TMI-11-060, Response to a Request for Additional Information - Relief Request RR-10-01 Concerning Control Rod Drive Housing Examinations Associated with the Third Inservice Inspection Interval

Response to a Request for Additional Information - Relief Request RR-10-01 Concerning Control Rod Drive Housing Examinations Associated with the Third Inservice Inspection Interval

ML110960228
Person / Time
Site:	Three Mile Island
Issue date:	04/05/2011
From:	David Helker Exelon Corp, Exelon Generation Co, Exelon Nuclear
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
RR-10-01, TMI-11-060
Download: ML110960228 (9)

Text

10 CFR 50.55a TMI-11-060 April 5, 2011 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 Three Mile Island Nuclear Station, Unit 1 Renewed Facility Operating License No. DPR-50 NRC Docket No. 50-289

Subject:

Response to a Request for Additional Information - Relief Request RR-10-01 Concerning Control Rod Drive Housing Examinations Associated with the Third Inservice Inspection (lSI) Interval

References:

1) Letter from P. Cowan (Exelon Generation Company, LLC) to U.S. Nuclear Regulatory Commission, "Submittal of Relief Request RR-10-01 Concerning Control Rod Drive Housing Examinations Associated with the Third Inservice Inspection (lSI) Interval," dated October 13, 2010

2) Letter from P. Bamford (U.S. Nuclear Regulatory Commission) to M. Pacilio (Exelon Generation Company, LLC), "Three Mile Island Nuclear Station, Unit 1 - Request for Additional Information Regarding Relief Request RR-1 0-01, Control Rod Drive Housing Examinations Associated with the Third Inservice Inspection Interval (TAC NO. ME4882)," dated March 16, 2011 In the Reference 1 letter, Exelon Generation Company, LLC (Exelon) submitted for your review a relief request associated with the third Inservice Inspection (lSI) interval for Three Mile Island Nuclear Station (TMI), Unit 1 requesting relief from Table IWB-2500-1, Examination Category B-O, Item Number B14.10, which requires volumetric or surface examination of the pressure retaining Control Rod Drive (CRD) butt welds in 10% of the peripheral CRD housings.

In the Reference 2 letter, the U.S. Nuclear Regulatory Commission requested additional information. Attached is our response to this request.

There are no regulatory commitments in this letter.

Response to a Request for Additional Information-Relief Request RR-10-01 April 5, 2011 Page 2 If you have any questions concerning this letter, please contact Tom Loomis at (610) 765-5510.

Respectfully, David P. Helker Manager - Licensing Exelon Generation Company, LLC

Attachment:

Response to a Request for Additional Information - Relief Request RR-10-01 cc: Regional Administrator, Region I, USNRC USNRC Senior Resident Inspector, TMI USNRC Project Manager, [TMI] USNRC

ATTACHMENT Response to a Request for Additional Information - Relief Request RR-10-01

Response to a Request for Additional Information Relief Request RR-10-01 April 2011 Page 1 Question:

1. Regarding page 2 of the relief request, paragraph 2, provide the specific type(s) of examination(s), Le., visual (VT-2), dye penetrant (PT), magnetic particle (MT), ultrasonic (UT), etc., referred to in the statement" ... six (6) CRDs not in the periphery were examined

"

The six (6) CRDs not in the periphery examined in 2001 were examined using the dye penetrant (PT) method.

Question:

2. Regarding page 2 of the relief request, paragraph 2, provide the specific type(s) of examination(s), Le., VT-2, PT, MT, UT etc., referred to in the statement, "A review of lSI

[inservice inspection] data for examinations of welds "A", "B", and "C" completed since 1986 identified no degradation."

Response

Table 1 below provides specific examination history, nondestructive examination (NDE) methods, coverage, and results data for "A", "B", and "C" CRD weld examinations completed since 1986. Drawing 1D-ISI-RC-011 (Figure 1) has been included with this response in order to provide additional information on the weld locations both in terms of elevation, azimuthal and radial location on the reactor vessel closure head.

Question:

3. Regarding page 2 of the relief request, paragraph 2, the second sentence states, "There were no examination limitations reported for these welds." Please clarify this statement.

Does it refer to the accessibility of the welds for examination or that there were no defects in the welds?

Response

Table 1 has identified that examinations completed were acceptable to ASME Section XI requirements (no degradation was noted). Examination coverage was in accordance with ASME Section XI requirements with the one exception noted in Table 1 and Figure 2 for a 1987 UT examination for weld CRD-151. In this case, an accompanying liquid penetrant examination was completed providing additional NDE coverage for the small area not examined during the UT examination.

Response to a Table 1 CRD Examination Summa Examination Coverage Notation Examination Results indications

Response to a Request Relief RR-1 1

3 CRDID CRD lSI Weld Exam Exam Examination Coverage Notation Examination Results No.* Weld 10** 10 No. Year Method 51 A CRD-151 1987 PT No limitation noted I A 0° no limitation. 45° one sided 51 I A CRD-151 1987 UT limitation (see Fiqure 2).

PT No limitation noted limitation noted indications No limitation noted

• 1D-ISI-RC-011 CRD location identification number

• • 1D-ISI-RC-011 Enlargement "A" and Elevation View weld location identification

Figure 1 Drawing 1D-ISI-RC-011

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Figure 2 Weld CRD-151 45 Degree Examination Coverage Sketch