ML22024A009

Breakout Questions - Trp 3 - RPV Closure Head Studs

ML22024A009
Person / Time
Site:	Oconee
Issue date:	01/20/2022
From:	Angela Wu NRC/NRR/DNRL/NLRP
To:
Wu A, 301-415-2995
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References
Download: ML22024A009 (3)

Text

Oconee SLRA: Breakout Questions SLRA Section B2.1.3 Reactor Head Closure Stud Bolting TRP 3 Question SLRA SLRA Background / Issue Discussion Question /

Number Section Page (As applicable/needed) Request 1 B2.1.3 B - 35 One of the degradation mechanisms Discuss the results of the addressed by this AMP is stress ASME Code Section XI IWB corrosion cracking (SCC) within the volumetric examinations for reactor head closure studs (Item No. the 60 reactor closure head B6.20) and the threads in the studs (B6.20) and the 60 reactor vessel flange (Item B6.40). threads-in-flange (B6.40) of The ASME Code Section XI each Oconee Nuclear Station volumetric examinations for the (ONS) unit from the last reactor head closure studs (RHCSs) required examinations.

and the threads in the reactor vessel flange are the most effective examinations to detect SCC.

2 B2.1.3 B - 40 Operating experience #1 (April a) Put Dominion Engineering 2011) in the SLRA for the AMP is Calc R-3181-003 in the discussed in AR 01806638. This ePortal and discuss the AR discusses studs that had gouges engineering evaluation, that and missing threads in lower determined that the damaged threads and scratch across six studs were acceptable for threads near top. An engineering continued use.

evaluation per guidance in Dominion Engineering Calc R-3181-003 was b) Discuss potential causes of performed to determine acceptability the damage in the studs.

of these studs for continued use.

3 B2.1.3 B - 36 Details of measured ultimate a) Clarify that the 60 installed to strengths of the ONS reactor closure RHCSs and 12 spare RHCSs B - 37 studs from CMTR data are in SLR- of ONS Unit 1 are made from ONS-AMPR-XI.M3. heat 6780366, and the data shown on page 13 of SLR-ONS-AMPR-XI.M3 are the only data on this heat.

b) Similarly, clarify that the 60 installed RHCSs of ONS Unit 2 are made from heat Oconee SLRA: Breakout Questions Question SLRA SLRA Background / Issue Discussion Question /

Number Section Page (As applicable/needed) Request 6880366, and the data shown on page 14 of SLR-ONS-AMPR-XI.M3 are the only data on this heat.

c) Similarly, clarify that the 60 installed RHCSs and 3 spare RHCSs of ONS Unit 3 are made from heat 159628, and the data shown on page 14 of SLR-ONS-AMPR-XI.M3 are the only data on this heat.

4 B2.1.3 B - 42 Operating experience #3 (December a) Discuss whether a request to 2013) in the SLRA for the AMP is for alternative through the 10 B - 43 discussed in PIP O-13-15069. This CFR 50.55a(z) process (10 AR discusses and summarizes CFR 50.55a(g)(5) back in differences between EPRI 2013) was ever submitted performance demonstration initiative and approved for the EPRI (PDI) used to volumetrically PDI program and if not, why examine the ONS RHCSs and the not. Will an alternative volumetric examination methods in request be submitted for ASME Code,Section XI, Appendix future required volumetric VIII, Supplement 8. examinations? Or, alternatively, clarify whether the EPRI PDI program was ever compliant with Appendix VIII Supp 8 (i.e., provide the historical context of the EPRI PDI program as it relates to the requirements of Appendix VIII; it could be that the program was compliant or it was developed to be compliant with App VIII Supp 8, then the Dec 2013 alert came out that identified a discrepancy).

Oconee SLRA: Breakout Questions Question SLRA SLRA Background / Issue Discussion Question /

Number Section Page (As applicable/needed) Request b) The discussion of operating experience #3 states that the volumetric exams for the ONS RHCSs were reperformed. Were they reperformed with volumetric examination methods that closed the gaps identified in the Dec 2013 alert and therefore compliant with ASME Code,Section XI, Appendix VIII, Supplement 8?

c) Have the PDI examination procedures been updated to close the gaps identified in the Dec 2013 alert, and therefore, all future examinations for the ONS RHCSs will be compliant with ASME Code,Section XI, Appendix VIII, Supplement 8?