L-2017-033, Inservice Inspection Plan, Fifth Ten-Year Interval Unit I Relief Request No. 3, Revision 0
| ML17047A283 | |
| Person / Time | |
|---|---|
| Site: | Saint Lucie  |
| Issue date: | 02/16/2017 |
| From: | Synder M Florida Power & Light Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| L-2017-033 | |
| Download: ML17047A283 (14) | |
Text
- F=PL.
FEB 1 6' 2017 L-2017-033 10 CFR 50.4 10 CFR 50.55a U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555 Re: St. Lucie Unit 1 Docket No. 50-335 Insenrice Inspection Plan Fifth Ten-Year Interval Unit 1 Relief Request No.3, Revision 0 Pursuant to 10 CFR 50.55a(z)(2), Florida Power & Light, is requesting relief from the requirements of ASME Code,Section XI, Subsection IWA-4000 for defect removal prior to repair, since compliance would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety. The details and justification for this request are provided in Attachment 1 to this letter.
This relief request is applicable to the St. Lucie Unit 1 Fifth Inservice Inspection Interval which will begin February 11, 2018 and ends February 10, 2028.
Please contact Ken F rehafer at (772) 467-77 48 if there are any questions about this submittal.
Sincerely,
!~
Licensing Manager St. Lucie Plant Attachment MJS/KWF cc: USNRC Regional Administrator, Region II USNRC Senior Resident Inspector, St. Lucie Units 1 and 2 Florida Power & Light Company 6501 S. Ocean Drive, Jensen Beach, FL 34957
L-2017-033 Attachment 1 of 13 St. Lucie Unit 1 FIFTH INSPECTION INTERVAL 50.55a REQUEST NUMBER 3, Revision 0 Proposed Alternative In Accordance with 10CFR50.55a(z)(2)
Hardship without a Compensating Increase in Quality and Safety
- 1. ASME Code Component(s) Affected Class 3 Intake Cooling Water (ICW) System 30 diameter piping in Unit 1 as follows:
System 21, I-30-CW-29 and I-30-CW-30 (Discharge piping downstream of Component Cooling Water (CCW) Heat Exchangers only)
2. Applicable Code Edition and Addenda
The American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code, Rules for Inservice Inspection of Nuclear Power Plant Components,Section XI, 2007 Edition with Addenda through 2008[1] as amended by 10CFR50.55a, is the Code of Record for the St. Lucie Unit 1 5th 10-year interval.
USAS B31.7 Class 3, 1969 Edition [2] is the Construction Code for St. Lucie Unit 1. The American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code, Rules for Construction of Nuclear Power Plant Components,Section III, Class 3, 1971 Edition with Addenda through Summer 1973[3], is the Code of Record for St. Lucie Unit 1 based on reconciliation with the Construction Code[4].
3. Applicable Code Requirement
ASME Code,Section XI, Paragraph IWA-4421 of the 2007 Edition with Addenda through 2008[1]
states that Defects shall be removed or mitigated in accordance with the following requirements:
Subparagraph IWA-4422.1 states that A defect is considered removed when it has been reduced to an acceptable size.
4. Reason for Request
The nuclear safety related ICW System for St. Lucie Unit 1 is comprised of two redundant trains (i.e., A and B). I-30-CW-29 and I-30-CW-30 are open ended discharge pipes to the ocean discharge canals. Due to the seawater content, the ICW piping constructed from Standard Wall 30 (0.375 inch wall), A-155 KC-65 (equivalent to SA 106 Grade B) Carbon Steel, has an internal liner to preclude the loss of internal pipe wall due to corrosion. The piping being addressed in this relief request is cement or epoxy lined 30 inch nominal diameter buried piping with a nominal liner thickness of 1/8-inch. The outer surface of the piping is coated with Coal-Tar Epoxy. The ICW piping is classified as a Class 3 component, qualified in accordance with ASME Code,Section III, Subsection ND criteria. Burial depths to the centerline range from 4 feet-3 inch to 16 feet below grade.
L-2017-033 Attachment 2 of 13 St. Lucie Unit 1 FIFTH INSPECTION INTERVAL 50.55a REQUEST NUMBER 3, Revision 0 St. Lucie station performs single train internal pipe inspections each outage, resulting in 100%
inspection every other outage. The inspections are performed in accordance with St. Lucie's commitment to the NRC Generic Letter GL 89-13[5]. The objective of this commitment is to perform routine inspection to ensure that corrosion, erosion, protective coating failure, silting, and biofouling does not degrade the performance of the ICW safety-related system. ICW pipe inspections at St. Lucie are performed by a qualified pipe inspector. The inspection methodology consists of draining the pipe and removing a section to allow internal access, cleaning the pipe surface, and performing a visual examination of the cement or epoxy liner. The inspector observes for signs of corrosion deposits, staining, cracks, missing lining, area blisters, peeling/delamination, surface irregularities, or discoloration. UT inspection of degraded pipe metal is performed where there is degradation.
The above described pipe inspections have from time to time identified localized areas of liner loss resulting from corrosion cells in the underlying piping. Should measurements detect a pipe wall loss resulting in a remaining pipe wall thickness less than the prescribed ASME Code required minimum pipe wall thickness or a through-wall leak is identified, a repair in compliance with ASME Code Section XI, Article IWA-4000 Repair/Replacement Activities would be required. Full defect removal of discovered localized thinning per IWA-4000 may result in a through-wall defect. This case and in those instances where a through-wall defect is discovered, would result in the potential for leakage due to damage to the external coating. If the external coating was not damaged during the defect removal, a traditional repair of cutting a hole and installing a welded rolled plate to return the piping to its original design condition is not possible as the pipe is buried and the outside of the pipe is not easily accessible. Welding would destroy the surrounding exterior coating and the location would prevent NDE of the exterior of the pipe. Consequently, Florida Power & Light, pursuant to 10 CFR 50.55a(z)(2), is requesting relief from the requirements of ASME Code,Section XI, Subsection IWA-4000 for defect removal prior to repair since compliance would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.
Florida Power and Light has installed several repairs without removing the defects, and is requesting relief to leave the existing repairs in place and to allow installation of additional repairs in the future to repair similarly damaged areas. The earliest existing repairs that are still in service were installed in 2005. The ASME Code,Section XI requirements before the current 10-year inspection interval regarding removal of defects are equivalent to those listed in Section 2 and Section 3 above.
The existing repairs include eight installed plates in I-30-CW-29 (Train B) consisting of sizes of 3.5x3.5, 7.5x11.5, and 10x11. The plates in I-30-CW-29 were all installed in 2012 or 2013. An additional nineteen plates consisting of sizes of 3.5x3.5, 11x11, 8x8, and 10x11 are installed in I-30-CW-30 (Train A). One of the plates was installed in 2005, one in 2008 and the remainder in 2012. The total length of pipe in both trains that contains the bolted patch plates is approximately 200 feet. Isometric views showing the relative location of the bolted patch plate repairs in the ICW piping are provided in Figure 3 through Figure 7.
L-2017-033 Attachment 3 of 13 St. Lucie Unit 1 FIFTH INSPECTION INTERVAL 50.55a REQUEST NUMBER 3, Revision 0
- 5. Proposed Alternative and Basis for Use Proposed Alternative Install internal bolted patch plate repairs typical of that illustrated in Figure 1 and Figure 2 to cover the damaged areas of the inside surface of the pipe. The internal bolted patch plates are designed to meet the criteria of the applicable Code of Record[3], as required by ASME Code, Section XI[1],
Paragraph IWA-4221.
Basis A description of the process used to qualify the design, a description of the installation process, and the inspection program to monitor the condition of the repairs is included in this section.
Design Qualification Process:
The design qualification process determines the minimum pipe wall thickness using design formulas of ASME Code,Section III and the criteria presented within FSAR Table 3.9-3 for reviewing interactions of pressure stress and longitudinal bending stresses. The calculations evaluate the required reinforcement versus the actual reinforcement available around the corrosion holes and reviews bolting requirements for the patch plate which is analyzed as a blind flange. Reinforcement interaction is reviewed for the multiple holes to ensure additional reinforcement is not required.
The design qualification process includes the following steps:
- 1. Develop a minimum pipe wall thickness based on hoop stress and longitudinal bending stress per ASME Code,Section III, ND-3641.1 as required by Subsection ND.
- 2. Determine required and actual reinforcement areas and zones per ASME Code,Section III, Subsection ND.
- 3. Determine patch plate thickness requirements per ASME Code,Section III, Subsection ND.
The installed plate nominal thickness is at least equal to the nominal thickness of the undamaged pipe.
- 4. Determine the gasket loading and bolt requirements per ASME Code,Section III, Appendix E.
- 5. Review thread engagement using machinery principles.
- 6. Address interaction or reinforcement zones per ASME Code,Section III, Subsection ND.
- 7. Perform stress intensification factor review.
Installation Process Summary:
- 1. Avoiding damage to any external coatings on the pipe outside surface (OD), prepare the surface of corrosion holes by blast cleaning and fill with epoxy material to the profile of the pipe ID.
- 2. Remove a section of the pipe lining centered on the affected area.
L-2017-033 Attachment 4 of 13 St. Lucie Unit 1 FIFTH INSPECTION INTERVAL 50.55a REQUEST NUMBER 3, Revision 0
- 3. Clean and smooth interior of pipe to support closure plate fit-up.
- 4. Layout bolt hole locations on pipe and ultrasonically inspect for thickness. The degraded areas are ultrasonically inspected to determine surrounding wall thickness. All readings outside of the areas of degradation are within the manufacturers tolerance of nominal wall thickness.
- 5. Drill and tap 1/4 deep bolt holes. Do not allow holes to exceed 1/4 depth to maintain minimum wall thickness.
- 6. Install the studs wrench tight without lubrication.
- 7. Apply epoxy to pipe beneath closure plate area including corrosion holes previously filled and the gasket area.
- 8. Before epoxy hardens, install gasket, closure plate, washers and nuts (lightly lubricated).
- 9. Trim studs flush with the tops of the nuts, degrease and surface prep the exposed area, and cover the entire repair area with epoxy coating. Ensure that the coating is blended to provide smooth transitions to minimize ICW flow turbulence.
Post-installation Inspections:
The piping inspections described in Section 4 are continued after the internal bolted plate repairs are performed. In addition to the visual inspection, a hammer test is generally performed for all patches installed in the pipe. Partial disbondment of a patch will produce a hollow sound when tapped with a chipping hammer. A solid, non-hollow sound indicates that the patch remains in good condition. If a patch is suspect based on visual examination or hammer test results, the patch is removed from the pipe surface for further examination.
Since the bolted patch plate is installed on the inside surface of the piping and it completely covers the damaged area with a gasketed closure, the damaged area is isolated from the corrosive environment. Also, the damaged area is covered with an epoxy coating prior to the repair, including filling the damaged areas for a smooth repair surface, and after the repair, further isolating the damaged area from the corrosion surface. There is therefore minimal potential for the damaged area to expand over time during service such that the repair would no longer be effective. Based on a typical corrosion rate of carbon steel exposed to seawater of 30 mils per year (mpy)[6], the maximum extent of corrosion should the epoxy coating and gasket be breached to allow access to the original defect area would be 0.09-inch, assuming a 3-year inspection interval. The extent of the bolted plate beyond the defect area is always much greater than 0.09 inch so any additional corrosion of the defected area would be identified and corrected during the next inspection. Note that the minimum nominal thickness of the bolted plate is at least as thick as the undamaged piping so the potential corrosion of the plate is no greater than that of the undamaged piping.
Periodic inspections completed to date have not identified any degradation of the existing internal bolted plate repairs.
L-2017-033 Attachment 5 of 13 St. Lucie Unit 1 FIFTH INSPECTION INTERVAL 50.55a REQUEST NUMBER 3, Revision 0 In early 2012 during the SL1-24 outage, the Unit 1 discharge headers were internally refurbished with Plascite coatings from the CCW Building to 45-degree elevation drop near the discharge canal. This is the area that includes the existing bolted patch plates. The remainder of the two headers and overflow pipes were replaced with new carbon steel piping internally and externally coated with Plascite. This section is normally below the level of the discharge canal and requires divers for inspection.
As discussed above, the bolted patch plate repair is installed on the inside surface of the piping which isolates the damaged area from the corrosive environment. Also, the damaged area is covered with an epoxy coating prior to the repair, including filling the damaged areas for a smooth repair surface, and subsequent to the repair, further isolating the damaged area from the corrosion surface. There is therefore minimal potential for the damaged area to expand over time during service such that the repair would no longer be effective. Limitation on the life of the repair based on the potential degradation to grow to an unacceptable size for the repair or additional subsequent inspections is not required.
The design qualification process, installation process, and the post-installation inspections for the bolted patch plate repairs provide reasonable assurance of the structural integrity of the repair. The location of the defects and the potential additional damage that could occur if the defects were removed prior to the repair as required by the ASME Code,Section XI support the request for an alternative to the ASME Code,Section XI requirement because complying with the requirement would represent a hardship or unusual difficulty without a compensating increase in the level of quality or safety.
- 6. Duration of Request This relief request is applicable to the St. Lucie Unit 1 Fifth Inservice Inspection Interval which will begin February 11, 2018 and ends February 10, 2028.
- 7. Precedents There are several precedents for installation of a repair without removal of the initiating defect.
Examples of these precedents are listed below:
St. Lucie Plant, Unit No. 1 - Relief Request No. 7 Regarding Alternate Repair for Intake Cooling Piping (TAC No. MF2529), SER Dated January 30, 2014, Ascension No. ML14013A304.
Seabrook Station, Unit 1 - Request for Relief to Use an Alternative to the Requirements of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code,Section XI (TAC No.
ME9187), SER Dated January 14, 2013, Accession Number ML12185A069.
Indian Point Nuclear Generating Unit No. 3 - Relief Request (RR) No. RR-3-43 for Temporary Non-Code Repair of Service Water Pipe (TAC No. MD6831), SER Dated February 22, 2008, Accession No. ML080280073.
L-2017-033 Attachment 6 of 13 St. Lucie Unit 1 FIFTH INSPECTION INTERVAL 50.55a REQUEST NUMBER 3, Revision 0
- 8. References
- 1. ASME Code,Section XI, Rules For Inservice Inspection of Nuclear Power Plant Components,2007 Edition with Addenda through 2008.
- 3. ASME Code,Section III, Rules for Construction of Nuclear Power Plant Components, 1971 Edition with Addenda through Summer 1973.
- 4. St. Lucie Unit 1 UFSAR Amendment 27A
- 5. St. Lucie Letter No. L-2013-005 10 CFR 50.4, dated January 10, 2013 to the USNRC Re: St.
Lucie Units 1 and 2, Docket Nos. 50-335 and 50-389, Clarification of NRC Commitment Regarding Generic Letter 89-13, Accession No. ML13025A208.
- 6. Seabrook Station, Unit 1 - Request for Relief to Use an Alternative to the Requirements of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code,Section XI (TAC No. ME9187), SER Dated January 14, 2013, Accession Number ML12185A069.
L-2017-033 Attachment 7 of 13 St. Lucie Unit 1 FIFTH INSPECTION INTERVAL 50.55a REQUEST NUMBER 3, Revision 0 I-30'-C\J-29
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A-155 KC65 Concrete Lined Center Plate Over Damaged Area. Plate Shall Be Rolled To Conform To The ID Of The Pipe Or Made From 30"0 Pipe.
Section J-J Plate Location # 8 Figure 1: Typical Bolted Patch Plate Drawing Key Plan and Section J-J View
L-2017-033 Attachment 8 of13 St. Lucie Unit 1 FIFTH INSPECTION INTERVAL SO.SSa REQUEST NUMBER 3, Revision 0 DRILL FOR TAPPING X' <Mux.)
1/4 BLII'.JD HOLE .
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Section F-F Plate Location #2, 6, 7 & 8
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Figure 2: Typical Bolted Patch Plate Drawing Sections F-F and G-G Views
L-2017-033 Attachment 9 of13 St. Lucie Unit 1 FIFTH INSPECTION INTERVAL SO.SSa REQUEST NUMBER 3, Revision 0 BOI.. TD CLOSUI{E PLATE LOCATION~
@3:3o ecz74B59 * *** *
@5:30 EC235503 (MSP 051~2) .
@11~00..12:00 EC235964 (MSP 08168)
Figure 3: Bolted Patch Plate Repair Locations I-30"-CW-30 (Train A) (Three Locations)
L-2017-033 Attachment 10 of 13 St. Luci~~~iltN~ERVAL FIFTH INSPECT MBER 3, Revision 0 50.55 a REQUEST NU
' . Locations Figure 4: Bolte~t~W-30 tch Plate Repair (Train A) 1-30 L ations)
(Sixteen oc tion Listing See Figure 5 for Loca
L-2017-033 Attachment 11 of 13 St. Lucie Unit 1 FIFTH INSPECTION INTERVAL SO.SSa REQUEST NUMBER 3, Revision 0 I-30-CW-30 BOLTED CLOSURE PLATE LOCATIONS BOLTED PLATE REPAIR LOCATION #1 @6:30 EC275645 BOLTED PLATE REPAIR LOCATION #2 @7:00 EC275645 .*
BOLTED PLATE REPAIR LOCATION #3 @5:00 EC275645 BOLTED PLATE REPAIR LOCATION #4 @6:00 EC275645 *.
BOLTED PLATE REPAIR LOCATION #5 @5:30 EC275645 **.
BOLTED PLATE REPAIR LOCATION #6 @12:00 EC275645 BOLTED PLATE REPAIR LOCATION #7 @9:30EC275645 : *.
BOLTED PLATE REPAIR LOCATION #8 @2:30 EC275645 * .*
BOLTED PLATE*REPAIR LOCATION #9 @10:00 EC275645 .
BOLTED PLATE REPAIR LOCATION.#lO @5:30 EC275645 .*
BOLTED PLATE REPAIR LOCATION #13 @7:00 EC275645 *.
BOLTED PLATE REPAIR LOCATION #14 @4:00 EC275645 *.
BOLTED PLATE REPAIR LOCATION #15 @8:15 EC275645 * .
BOLTED PLATE REPAIR LOCATION #16 @8:00 EC275645 Figure 5: Bolted Patch Plate Repair Location Listing for Figure 4
L-2017-033 Attachment 12 of 13 St. Lucie Unit 1 FIFTH INSPECTION INTERVAL SO.SSa REQUEST NUMBER 3, Revision 0 Figure 6: 1-30"-CW-29 (Train B)
(Two Locations)
L-2017-033 Attachment 13 of 13 St. Lucie Unit 1 FIFTH INSPECTION INTERVAL SO .SSa REQUEST NUMBER 3, Revision 0 LINES I-30-CW-29 &30 WERE REFURBISHED IN 2012 (SL!-24) WITH PLASITE COATINGS EXCEPT WHERE NOTED CEMENT LINED PIPE IS LOCATED.
I-30-CW-29 SOLTED CLOSURE PLATE LOCATIONS SOLTED PLATE REPAIR LOCATION# 1@7:00-10:00 EC275443 BOLTED PLATE REPAIR LOCATION #2 @5:00 EC275443 BOLTED PLATE LOCATIONS #3  DO NOT EXIST BOLTED PLATE REPAIR LOCATION #5 @3:00-6:00 EC275443 BOLTED PLATE REPAIR LOCATION #6 @5:00 EC275443 BOLTED PLATE REPAIR LOCATION #7 @3:00 EC275443 .
BOLTED PLATE LOCATIONS #8 	 SHOWN ON BnO-G-125 SH. CW-F-3 BOLTED PLATE REPAIR LOCATION #10 @6:00 EC280123 Figure 7: 1-30"-CW-29 (Train B)
(Six Locations)