ML17165A409
| ML17165A409 | |
| Person / Time | |
|---|---|
| Site: | Three Mile Island  |
| Issue date: | 06/14/2017 |
| From: | David Helker Exelon Generation Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| TMl-17-059 | |
| Download: ML17165A409 (19) | |
Text
Exelon Generation 10 CFR 54 TMl-17-059 June 14, 2017 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555 Three Mile Island Nuclear Station, Unit 1 (TMI)
Renewed Facility Operating License No. DPR-50 NRC Docket No. 50-289
Subject:
T1 R22 Refuel Outage MRP-227-A Reactor Internals Scope Deferral Review
References:
(1) TMl-12-069, "Submittal of Inspection Plan for Reactor Internals,"
dated April 16, 2012 (2) Letter, Meena K. Khanna, Chief, Plant Licensing Branch 1-2 to Michael J. Pacilio, President and Chief Nuclear Officer, Exelon Nuclear, "Three Mile Island Nuclear Station, Unit 1 - Staff Assessment of the Reactor Vessel Internals Inspection Plan (TAC NO. MF1459)," dated December 19, 2014 In Reference 1 TMI provided the Inspection Plan for TMI Reactor Vessel Internals in accordance with License Renewal Activity No. 36 of Appendix A of NUREG-1928, "Safety Evaluation Report Related to the License Renewal of Three Mile Island Nuclear Station, Unit 1," dated October 2009, and MRP-227-A, "Materials Reliability Program: Pressurized Water Reactor Internals Inspection and Evaluation Guidelines (MRP-227-A)," dated December 2011.
In Reference 2 the U.S. Nuclear Regulatory Commission (NRC) reviewed the TMI Inspection Plan for Reactor Vessel Internals (RVI) and concluded that the licensee's RVI Inspection Plan was acceptable because it was consistent with the inspection and evaluation guidelines of MRP-227-A, the licensee had addressed six of the eight licensee action items specified in MRP-227-A appropriately, and had made regulatory commitments to submit analyses fulfilling the other two action items on an acceptable schedule.
TMI has elected to delay implementation of the final scope of RVI MRP-227-A examinations from the T1 R22 (2017) refueling outage to the T1 R23 (2019) refueling outage. Per the requirements of MRP-227-A, these "needed" examinations are to be
U.S. Nuclear Regulatory Commission T1 R22 Refueling Outage MRP-227-A Reactor Internals Scope Deferral June 14, 2017 Page 2 completed no later than two refueling outages from the beginning of the license renewal period or during the next 10-year ISi interval. T1 R22 (2017) is the second refueling outage after entry into the period of extended operation (April 2014).
The examinations are being rescheduled due to the economic uncertainty surrounding the continued operation of TMI. On May 30, 2017, Exelon announced that it will prematurely retire TMI on or around September 30, 2019, absent needed policy reforms.
In light of this decision and based on the industry experience from performing the required examinations, Exelon has evaluated the remaining MRP-227-A examinations scheduled for the T1 R22 refueling outage and determined that it is technically justifiable to defer the examinations to the following T1 R23 refueling outage. provides a revised commitment. The remaining commitments in Reference 1 remain unchanged. Attachment 2 provides the Exelon Materials Degradation Management Process (MDMP) Deviation Form. Attachment 3 provides the Technical Evaluation 04020993-02, TMI MRP-227-A Inspection Deviation-T1 R22.
Should you have any questions concerning this submittal, please contact Frank Mascitelli at 610-765-5512.
Respectfully, David P. Helker Manager, Licensing & Regulatory Affairs Exelon Generation Company, LLC Attachments: 1) Summary of Regulatory Commitments
- 2) Exelon Materials Degradation Management Process (MDMP)
Deviation Form
cc: USNRC Regional Administrator, Region I USNRC Project Manager, TMl-1 USNRC Senior Resident Inspector TMl-1 Director, Bureau of Radiation Protection - PA Department of Environmental Resources Chairman, Board of County Commissioners of Dauphin County, PA Chairman, Board of Supervisors of Londonderry Township, PA R. R. Janati, Commonwealth of Pennsylvania
ATTACHMENT 1
SUMMARY
OF REGULATORY COMMITMENTS The following table identifies commitments made in this document. (Any other actions discussed in the submittal represent intended or planned actions. They are described to the NRC for the NRC's information and are not regulatory commitments.)
COMMITMENT TYPE COMMITTED DATE One-Time COMMITMENT Programmatic OR "OUTAGE" Action
{Yes/No)
(Yes/No)
Yes No TMI will complete the deferred MRP- T1 R23 (2019) refueling 227-A inspections (described in outage. of TMl-17-059 letter to NRC) during the T1 R23 (2019) refueling outage.
ATTACHMENT 2 EXELON MATERIALS DEGRADATION MANAGEMENT PROCESS (MDMP) DEVIATION FORM
ERAA4003 Attachment 2 MDMP Deviation Form Utility: Exelon Applicable Site(s) and Unit No.: Three Mile Island Unit 1 Utility Contact(s): Ross Shacklett / Mark Torborg, TMI Engineering Programs, Heather Malikowski, Corporate Asset Management Issue Program (IP) activity or document: Materials Reliability Program: Pressurized Water Reactor Internals Inspection and Evaluation Guidelines (MRP227A)
Scope / Description of Deviation:
TMI has elected to delay implementation of the final scope of Reactor Vessel Internals MRP227A examinations for one refueling outage (from T1R222017 to T1R232019). Per the requirements of MRP 227A, the needed examinations shall be completed no later than two refueling outages from the beginning of the license renewal period or during the next 10year ISI interval. T1R22 (2017) is the second refueling outage after entry into the period of extended operation (April 2014). Through correspondence with the NRC, approved on December 19, 2014 (ML14297A411), Exelon stated that examination of RVI components that are accessible only while the Core Support Assembly (CSA) is removed will be performed during the 2015 refueling outage (RFO), and that other RVI components will be examined during the 2017 RFO.
During refueling outage T1R21, (October 2015) Exelon successfully executed a partial implementation of the MRP227A examinations.
Completed MRP227A Inspections - T1R21 Component Exam Type Upper Core Barrel Bolts and Locking Devices UT Lower Core Barrel Bolts and Locking Devices UT Flow Distributor Bolts and Locking Devices UT Lower Grid Assembly Alloy X750 Doweltoguide Block Welds VT3 Lower Grid Shock Pad Bolting and Locking Devices (proactive augmented exam) UT & VT3 The remaining examinations, originally scheduled for T1R22, being delayed until T1R23 are listed below.
Remaining MRP227A Inspections Component Exam Type Plenum Wear Pads (Weldment Rib Pads) VT3 Plenum Cover Support Flange VT3 Control Rod Guide Tube (CRGT) spacer castings VT3 CSS vent valve top & bottom retaining rings VT3 Baffletoformer bolts UT Locking Devices, including Locking Welds, of BaffletoFormer Bolt and Internal VT3 BaffletoBaffle Bolts Baffle plates VT3 IMI guide tube spiders VT3 IMI guide tube spidertolower grid rib section welds VT3 Page 1 of 2
ERAA4003 Attachment 2 MDMP Deviation Form Reason for Deviation:
The examinations are being rescheduled due to the economic uncertainty surrounding the continued operation of Three Mile Island Unit 1. On May 30, 2017, Exelon announced that they will prematurely retire Three Mile Island Generating Station on or around September 30, 2019, absent needed policy reforms. In light of this decision and based on the industry experience from performing the required examinations, Exelon has determined it is not prudent to perform the remaining MRP227A examinations during T1R22 and is technically justifiable to defer the examinations to the following refueling outage, T1R23. Reference the EC listed below for additional technical evaluation.
IR Number: 04020993 EC Number: 0402099302 Time Frame the Deviation will be in Effect: This deviation will be in effect until refueling outage T1R23 (2019) or TMI1 retirement in 2019.
Deviation from this IP document is classified as: NEEDED The only NEI 0308 recommendation in MRP227A that would not be met is "Needed" item 7.3, Reactor Internals Guidelines Implementation Requirement. Each commercial U.S. PWR unit shall implement Tables 41 through 49 and Tables 51 through 53 for the applicable design within twentyfour months following issuance of MRP227A.
Prepared By: Ross Shacklett Date:
Station Program Manager: Mark Torborg Date:
Site Engineering Director: Blair Wunderly Date:
Corporate MDMP Owner: Harry L. Smith Date:
Corporate Asset Management Manager: James Cirilli Date:
Corporate Programs Director: Thomas Basso Date:
Site Vice President: Edward Callan Date:
Senior VP of Engineering &
Technical Services: Scot Greenlee Date:
Page 2 of 2
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ATTACHMENT 3 TECHNICAL EVALUATION 04020993*02 TMI MRP-227-A INSPECTION DEVIATION-T1R22.
TMI MRP227A Inspection Deviation - T1R22 Technical Evaluation 0402099302
- 1. Reason For Evaluation/Scope:
TMI has elected to delay implementation of the final scope of MRP227A examinations for one refueling outage, from T1R22 in 2017 to T1R23 in 2019. The examinations are being rescheduled due to the economic uncertainty surrounding the continued operation of Three Mile Island Unit 1. On May 30, 2017, Exelon announced that they will prematurely retire Three Mile Island Generating Station on or around September 30, 2019, absent needed policy reforms.
Per the requirements of MRP227A, the needed examinations shall be completed no later than two refueling outages from the beginning of the license renewal period or during the next 10year ISI interval. T1R22 (2017) is the second refueling outage after entry into the period of extended operation (April 2014). Through correspondence with the NRC, approved on December 19, 2014 (ML14297A411),
Exelon stated that examination of RVI components that are accessible only while the Core Support Assembly (CSA) is removed will be performed during the 2015 refueling outage (RFO), and that other RVI components will be examined during the 2017 RFO.
During refueling outage T1R21 (October 2015), Exelon executed a partial implementation of the MRP 227A examinations (components only accessible while the Core Support Assembly (CSA) is removed).
The remaining examinations, originally scheduled for T1R22 and being delayed until T1R23 are listed below. All other MRP227A required exams were completed in T1R21 (2015):
Remaining MRP227A Inspections Component Exam Type Plenum Wear Pads (Weldment Rib Pads) VT3 Plenum Cover Support Flange VT3 Control Rod Guide Tube (CRGT) spacer castings VT3 CSS vent valve top & bottom retaining rings VT3 Baffletoformer bolts UT Locking Devices, including Locking Welds, of BaffletoFormer Bolt and Internal VT3 BaffletoBaffle Bolts Baffle plates VT3 IMI guide tube spiders VT3 IMI guide tube spidertolower grid rib section welds VT3 This evaluation will determine the acceptability of delaying the remaining MRP227A needed examinations by one refueling outage (from T1R22 in 2017 to T1R23 in 2019).
- 2. Detailed Evaluation:
The following component examinations are needed to fulfill the MRP227A reactor internals primary examination requirements. All other MRP227A required exams were completed in T1R21 (2015).
Operating Experience from Oconee 1, 2, 3 and Arkansas Nuclear One 1 MRP227A examinations was reviewed for relevant findings. Oconee 1, 2, 3 and Arkansas Nuclear One 1 share a similar B&W Reactor Page 1 of 11
TMI MRP227A Inspection Deviation - T1R22 Technical Evaluation 0402099302 Vessel Internal design and account for four of the six operating B&W sites. Three Mile Island and Davis Besse have not completed the MRP227A examination and account for the remaining two B&W sites.
For age comparison, TMI1 will be at approximately 32.2 EFPY during T1R22 and 34.00 EFPY during T1R23. Oconee 1 was at 30.61 EFPY, Oconee 2 was at 31.82 EFPY, Oconee 3 was at 31.67 EFPY, and ANO1 was at 32.403 EFPY when MRP227A inspections were performed. While the estimated EFPY for TMI1 performing MRP227A exams in T1R23 is greater than the other B&W units by approximately 1.5 3.5 EFPY, all of the examination findings at these sites allowed for a 10year reinspection interval.
Therefore there is low risk that waiting another fuel cycle to complete the MRP227A examinations would allow significant aging degradation to develop that would be considered unacceptable for continued service. No TMI1 specific historical operating practices or design differences were identified that would cause concern for having worse findings than the other B&W units.
2.1 Plenum Wear Pads (Weldment Rib Pads) 2.1.1 NEI 0308 Inspection Requirements The NEI 0308 inspection requirements for the Plenum Wear Pads (Weldment Rib Pads) are comprised of 1) a onetime physical measurement to determine the differential height of the top of plenum rib pads to reactor vessel seating surface, with the plenum in the reactor vessel and 2) subsequent visual (VT3) examination on the 10year ISI interval.
This inspection is intended to identify loss of material and associated loss of core clamping preload (wear).
2.1.2 Industry OPEX MRP227A inspection reports from Oconee 1, 2, 3 and Arkansas Nuclear One 1 were reviewed for significant discoveries. No service related degradation or relevant indications were noted during the MRP227A inspections of the Plenum Wear Pads (Weldment Rib Pads) at any of the similar units.
2.1.3 TMI Inspection Results Core clamping measurements were obtained at TMI1 by AREVA in 2010 to satisfy the MRP227A examination requirements for a onetime physical measurement of the differential height of top of the plenum rib pads to the reactor vessel seating surface. This measurement was taken with the plenum cover weldment rib pads, plenum cover support flange, and CSS top flange inside the RV, but with the fuel assemblies removed per Section 4.3.1 of MRP227A. The conclusions of the core clamping summary document are that there was no evidence of wear occurring during the service period and the measurements were acceptable. Therefore, the core clamping measurements at TMI1 meet the one time physical measurement requirement in MRP227A. (Reference 4.3 & 4.4) 2.1.4 Conclusion Page 2 of 11
TMI MRP227A Inspection Deviation - T1R22 Technical Evaluation 0402099302 Delaying the visual inspection (VT3) of the Plenum Wear Pads (Weldment Rib Pads) by one cycle is acceptable. Inspections at similar B&W units have not revealed any concerns with material condition.
Previous TMI inspections did not identify evidence of wear occurring. Therefore, there are no technical concerns with delaying the visual inspection.
2.2 Plenum Cover Support Flange 2.2.1 NEI 0308 Inspection Requirements The NEI 0308 inspection requirement for the Plenum Cover Support Flange is a visual (VT3) examination on the 10year ISI interval.
This inspection is intended to identify loss of material and associated loss of core clamping preload (wear).
2.2.2 Industry OPEX MRP227A inspection reports from Oconee 1, 2, 3 and Arkansas Nuclear One 1 were reviewed for significant discoveries. No service related degradation or relevant indications were noted during the MRP227A inspections of the Plenum Cover Support Flange at any of the similar units.
2.2.3 TMI Inspection Results Visual inspections of the Plenum Cover Support Flange that meet the scope of MRP227A have not been performed previously. However, during T1R22 (2015), ASME Section XI visual (VT3) inspections of the Plenum Cover Support Flange were performed. The exam covered 360° of the accessible surfaces of the Plenum Cover Support Flange for wear (Section XI). There were limitations due to the cavity wall configuration. The bottom and the inboard flange surfaces were examined in conjunction with the Clamping Surfaces and the Plenum Cover and Rib attachments examinations. No service related degradation or relevant indications were noted during this inspection. (Reference 4.5) 2.2.4 Conclusion Delaying the visual inspection (VT3) of the Plenum Cover Support Flange by one cycle is acceptable.
Inspections at similar B&W units have not revealed any concerns with material condition. Previous TMI inspections did not identify any degradation.
2.3 Control Rod Guide Tube (CRGT) Spacer Castings 2.3.1 NEI 0308 Inspection Requirements The NEI 0308 inspection requirement for the CRGT Spacer Castings is a visual (VT3) examination of accessible surfaces at each of the four screw locations (at every 90°) of 100% of the CRGT Spacer Castings on the 10year ISI interval.
Page 3 of 11
TMI MRP227A Inspection Deviation - T1R22 Technical Evaluation 0402099302 This inspection is intended to identify cracking (thermal embrittlement), including the detection of fractured spacers or missing screws.
2.3.2 Industry OPEX MRP227A inspection reports from Oconee 1, 2, 3 and Arkansas Nuclear One 1 were reviewed for significant discoveries. No service related degradation, missing screws, or relevant indications were noted during the MRP227A inspections of the CRGT Spacer Castings at any of the similar units.
2.3.3 TMI Inspection Results Visual inspections of the CRGT Spacer Castings that meet the scope of MRP227A have not been performed previously. However, during T1R22 (2015), ASME Section XI visual (VT3) inspections of the accessible areas of 69 Control Rod Guide Tube Assemblies were performed. The inspection examined the accessible areas of the control rod guides tubes from the top looking down, around the periphery and through the holes in the cylinder. The inspection identified a small flake of foreign material that was likely introduced during refueling activities and was easily retrieved. (Reference 4.16) No other indications were noted. (Reference 4.5)
AREVA has noted that issues with Control Rod insertion times are a potential indicator of issues with the CRGT Spacer Castings. Recent Control Rod insertion timing during T1R21 did not indicate any issues.
Therefore, it is less likely an issue with the CRGT Spacer Castings exists.
2.3.4 Conclusion Delaying the visual inspection (VT3) of the CRGT Spacer Castings by one cycle is acceptable. Inspections at similar B&W units have not revealed any concerns with material condition. Previous TMI inspections did not identify any degradation.
2.4 Core Support Shield (CSS) Vent Valve Top & Bottom Retaining Rings 2.4.1 NEI 0308 Inspection Requirements The NEI 0308 inspection requirement for the CSS Vent Valve Top & Bottom Retaining Rings is a visual (VT3) examination of 100% of accessible surfaces during the 10year ISI interval.
This inspection is intended to identify cracking (thermal embrittlement), including the detection of surface irregularities, such as damaged, fractured materials, or missing items.
2.4.2 Industry OPEX MRP227A inspection reports from Oconee 1, 2, 3 and Arkansas Nuclear One 1 were reviewed for significant discoveries. No significant material degradation or missing items were discovered during the MRP227A inspections of the CSS Vent Valve Top & Bottom Retaining Rings at any of the similar units.
Page 4 of 11
TMI MRP227A Inspection Deviation - T1R22 Technical Evaluation 0402099302 ANO1 identified some relevant indications on the original and modified locking devices. However, these indications were determined to be acceptable for continued service and not interfere with the vent valve function.
2.4.3 TMI Inspection Results Vent valve testing and inspections are required to be performed each refueling outage, per Tech Spec 4.16. This requirement is fulfilled by the TMl1 Reactor Internals Vent Valve Inspection and Exercise procedure. The accessible areas of the vent valve are typically inspected, including the locking devices.
Additionally, vent valve operation is tested through manual actuation.
Recent inspections in 2015 did not identify any issues with vent valve retaining rings. However, vent valve RCV144A was replaced due to external impact damage to the pressure plate and locking device.
Vent valve locking devices were examined for all vent valves Tech Spec requirements and TMI specific commitment to MRP227A and PWROG interim guidance. RCV144A (adjacent to the hot leg) was found with a failed locking device in which the spring retainer had worn through the locking cup. The locking cup and spring retainer were functional asfound, but an assessment of operability over the next cycle could not be made. The damage mechanism was flow induced wear and was believed to originate in 1R18 after external impact from the Plenum. This vent valve was of the original design. (Reference 4.6)
Remaining vent valves exhibited impact damage on the locking devices from the installation of the Plenum. This impact damage did not affect the ability of the locking devices to perform their design functions 2.4.4 Conclusion Delaying the visual inspection (VT3) of the CSS Vent Valve Top & Bottom Retaining Rings by one cycle is acceptable. Inspections at similar B&W units have not revealed any concerns with material condition of the vent valve retaining rings. Previous TMI inspections did not identify evidence of service related cracking or missing items. Functional testing will continue to be performed in T1R22. Therefore, there are no technical concerns with delaying the visual inspection.
2.5 BaffletoFormer Bolts 2.5.1 NEI 0308 Inspection Requirements The NEI 0308 inspection requirement for the BaffletoFormer Bolts is a baseline volumetric examination (UT) of 100% of accessible bolts no later than two refueling outages from the beginning of the license renewal period.
This inspection is intended to identify cracking (Irradiation Assisted Stress Corrosion Cracking, Irradiation Embrittlement, and Overload).
Page 5 of 11
TMI MRP227A Inspection Deviation - T1R22 Technical Evaluation 0402099302 2.5.2 Industry OPEX BaffletoFormer Bolt UT examinations have been of concern with the recent inspection results from several Westinghouse 4loop downflow units. AREVA issued a Customer Service Bulletin (CSB) 1602 in response to Westinghouse NSAL 161. CSB 1602 concluded that the OE is limited, at this time, to a subset of design and operating conditions for the Westinghouse 4loop downflow operating units and not an immediate risk to the safety and operability of the B&W designed 177FA units.
Oconee 1 shares a similar bolt design with TMI1. MRP227A inspection reports were reviewed for significant discoveries. No service related degradation, relevant indications, or missing, nonfunctional, or removed locking devices or welds were discovered during the Oconee 1 MRP227A inspections.
Other B&W units (ANO1, Oconee 2 & 3) have a different bolt design but similar operating conditions.
These exam results provide further supporting inspection data that the issue is not a concern for B&W units.
Based upon the operating experience and conclusions from the AREVA CSB, there is low risk for delaying the exam at TMI.
2.5.3 TMI Inspection Results Visual inspections of the BaffletoFormer Bolts were performed in T1R21 (2015). These inspections did not identify any service related material degradation issues. Although the scope of these inspections did not cover the MRP227A scope of UT inspections, no visual material degradation issues were noted.
(Reference 4.5) 2.5.4 Conclusion Delaying the baseline volumetric examination (UT) of the BaffletoFormer Bolts by one cycle is acceptable. UT inspections at similar B&W units have not revealed any concerns with material condition.
Previous visual inspections at TMI did not identify any service related degradation issues. Therefore, there are no technical concerns with delaying the UT inspection one cycle.
2.6 Locking Devices, Including Locking Welds, of BaffletoFormer Bolt and Internal BaffletoBaffle Bolts 2.6.1 NEI 0308 Inspection Requirements The NEI 0308 inspection requirement for locking devices of baffletoformer bolt and internal baffleto baffle bolts is a visual (VT3) examination of 100 % of accessible baffletoformer and internal baffleto baffle bolt locking devices during the 10year ISI interval.
This inspection is intended to identify cracking (Irradiation Assisted Stress Corrosion Cracking, Irradiation Embrittlement, and Overload), including the detection of missing, nonfunctional, or removed locking devices or welds.
Page 6 of 11
TMI MRP227A Inspection Deviation - T1R22 Technical Evaluation 0402099302 2.6.2 Industry OPEX Oconee 1 shares a similar B&W Reactor Vessel Internal design with TMI1. MRP227A inspection reports were reviewed for significant discoveries. No service related degradation, relevant indications, or missing, nonfunctional, or removed locking devices or welds were discovered during the MRP227A inspections of the locking devices at any of the similar units.
2.6.3 TMI Inspection Results Visual inspections of the baffletoformer bolts were performed in T1R21 (2015). Although the scope of these inspections did not cover the full MRP227A scope, no service related degradation issues or missing locking devices were noted. (Reference 4.5) 2.6.4 Conclusion Delaying the visual inspection (VT3) of the locking devices of baffletoformer bolt and internal baffle tobaffle bolts by one cycle is acceptable. Inspections at similar B&W units have not revealed any concerns with material condition. Previous TMI visual inspections of the baffletoformer bolts did not identify evidence of service related degradation issues or missing locking devices. Therefore, there are no technical concerns with delaying the MRP227A visual inspection.
2.7 Baffle plates 2.7.1 NEI 0308 Inspection Requirements The NEI 0308 inspection requirement for the baffle plates is a visual (VT3) examination of 100% of the accessible surfaces within one inch around each flow and bolt hole during the 10year ISI interval.
This inspection is intended to identify cracking (irradiation embrittlement), including the detection of readily detectible cracking in the baffle plate.
2.7.2 Industry OPEX MRP227A inspection reports from Oconee 1, 2, 3 and Arkansas Nuclear One 1 were reviewed for significant discoveries. No service related degradation, cracking, or relevant indications were noted during the MRP227A inspections of the baffle plates at any of the similar units.
2.7.3 TMI Inspection Results General examinations of the baffle plates during normal refueling outages have not identified any material degradation. Visual inspections of the baffle plates that meet the scope of MRP227A have not been performed previously. During T1R21 (2015), visual (VT3) inspection of the accessible areas of the Core Barrel Assembly Former Plates was performed. There was limited access due to Upper CSA Flange and Baffle Plates. No relevant indications observed. (Reference 4.5)
Page 7 of 11
TMI MRP227A Inspection Deviation - T1R22 Technical Evaluation 0402099302 2.7.4 Conclusion Delaying the visual inspection (VT3) of the baffle plates by one cycle is acceptable. Inspections at similar B&W units have not revealed any concerns with material condition. Previous TMI inspections did not identify evidence of service related degradation. Therefore, there are no technical concerns with delaying the visual inspection.
2.8 Incore Monitoring Instrumentation (IMI) Guide Tube Spiders 2.8.1 NEI 0308 Inspection Requirements The NEI 0308 inspection requirement for the IMI Guide Tube Spiders is a visual (VT3) examination of 100% of top surfaces of the 52 spider castings no later than two refueling outages from the beginning of the license renewal period.
This inspection is intended to identify cracking (thermal embrittlement, irradiation embrittlement),
including the detection of fractured or missing spider arms.
2.8.2 Industry OPEX MRP227A inspection reports from Oconee 1, 2, 3 and Arkansas Nuclear One 1 were reviewed for significant discoveries. No service related degradation or fractured or missing spider arms were noted during the MRP227A inspections of the IMI Guide Tube Spiders at any of the similar units.
2.8.3 TMI Inspection Results Visual inspections of the IMI Guide Tube Spiders that meet the scope of MRP227A have not been performed previously.
2.8.4 Conclusion Delaying the visual inspection (VT3) of the IMI Guide Tube Spiders by one cycle is acceptable.
Inspections at similar B&W units have not revealed any concerns with material condition. Therefore, there are no technical concerns with delaying the visual inspection.
2.9 Incore Monitoring Instrumentation (IMI) Guide Tube SpidertoLower Grid Rib Section Welds 2.9.1 NEI 0308 Inspection Requirements The NEI 0308 inspection requirement for the IMI Guide Tube SpidertoLower Grid Rib Section Welds is a visual (VT3) examination of 100% of spider casting welds to the adjacent lower grid rib section no later than two refueling outages from the beginning of the license renewal period.
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TMI MRP227A Inspection Deviation - T1R22 Technical Evaluation 0402099302 This inspection is intended to identify cracking (irradiation embrittlement), including separation of spider arms from the lower grid rib section at the weld.
2.9.2 Industry OPEX MRP227A inspection reports from Oconee 1, 2, 3 and Arkansas Nuclear One 1 were reviewed for significant discoveries. No significant material degradation was noted during the Oconee 1 & 2 MRP 227A inspections.
Oconee 3 identified two linear indications, one located just below the vertical weld toe in the base material of the lower grid and the other coming from the top of the casting at the weld toe and going downward into the casting material. The linear indication in the lower grid material is in a relatively low stress area and does not resemble IGSCC.
ANO1 identified indications on the IMI tube spidertolower grid rib section welds which exceeded the criteria for triggering scope Expansion per MRP227A. However, in reviewing the results with ANO, ANO considered the determination as conservative, and no repairs or replacements were needed to address any of the inspection findings.
The expansion components for the IMI tube spidertolower grid rib section welds are the lower grid fuel assembly support pad items: pad, padtorib section welds, Alloy X750 dowel, cap screw, and their locking welds. ANO1 examined these items during the last refueling outage as part of the ASME Section XI BN3 VT3 visual examinations and no indications were found.
2.9.3 TMI Inspection Results Visual inspections of the IMI tube spidertolower grid rib section welds that meet the scope of MRP 227A have not been performed previously. TMI completed the ASME Section XI BN3 examinations in T1R21 (2015) and no relevant indications were found in this area. Therefore, there is no concern for the expansion item if the Primary component is not examined in T1R22. (Reference 4.5) 2.9.4 Conclusion Delaying the visual inspection (VT3) of the IMI tube spidertolower grid rib section welds by one cycle is acceptable. Inspections at similar B&W units have not revealed any significant concerns with material condition. Previous TMI inspections for ASME Section XI BN3 examinations did not identify any material condition issues with the expansion items for the primary component (i.e. the lower grid fuel assembly support pad items). Therefore, there are no technical concerns with delaying the visual inspection.
- 3. Conclusion/Findings:
Delaying the remaining MRP227A needed examinations by one refueling outage is acceptable. There have been no significant discoveries from similar B&W plants that have performed the MRP227A Page 9 of 11
TMI MRP227A Inspection Deviation - T1R22 Technical Evaluation 0402099302 inspections. Based on industry Operating Experience, previous TMI inspections, and the duration of the delay (one cycle), there are no technical concerns with delaying the MRP227A examinations.
- 4.
References:
4.1 ANP2952, Rev. 1; Inspection Plan for the Three Mile Island Unit 1 Reactor Vessel Internals 4.2 AREVA Customer Service Bulletin 1602; Relevance of Recent BaffletoFormer Bolt Degradation at Westinghousedesigned 4Loop Units and Its Impact on B&Wdesigned 177FA RV Internals Operability 4.3 AREVA Doc 519129887000, Three Mile Island RV Internals Clamping Task 4.4 AREVA Doc 519199311000; PWROG PAMSC0835 Technical Justification for the Core Clamping Area Visual Examination 4.5 AREVA Doc 1809249614000; IVVI 10Year ISI and MRP227 Final Report (T1R21) 4.6 C2034392; Contingent Replacement RV Internal Vent Valve (T1R21) 4.7 CCAA309101, Rev. 15; Engineering Technical Evaluations 4.8 ERAA4003, Rev. 4; Materials Degradation Management Process (MDMP) Deviation Guidance 4.9 MRP219, Rev. 11; Materials Reliability Program: Inspection Report, 2015 (Oconee 1, 2, 3) 4.10 MRP227A; Materials Reliability Program: Pressurized Water Reactor Internals Inspection and Evaluation Guidelines, 2011 4.11 NEI 0308, Rev. 3; Guideline for the Management of Material Issues, February 2017 4.12 NSAL161; Westinghouse Nuclear Safety Advisory Letter, BaffleFormer Bolts 4.13 Table for Reporting MRP227A Inspection Results for B&W Plants; Arkansas Nuclear One - Unit 1, 10/2/2016 to 11/16/2016 4.14 TMI1 Technical Specifications, Section 4.16 4.15 02585279; Reactor Vessel IVV Has Damage 4.16 02589021; T1R21 FME: Flake Found on Plenum 4.17 NRC Correspondence ML14297A411, Staff Assessment of the Reactor Vessel Internals Inspection Plan, December 19, 2014 Page 10 of 11
TMI MRP227A Inspection Deviation - T1R22 Technical Evaluation 0402099302
- 5. Approval:
Prepared By: Ross Shacklett (See Passport for Approval) Date:
Corporate PWR Internals Program Heather (See Passport for Approval)
Owner Review: Malikowski Date:
Independent Review: Robert Marcello (See Passport for Approval) Date:
Station Program Manager Approval: Mark Torborg (See Passport for Approval) Date:
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