AMP B2.1.7, PWR Vessel internals.

1. 1 Cont.