ML15327A081

Fall 2015 Outage Call Regarding the Steam Generator Tube Inservice Inspections - Slides

ML15327A081
Person / Time
Site:	Three Mile Island
Issue date:	11/09/2015
From:	Exelon Generation Co
To:	Office of Nuclear Reactor Regulation
AHUYNH, NRR/DE/ESGB, 415-1137
References
TAC MF6779
Download: ML15327A081 (15)

Text

TMI T1R21 SG Tube In-service Inspection NRC Call Tim Heindl Steam Generator Program Engineer November 9,, 2015

Agenda Design Overview of TMI-1 Enhanced Once-Through Steam Generator (EOTSG)

T1R21 Steam Generator (SG) Inspection Overview SG Tube Inspection Discussion Points Q&A Acquisition Status:

A OTSG - Acquired 86.0%, Analyzed 82.9%

B OTSG - Acquired q 96.0%,, Analyzed y 95.8%

TMI-1 EOTSG Overview PRIMARY INLET Tube Information Number of Tubes: 15,597 Tube Material: Alloy 690TT Nominal OD: 0.625 inch Nominal Thickness: 0.037 inch Tube Length: 673.375 inch STEAM OUTLET UPPER SHROUD Support Information TSP Material: SA 240 type 410M SS TSP Thickness: 1.18 LOWER MAIN SHROUD TSPs Trefoil broached (15th TSP drilled on periphery) FEEDWATER HEADER Tubes hydraulically expanded full length of the TS Normal Operating Parameters NOP (Primary) = 2,155 psig The image cannot be display ed. Your computer may not hav e enough memory to open the image, or the image may hav e been corrupted. Restart y our computer, and then open the file again. If the red x still appears, y ou may hav e to delete the image and then insert it again.

NOPD = 1271 psid THot = 603oF OUTLET NOZZLES

T1R21 Steam Generator Inspections Inspection Scope:

100% full-length inspection (bobbin probe) 2-Tube Periphery for Loose Parts (combo array probe) TTS to 01S Diagnostic Di ti EExams anddTTube b Pl Plugging i as needed d d Other Actions Taken:

Revised plant heat-up procedures to equalize temperatures to mitigate wear Met with NRC Region I & Site Residents to achieve alignment on inspection scenarios/strategy

1. Primary-to-Secondary Leakage No observable primary-to-secondary leakage (PSL) during Cycle 20.

RM-A-5/15 monitor PSLR Continuously.

No observable trends.

2. Secondary Side Pressure Tests There were no secondary side pressure tests performed during T1R21.

A drip or bubble test was not required due to the absence of existing primary primary-to-secondary to secondary leakage leakage.

3. EPRI Guideline Exceptions TMI-1 has not taken any exceptions or deviations from the EPRI SGMP Guidelines.

4. Detailed Scope Evaluation

• 100% full length exam of both OTSGs with bobbin probe

• 2-tube periphery array combo probe exam from TTS to 01S

• All bobbin I codes, PLPs, new DNG /DNT >=

DNGs/DNTs > 1.0V 1 0V examined i d withith array probe

• Deepest 20 TTW indications in both OTSGs examined with array probe and sample of new and repeat indications for flaw characterization.

characterization

• TSP SI Thresholds:

• New 20% TW

• Repeat 25% TW

• Growth 12%TW

• No expansion criteria due to 100%

base scope exam.

5. Summary of Inspection Results Tube-to-Tube Wear TSP Wear A B A B Number of New 6 6 2023 2132 Number of Repeat 105 276 2502 3282 Total Indications 111 282 4525 5414 Avg.

g Growth Rate 0.19%/EFPY

/ 0.31%/EFPY

/ 0.54%/EFPY

/ 0.83%/EFPY

/

95th Percentile 1.06%/EFPY 1.06%/EFPY 3.17%/EFPY 4.23%/EFPY Largest New 10% 10% 33% 35%

Largest Repeat 20% 17% 24% 64%

Location of Largest Flaw 70-100 22-63 137-1 2-4

A OTSG TSP Wear Distribution B OTSG TSP Wear Distribution

6. Repair/Plugging Plans All tubes repaired will be mechanically roll plugged and stabilized in accordance with stabilization criteria.

All tubes with indications 40% through-wall (TW) will be plugged per Tech Specs.

A total of 25 tubes are currently 40% the Tech Spec Plugging Limit Limit.

The team has developed p a base p plugging gg g strategygy which provides a 99% POS in the W-axis.

7. In-situ Pressure Test / Tube Pulls There are currently zero indications that exceed the Condition Monitoring limit (e.g., no in situ pressure testing is required).

required)

8. Loose Parts Inspections performed to detect loose parts:

• Two (2) tube periphery with array probe - Approximately 902 tubes/SG Loose parts detected to date:

• NONE Loose parts removal plan/damage:

• N/A - No loose parts to date 9 Secondary Inspections/Maintenance 9.

No secondary inspections or maintenance planned for T1R21 steam generator inspections Perform sludge mapping with ECT

10. Unexpected or Unusual Results There are no unexpected or unusual results from the T1R21 eddy current inspections.

T1R20 Operational Assessment Prediction:

• Median deepest projected indication is 69% TW

• Upper 95th value, max projected depth is 77% TW

• Number of New Flaws Predicted: 3,000 in B OTSG Results of the T1R21 inspection are within the previous OA projections and bounded by T1R20 results.

11. Schedule A OTSG - Acquired 86.0%, Analyzed 82.9%

B OTSG - Acquired 96.0%, Analyzed 95.8%

Expected to complete eddy current inspections 11/10 @

02:00 Tube Plugging gg g ((as needed)) window is 11/10/15 - 11/13/15