05000250/LER-2023-001, RCS Pressure Boundary Degraded
| ML23165A158 | |
| Person / Time | |
|---|---|
| Site: | Turkey Point  |
| Issue date: | 06/14/2023 |
| From: | Strand D Florida Power & Light Co |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| L-2023-083 LER 2023-001 | |
| Download: ML23165A158 (1) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(iv)(A), System Actuation 10 CFR 50.73(a)(2)(x) 10 CFR 50.73(a)(2)(v)(A), Loss of Safety Function - Shutdown the Reactor 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(viii)(B) 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(ix)(A) 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 2502023001R00 - NRC Website | |
text
U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555 Re:
Turkey Point Unit 3 Docket No. 50-250 Reportable Event: 2023-001-00 Date of Event: April 15, 2023 RCS Pressure Boundary Degraded June 14, 2023 L-2023-083 10 CFR 50.73 The attached Licensee Event Report 2023-001 is being submitted pursuant to the requirements of 10 CFR 50.73 to provide notification of the subject event.
Respectfully, General Manager, Regulatory Affairs Florida Power & Light Company Attachment cc:
Turkey Point NRC Senior Resident Inspector Turkey Point Station NRC Program Manager Florida Power & Light Company 9760 SW 344th Street, Homestead, FL 33035
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY 0MB: NO. 3150-0104 EXPIRES: 08/31/2023 (08-2020)
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3.Page Turkey Point Unit 3 05000250 1 of 2
- 4. Title RCS Pressure Boundary Degraded
- 5. Event Date 6, LER Number 7, Report Date
- 8. Other Facilities Involved Year I Sequential I Revision Facility Name Docket Numbe1 Month Day Year Number Number Month Day Year n/a 05000 Facility Name Docket Numbe1 04 15 2023 2023 -
001 -
00 06 14 2023 n/a 05000
- 9. Operating Mode 110. Power Level 6
N/A
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all tf!at apply) 10 CFR Part 20 20.2203(a)(2)(vi) 50.36(c)(2) 50.73(a)(2)(iv)(A) 50.73(a)(2)(x) 20.2201(b) 20.2203(a)(3)(i) 50.46(a)(3)(ii) 50.73(a)(2)(v)(A) 10 CFR Part 73 20.2201(d) 20.2203(a)(3)(ii) 50.69(g)
- 50. 73(a)(2)(v)(B) 73.71 (a)(4)
D 20.2203(a)(1) 20.2203(a)(4)
- 50. 73(a)(2)(i)(A)
D 50.73(a)(2)(v)(C)
D 73.71(a)(5) 20.2203(a)(2)(i) 10 CFR Part 21 IX! 50. 73(a)(2)(i)(B) 50.73(a)(2)(v)(D)
D 73.77(a)(1) 20.2203(a)(2)(ii)
D 21.2(c) 50.73(a)(2)(i)(C)
- 50. 73(a)(2)(vii) 73.77(a)(2)(i) 20.2203(a)(2)(iii) 10 CFR Part 50 IX! 50. 73(a)(2)(ii)(A)
- 50. 73(a)(2)(viii)(A) 73.77(a)(2)(ii) 20.2203(a)(2)(iv) 50.36(c)(1 )(i)(A)
- 50. 73(a)(2)(ii)(B) 50.73(a)(2)(viii)(B) 20.2203(a)(2)(v) 50.36(c)(1 )(ii)(A) 50.73(a)(2)(iii) 50.73(a)(2)(ix)(A)
OTHER (Specify here, in abstract or in NRC 366A)
- 12. Licensee Contact for this LER licensee Contact I
Telephone Number (Include area code)
Bob Murrell, Licensing Engineer 319-651-9496 Cause System Component Manufacturer Reportable
Cause
System Component Manufacturer Reportable To IRIS To IRIS X
AB 27 y
11
- 14. Supplemental Report Expected
- 15. Expected Month Day Year DYES (If yes, complete 15. Expected Submission Date)
IX] NO Submission Date Abstract (Limit to 1560 spaces, i.e., approximately 15 single-spaced typewritten lines)
On April 15, 2023, while in Mode 6, it was determined that the Reactor Coolant System (RCS)
Pressure Boundary did not meet ASME Section XI, Table IWB-341 0-1, Acceptable Standards, after a rejectable indication was identified during non-destructive testing on the Flux Mapper Seal Table Guide Tube H-6. The cause of the through-wall leak was intergranular stress-corrosion cracking (IGSCC) and was corrected by repairing the flux mapper guide tube prior to startup from the planned refueling outage. The safety significance of this event was low. No safety system actuation was required. The through-wall leakage was non-quantifiable and well within RCS makeup capability. No safety margins were challenged or reduced. This event is being reported pursuant of 10 CFR
- 50. 73(a)(2)(ii)(A), Degraded Condition, and 1 O CFR 50. 73(a)(2)(i)(B), Condition Prohibited by Technical Specifications.
Description
- 2. Docket 05000250 Year 2023
- 6. LER Number I
Sequential Number 001 I
Rev No.
00 On April 15, 2023, while in Mode 6, it was determined that the Reactor Coolant System (RCS)
Pressure Boundary did not meet ASME Section XI, Table IWB-341 0-1, Acceptable Standards, after a rejectable indication was identified during non-destructive testing on the Flux Mapper Seal Table Guide Tube H-6.
Cause of the Event
The most likely cause of the through-wall crack is intergranular stress-corrosion cracking (IGSCC).
For IGSCC to occur, the following factors must be present: susceptible material, environment, and stress. The pressure stresses due to RCS pressure and the stress intensification of the geometry (i.e.
the shoulder) contributed to the crack propagation. Additionally, the observed cracks and deterioration occurred in a sensitized region of the tube material, making it more susceptible to IGSCC.
Analysis of the Event
This license event report is being reported pursuant of 10 CFR 50. 73(a)(2)(ii)(A), Degraded Condition, and 10 CFR 50.73(a)(2)(i)(B), Condition Prohibited by Technical Specifications, since the indication was most likely present prior to the planned refueling outage.
This event did not result in a Safety System Functional Failure.
Safety Significance
This safety significance of this event was low. No safety system actuation was required. The through-wall leakage was non-quantifiable and well within RCS makeup capability. No safety margins were challenged or reduced. Post-event evaluation determined that the condition did not affect the structural ability of the guide tubes.
Corrective Actions
The affected guide tube was corrected by removing guide tube stub from below the seal table. An engineered patch plate was added to the seal table as well as an extra coupling on the guide tube.
These actions were completed prior to startup.
Similar Events
A review of reportable events dating back 10 years, did not identify any previous events or conditions that involved the same underlying cause as this event. Page 2 of 2