05000325/LER-2005-005, Regarding Automatic Reactor Protection System Actuation Due to No Load Disconnect Switch Failure
| ML052630377 | |
| Person / Time | |
|---|---|
| Site: | Brunswick  |
| Issue date: | 09/12/2005 |
| From: | Waldrep B Progress Energy Carolinas |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| BSEP 05-0119 LER 05-005-00 | |
| Download: ML052630377 (7) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i) 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)(viii)(A) 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2) 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(ix)(A) 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)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(iv)(A), System Actuation 10 CFR 50.73(a)(2)(iv)(B), System Actuation |
| 3252005005R00 - NRC Website | |
text
aj Progress Energy SEP, 2 2005 SERIAL! BSEP 05-0119 10 CFR 50.73 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001
Subject:
Brunswick Steam Electric Plant, Unit No. 1 Docket No. 50-325/License No. DPR-71 Licensee Event Report 1-2005-005 Ladies and Gentlemen:
In accordance with the Code of Federal Regulations, Title 10, Part 50.73, Carolina Power
& Light Company, now doing business as Progress Energy Carolinas, Inc., submits the enclosed Licensee Event Report. This report fulfills the requirement for a written report within sixty (60) days of a reportable occurrence.
Please refer any questions regarding this submittal to Mr. Edward T. O'Neil, Manager-Support Services, at (910) 457-3512.
Sincerely, B. C. Waldrep Plant General Manager Brunswick Steam Electric Plant MAT/mat
Enclosure:
Licensee Event Report Progress Energy Carolinas, Inc.
Brunswick Nuclear Plant P.O. Box 10429 Southport, NC 28461
Document Control Desk BSEP 05-0119 / Page 2 cc (with enclosure):
U. S. Nuclear Regulatory Commission, Region II ATTN: Dr. William D. Travers, Regional Administrator Sam Nunn Atlanta Federal Center 61 Forsyth Street, SW, Suite 23T85 Atlanta, GA 30303-8931 U. S. Nuclear Regulatory Commission ATTN: Mr. Eugene M. DiPaolo, NRC Senior Resident Inspector 8470 River Road Southport, NC 28461-8869 U. S. Nuclear Regulatory Commission ATTN: Ms. Brenda L. Mozafari (Mail Stop OWFN 8G9) (Electronic Copy Only) 11555 Rockville Pike Rockville, MD 20852-2738 Ms. Jo A. Sanford Chair - North Carolina Utilities Commission P.O. Box 29510 Raleigh, NC 27626-051
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- 3. PAGE Brunswick Steam Electric Plant (BSEP), Unit 1 05000325 1 OF 5
- 4. TITLE Automatic Reactor Protection System Actuation Due to No Load Disconnect Switch Failure
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED MONTH DAY YEAR YEAR SEUENTIAL REV MONTH DAY YEAR FACILIIY NAME DOCKET NUMBER NUMBER NO_
_05000 07 13 2005 2005 005 00 09 1212005 FACLT NAME DOCKET NUMBER 10 5 0 0 0
- 9. OPERATING MODE
- 1. THIS REPORT IS SUBMITTED PURSUANT TOTHE REQUIREMENTS OF 10 CFR §: (Check one or more) 1 0
20.2201 (b) 0 20.2203(a)(3)(i) 0 50.73(a)(2)(i)(C) 0 50.73(a)(2)(vii) o 20.2201(d) 0 20.2203(a)(3)(ii) 0 50.73(a)(2)(ii)(A) 0 50.73(a)(2)(viii)(A) o 20.2203(a)(1) 0 20.2203(a)(4) 0 50.73(a)(2)(ii)(B) 0 50.73(a)(2)(viij)(B) 0 20.2203(a)(2)(i) 0 50.36(c)(1)(i)(A) 0 50.73(a)(2)(iii) 0 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL 0 20.2203(a)(2)(ii) 0 50.36(c)(1)(ii)(A) 0 50.73(a)(2)(Iv)(A)
E 50.73(a)(2)(x) 100 0
20.2203(a)(2)(iii) 0 50.36(c)(2) 0 50.73(a)(2)(v)(A) 0 73.71(a)(4) o 20.2203(a)(2)(iv) 0 50.46(a)(3)(ii) 0 50.73(a)(2)(v)(B) 03 73.71(a)(5) o 20.2203(a)(2)(v) 0 50.73(a)(2)(i)(A) 0 50.73(a)(2)(v)(C)
OTHER 202203(a)(2)(vi) 0 50.73(a)(2)(i)(B) 0 50.73(a)(2)(v)(D) orSinC Formn A
6s A
- 12. UCENSEE CONTACT FOR THIS LER FACILITY NAME TELEPHONE NUMBER (Include Area Code)
Mark A. Turkal, Lead Engineer - Licensing 1(910) 457-3066
- 13. COMPLETE ONE UNE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT MAU_
RPOTI EMANU-REPORTABLE
CAUSE
SYSTEM COMPONENT FACTURER REPORTABLE
CAUSE
SYSTEM COMPONENT FACTURER TO EPIX B
EL DISC Delta-Unibus Y
- 14. SUPPLEMENTAL REPORT EXPECTED
- 15. EXPECTED MO DAY YEAR SUBMISSION YES (If yes, complete EXPECTED SUBMISSION DATE).
X NO DATE AtSTb IHA tumn to 14u spaces, i.e., approximateiy i singie-spacea iypewrnen lines)
On July 13, 2005, at 0917 hours0.0106 days <br />0.255 hours <br />0.00152 weeks <br />3.489185e-4 months <br />, Unit 1 received a Main Turbine trip followed by an automatic Reactor Protection System (RPS) actuation. The cause of the Main Turbine trip was the failure of the B phase of the Main Generator No Load Disconnect Switch (NLDS). Plant systems responded per design. All control rods fully inserted. An expected Reactor Pressure Vessel coolant level shrink resulted in the coolant level decreasing below the Reactor Vessel Water Level - Low Level I setpoint, which resulted in appropriate Primary Containment Isolation System (PCIS) isolations. Additionally, coolant level momentarily satisfied the Low Level 2 actuation logic requirements, at which point an additional PCIS isolation occurred and the High Pressure Coolant Injection (HPCI) system initiated but did not inject. Safety/Relief valves B, C, D, and E operated to control pressure. This condition is being reported in accordance with 10 CFR 50.73(a)(2)(iv)(A) as an event that resulted in valid actuation of systems listed in 10 CFR 50.73(a)(2)(iv)(B).
The root cause of this event is inadequate design and testing of the NLDS by the vendor; resulting in the NLDS not meeting its nameplate design rating. A temporary modification has been installed on both Unit 1 and Unit 2 which replaced the NLDSs with removable bus bars.
NRC FORM 366 (6-2004)
(Ifmore space Is required, use additionalcopies of NRC Formr 66A) (17)
Energy Industry Identification System (EIIS) codes are identified in the text as [XX].
INTRODUCTION
On July 13, 2005, at 0917 hours0.0106 days <br />0.255 hours <br />0.00152 weeks <br />3.489185e-4 months <br />, Unit 1 received a Main Turbine [TA] trip followed by a Reactor Protection System (RPS) [JCI actuation. Plant systems responded per design, including the automatic transfer of loads from the Unit Auxiliary Transformer to the Startup Auxiliary Transformer. All control rods fully inserted.
An expected Reactor Pressure Vessel (RPV) coolant level shrink caused the reactor vessel water level to decrease below the Reactor Vessel Water Level -Low Level 1 setpoint, which resulted in a Primary Containment Isolation System (PCIS) [JM] isolation signal to Group 2 (i.e., Drywell Equipment and Floor Drain, Traversing In-Core Probe, Residual Heat Removal (RHR) Discharge to Radwaste, and RHR Process Sample) primary containment isolation valves (PCIVs), Group 6 (i.e., Containment Atmosphere Control/Dilution, Containment Atmosphere Monitoring, and Post Accident Sampling System) PCIVs, and Group 8 (i.e., RHR Shutdown Cooling Suction and RHR Inboard Injection) PCIVs. Additionally, minimum reactor vessel water level momentarily satisfied the Reactor Vessel Water Level - Low Level 2 actuation logic requirements, which caused a Group 3 (i.e., Reactor Water Cleanup System) isolation to occur. The isolation signals closed all of the PCIVs that were open at the time of the actuations.
Safety/Relief valves (SRVs) [RV] B, C, D, and E operated to control pressure.
At 1303 hours0.0151 days <br />0.362 hours <br />0.00215 weeks <br />4.957915e-4 months <br />, the NRC was notified (i.e., Event Number 41837), in accordance with 10 CFR 50.72(b)(2)(iv)(B), of the Unit 1 RPS actuation and, in accordance with 10 CFR 50.72(b)(3)(iv)(A), of the valid actuation of systems listed in 10 CFR 50.73(a)(2)(iv)(B). This condition is being reported in accordance with 10 CFR 50.73(a)(2)(iv)(A) as an event that resulted in valid actuation of systems listed in 10 CFR 50.73(a)(2)(iv)(B).
EVENT DESCRIPTION
Initial Conditions Unit 1 was in Mode 1, at approximately 100 percent rated thermal power. All required safety-related systems were operable.
Discussion The direct cause of the Main Turbine trip was the shorting to ground of the B phase of the Unit 1 Main Generator [TB] No Load Disconnect Switch (NLDS) [EL], manufactured by Delta-Unibus Corporation, which electrically connects the generator to the main transformer. This ground resulted in actuation of the generator ground current relay and the generator backup lockout relay, followed by fast closure of the turbine control valves. Turbine Control Valve Fast Closure, Control Oil Pressure - Low (i.e., Function 9 of (if more space Is required, use additional copies of (If more space is required, use additional copies o (If more space is required, use additional coples of NRC Form 3664) (17)assistance was required to open the switch. However, this activity was completed in a relatively short time (i.e., approximately 1 to 1.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />). Therefore, if the backfeed lineup had been required, the necessary NLDS lineup could have been achieved in relatively short order.
PREVIOUS SIMILAR EVENTS
A review of events which have occurred within the past three years has not identified any previous similar occurrences related to inadequate vendor design.
COMMITMENTS
No regulatory commitments are contained in this report. Those actions discussed in this submittal will be implemented in accordance with corrective action program requirements.