ML14352A425

NRR E-mail Capture - FW: Draft Second Request for Additional Information Regarding Dresden Fourth 10-Year Inservice Inspection Interval - Request for Relief I4R-17

ML14352A425
Person / Time
Site:	Dresden
Issue date:	12/17/2014
From:	Mozafari B Plant Licensing Branch III
To:	Mathews M Exelon Corp
References
TAC MF3352, TAC MF3353
Download: ML14352A425 (4)

Text

NRR-PMDAPEm Resource From: Mozafari, Brenda Sent: Wednesday, December 17, 2014 4:50 PM To: 'Mitchel.Mathews@exeloncorp.com' Cc: Tate, Travis; Purnell, Blake

Subject:

FW: DRAFT SECOND Request for Additional Information regarding Dresden Fourth 10-Year Inservice Inspection Interval - Request for Relief I4R-17 (TAC MF3352 and MF3353)

Importance: High

Mitch, Below are DRAFT questions associated with the subject Second RAI for Dresden units 2 and 3.

SUBJECT:

REQUEST FOR ADDITIONAL INFORMATION REGARDING THE DRESDEN NUCLEAR POWER STATION, UNITS 2, AND 3 FOURTH 10-YEAR INTERVAL INSERVICE INSPECTION PROGRAM PLAN REQUESTS FOR RELIEF (TAC NOS. MF3352 AND MF3353)

The NRC staff has reviewed and evaluated the information provided by, Exelon Generation Company, LLC (EGC) (the licensee) in its letter dated October 16, 2014. The licensee submitted additional information for Request for Relief (RR) I4-17 from the requirements of the American Society of Mechanical Engineers (ASME)

Boiler and Pressure Vessel Code,Section XI for Dresden Nuclear Power Station, Units 2 and 3 (DNPS 2 and 3). The requests for relief apply to the fourth 10-year inservice inspection interval, in which the licensee adopted the 1995 Edition through the 1996 Addenda of ASME Code Section XI as the code of record.

The staff's request for additional information (RAI) or to clarify RAI responses is shown below. In order for the staff to meet the established due date, the licensee will need to respond to the RAI by January 16, 2015. If a teleconference is needed to clarify the RAI please contact me to schedule a clarification teleconference to provide your response by the requested date.

DRAFTSECOND REQUEST FOR ADDITIONAL INFORMATION ON THE FOURTH TEN YEAR 10-YEAR INSERVICE INSPECTION INTERVAL REQUEST FOR RELIEF I4R-17 FOR EXELON GENERATION COMPANY, LLC. DRESDEN NUCLEAR POWER STATION, UNITS 2 AND 3 DOCKET NUMBERS: 50-237 AND 50-249

1. SCOPE By letter dated December 30, 2013, (Agencywide Documents Access & Management System (ADAMS)

Accession Number ML13364A361), the licensee, Exelon Generation Company, LLC (EGC), submitted Request for Relief (RR) I4R-17 from the requirements of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code,Section XI, Rules for Inservice Inspection of Nuclear Power Plant Components for Dresden Nuclear Power Station, Units 2 and 3 (DNPS 2 and 3). The request for relief applies to the fourth 10-year inservice inspection (ISI) interval, in which the licensee adopted the 1995 Edition through the 1996 Addenda of ASME Code Section XI as the code of record. The NRC requested that the licensee provide further information, and the licensee provided a response to the Request for Additional Information (RAI) in a letter dated October 16, 2014 (ADAMS Accession Number ML14293A255).

However, certain requested information was not provided and/or requires clarification in order for the staff to complete the evaluation of the licensees request. Please submit answers to the following questions.

1

2. REQUEST FOR ADDITIONAL INFORMATION

1) It appears the licensee provided only cross-sectional sketches showing idealized beam projections that were part of the ISI examination reports, but did not include volumetric coverage maps obtained on all of the subject components, as requested by NRC in general question 1.d of the original RAI:

Show cross-sectional or surface coverage plots to describe the ASME Code volumes and surfaces examined.

Because this material may have been omitted, it is unclear where this information is located in the October 16, 2014 RAI response. The staff requires this information to determine whether specific volumetric coverage(s) included areas near the inner surface using the appropriate ultrasonic wave angles and modalities. These are typically the most highly stressed regions, exposed to operating environments where service degradation would be expected to occur, should it be manifested. One would have to make assumptions on coverage in these regions, if the beam projection sketches are employed during the Staffs evaluations. Please submit or clarify where the information provided is located in the October 16, 2014 RAI response for the requested cross-sectional plots showing volumetric coverage obtained.

2) The licensees RAI response states that all ASME Category B-A, Items 1.12 (longitudinal welds) and B.140 (top head-to-flange welds) were conducted using ASME Code,Section XI, Appendix VIII, performance-demonstrated techniques. However, Mandatory Appendix I of ASME Code,Section XI states that the RPV top head-to-flange weld is excluded from Appendix VIII rules and is required to meet the requirements of ASME Code,Section V, Article 4.

3) Clarify whether examination procedure GE-UT-300 listed in Attachment 2 NDE Summary Sheet, Page 326 of 818 is pattern after ASME Code,Section XI, Appendix VIII or ASME Code,Section V, Article 4.

4) The licensee states that, for Unit 2, only 41.7 percent coverage was obtained on the top head-to-flange weld, and the drawing submitted in the RAI response appears to support the claim that examinations may only be conducted from the head side of the weld due to geometry. However, it is stated that Unit 3 was able to get 72 percent volumetric coverage, while the drawing shows the top head-to-flange welds at DNPS 2 and 3 to be geometrically similar. Please clarify why the licensee was able to obtain a marked increase in volumetric coverage on DNPS 3.

5) Mandatory Appendix I of ASME Section XI requires that Class 2 welds on vessels less than 2-inches in thickness are to be performed to the requirements of ASME XI, Appendix III, in lieu of performance demonstrated techniques, as required by Appendix VIII. Regarding examinations performed for nozzle-to-head welds on the isolation (ISO) condenser vessels, it was noted that the licensee used what appear to be Appendix III techniques for DNPS 2. However, in the 2008 examination reports from DNPS 3, it is stated that Appendix VIII-based procedures were used for detection and sizing of indications, then, during the 2010 examinations, it appears the licensee went back to the Appendix III-based techniques at DNPS 3. Please clarify the following:

a. State whether the licensee has an NRC-approved alternative in place to use PDI-qualified methods on the ISO condenser nozzle-to-vessel welds instead of those required by ASME XI, Appendix III. Reference the NRC SER that approves this deviation, and the PDI-certification document.

b. If an NRC-approved alternative is in-place, discuss the decision to go back to Appendix III-based techniques in 2010 at DNPS 3. It was noted that no indications were detected during the 2010 examinations. Based on the indications detected in 2008, albeit found to be 2

acceptable, by the PDI techniques employed at that time, explain why the obviously less sensitive Appendix III techniques were used, causing historical indications to remain untracked in 2010.

Brenda L. Mozafari Senior Project Manager, NRR/DORL U.S. Nuclear Regulatory Commission Dresden 2/3 and QuadCities 1/2 301-415-2020 email: brenda.mozafari@nrc.gov 3

Hearing Identifier: NRR_PMDA Email Number: 1783 Mail Envelope Properties (9C2386A0C0BC584684916F7A0482B6CA0114713C0DB9)

Subject:

FW: DRAFT SECOND Request for Additional Information regarding Dresden Fourth 10-Year Inservice Inspection Interval - Request for Relief I4R-17 (TAC MF3352 and MF3353)

Sent Date: 12/17/2014 4:50:20 PM Received Date: 12/17/2014 4:50:00 PM From: Mozafari, Brenda Created By: Brenda.Mozafari@nrc.gov Recipients:

"Tate, Travis" <Travis.Tate@nrc.gov>

Tracking Status: None "Purnell, Blake" <Blake.Purnell@nrc.gov>

Tracking Status: None

"'Mitchel.Mathews@exeloncorp.com'" <Mitchel.Mathews@exeloncorp.com>

Tracking Status: None Post Office: HQCLSTR02.nrc.gov Files Size Date & Time MESSAGE 7162 12/17/2014 4:50:00 PM Options Priority: High Return Notification: No Reply Requested: No Sensitivity: Normal Expiration Date:

Recipients Received: