RS-20-142, Proposed Alternative to Utilize Code Case N-893

Proposed Alternative to Utilize Code Case N-893

ML20321A234
Person / Time
Site:	Calvert Cliffs, Nine Mile Point, Byron, Braidwood, Limerick, Clinton, LaSalle
Issue date:	11/16/2020
From:	David Gudger Exelon Generation Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
Shared Package
ML20321A233	List: RS-20-142, Proposed Alternative to Utilize Code Case N-893
References
RS-20-142
Download: ML20321A234 (12)

Text

PROPRIETARY INFORMATION - WITHHOLD UNDER 10 CFR 2.390 200 Exelon Way Kennett Square, PA 19348 www.exeloncorp.com 10 CFR 50.55a RS-20-142 November 16, 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 Clinton Power Station, Unit 1 Facility Operating License No. NPF-62 NRC Docket No. 50-461 LaSalle County Station, Units 1 and 2 Renewed Facility Operating License Nos. NPF-11 and NPF-18 NRC Docket Nos. 50-373 and 50-374 Limerick Generating Station, Units 1 and 2 Renewed Facility Operating License Nos. NPF-39 and NPF-85 NRC Docket Nos. 50-352 and 50-353 Nine Mile Point Nuclear Station, Unit 2 Renewed Facility Operating License No. NPF-69 NRC Docket No. 50-410

Subject:

Proposed Alternative to Utilize Code Case N-893 In accordance with 10 CFR 50.55a(z)(1), Exelon Generation Company, LLC (Exelon) is requesting a proposed alternative to the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code,Section XI, "Rules for Inservice Inspection of Nuclear Power Plant Components," on the basis that the proposed alternative Attachment 2 transmitted herewith contains Proprietary Information. When separated from attachments, this document is decontrolled.

Proposed Alternative to Utilize Code Cas N-893 November 16, 2020 Page 2 provides an acceptable level of quality and safety, equivalent to compliance with ASME Section III and XI requirements. Specifically, this proposed alternative concerns the use of Code Case N-893, "Use of Alloy Steel Bar and Mechanical Tubing in Class 2 and 3 Patented Mechanical Joints and Fittings,Section III, Division 1. This Code Case allows the use of a material that does not comply with the limitations on material specifications and grades mandated by ASME Section Ill. contains information proprietary to Lokring Technology, LLC (Lokring).

Lokring requests that Attachment 2 be withheld from public disclosure in accordance with 10 CFR 2.390(b)(4). An Affidavit supporting this request is contained in Attachment 4.

There are no regulatory commitments contained in this letter. Exelon requests your review and approval of this fleet request by October 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 Attachments: 1) Proposed Alternative to Utilize Code Case N-893

2) Material Impact Tests Results Summary (Proprietary Information)

3) Material Impact Tests Results Summary (Non-Proprietary Information)

4) Affidavit 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 - Clinton Power Station NRC Senior Resident Inspector - LaSalle County Station NRC Senior Resident Inspector - Limerick Generating Station NRC Senior Resident Inspector - Nine Mile Point Nuclear Station NRC Project Manager - Braidwood Station NRC Project Manager - Byron Station NRC Project Manager - Calvert Cliffs Nuclear Power Plant NRC Project Manager - Clinton Power Station NRC Project Manager - LaSalle County Station NRC Project Manager - Limerick Generating Station NRC Project Manager - Nine Mile Point Nuclear Station Maryland DNR - S. Seaman

Attachment 1 Proposed Alternative to Utilize Code Case N-893

10 CFR 50.55a RELIEF REQUEST Revision 0 (Page 1 of 4)

Proposed Alternative to Utilize Code Case N-893 in Accordance with 10 CFR 50.55a(z)(1)

1. ASME Code Component(s) Affected:

All ASME Class 2 and 3 carbon steel piping systems Nominal Pipe Size (NPS) 4 and smaller.

2. Applicable Code Edition and Addenda

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

Clinton Power Station, Fourth 2013 Edition July 1, 2020 June 30, 2030 Unit 1 LaSalle County Stations, 2007 Edition, through 2008 Fourth October 1, 2017 September 30, 2027 Units 1 and 2 Addenda Limerick Generating 2007 Edition, through 2008 Fourth February 1, 2017 January 31, 2027 Station, Units 1 and 2 Addenda Nine Mile Point Nuclear Fourth 2013 Edition August 23, 2018 August 22, 2028 Station, Unit 2

3. Applicable Code Requirements

ASME Code,Section III, NC/ND-2121(a), of the 1971 Edition through the 2017 Edition, provides requirements for materials to be used in Class 2 and 3 piping systems.

4. Reason for Request

In accordance with 10 CFR 50.55a(z)(1), Exelon Generation Company, LLC (Exelon) is requesting a proposed alternative from the ASME Section Ill, NC/ND-2121(a) requirements for compliance with the specifications for ferrous materials given in ASME Section II, Part D, Subpart 1, Table 1A (previously Section III, Division 1, Appendix I, Tables I-7.1 and I-8.1), on the basis that Code Case N-893 provides an acceptable level of quality and safety, equivalent to compliance with the requirements of ASME Section Ill, NC/ND-2121(a) and Section II, Part D Subpart 1, Table 1A, for ferrous materials.

Exelon desires to use nonstandard, proprietary, nonwelded pipe fittings in applications requiring compliance with ASME Section Ill, without having to comply with the limitations on material specifications and grades mandated by Section Ill. Compliance with the ASME Code results in additional critical path time, cost, and radiation exposure, that can be avoided through use of the Code Case.

10 CFR 50.55a RELIEF REQUEST Revision 0 (Page 2 of 4)

Most piping fabrication and installation joints have been traditionally fabricated by welding.

Installation of pipe and piping subassemblies by mechanical means can save significant amounts of time, money, critical path time, and radiation exposure to plant personnel and installation and examination contractors. In systems containing radioactive materials, or in systems near irradiated components, personnel can be subjected to significant amounts of radiation during preparation for welding, during welding, and nondestructive examination (NDE) of the welds. Most of this exposure can be eliminated by use of mechanical connections. The amount of time to which mechanical installation personnel are exposed is a fraction of the time to which a welder or a nondestructive examiner would be exposed.

Without installation welds, there is no associated installation NDE.

5. Proposed Alternative and Basis for Use:

Exelon proposes to implement the requirements of Code Case N-893 for procurement of nonstandard, proprietary, nonwelded pipe fittings, NPS 4 or smaller.

ASME Section XI requires the fittings to be designed and manufactured in accordance with the original Construction Code, which, for these applications, is ASME Section Ill. The only ASME Code requirement for which Exelon is seeking an alternative is that of ASME Section Ill, NC/ND-2121(a), which requires compliance with the specifications for material given in ASME Section II, Part D, Subpart 1, Table 1A (previously Section Ill, Division 1, Appendix I, Tables I-7.1 and I-8.1), for ferrous materials.

The requested alternative is provided in ASME Code Case N-893, "Use of Alloy Steel Bar and Mechanical Tubing in Class 2 and 3 Patented Mechanical Joints and Fittings,Section III, Division 1, which permits use of a low-alloy (Grade 4130) steel composition made to ASTM A 322 (for bar) and ASTM A 519/519M (for mechanical tubing), similar to what is permitted by ASME SA-29 (for bar) and SA-513 (for mechanical tubing). This grade of material is also permitted to be used in SA-193 Grade B7M or SA-320 Grade L7M bolting, which are permitted to be used in construction of ASME Section VIII vessels.

The tensile and yield strength provided by the 4130 alloy composition (95 ksi and 80 ksi, respectively) are needed to ensure a high-strength, leak-tight mechanical joint. This material strength ensures that the deformation produced during installation of the fittings occurs in the pipe material, rather than in the fitting material, and produces the residual stresses necessary for the joint structural and leak-tight integrity.

This Code Case will expand Exelon's ability to use these proprietary fittings in safety-related piping, by including coverage for ASME Section III, Class 2 and 3 systems, NPS 4 or smaller.

These fittings are already permitted to be used in safety-related piping constructed in accordance with ASME B31.1, paragraph 123.1.2. This material is also already permitted to be used in compression-type fittings in ASME Section Ill, Class 1, 2, and 3 instrument lines, up to NPS 1, in accordance with NB/NC/ND-2121, in the 1971 Edition through the 2017 Edition; however, for piping systems in nuclear power plants for which Section III was used for construction, the applicable material requirements in NB/NC/ND-2121 do not address, or specifically permit, use of this material in fittings other than instrument lines up to NPS 1.

Section Ill does not require fracture toughness testing for this material, because tubular products of the desired size are too small and too thin to make fracture toughness test specimens. Nonetheless, this material has been impact tested in forging, bar, and mechanical

10 CFR 50.55a RELIEF REQUEST Revision 0 (Page 3 of 4) tubing fitting form. The fracture toughness values are in Attachment 2. The results demonstrate that fracture toughness testing is not necessary. Lokring imposes Charpy V-Notch impact testing requirements of 40 ft-lbs average and 30 ft-lbs minimum at -50°F, which is necessary for its outdoor petrochemical piping environments, but not for nuclear power plant piping containing water at temperatures above +32°F. Some of the Lokring tests have been performed in specimens taken transverse to the rolling/forging direction, which is conservative with respect to the ASME Section III requirements for taking test specimens in the axial/longitudinal direction.

The test data received to date, from many heats and heat treatment lots of non-safety-related fittings, has been compared with ASME Section III requirements that would be mandatory for larger, thicker fittings. These data comply with the requirements of Table NC-2332.1-1 for material up to 2-1/2 inches thick (average 35 mle, lowest 30 mle). When tested in the longitudinal direction at -50°F, all of the values exceeded 30 mils lateral expansion. When tested in the longitudinal direction at +32°F, all of the values exceeded 70 mils lateral expansion, which far exceeds what would be required of thicker materials in larger fittings for ASME Section III applications. Exelon concludes that this material has more-than-adequate toughness for nuclear safety-related piping applications.

This material is not suitable for welding, because it can harden significantly in the heat affected zone (HAZ); therefore, Code Case N-893 prohibits welding on this material. Exelon will assure that no welding is performed on fittings manufactured from this material.

The Section Ill Code Editions and Addenda used in constructing the Class 2 and 3 piping systems at Braidwood, Byron, Calvert Cliffs, Clinton, LaSalle, Limerick, and Nine Mile Point Nuclear Station, Unit 2 include primarily the Winter 1972 Addenda, the 1974 Edition, including the Summer 1974 and Summer 1975 Addenda, and the 1977 Edition with the Summer 1978 and Summer 1979 Addenda. At Calvert Cliffs Nuclear Power Plant, Units 1 and 2, several new post-TMI modifications were designed to add systems constructed using the 1977 Edition of Section Ill, including the Summer 1978 Addenda.

Exelon desires to be able to install fittings made using the material permitted by Code Case N-893 for any application in which plain carbon steel materials, such as SA-106 Grade B are used, subject to the proposed NPS 4 size limitation; however, the typical applications in which the subject proprietary fittings will be used are generally limited to instrumentation, sampling, and cooling water piping lines. They exclude Class 1 systems and any systems containing boric acid. Design temperatures may be up to 650°F. Design pressures could be as high as 2000 psi but will generally be less than 200 psi. The environmental conditions are anything in the nuclear power plant environment, including air, water, or steam systems, and possibly lube oil or fuel systems. They could be inside or outside containment. Prior operating experience for these fittings in these environments have shown successful performance, with no leaks or structural failures, as long as they are installed in accordance with the manufacturer's instructions. They have been successfully used in pipe schedules from 40 to 160, subject to the manufacturer's recommendations and limitations.

The material addressed in Code Case N-893 is somewhat unique in that it will be used in fittings designed and qualified by testing, rather than by calculating stresses. Due to the complex shape of the fittings, calculating stresses is not practical. For this reason, B31.1 and Section Ill contain provisions for proving the capability of such fittings by testing.

These requirements do not include design margins or load combinations based on allowable stresses. Rather, the margins are based on the ratio between burst pressure and

10 CFR 50.55a RELIEF REQUEST Revision 0 (Page 4 of 4) the design pressure of the coupled piping. The rated pressure is downrated from the burst pressure, based on elevated-temperature tensile testing, in the same manner as was used to rate the fittings made from the material in Code Case N-879.

The proprietary fittings that Exelon desires to use are designed in accordance with ASME Section Ill, NC/ND-3671.7, "Sleeve-Coupled and Other Patented Joints," using the option of prototype testing. All fittings sizes will be tested prior to installation.

The fittings Exelon desires to use have been extensively tested to demonstrate that the fittings will not fail before the pipe on which they are installed. The fittings have been tested by tensile (pull-out) testing, pressurization to burst, fatigue testing, and torsion testing.

Fatigue analysis is not required for the requested applications but is performed for the purpose of establishing a stress intensification factor (SIF), for use by the piping system designer.

Reconciliation and use of editions and addenda of ASME Section Ill will be in accordance with ASME Section XI, IWA-4220, and only editions and addenda of ASME Section Ill that have been accepted by 10 CFR 50.55a may be used. The Code of Record for the specific 10-year ISI interval at each nuclear unit as identified under Section 2 above, will be used when applying the requirements of Section XI, unless specific regulatory relief to use other editions or addenda is approved.

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. All other Section Ill requirements, other than NC/ND-2121, will remain applicable.

Based on the above, use of Code Case N-893 provides an acceptable level of quality and safety when compliance with the ASME Section Ill requirements for material given in ASME Section II, Part D, Subpart 1, Table 1A (previously Section Ill, Division 1, Appendix I, Tables I-7.1 and I-8.1), for ferrous materials are mandatory.

Code Case N-893 was approved by the ASME Board on Nuclear Codes and Standards on December 21, 2019, and was published in ASME Nuclear Code Cases, 2019 Edition, Supplement 4. It has not yet been incorporated into NRC Regulatory Guide 1.84, "Design, Fabrication, and Materials Code Case Acceptability, ASME Section Ill," and thus is not available for application at nuclear power plants without specific NRC approval; therefore, Exelon requests use of the alternative material requirements described in this Code Case via this relief request.

6. Duration of Proposed Alternative:

The proposed alternative is for use of the Code Case for the remainder of each plant's 10-year inspection interval as specified in Section 2 and for the remainder of the plant's life.

7. Precedent:

None

Attachment 3 Material Impact Tests Results Summary (Non-Proprietary Information)

Non-Confidential Information Submitted Under 10 CFR 2.390 Page 1 of 1 Material Impact Test Results Summary Affidavit

ATTACHMENT Reference 1 AFFIDAVIT I, William H. Lennon, the sole Member and Chief Executive Officer of Lokring Technology, LLC, do hereby affom and state:

1. I am the sole Member and the Chief Executive Officer of Lokring Technology, LLC, and 1 am authorized to execute this Affidavit on its behalf. I am further authorized to review Information submitted to the Nuclear Regulatmy Commission (NRC) and apply for the withholding oflnfmmation from disclosure.

2. Lokring Technology, LLC is providing Information pursuant to 10 CFR 50.55a, which constitutes proprietary trade secret Information that should be held in confidence by the NRC pursuant to the policy reflected in 10 CVF 2.390(a)(4), because:

i. This Information Reference (Attachment 2 Material Impact Test Results Summaiy) is and has been held in confidence by Lokring Technology, LLC.

ii. This information is of a type that is held in confidence by Lokring Technology, LLC and there is a rational basis for doing so because the Information contains sensitive trade secret Information concerning detailed design and testing details.

iii. This Info1mation is being transmitted to the NRC in confidence.

iv. This Infmmation is not available in public sources and could not be gathered readily from other publicly available Information.

v. Public disclosure of this Information would create substantial hatm to the competitive position ofLokring Technology, LLC by disclosing Lokring Technology, LLC design and testing details to other paities whose commercial interests may be adverse to those ofLokring Technology, LLC.

3. Accordingly, Lokring Technology, LLC requests that the designated documents be withheld from public disclosure pursuant to the policy reflected in 10 CFR 2.390(a)( 4) and that prompt written notice be provided to Lokring Technology, LLC of any request for disclosure ofLokring Technology, LLC trade secret or confidential information, as well as the maximum amount of time available under the applicable statute to object in writing to any disclosure of such information.

Lokring Technology, LLC

STATE OF OHIO )

) SS.

COUNTY OF LAKE )

Before me, a Notaty Public, in and for said County and State, personally appeared MR. WILLIAM H. LENNON, who acknowledged that he did execute the foregoing Affidavit and such execution is his free act and deed.

IN WI~ESS WHEREOF, I have hereunto set my hand and official seal a1:>~?j',,//7, Ohio, this ;/t_L day ofNovember, 2020. * ,/ (J