NMP2L2711, Byron Station; Calvert Cliffs; Clinton Power Station; LaSalle County Station; Limerick Generating Station; and Nine Mile Point Nuclear Station - Proposed Alternative to Utilize Code Case N-879

Byron Station; Calvert Cliffs; Clinton Power Station; LaSalle County Station; Limerick Generating Station; and Nine Mile Point Nuclear Station - Proposed Alternative to Utilize Code Case N-879

ML19289A276
Person / Time
Site:	Calvert Cliffs, Nine Mile Point, Byron, Braidwood, Limerick, Clinton, LaSalle
Issue date:	10/16/2019
From:	David Gudger Exelon Generation Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NMP2L2711, RS-19-105
Download: ML19289A276 (12)

Text

200 Exelon Way Exelon Generation Kennett Square. PA 19348 www.exeloncorp.com 10 CFR 50.55a RS-19-105 NMP2L2711 October 16, 2019 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 NRG 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 NRG 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 NRG Docket Nos. 50-317 and 50-318 Clinton Power Station, Unit 1 Facility Operating License No. NPF-62 NRG Docket No. 50-461 LaSalle County Station, Units 1 and 2 Renewed Facility Operating License Nos. NPF-11 and NPF-18 NRG Docket Nos. 50-373 and 50-374 Limerick Generating Station, Units 1 and 2 Renewed Facility Operating License Nos. NPF-39 and NPF-85 NRG Docket Nos. 50-352 and 50-353 Nine Mile Point Nuclear Station, Unit 2 Renewed Facility Operating License Nos. DPR-63 and NPF-69 N RC Docket Nos. 50-220 and 50-41 o

Subject:

Proposed Alternative to Utilize Code Case N-879

Proposed Alternative to Utilize Code Case N-879 October 16, 2019 Page 2

References:

1. Letter from J. Barstow to U.S. Nuclear Regulatory Commission, "Proposed Alternative to Utilize Code Case N-879," dated April 30, 2018.

2. Email from B. Purnell (U .S. Nuclear Regulatory Commission) to T. Loomis (Exelon Generation Company, LLC), "Exelon Generation Company, LLC -

Acceptance of Fleet Request for Alternative to Use ASME Code Case N-879 (EPID L-2019-LLR-0037)," dated May 31, 2019.

3. Letter from B. Purnell (U.S. Nuclear Regulatory Commission) to B. Hanson (Exelon Generation Company, LLC), Supplemental Information Needed to Support Request for Withholding Information Regarding Proposed Alternative to Use ASME Code Case N-879 (EPID L-2019-LLR-0037),

dated July 19, 2019.

4. Letter from D. Gudger (Exelon Generation Company, LLC) to U.S. Nuclear Regulatory Commission, "Proposed Alternative to Utilize Code Case N-879," dated August 15, 2019.

5. Email from B. Purnell (U.S. Nuclear Regulatory Commission) to T. Loomis (Exelon Generation Company, LLC), "Exelon Generation Company, LLC -

Request for Additional Information Regarding Request to Use ASME Code Case N-879 (EPID L-2019-LLR-0037}," dated October 2, 2019 . .

6. Letter from B. Purnell (U.S. Nuclear Regulatory Commission) to B. Hanson (Exelon Generation Company, LLC}, "Request for Withholding Information Regarding Proposed Alternative to Use ASME Code Case N-879 (EPID L-2019-LLR-0037)," dated October 3, 2019.

In the Reference 1 letter, Exelon Generation Company, LLC (Exelon) requested a proposed alternative to the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code, Section XI, "Rules for lnservice Inspection of Nuclear Power Plant Components," on the basis that the proposed alternative provides an acceptable level of quality and safety, equivalent to compliance with ASME Section Ill and XI requirements.

Specifically, this proposed alternative concerns the use of Code Case N-879, "Use of Micro-Alloyed Carbon Steel Bar in Patented Mechanical Joints and Fittings, Classes 1, 2, and 3 Section Ill, Division 1." This Code Case permits use of a material that does not comply with the limitations on material specifications and grades mandated by ASME Section Ill, NB/NC/ND-2121(a).

In the Reference 5 email, the U.S. Nuclear Regulatory Commission requested additional Information. Attached is our response.

Proposed Alternative to Utilize Code Case N-879 October 16, 2019 Page 3 There are no regulatory commitments contained in this letter.

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

RespiJtfully, j lAk'~--J -r 4 Jyv--

David T. Gudger Acting Director - Licensing Exelon Generation Company, LLC Attachments: 1) Response to Request for Additional Information

2) Revised Proposed Alternative to Use Code Case N-879 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 Illinois Emergency Management Agency - Department of Nuclear Safety R. R. Janati - Bureau of Radiation Protection, Commonwealth of Pennsylvania D. A. Tancabel - State of Maryland A. L. Peterson - NYSERDA

ATTACHMENT 1 Response to Request for Additional Information

Response to Request for Additional Information Proposed Alternative to Utilize Code Case N-879 Page 1 Request 1:

For each plant, either (1) limit the scope of the request to the current 10-year inservice inspection interval or (2) identify the specific ASME Code edition and addenda applicable to future 10-year inservice inspection intervals in which the proposed alternative will be used. In addition, provide a basis for each plant where use of the alternative is requested beyond the current interval.

Response

The relief request has been revised to limit the relief request to the 10-year interval. The revised relief request is contained in Attachment 2. Changes are identified with revision bars.

Request 2:

Provide a summary of the qualification testing (with applicable testing specifications) that has been or will be performed for all Class 2 and 3 Lokring fittings made using Code Case N-879.

Clarify if the specific sizes of fittings used for repairs will be tested or will credit be taken for the testing of fitting of other sizes (e.g., specify whether NPS 2 fitting will be specifically tested or will NPS 2 fittings credit the testing of smaller fittings). If credit will be taken for fitting sizes other than those that were or will be specifically tested, provide a justification.

Response

The relief request has been revised to delete reference to NC/ND-3671 .7. The revised relief request is contained in Attachment 2. Changes are identified with revision bars.

We also note that reference to Three Mile Island Nuclear Station, Unit 1 has been deleted as denoted by the revision bars.

The previously supplied enclosures are still applicable.

ATTACHMENT 2 Revised Proposed Alternative to Use Code Case N-879

10 CFR 50.55a RELIEF REQUEST Revision 0 (Page 1of6)

Proposed Alternative to Use Code Case N-879 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) 2 and smaller. Note that Case N-879 is also applicable to Class 1 piping; however, Exelon is not requesting permission to use Case N-879 for Class 1 fittings. This request applies only to Class 2 and 3 fittings.

2. Applicable ASME Section XI Edition and Addenda:

PLANT INTERVAL EDITION START END Braidwood Station, Units Fourth 2013 Edition August 29, 2018 July 28, 2028 1and2 November 5, 2018 October 16, 2028 Byron Station, Units Fourth 2007 Edition, through 2008 July 16, 2016 July 15, 2025 Addenda 1and2 Calvert Cliffs Nuclear Fifth 2013 Edition July 1, 2019 June 30, 2029 Power Plant, Units 1 and 2

Clinton Power Station, Third 2004 Edition July 1, 2010 June 30, 2020 Unit 1 Clinton Power Station, Fourth 2013 Edition July 1, 2020 June 30, 2030 Unit 1 LaSalle County Stations, Fourth 2007 Edition, through 2008 October 1, 2017 September 30, 2027 Units 1 and 2 Addenda Limerick Generating Fourth 2007 Edition, through 2008 February 1, 2017 January 31, 2027 Station, Units 1 and 2 Addenda Nine Mile Point Nuclear Fourth 2013 Edition October 6, 2018 August22,2028 Station, Unit 2

3. Applicable Code Requirements:

ASME Code, Section Ill, 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. This requirement is mandated by IWA-4220, of the ASME Section XI Edition and Addenda applicable to each nuclear power plant. Exelon has determined that relief is not needed from ASME Code 831.1 and 831.7.

10 CFR 50.55a RELIEF REQUEST Revision 0 (Page 2 of 6)

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 material given in ASME Section II, Part D (previously Section Ill, Division 1, Appendix I, Tables 1-1.1, 1-7.1, and 1-8.1 ), Subpart 1, Table 1A, for ferrous materials, on the basis that Code Case N-879 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, welded, or 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, NC/ND-2121 (a).

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 (NOE) 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 NOE.

5. Proposed Alternative and Basis for Use: 1 Exelon proposes to implement the requirements of Code Case N-879 for procurement of nonstandard, proprietary, welded and nonwelded pipe fittings, NPS 2 or smaller.

ASME Section XI requires fittings to be designed and manufactured in accordance with the original Construction Code, which, for these specific 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 (previously Section Ill, Division 1, Appendix I, Tables 1-1.1, 1-7.1, and 1-8.1 ), Subpart 1, Table 1A, for ferrous materials.

The requested alternative is provided in Code Case N-879, "Use of Micro-Alloyed Carbon Steel Bar in Patented Mechanical Joints and Fittings, Classes 1, 2, and 3 Section Ill, Division 1,"

which permits use of a micro-alloyed steel composition similar to that of ASME SA-675 and ASTM A 576 Grade 1524, with additions of carbon, manganese, vanadium, and nitrogen, to increase the yield strength to 80 ksi, to ensure a high-strength, leak-tight, mechanical joint.

The material meets all other requirements of ASME Section II, Part A, SA-675. It has chemical composition similar to ASME SA-737, Grade C, which is approved for use in ASME Section Ill applications. The additional material strength ensures that the 1 Responds to NRC Question 4 (Reference 1).

10 CFR 50.55a RELIEF REQUEST Revision 0 (Page 3 of 6) deformation produced during installation of the fittings occurs in the pipe material, rather than in the fitting material. It is this deformation that produces the 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 Ill, Class 2 and 3 systems NPS 2 or smaller.

The material described in Code Case N-879 is already permitted to be used in safety-related pipe fittings manufactured 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 Ill 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 bar form. The fracture toughness values are attached in Enclosure 1. The results demonstrate that fracture toughness testing is not necessary, and that the increase in hardness in the HAZ is minimal. Lokring imposes a maximum tensile strength of 130 ksi. 2 P-Numbers for welding procedure and performance qualification are normally provided by ASME Section IX. Because this material is not a standard product and is used only in limited applications, the Section IX committee has not been requested to provide a P-Number. Section IX, QW-420 identifies that P-Numbers are provided for the purpose of reducing the number of welding qualifications required, but are not necessary. Materials not having a P-Number are required to be qualified separately. Separate qualifications have been performed for this material welded to P-No. 1 piping materials, such as SA-106 Grade B. 3 The filler material is that most applicable to welding of SA-106 Grade B pipe, such as ER70. 4 Any welds will be preheated to 70°F and will not be post-weld heat treated.

Post-weld heat treatment (PWHT) is undesirable, as it decreases the yield strength to the point that the fittings would not be able to resist the compression forces necessary to produce a leak-tight joint. 5 A typical welding procedure and results of welding qualifications are shown in Enclosure 2. There is minimal heat-affected-zone hardening and no evidence of martensite formation in the HAZ. A metallurgical test report, with photomicrographs, is shown in Enclosure 3. HAZ hardness testing results are shown in Enclosure 4. Bend tests have been demonstrated to meet ASME Section IX requirements as shown in Enclosure 2.

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 2 Responds to NRC Question 5 (Reference 1).

3 Responds to NRC Question 8 (Reference 1).

4 Responds to NRC Question 7 (Reference 1).

5 Responds to NRC Question 6 (Reference 1).

10 CFR 50.55a RELIEF REQUEST Revision 0 (Page 4 of 6) 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. 6 Exelon desires to be able to install fittings made using the material permitted by Code Case N-879 for any application in which plain carbon steel materials, such as SA-106 Grade 8 are used, subject to the NPS 2 size limitation of Code Case N-879. 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, but will generally be less than 200°F. Design pressures could be as high as 1000 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 10 to 160, subject to the manufacturer's recommendations and limitations.7 The material addressed in Code Case N-879 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, 831.1 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.8 Rather, the margins are based on the ratio between burst pressure and the design pressure of the coupled piping. The rated pressure is downrated from the burst pressure, based on elevated-temperature tensile testing. The results of these tests are shown in Enclosure 5.

The proprietary fittings that Exelon desires to use are designed in accordance with ASME Section Ill, N8-3671.7, "Sleeve Coupled and Other Patented Joints," using the option of prototype testing. The fittings will also comply with similar requirements in ASME 831.1, paragraph 123.1.2.9 All fittings sizes will be tested prior to installation.

The fittings Exelon desires to use have been extensively tested by Exelon and Lokring 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. 10 6 Responds to NRC Question 1 (Reference 1).

7 Responds to NRC Questions 2 and 4 (Reference 1).

6 Responds to NRC Question 10 (Reference 1).

9 Responds to NRC Question 9 (Reference 1).

10 Responds to NRC Question 10 (Reference 1).

10 CFR 50.SSa RELIEF REQUEST Revision 0 (Page 5 of 6)

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 also remain applicable.

Based on the above, use of Code Case N-879 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 (previously Section Ill, Division 1, Appendix I, Tables 1-1 .1, 1-7.1, and 1-8.1 ),

Subpart 1, Table 1A, for ferrous materials are mandatory.

Code Case N-879 was approved by the ASME Board on Nuclear Codes and Standards on May 10, 2017, and was published in ASME Nuclear Code Cases, 2017 Edition, Supplement 1. 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.

In addition to the above-referenced documents, attached is the PowerPoint Presentation from the NRG-Exelon meeting on January 23, 2019 (Enclosure 6). 11

6. Duration of Proposed Alternative:

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

7. Precedent:

None

8.

Enclosures:

1) Affidavit and "Impact Test Results"

2) Affidavit and "Welding Procedure and Qualification Record"

3) Affidavit and "Metallurgical Test Report"

4) Affidavit and "HAZ Hardness Testing"

5) Affidavit and "Elevated Temperature Tensile Testing"

6) Exelon PowerPoint Presentation, "Request for Use of ASME Code Case N-879 for Exelon Nuclear Power Plants," January 23, 2019 (ML19022A200) 11 Responds to NRC Question 3 (Reference 1).

10 CFR 50.55a RELIEF REQUEST Revision 0 (Page 6 of 6)

9.

References:

1} Letter from 8. Purnell (U.S. Nuclear Regulatory Commission} to B. Hansen (Exelon Generation Company, LLC}, Supplemental Information Needed for Acceptance of Requests to Use ASME Code Cases N-878, N-879, and N-880 (EPIDS L-2018-LLR-0076 and L-2018-LLR-0077}, dated July 10, 2018