05000266/LER-2013-001, Loss of Offsite Power to Unit 1 Safeguards Buses
| ML13095A183 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 04/05/2013 |
| From: | Meyer L Point Beach |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk, NRC/RGN-III |
| References | |
| NRC 2013-0033 LER 13-001-00 | |
| Download: ML13095A183 (4) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(vi)(A) 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 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) 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(v), Loss of Safety Function |
| 2662013001R00 - NRC Website | |
text
April 5, 2013 ENERGY f
- - u,PJ+
BEACH NRC 201 3-0033 10 CFR 50.73 Regional Administrator, Region Ill U. S. Nuclear Regulatory Commission 2443 Warrenville Road, Suite 210 Lisle, IL 60532-4352 Point Beach Nuclear Plant, Units 1 Dockets 50-266 Renewed License Nos. DPR-24 Licensee Event Report 2661201 3-001 -00 Loss of Offsite Power to Unit 1 Safequard Buses Enclosed is Licensee Event Report (LER) 2661201 3-001-00 for Point Beach Nuclear Plant (PBNP), Unit 1. Pursuant to 10 CFR 50.73(a)(2)(vi)(A), the event is reportable as an event or condition that resulted in manual or automatic actuation of the emergency diesel generators.
This submittal contains no new or revised regulatory commitments.
If you have questions or require additional information, please contact Mr. Michael Millen at 9201755-7845.
Very truly yours, NextEra Energy Point Beach, LLC Enclosure cc:
Administrator, Region Ill, USNRC Project Manager, Point Beach Nuclear Plant, USNRC Resident Inspector, Point Beach Nuclear Plant, USNRC PSCW NextEra Energy Point Beach, LLC, 6610 Nuclear Road, Two Rivers, WI 54241
NCR FORM 366 (10-2010)
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION (1 0-201 0)
LICENSEE EVENT REPORT (LER)
- 1. FACILITY NAME Point Beach Nuclear Plant Unit 1 APPROVED BY OMB: NO. 3150-0104 EXPIRES: 10/31/2013 Estimated burden per response to comply with this mandatory collection request: 80 hours9.259259e-4 days <br />0.0222 hours <br />1.322751e-4 weeks <br />3.044e-5 months <br />. Reported lessons learned are incorporated into the licensing process and fed back to industry. Send comments regarding burden estimate to the FOlNPrivacy Section T 5 F53), U.S. Nuclear Re~ulat?ry Commission. Washington. DC 2055b-iool, or by internet e-mall to ~nfocollects.resourse@nrc.gov, and to the Desk Officer, Office of Information and Regulatory Affairs, NEOB-10202, (3150-0104), Office of Management and Budget, Washington, DC 20503. If a means used to impose an information collection does not display a currently valid OMB control number, the NRC ma not conduct or sponsor, and a person is not required to respond to, the inLrmation collection.
- 2. DOCKET NUMBER
- 3. PAGE 05000266 1 of 3
- 4. TITLE Loss of Offsite Power to Unit 1 Safeguards Buses
- 5. EVENT DATE MONTH 02
- 6. LER NUMBER
- 12. LICENSEE CONTACT FOR THlS LER
- 11. THlS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFRS: (Check all that apply) 20.2201(b) 20.2203(a)(3)(i)
[7 50.73(a)(Z)(i)(C)
[7 50.73(a)(2)(vii) 20.2201(6) 20.2203(a)(3)(ii)
- 50.73(a)(2)(ii)(A) 50.73(a)(Z)(viii)(A)
- 20.2203(a)(I)
[7 20.2203(a)(4)
- 50.73(a)(2)(ii)(B) 50.73(a)(Z)(viii)(B) 20.2203(a)(2)(i) 50.36(c)(l)(i)(A) 50.73(a)(2)(iii)
I7 50.73(a)(2)(ix)(A)
[7 20.2203(a)(Z)(ii) 50.36(c)(I)(ii)(A)
IXI 50.73(a)(2)(iv)(A)
[7 50.73(a)(2)(x) 20.2203(a)(2)(iii) 50.36(~)(2)
[7 50.73(a)(2)(v)(A) 73.71 (a)(4)
I7 20.2203(a)(2)(iv) 50.46(a)(3)(ii)
[7 50.73(a)(2)(v)(B)
I7 73.71 (a)@)
20.2203(a)(2)(v) 50.73(a)(Z)(i)(A)
[7 50.73(a)(2)(~)(C)
OTHER [7 20.2203(a)(2)(vi)
[7 50.73(a)(2)(i)(B)
[7 50.73(a)(2)(v)(D)
Specify In ~bstract below or in low voltage station auxiliary transformer 1X-04. Similarly, the H-03 bus supplies Unit 2 and is normally supplied by high voltage station auxiliary transformer 2X-03. The H-03 bus supplies power to the low voltage station auxiliary transformer 2X-04. The units can be interconnected to alternate supplies by arranging bus tie breakers to connect H-02 to H-01 and H-03 to H-01.
Safety Analysis
The spurious action of the circuit switcher resulted in a low voltage condition on the 1A-05 and 1A-06, safety-related buses, which started the four EDGs. However, the opening of the circuit switcher did not cause a lockout of 1X-03. This was in accordance with the design of the lockout sensor. An undervoltage alone does not cause a transformer lockout. As a result, the automatic transfer to close in the redundant offsite power supply in the switchyard was not initiated, and the GO1 and GO3 EDGs proceeded to automatically load to the Unit 1 safety system buses, once they had reached operating voltage and frequency.
An assessment confirmed that the redundant circuit for offsite power remained available. Offsite power was restored to the Unit 1 safeguards buses by synchronizing the running EDGs to the grid and closing the alternate feed from offsite power. Offsite power remained available to the affected unit from this redundant path.
Corrective Actions
The corrective action to prevent the recurrence is to modify circuit switchers 1 F89-112 and 2F89-152 control logic circuitry to remove the spurious actuation. The actions have been entered into the corrective action program.
Similar Events
LER 2661201 1-001 -00, Loss of Offsite Power to Unit 1 Safeguards Buses
Component Failure Data
Manufacturer
Description
S & C Circuit Switcher Model Number Type G, 3 Gap, Center-Break