ML19022A200
| ML19022A200 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs, Dresden, Peach Bottom, Nine Mile Point, Byron, Three Mile Island, Braidwood, Limerick, Ginna, Clinton, Quad Cities, FitzPatrick, LaSalle  |
| Issue date: | 01/23/2019 |
| From: | Blake Purnell Plant Licensing Branch III |
| To: | Tom Loomis Exelon Generation Co, Exelon Nuclear |
| Purnell B, 415-1380 | |
| References | |
| Download: ML19022A200 (28) | |
Text
Request for use of ASME Code Case N-879 for Exelon Nuclear Power Plants January 23, 2019
Relief Request Scope/Subject Matter
- Requesting use of ASME Case N-879 for alternative material for use in Lokring Pipe Fittings for Class 2 and 3 Applications
- This request is for the material only - not for design, fabrication, or testing
- Case N-879 has been approved and published by ASME
- Published in ASME Nuclear Cases, 2017 Edition, Supplement 1
- Not yet generically endorsed in Reg. Guide 1.84
- Case N-879 material has micro-alloying elements (C, Mn, V, N) to enhance yield strength.
- Although containing extra alloying elements (Mn, V, N), meets all other requirements in ASME Section III-approved material specification SA-675.
- N-879 material has a composition very similar to Pressure Vessel Plate Specification SA-737 Grade C (also approved for ASME Section III).
- Yield strength of 80 ksi is required, to confine installation deformation to pipe, rather than fitting.
- Specified properties ensure no leakage or separation of joint during service 2
Existing ASME Code Requirements
- ASME Section XI, IWA-4220 requires compliance with Construction Code requirements (or later Codes) for materials used in repair/replacement activities.
- For older plants, B31.1 is required
- Case N-879 material is permitted by B31.1 for these applications.
- B31.1 Case 164 or B31.1, 123.1.2, Unlisted Materials
- For newer plants,Section III is required
- NC/ND-2121(a) requires materials selected from Section III, Appendix I or Section II, Part D.
- NC/ND-2121(d) permits use of other materials, such as Case N-879 material, for fittings up to NPS 1.
3
Applications Currently Permitted
- Lokring fittings made from stainless steel materials are already permitted without restrictions.
- Lokring fittings made from micro-alloyed carbon steel material permitted by Case N-879 are already permitted by ASME B31.1.
- Therefore permitted to be used in safety-related service with no restrictions at
- Calvert Cliffs, Dresden, Fitzpatrick, Ginna, Nine Mile Point 1, Peach Bottom, Quad Cities, and TMI
- Lokring fittings made with Case N-879 material are already permitted in piping up to NPS 1, for all design conditions.
4
Relief Being Requested
- NRC acceptance of Case N-879 will permit use of micro-alloyed carbon steel material in Class 2 and 3 piping larger than NPS 1 and up to NPS 2 at
- Braidwood, Byron, Clinton, LaSalle, Limerick, Nine Mile Point 2 5
Hardship Reasons for Relief Request
- Safety hazards
- Welding and NDE in high-radiation environments
- Lokring mechanical installation - without welding or associated weld NDE - reduces radiation exposure and outage time.
- None of the carbon or low-alloy steel materials listed for Section III applications are suitable for both the service conditions and the Lokring installation conditions.
- The materials listed for Section III application do not have both of the following characteristics in combination.
- Similar chemistry to the pipe materials on which the fittings will be applied.
- Adequate yield strength to limit deformation to less than that of the pipe materials on which the fittings will be applied.
6
Responses to NRC Questions/Concerns
- Construction Code Editions and Addenda used:
- B31.1: 1965 through 1968
- Section III: 1971, 1974, S74, S75
- Some later Editions and Addenda for new or modified systems, such as TMI modifications at Calvert Cliffs
- Typically, instrumentation, sampling, cooling water piping
- Excludes borated systems (RCS, charging, chemical and volume control, etc.)
- Design temperature: ambient to 650°F
- Design pressure: ~100 to ~1000 psi
- Environment: air, water, or steam, inside or outside containment 7
Responses to NRC Questions/Concerns Lokring Technology is a manufacturer of pipe and tube fittings developed and qualified for use in ASME B31 pressure piping systems
- Pipe Schedules 10, 40, 80, 160
Responses to NRC Questions/Concerns
- Description and drawing 9
Responses to NRC Questions/Concerns
- Description and drawing 10
Responses to NRC Questions/Concerns
- Dimensions 11
Partial Application List - Exelon Installations - 2016 - 2018 Site Services in which Lokring Fittings are Installed # of Lokring Fittings Installed Braidwood
- Circulating water system small bore piping (1-inch)
- 4-inch vent line in diesel oil storage tank system
- Service Building Chiller rerouting water lines above the chiller heads 202
- Aux Boiler modification for diesel line
- Line replacement on WE in RH pump room Byron
- Diesel Oil Storage Tank loop seal modification. Used to prevent the need for welding on diesel piping 20 LaSalle
- 3-inch repair to exciter cooler service water piping
- SPE modification / line replacement 187
- Generic EC for up to 2-inch non-safety pipe Quad Cities
- Upgrade drain line and vent lines for waste collector filter dome piping
- Replace fuel pool filter demin dome drain valve
- Replace piping associated with turbine bearing lift pump discharge bearing 5 RV & 7 RV 117
- Reroute vent lines so travelling screen could be removed (TMod)
- Reroute U-1 and U-2 reactor building sink outlets
- Offgas piping
- Gland water supply to circ pump Dresden
- EHC modification to install vertical pumps
- "A" Concentrator replacement
- 3A RFP casing replacement 347
- 3A IAC Replacement
- Feedwater Heater Drain Valves Clinton
- Scheduled to use on 2FP52A Fuel Line Replacement 187 Nine Mile Point
- Feedwater and condensate system; used in three different applications
- EHC system isolation valves installed at turbine valves (1600 psi) 377 Oyster Creek
- Reactor Water clean up and Boiler system 27 12
Partial Application List - Non-Nuclear Applications Industry Year Work Description Product (Pipe and Fitting Material and Size) Pressure Temperature Steel Manufacturing 2005 6 Temper Mill Hydraulics CS, NPS 1/2 - NPS 3, Sch. 40 250-1000 psi Ambient Steel Manufacturing 1999 Hydraulics CS, Sch. 40/80 1500 psi Ambient Steel Manufacturing 2009 3000 - 5000 psi Hydraulics; high vibration NPS 2, Sch. 160 3000-5000 psi Steel Manufacturing 2009 Hydraulics CS & SS, NPS 1/2 through 2 1000 psi Refining 1999 Condensate Lines NPS 1, NPS 1-1/2, Sch. 80 2250 psi Ambient Petrochem 1999 Propylene NPS 1-1/2, Sch. 80 2068 kPa 100ºC Offshore/Onshore 2007 Class 900 and Class 1500 RTJ flanges and couplings 1435 psi Pulp & Paper 1991 Hydraulic Fluid NPS 1-1/4, NPS 1-1/2, Sch. 40 1000 psi 200ºF Chemical 1993 Lube Oil NPS 1-1/2, Sch. 80 1200-3500 psi Ambient Chemical 1991 Hydraulics NPS 3/4, Sch.40 1500 psi Ambient Chemical 2009 Natural Gas CS, NPS 1/2 3800 psi Ambient Petrochem 1997 - Paraxylene Unit and Ethylene Unit; 1/2" fittings installed in high NPS 1/2 - NPS 3 1450 psi 2009 vibration service in Ethylene Unit Product Compressors.
Automotive 1998 Sealer CS, NPS 2, Sch.160 3500 psi 125ºF Railroad 2004 Hydraulic Lines on Equipment CS, A53 Seamless, NPS 1/2, NPS 1, Sch. 80 3000 psi Ambient Steel Manufacturing 1999 Hydraulics CS, NPS 1/2 - NPS 2, Sch. 40 3000 psi Ambient Petrochem 1998 Gas Dehydration NPS 1, NPS 1-1/2, NPS 2, Sch. 80 1500 psi 250ºF Petrochem 1993 Hydrogen NPS 1-1/2 2400 psi Petrochem 1993 Hydrogen NPS 1/2 2400 psi Ambient Petrochem 1992 Helium NPS 1/2, Sch. 40 2400 psi Ambient Pulp & Paper 1993 Hydraulic Oil NPS 1, Sch. 40 2500 psi 120ºF Chemical 1999 Treated Boiler Feedwater NPS 1-1/2, Sch. 80 1270 psi 400ºF Chemical 1989 Hydraulics NPS 1-1/2, NPS 2 1200 psi Ambient CS = Carbon Steel SS = Stainless Steel 13
Tensile Strength and Fracture Toughness
- Minimum tensile strength: 110 ksi
- Maximum tensile strength: 130 ksi
- Fracture toughness is difficult to determine, because material is too thin to obtain impact test specimens.
- Maximum thickness of Lokring fittings for use with NPS 2 Schedule 80 pipe is ~ 3/8 in.
- Impact testing is not required by B31.1.
- Impact testing is exempted by Section III, NC/ND-2311, based on section thickness < 5/8 in., and based on diameter < NPS 6.
14
Welding Variables
- P-Number of Micro-alloyed, 80ksi Steel
- This material has no P-Number assigned by ASME.
- Separate Welding Procedure Qualification was performed using the micro-alloyed, 80ksi steel.
- Filler Material
- ER70, plain carbon steel, corresponding to the properties of the A106 Grade B (or equivalent) pipe, tee, or elbow to which the Lokring fitting is attached.
- Preheat and Postweld Heat Treatment
- Preheat temperature is 70ºF minimum.
- No PWHT is permitted, as it would degrade the required mechanical strength.
15
Weld Configuration 16
Welding Qualification Test Results
- PQR Test Results
- Tensile Strength 81 ksi
- Tensile specimen fracture was ductile and in the weld metal
- Procedure qualification base metal tensile strength is 114 ksi. Base metal hardness corresponds to 114 ksi. HAZ hardness with no preheat or PWHT corresponds to 124 ksi.
- Bend tests were acceptable.
17
Structural Integrity and Qualification Methods
- Lokring fittings, with Case N-879 material, have extensive testing and service experience.
- Proven by testing in accordance with Section III, NC/ND-3671.7 and NC/ND-3649.
- Stress analysis is impractical, due to fitting configuration.
- Testing performed:
- Burst
- Fatigue
- Tensile (pull out)
- Torsion
- Vibration
- Extensive use in similar, but non-safety-related, service in multiple applications.
18
Structural Integrity and Qualification Methods
- Burst Testing
- Lokring performs proof tests in accordance with ASME B16.9, MSS SP-97, or Section VIII, Division 1, UG-101, and Section 1
- Test per ASME B31H 19
Structural Integrity and Qualification Methods Burst pressure test chamber 20
Structural Integrity and Qualification Methods Burst test specimen- MAS 3000 CAP P16 installed on ASTM A106 B, A53 B, API 5L B schedule 80 21
Structural Integrity and Qualification Methods
- Fatigue Testing
- Lokring performs proof tests in accordance with ASME B31.1 Section 119.7.3 method to determine Flexibility and Stress Intensification Factors for components of piping systems
- Test per ASME B31J 22
Structural Integrity and Qualification Methods 23
Structural Integrity and Qualification Methods
- Vibration Testing
- Lokring performs proof tests in accordance with ASME BPVC,Section III Article NB-3200
- Experimental Stress Analysis Testing for the effects of Vibration (High Cycle, Low Amplitude) fatigue 24
Structural Integrity and Qualification Methods
- Lokring fittings being tested under low amplitude, high cycle loading.
25
Design Margins, Load Combinations, Cumulative Usage Factor
- Design Margins and Load Combinations are not relevant, because Lokring fittings are qualified by testing and have been demonstrated in accordance with Section III, NC/ND-3671.7 and NC/ND-3649 to be as good as 2:1 socket welded joints.
- Cumulative Usage Factors are not applicable, because Lokring fittings made from Case N-879 material are used only in applications where fatigue analysis is not required.
- However, Lokring has conducted an extensive testing program to determine appropriate stress indices for its fittings, for use in the piping system design.
26
Overall Summary
- Requesting use of ASME Case N-879 for alternative material for use in Lokring Pipe Fittings larger than NPS 1 and up to NPS 2.
- Extra alloying elements in CC N-879 Micro-Alloyed Carbon Steel Material, refine the grain size and significantly increase the tensile and yield strengths of the material while still maintaining acceptable ductility, toughness and corrosion resistance.
- Case N-879 has been approved and published by ASME.
- Case N-879 material is permitted by B31.1. NRC acceptance is not required for these applications.
- Case N-879 material is permitted by NC/ND-2121(d) for fittings up to NPS
- 1. NRC has already accepted the Section III provisions that permit use of this material for this application.
- Lokring mechanical installation reduces radiation exposure and outage 27 time.
Questions and Feedback
- Questions and feedback?
28