ML110840671
| ML110840671 | |
| Person / Time | |
|---|---|
| Site: | Byron  |
| Issue date: | 03/25/2011 |
| From: | Nicholas Difrancesco Plant Licensing Branch III |
| To: | Mcintosh R Exelon Corp |
| Di Francesco N, NRR/DORL/LPL3-2, 415-111 | |
| References | |
| TAC ME5877 | |
| Download: ML110840671 (1) | |
Text
From:
DiFrancesco, Nicholas Sent:
Friday, March 25, 2011 3:57 PM To:
Richard.McIntosh@exeloncorp.com Cc:
jeff.hansen@exeloncorp.com; Lisa.Schofield@exeloncorp.com; Carlson, Robert; Lupold, Timothy; Collins, Jay; Wohl, Marilyn
Subject:
Byron Station, Unit No. 1 - Request for Additional Information Re: Relief Request I3R-19 (TAC No. ME5877)
Mr. McIntosh, By letter dated March 24, 2011 (Agencywide Documents Access and Management Systems (ADAMS) Accession No. ML110830837), Exelon Generation Company, LCC (the licensee) submitted a relief request (RR) for Byron Station, Unit No. 1. The RR proposed an alternative to certain American Society of Mechanical Engineers Boiler and Pressure Vessel Code requirements.
The NRC staff is reviewing your submittal and has determined that additional information is required to complete its review. The specific information requested is contained in the Request for Additional Information (RAI) below. Your staff has agreed to provide a response to the RAI by March 28, 2011.
The NRC staff considers that timely responses to RAls help ensure sufficient time is available for NRC staff review and contribute toward the NRC's goal of efficient and effective use of its staff resources. If circumstances result in the need to revise the requested response date, please contact me.
Sincerely, Nicholas DiFrancesco Project Manager - Braidwood, Byron, and Clinton U.S. Nuclear Regulatory Commission Office of Nuclear Reactor Regulation Division of Operating Reactor Licensing nicholas.difrancesco@nrc.gov l Tel: (301) 415-1115 REQUEST FOR ADDITIONAL INFORMATION REQUEST FOR RELIEF FROM ASME CODE REQUIREMENTS FOR REPAIR OF REACTOR VESSEL HEAD PENETRATION NUMBERS 64 AND 76 (I3R-19)
EXELON GENERATION COMPANY, LLC, BYRON STATION, UNIT 1 DOCKET NO. 50-454 By letter dated March 24, 2011, Exelon Generation Company, LCC (the licensee), proposed an alternative to certain American Society of Mechanical Engineers Boiler and Pressure Vessel Code requirements for Byron Station, Unit 1. The requirements pertain to the repair of the
reactor pressure vessel upper head penetration nozzle numbers 64 and 76 and future defects that may be identified at Byron Station, Unit 1. The duration of request is for the third 10-year ISI interval.
The NRC staff has reviewed and evaluated the information provided by the licensee and has determined that the following information is needed in order to complete its review of the relief request.
RAI-1: NRC staff notes that the licensee requests expedited verbal relief by 1 PM Central Standard Time on March 28, 2011. Staff notes that expedited review and verbal authorization would be difficult for the generic application of the licenses submittal within that time frame. Therefore, staff requests licensee reconsider the scope of this relief request under Section 1.0 ASME Code Component(s) Affected to the items needed for repair this outage, in order to meet the licensees requested date of verbal authorization.
RAI-2: In Reference 2 of the submittal, the NRC requested the following, The NRC must be notified of changes in flaw(s) or finding new flaw(s) in the j-groove weld beneath a seal weld repair or in the seal weld repair. In order to add clarity to this request the NRC staff requests that the licensee commit to the following statement; The licensee will notify NRC staff of the Division of Component Integrity or its successor of changes in indication(s) or findings of new indication(s) in the penetration nozzle or J-groove weld beneath a seal weld repair, or new linear indications in the seal weld repair, prior to commencing repair activities.
NRC staff requests this commitment as a finding of these types of indications may invalidate the embedded flaw repair technique as an effective repair for the penetration nozzle in question. Timely notification of NRC staff of ISI indications will allow clear communications to assist NRC staff in determination of the effectiveness of the repair due to the indication in question.
RAI-3: In Section 5.0 of the submittal, Step 1 states that an unacceptable axial or circumferential flaw in a tube below a J-groove attachment weld will be sealed off with an Alloy 52 or 52M weldment, with no additional detail as to the scope of the weldment.
WCAP-15987-P Rev. 2, Reference 1 of the submittal, states in Section 2.2.3, for axial cracks on the penetration tube OD below the j-weld, that the overlay begins 1/2 beyond the Alloy 600/stainless steel interface at the outer periphery of the J-weld and extends down the outer surface of the penetration tube to a point 1/2 beyond the flaw indication.
Section 2.2.4, for circumferential cracks in the penetration tube, the scope of the weldment is not specific other than isolation of the flaw. In order to clarify the licensees implementation of requirements, provide the following; a) State the generic scope of the weldment that will be used to repair an OD flaw in the nozzle below the J-groove weld.
b) State the scope of the weldment being used to repair reactor pressure vessel upper head penetration numbers 64 and 76.
c) In regards to the Table of Item 3 of Section 5.0, Conditions and Limitations of Reference 2 of the submittal, answer the following;
- 1. How will each of the four(4) indications be characterized for;
- i. Repair Location, ii. Flaw Orientation, and iii. Repair NDE
- 2. Will Note 3 be implemented for ISI NDE of the repair for penetration numbers 64 and 76?