SBK-L-20103, Inservice Inspection Examination Report
| ML20209A520 | |
| Person / Time | |
|---|---|
| Site: | Seabrook  |
| Issue date: | 07/27/2020 |
| From: | Browne K NextEra Energy Seabrook |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| SBK-L-20103 | |
| Download: ML20209A520 (11) | |
Text
NEXTera ENERGY ~
SEABROOK July 27, 2020 Docket No. 50-443 SBK-L-20103 United States Nuclear Regulatory Commission Attn.: Document Control Desk Washington, D.C. 20555-0001 Seabrook Station Inservice Inspection Examination Report Enclosed is the NextEra Energy Seabrook, LLC Inservice Inspection Examination Report for inspections conducted prior to and during the twentieth refueling outage that concluded on April 27, 2020.
The enclosed report is submitted pursuant to the requirements of paragraph IWA-6240 of the 2004 Edition of Section XI of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code and approved ASME Code Case N-532-5 and N-729-4. Additionally, a copy of this letter and the enclosed report are being submitted to the State of New Hampshire.
Should you have any questions regarding this information, please contact Mr. Brian O'callahan, Engineering Site Manager - Programs, at (603) 773-7046.
Sincerely, e
Safety Assurance and Learning Site Director NextEra Energy Seabrook, LLC, P.O . Box 300, Lafayette Road, Seabrook, NH 03874
United States Nuclear Regulatory Commission SBK-L-20103/Page 2 cc: NRC Region I Administrator NRC Project Manager, Project Directorate I-2 NRC Senior Resident Inspector Wayne Brigham, Boiler Inspector New Hampshire Department of Labor Inspection Division PO Box 2076 Concord, NH 03302-2076
Enclosure to SBK-L-20103 OR20 OAR-1 Summary Report EC294767 Rev. 0 Engineering Evaluation: EE-20-004 Rev. 0
Enclosure to SBK-L-20103 Page 1of8 Report Number: ISl-SBK-OR20-2020 Plant: NextEra Energy Seabrook, LLC P.O. Box 300 Seabrook, NH 0387 4 Commercial Service Date: August 19, 1990 Refueling Outage No.: OR20 Current Inspection Interval: ISi- Third Interval and IWE- Second Interval Current Inspection Period: ISi- Third Period and IWE- Third Period Edition and Addenda of Section XI applicable to the inspection plans:
ISi Third lnterval-2004 Edition No Addenda and IWE Second lnterval-2004 Edition No Addenda Date and Revision of inspection plans: ISi Third Interval and IWE Second Interval - December 13, 2019 Rev. 18 Edition and Addenda of Section XI applicable to repairs and replacements, if different than the inspection plan: Same Code Cases Used: N-532-5, N-729-4 CSRUFfCATE OF CONFORMANCE I certify lhat (a) the statements made fn this report are corred, (b) the e.xaminations and tests meet the Inspection plan as required by the ASME Code.Section XI; and (c) the repair/replacement adMties and evaluations supPQrting the completion of OR20 conform to the requirements of Section XI Signed ~ or Owner's
§ji:....;.:1 1'"'1- ~'Date iµ,L.io signee. Title t CERTIFICATE OF INSERVICE INSPECTION I. the undersigned, holding a valid commission issued by the National Board of Boiler and Pressure Vessel Inspectors and the State or Province of New Hampshire and employed by The Hartford Steam Boiler Inspection and Insurance Company of Hartford, CT have inspected the items described in this Owner's Activity Report, and state that. to the best of my knowledge and belief, the Owner has performed aH activities represented by this report in accordance with the requirements of Section XI.
By signing this certificate neither the Inspector nor his employer makes any warranty, expressed or implied, concerning the repair/replacement activities and evaluation described in this report. Furthermore, neither the insP,Sctor is employer shall be liable in any manner for any personal injury or property damage or ross o tfiny kind sing from or connected with this inspection.
Date 7-d-Y 4e80
Enclosure to SBK-L-20103 Page 2 of 8 TABLE 1 ITEMS WITH FLAWS OR RELEVANT CONDITIONS THAT REQUIRED EVALUATION FOR CONTINUED SERVICE Examination Item Category and Evaluation Description Description Item Number E-A Moisture barrier AR2353146, 02351311, 02351991, 02351984 - Water identified E1.30 Leak Chase in Leak Chase The outer debris cover for the containment leak chase zone for HL2-19, HL 1-22, HL2-19 & HL5-2 and the inner plugs have conditions that require evaluation. As noted in reference 1, the leak chase test connections (LCTCs) are functioning as moisture barriers as defined by ASME Section XI 2004 Edition, Subsection IWE (Ref 2).
The LCTCs consist of the cover plate, inner plug, and the access box.
ASME Section XI 2004 Edition, Subsection IWE requirements Visual examination acceptance criterion of the moisture barrier is per IWE-3510.4 which states "Moisture barriers with wear, damage, erosion, tear, surface cracks, or other defects that permit intrusion of moisture against inaccessible areas of the pressure retaining surfaces of the metal containment shell or liner shall be corrected by corrective measures." The moisture barrier degradation has the potential for moisture intrusion and accelerated corrosion in the portion of the liner protected by the moisture barrier -the liner inside the associated leak chase channel.
IWE-3122.3, Acceptance by Engineering Evaluation, allows for continued service of the component without repair/replacement activity for areas of degradation not meeting the acceptance standards of IWE-3500 provided that the engineering evaluation concludes that the flaw or area of degradation is nonstructural in nature or has no unacceptable effects on structural integrity of the containment.
Containment/Liner Design The containment is a seismic Category I reinforced concrete structure. It consists of an upright cylinder topped with a hemispherical dome, supported on a reinforced concrete foundation mat which is keyed into the bedrock by the depression for the reactor pit and by continuous bearing around the periphery of the foundation mat. The inside diameter of the cylinder is 140 feet and the inside height from the top of the base mat to the apex of the dome is approximately 219 feet; the net free volume is approximately 2,704,000 cubic feet.
Enclosure to SBK-L-20103 Page 3 of 8 A welded steel liner plate, anchored to the inside face of the containment, serves as a leak-tight membrane. The liner on top of the foundation mat is protected by a four feet thick concrete fill mat which supports the containment internals and forms the floor of the containment.
The containment is designed to assure that the base mat, cylinder, and dome behave integrally to resist all loads. The mat liner plate is 1/4" thick with joints welded to leveling angles that serve as welding backing strips. The liner plate in the cylinder walls is 3/8" thick in all areas except at the penetrations and the junction of the base mat and cylinder. The liner plate is 3/4" thick at these locations. The liner is provided with an anchorage system to assure that it can withstand accident loadings while maintaining leak tightness. In addition, the anchorage system assures that the liner, which is used as a form during construction, can resist the hydrostatic concrete loads while maintaining liner tolerances within allowable values. The dome liner is 1/2" thick and flush with the outside face of the cylindrical liner.
The metallic liner of containment is credited as being a leak-tight membrane. UFSAR 3.8.1.1 states "A welded steel liner plate, anchored to the inside face of the containment, serves as a leak-tight membrane." While the containment liner is not credited for structural capacity in the overall design of containment, Calculation C-S-1-10096 (Ref 4) was developed to determine the minimum containment liner wall thickness that would be acceptable and still maintain the design basis of the liner, i.e. the primary pressure boundary/leakage barrier of the containment building as required by General Design Criterion 16 of 10CFR Part 50.
EVALUATION QUANTITATIVE EXAMINATION RESULTS As previously noted in reference 1, no UT was possible due to the inadequate surface condition of the liner covered by the LCTCs.
Specifically, the areas were covered in debris and corrosion products that inhibited the adequate coupling of the transducer. No other quantitative examinations were able to be performed.
Qualified visual examinations were unsuccessful as well.
QUALITATIVE EXAMINATION RESULTS The Detailed Visual Examination (VT-1) results for LCTC HL2-19, HL 1-22, HL2-19 & HL5-2 noted water flow out of the port. Moderate surface corrosion was noted on the outer cover and light corrosion noted on the inner plug with no observations of material wastage.
The containment minimum liner wall calculation (Ref 4) establishes a minimum wall thickness of 0.0625 inches for the nominal 0.25-inch-thick base mat liner. For a general wall loss of 0.1875 inch in the liner thickness, the base mat liner would still be capable of
Enclosure to SBK-L-20103 Page 4 of 8 maintaining a leak tight barrier for containment during all design basis conditions.
Reference 1 completed an assessment to address the effects of future corrosion for wetted areas over the life of the plant. Results of the assessment determined a bounding corrosion rate of 0.0025 inches/year based on chemical analysis of water in the leak chase.
A water sample could not be taken at LCTC HL2-19 due to the minimal amount of water in the chase. While samples could not be taken for LCTC HL2-19, samples were taken at locations HL 1-22, HL2-19 & HL5-2 in the same relative proximity as LCTC HL2-19 (i.e. in or adjacent to the southwest quadrant of Containment).
Results of the chemical analysis validate use of the 0.0025 inches'/year corrosion rate for those three location and can also be applied to LCTC HL2-19.
For a general wall loss in the liner plate of 0.1875 inches (0.25-0.0625=0.1875) and a general corrosion rate of 0.0025 inches per year, a 75-year life is supported (0.1875/0.0025=75).
CONCLUSION In summary, based on:
- Design requirements for wall thickness of the containment mat liner
- Visual inspections of LCTC HL2-19, HL1-22, HL2-19 &
HL5-2
- Chemical analysis of fluid from leak chase channels during OR20 The conditions identified in AR 2353146, 02351311, 02351991, 02351984 requiring evaluation are acceptable for continued service in accordance with IWE-3122.3, Acceptance by Engineering Evaluation. The inaccessible areas of the liner plate at LCTC HL2-19, HL1-22, HL2-19 & HL5-2 are capable of performing their specified design function as a leak-tight barrier. Although a qualified NOE method could not be performed on the liner plate in locations associated with the degraded moisture barrier, the body of information included in this evaluation supports the conclusion that the inaccessible portions of the liner plate have not experienced any appreciable loss of material that would compromise the liner plate's ability to perform its specified design function.
TB-07-2, NSAL CROM Thermal AR02352366 - CROM THERMAL SLEEVE WEAR EXCEEDS 18-1 and Sleeve WCAP-16911-P CRITERIA. Thermal sleeve wear was observed NSAL 201-1 that exceeds that WCAP-16911-P criteria at multiple penetrations.
The OR20 CROM thermal sleeve ultrasonic thickness examination was performed to measure wall loss associated with ID and OD wear. Reference Westinghouse Technical Bulletin TB-07-2.
Enclosure to SBK-L-20103 Page 5 of 8 CONCLUSION The current measurements taken per the Technical Bulletin, WCAP-16911-P, and the supplemental guidance in Westinghouse Letter LTR-RIDA-20-84, Ref.7, are acceptable. As expected, the limiting wear was determined to be ID wear at the thread relief area just above the thermal sleeve (TS) funnel. The most significant measured wear was in the Thermal Sleeve Group 4, at penetration 1 thru 9 in the center of the RV head. The allowable time extension before the next recommended inspection, listed in Table One for the limiting ID wear, is estimated to be -16.881 EFPY based on the TS Group 4 (center of the RV head).
TS Groups 3/3A, 2 and 1 all have an allowable time extension greater than 60 EFPY. The OD thermal sleeve wear and allowable time extension before the next recommended inspection is greater than 50 EFPY.
Considering the TS wear rate curves are based on limited data, it is recommended that Seabrook perform a re-inspection of the thermal sleeve wall thickness during the next RV upper head volumetric inspection (ASME Code Case N-729-X) in OR25. This may be revised should additional industry data is obtained to support a longer or different re-inspection. Additionally, this may not be needed should repairs or mitigations occur prior to the next RV upper head volumetric examination.
AR-02353824 was generated to track the follow up actions needed to address the conditions evaluated here.
E-A E1 .11, Liner and AR 02352867 - Intermittent Separation of Moisture Barrier and E-C E4.11 Moisture Barrier Light corrosion on Liner E-A E1.30 During the OR20 ASME Section XI, Sub-Section IWE in-service Inspection examination of Class MC pressure retaining components, visual examinations for the containment liner and moisture barrier at El -26 conditions were observed. Acceptance of the conditions can be determined by corrective measures per IWE-3122.2 or acceptance by Engineering Evaluation per IWE-3122.3.
EVALUATION The conditions as documented in AR 02352867 reexamined the condition of the three (3) areas that exhibited corrosion previously captured in AR 02088130. The examination identified additional areas of coating failure (blistering, flaking, chipped) experiencing light surface corrosion on exposed metal, however these areas showed no apparent pitting or material wastage. The current moisture barrier profile allows water to accumulate at the interface of the liner and moisture barrier where the majority of the coating failure and surface corrosion is presenting itself. The pressure boundary/leak-tight function of the liner is not impacted based on the lack of any material wall loss in the liner thickness.
There were also intermittent areas of separation of the moisture barrier between the liner and concrete floor at El -26. In the areas
Enclosure to SBK-L-20103 Page 6 of 8 of moisture barrier degradation there was no evidence of material wall loss in the liner. Therefore, the pressure boundary/leak-tight function of the liner is not impacted. This condition is acceptable for OR20. WO 40629371, originally scheduled for OR20 but deferred as part of the pandemic response, has been recoded to OR21 to repair the degraded moisture barrier in the area behind the Letdown piping concrete shield plugs. AR 02353198/ WR 94208312 has been generated to address the coating deficiencies presently adjacent to and above the moisture barrier behind the concrete shield plugs in OR21. It was determined that the top potion of the moisture barrier has separated but the leak tight integrity of the barrier is still performing its function.
CONCLUSION The conditions identified in AR 02352867 do not impact the pressure boundary/leak-tight function of the liner. In accordance with IWE-3122.3 conditions identified in this AR are acceptable for continued service without a repair/replacement activity. The conditions noted have no unacceptable effect on the structural integrity or leak-tightness of the containment.
F-A AR02351996 4000-SV-9A Loose Jam Nut F1 .20 During an ASME Section XI inspection, a jam nut was found loose and not engaging the support 1-NHY-157-SG-1 turnbuckles. The support is a dead weight/seismic hanger providing vertical (Fy) support for 8" RH line 157-1. For this support type, typically, the turnbuckles are adjusted to level the hanger horizontal support member to ensure full contact/support under the pipe and the hex lock nut is then run down to lock the turnbuckle in position. The inspection report does not indicate any issues with the support configuration except the noted lock nut gaps. Review of the ISi photos attached to the AR show the support coating fully intact, with no cracking or indications of turnbuckle or other piece part movement. All other nuts visible in the photo appear to be tight Therefore, the support continues to provide the intended design function. A minor maintenance work order should be written to fully tighten the jam nuts CONCLUSION Support continues to provide the intended design function. A minor maintenance work order was written to fully tighten the jam nuts.
F-A AR02351559 4001-SV-9A Setting Out of Tolerance F1 .20 During an ASME Section XI examination, dual spring support 1-4001-SV-9A was found out of tolerance.
CONCLUSION Reset spring hangers to the settings in the applicable pipe support drawing.
F-A AR02351561 4002-SV-9A Setting Out of Tolerance
Enclosure to SBK-L-20103 Page 7 of 8 F1 .20 During an ASME Section XI examination, dual spring support 1-4002-SV-9A was found out of tolerance.
CONCLUSION Reset spring hangers to the settings in the applicable pipe support drawing.
8-P AR02354399 - Observed Minor Boric Acid Leak At Packing 815.10 Gland of RC-V-448 During Mode 3 VT-2 inspections of the seal table in Containment, a minor boric acid leak was observed at the packing gland of 1-RC-V-448. The boric acid buildup was observed approximately 60% of the circumference of the packing gland. No corrosion was present and the boric acid was white and dry, non-active.
CONCLUSION White dry inactive boric acid was evaluated and cleaned up.
8-P AR02352690 - Observed Large Boric Acid Leak At Packing 815.10 Gland of RC-V-147 During examination of the leak of line in Containment, during performance of reactor vessel head Leak-off line ISi, a large, dry boric acid leak was discovered at the packing Gland of RC-V-147. Residue is partly discolored and there is evidence of corrosion of the yoke arms.
CONCLUSION Valve was repacked per W040714951 8-P AR02354406 - Observed Minor Boric Acid Leak At Packing 815.10 Gland of RC-V-133 Inactive dry boric acid was found on RC-V-133 during the NOP/NOT walkdown in mode 3. Valve is to be cleaned upon mode 3 re-entry after 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> hold.
CONCLUSION White dry inactive boric acid was evaluated and cleaned up.
Enclosure to SBK-L-20103 Page 8 of 8 TABLE 2 ABSTRACT OF REPAIR/REPLACEMENT ACTIVITIES REQUIRED FOR CONTINUED SERVICE Code Item Description Date Repair/Replacement Class Description Of Work Completed Plan Number Temp Repair Modification per ND SW-1801-04-153-24" 05/15/2019 40662032 EC293162 and Relief Request RA-19-001 Implement Design ND SW-1801-04-153-24" Change For SW-1801- 0412412020 40709346 004 Per EC294429 Base Metal Repair for ND SW-1802-4-153-24" Service Water SW-1802 04/13/2020 40650753 per EC294665