RS-20-062, Proposed Alternative to Utilize Code Case N-885

Proposed Alternative to Utilize Code Case N-885

ML20119B061
Person / Time
Site:	Calvert Cliffs, Byron, Braidwood, Ginna
Issue date:	04/28/2020
From:	David Gudger Exelon Generation Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
RS-20-062
Download: ML20119B061 (6)

Text

200 Exelon Way Kennett Square, PA 19348 www.exeloncorp.com 10 CFR 50.55a RS-20-062 April 28, 2020 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 Braidwood Station, Units 1 and 2 Renewed Facility Operating License Nos. NPF-72 and NPF-77 NRC Docket Nos. STN 50-456 and STN 50-457 Byron Station, Units 1 and 2 Renewed Facility Operating License Nos. NPF-37 and NPF-66 NRC Docket Nos. STN 50-454 and STN 50-455 Calvert Cliffs Nuclear Power Plant, Units 1 and 2 Renewed Facility Operating License Nos. DPR-53 and DPR-69 NRC Docket Nos. 50-317 and 50-318 R.E. Ginna Nuclear Power Plant Renewed Facility Operating License No. DPR-18 NRC Docket No. 50-244

Subject:

Proposed Alternative to Utilize Code Case N-885 In accordance with 10 CFR 50.55a(z)(2), Exelon Generation Company, LLC (Exelon) is requesting a proposed alternative to the American Society of Mechanical Engineers (ASME)

Boiler and Pressure Vessel Code, Section Xl, "Rules for Inservice Inspection of Nuclear Power Plant Components," on the basis that compliance with the code results in hardship without a compensating increase in quality and safety. Specifically, this proposed alternative concerns the use of Code Case N-885 ("Alternative Requirements for Table IWB-2500-1, Examination Category B-N-1, Interior of Reactor Vessel, Category B-N-2, Welded Core Support Structures and Interior Attachments to Reactor Vessels, Category B-N-3, Removable Core Support StructuresSection XI, Division 1). This Code Case addresses alternative requirements for examination of reactor vessel interior accessible areas, welds, and surfaces required to be examined.

Proposed Alternative to Utilize Code Case N-885 April28,2020 Page2 There are no regulatory commitments contained in this letter. Exelon requests your review and approval of this request by February 1, 2021.

If you have any questions, please contact Tom Loomis (610) 765-5510.

Respectfully, David T. Gudger Senior Manager - Licensing Exelon Generation Company, LLC

Attachment:

Proposed Alternative to Utilize Code Case N-885 cc: Regional Administrator - NRC Region I Regional Administrator - NRC Region Ill NRC Senior Resident Inspector - Braidwood Station NRC Senior Resident Inspector - Byron Station NRC Senior Resident Inspector - Calvert Cliffs Nuclear Power Plant NRC Senior Resident Inspector - R.E. Ginna Nuclear Power Plant NRC Project Manager - Braidwood Station NRC Project Manager - Byron Station NRC Project Manager - Calvert Cliffs Nuclear Power Plant NRC Project Manager - R.E. Ginna Nuclear Power Plant Illinois Emergency Management Agency - Division of Nuclear Safety R. R. Janati, Commonwealth of Pennsylvania S. Seaman, State of Maryland A. L. Peterson, NYSERDA

Attachment Proposed Alternative to Utilize Code Cases N-885

10 CFR 50.55a RELIEF REQUEST Revision 0 (Page 1 of 3)

Proposed Alternative to Use Code Case N-885 in Accordance with 10 CFR 50.55a(z)(2)

-- Hardship without a Compensating Increase in Level of Quality or Safety --

1. ASME Code Component(s) Affected:

All ASME reactor vessel interior Examination Category B-N-1, B-N-2, and B-N-3, Item Number B13.10, B13.50, B13.60, and B13.70 accessible areas, welds, and surfaces required to be examined.

2. Applicable Code Edition and Addenda

PLANT INTERVAL EDITION START END Braidwood Station, Units Fourth 2013 Edition August 29, 2018 July 28, 2028 1 and 2 November 5, 2018 October 16, 2028 Byron Station, Fourth 2007 Edition, through 2008 July 16, 2016 July 15, 2025 Units 1 and 2 Addenda Calvert Cliffs Nuclear Fifth 2013 Edition July 1, 2019 June 30, 2029 Power Plant, Units 1 and 2

R. E. Ginna Nuclear Sixth 2013 Edition January 1, 2020 December 31, 2029 Power Plant

3. Applicable Code Requirements

Code Case N-885 - Alternative Requirements for Table IWB-2500-1, Examination Category B-N-1, Interior of Reactor Vessel, Category B-N-2, Welded Core Support Structures and Interior Attachments to Reactor Vessels, Category B-N-3, Removable Core Support StructuresSection XI, Division 1.

ASME Code,Section XI, IWB-2500(a), Table IWB-2500-1 (B-N-1, B-N-2, B-N-3) and IWB-3520, of the 2007 Edition with the 2008 Addenda and the 2013 Edition provide requirements and acceptance standards for examining reactor vessel interior surfaces, reactor vessel interior attachments, and core support structures.

4. Reason for Request

In accordance with 10 CFR 50.55a(z)(2), Exelon Generation Company, LLC (Exelon) is requesting proposed alternatives from the current ASME Section XI, IWB-2500(a), Table IWB-2500-1 (B-N-1, B-N-2, and B-N-3) and IWB-3520 requirements for performing VT-1 or VT-3 examination of the reactor vessel interior surfaces, reactor vessel interior attachments, and core support structures. Compliance with the ASME Code results in additional cost and radiation exposure, additional opportunity to introduce foreign material into the reactor vessel and could result in additional outage critical path time that can be avoided through use of Code Case N-885.

10 CFR 50.55a RELIEF REQUEST Revision 0 (Page 2 of 3)

The Electric Power Research Institute (EPRI) commissioned a study to assess the benefit and basis for performing Examination Category B-N-1 VT-3 examinations. The study is documented in EPRI report 3002012966, Evaluation of Basis for Periodic Visual Examination of Accessible Areas of Reactor Vessel Interior per Examination Category B-N-1 of ASME Section XI, Division 1. The report concluded that the purpose of B-N-1 examinations is to detect foreign material and debris and that other industry requirements and guidance are sufficient for detecting foreign material or debris in the reactor vessel.

The EPRI report is the technical basis used for ASME approval of Case N-885.

In a letter from L. Lund (U.S. Nuclear Regulatory Commission) to R. Porco (ASME Board on Nuclear Codes and Standards), ASME Request for Including Specific Code Cases in Draft Revisions to Regulatory Guides 1.147, 1.84, and 1.193, dated January 31, 2020 (ML20013F353), the NRC staff has evaluated the acceptability of the eleven Code Cases referenced in the letter which included Code Case N-885. NRC concluded that Code Case N-885 would be included in the next revision to Regulatory Guide 1.147.

5. Proposed Alternative and Basis for Use

Exelon proposes to implement the requirements of ASME Code Case N-885 in lieu of the requirements of Section XI, IWB-2500(a), Table IWB-2500-1 (B-N-1, B-N-2, B-N-3), and IWB-3520. The Code Case has eliminated Table IWB-2500-1 (B-N-1, B-N-2, B-N-3), Item Number B13.10 VT-3 examinations and associated acceptance standards. The current code technical requirements concerning Examination Category B-N-2 and B-N-3, Item Numbers B13.50, B13.60, and B13.70 examinations and associated acceptance standards are retained but with modified Examination Category and Item Number assignments.

The EPRI report identified that industry foreign material control work practices reduce the amount of foreign objects and debris that could be introduced as a result of human error.

The concern for the effects of foreign material and debris within the reactor vessel are adequately addressed by the routine Core Verification and Foreign Object Search and Retrieval (FOSAR) activities that are performed during refueling outages. If foreign material or debris is observed, maintenance practices are established to either remove the foreign material, or evaluate the consequences if not removing, prior to the reactor vessel head closure. These activities occur each refueling which is more frequent than the current code requirement of each inspection period and provide appropriate processes to adequately address detrimental foreign material within the reactor vessel. In addition, there are numerous other activities that occur during refueling outages that provide opportunities for detecting adverse conditions in the interior of the reactor vessel such as:

• FOSAR, which is performed during refueling outages.

• Core verification activities.

• PWR internals examinations performed during the period of extended operation per MRP-227.

• Other Section XI examinations including Examination Categories B-A, B-D, B-N-2, and B-N-3. The current code B-N-2 and B-N-3 examinations will continue under Case N-885 as Examination Category B-N, Item Numbers B13.10, B13.20, B13.30, and B13.40.

• Reactor vessel internals component maintenance and inspection activities such as normal component movement to support refueling, and industry and NSSS or fuel supplier bulletin inspections.

10 CFR 50.55a RELIEF REQUEST Revision 0 (Page 3 of 3)

All other ASME Section XI requirements for which relief was not specifically requested and authorized by the NRC Staff will remain applicable, including third party review by the Authorized Nuclear lnservice Inspector.

Without the use of this Code Case outage times could be increased, there will be additional exposure to introduce foreign material simply due to the B-N-1 examination itself, and plant and contractor personnel will receive higher radiation doses due to additional exposure times in the reactor building.

Code Case N-885 was approved December 4, 2018 by the ASME Board on Nuclear Codes and Standards. The case has not yet been incorporated into NRC Regulatory Guide 1.147, "lnservice Inspection Code Case Acceptability, ASME Section XI, Division 1, and thus is not available for application at nuclear power plants without specific NRC approval; therefore, Exelon requests use of the alternative examination requirements described in this Case via this relief request.

6. Duration of Proposed Alternative

The proposed alternative is for use of Code Case N-885 for the remainder of each plant's 10-year inspection interval as specified in Section 2 or such time as the NRC approves the Code Case in the Regulatory Guide or other document.

7. Precedent:

None