05000339/LER-2019-001, Manual Reactor Trip on Degrading Condenser Vacuum Due to a Failed Weld
| ML19123A099 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 04/26/2019 |
| From: | Lane N Virginia Electric & Power Co (VEPCO) |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 19-180 LER 2019-001-00 | |
| Download: ML19123A099 (4) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(ix)(A) 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)(B), Loss of Safety Function - Remove Residual Heat 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability |
| 3392019001R00 - NRC Website | |
text
10CFR50.73 Virginia Electric and Power Company North Anna Power Station 1022 Haley Drive Mineral, Virginia 23117 April 26, 2019 Attention: Document Control Desk U. S. Nuclear Regulatory Commission Washington, DC 20555-0001
Dear Sir or Madam:
Serial No.:
19-180 NAPS:
CKW
- Docket Nos.. : 50-339 License Nos.: NPF-7 Pursuant to 10CFR50.73, Virginia Electric and Power Company hereby submits the following Licensee Event Report applicable to North Anna Power Station Unit 2.
- Report No. 50-339/2019-001-00 This report has been reviewed by the Facility Safety Review Committee and will be forwarded to the Management Safety Review Committee for its review.
Sincerely,
{\\~*~
N. Larry Lane Site Vice President North Anna Power Station Enclosure Commitments contained in this letter: None cc:
United States Nuclear Regulatory Commission Region II Marquis One Tower 245 Peachtree Center Ave., NE, Suite 1200 Atlanta, Georgia 30303-1257 NRC Senior Resident Inspector North Anna Power Statfon
NRC FORM366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY 0MB: NO. 3150-0104 EXPIRES: 03/31/2020 (04-2018)
, the NRG may not conduct or sponsor, and a person is not required to respond to, the information collection.
3.Page North Anna Power Station, Unit 2 05000 339 1
OF 3
- 4. Title Manual Reactor Trip on Degrading Condenser Vacuum due to a Failed Weld
- 5. Event Date
- 6. LER Number
- 7. Report Date
- 8. Other Facilities Involved Month Day Year I Sequential I Rev Month Facility Name *
- Docket Number Year Number No.
Day Year 05000 02 001 Facility Name Docket Number 03 2019 2019.
00 04 26 2019 05000
- 9. Operating Mode
- 11. This Report is Submitted Pursuant to the Requirements of 1 O CFR §: (Check.all that apply)
D 20.2201(b)
D 20.2203(a)(3)(i)
D 50.73(a)(2)(ii)(A)
D 50. 73(a)(2)(viii)(A)
D 20.2201(d)
D 20.2203(a)(3)(ii)
D 50.73(a)(2)(ii)(B)
D 50. 73(a)(2)(viii)(B) 1 D 20.2203(a)(1)
D 20.2203(a)(4)
D 50.73(a)(2)(iii)
D 50.73(a)(2)(ix)(A)
D 20.2203(a)(2)(i)
D 50.36(c)(1)(i)(A) 0 50.73(a)(2)(iv)(A)
D 50.73(a)(2)(x)
- 10. Power Level D 20.2203(a)(2)(ii)
D 50.36(c)(1)(ii)(A)
D 50.73(a)(2)(v)(A)
D 73.71 (a)(4)
D 20.2203(a)(2)(iii)
D 50.36(c)(2)
D 50.73(a)(2)(v)(B)
D 73.71 (a)(5)
D 20.2203(a)(2)(iv)
D 50.46(a)(3)(ii)
D 50.73(a)(2)(v)(C)
D 73.77(a)(1) 012 D 20.2203(a)(2)(v)
D 50.73(a)(2)(i)(A)
D 50.73(a)(2)(v)(D)
D 73. 77(a)(2)(i)
D 20.2203(a)(2)(vi)
D 50.73(a)(2)(i)(B).
D 50.73(a)(2)(vii)
D 73.77(a)(2)(ii)
D 50. 73(a)(2)(i)(C)
D Other (Specify iri Abstract below or in
3.0 CAUSE
The direct cause of the reactor trip was determined to be loss of condenser vacuum caused by a socket weld failure between one of the HP Turbine Main Steam Supply Header Drain Valves and the Main Condenser. The failure mechanism is high-cycle fatigue due to vibration induced stresses on the pipe.
4.0 IMMEDIATE CORRECTIVE ACTIONS
The drain line with the failed socket weld, the intact drain line removed for destructive analysis, and their associated valves were replaced using a 2 to 1 profile ratio on all the socket welds. The remaining six drain lines on Unit 2 were inspected for indications ofcracks or through-wall conditions. During startup, the drain lines were monitored for temperature and vibration analysis. No anamolieswere identified.
5.0 ADDITIONAL CORRECTIVE ACTIONS
Extent of Condition inspections on the HP Main Steam Supply Header Drain Valves are planned for the next Unit 1 refueling outage.
The "A" Steam Generator PORV was repaired by work order prior to Unit startup.
The Abnormal Operating Procedures for "Malfunction of Nuclear Instrumentation" were performed for the issues associated with the intermediate range and source range instruments. Both instruments were repaired and returned to*
service.
6.0 ACTIONS TO PREVENT RECURRENCE The HP Turbine Main Steam Supply Header Drain lines on both Units will be monitored to capture steady state and dynamic transient vibration and temperature profiles. The HP Turbine Main Steam Supply Header Drain piping identified as the most susceptible to high vibrations and temperature transients will be replaced if required using socket welds with a 2 to 1 profile ratio.
7.0 SIMILAR EVENTS
There are no similar events at North Anna Power Station.
8.0 MANUFACTURER/MODEL NUMBER N/A
9.0 ADDITIONAL INFORMATION
Unit 1 continued to operate at 100% power, Mode 1, during this event. Page 3
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