05000327/LER-2009-003, Reactor Trip on Reactor Coolant Pump (RCP) Buses Undervoltage

Reactor Trip on Reactor Coolant Pump (RCP) Buses Undervoltage

ML091420540
Person / Time
Site:	Sequoyah
Issue date:	05/22/2009
From:	Cleary T Tennessee Valley Authority
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
LER 09-003-00
Download: ML091420540 (8)

LER-2009-003, Reactor Trip on Reactor Coolant Pump (RCP) Buses Undervoltage

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(iv)(A), System Actuation 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)(i) 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)(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)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2)(viii)(B) 10 CFR 50.73(a)(2)(ix)(A) 10 CFR 50.73(a)(2)(x)
3272009003R00 - NRC Website

text

Tennessee Valley Authority Post Office Box 2000 Soddy Daisy, Tennessee 37384-2000 Timothy P. Cleary Site Vice President Sequoyah Nuclear Plant May 22, 2009 U.S. Nuclear Regulatory Commission 10 CFR 50.73 ATTN:

Document Control Desk Washington, D.C. 20555-0001 TENNESSEE VALLEY AUTHORITY - SEQUOYAH NUCLEAR PLANT (SQN) UNITS 1 AND 2 - DOCKET NOS. 50-327 AND 50-328 - FACILITY OPERATING LICENSE DPR-77 AND DPR LICENSEE EVENT REPORT (LER) 50-327 AND 50-328/2009-003-00 The enclosed LER provides details concerning a condition where Sequoyah Units 1 and 2 received an automatic reactor trip because of loss of power to two reactor coolant pumps on each unit.

The loss of power condition was caused by a differential relay actuation that resulted from a fault on Common Station Service Transformer D.

This report is being submitted in accordance with 10 CFR 50.73(a)(2)(iv)(A), a condition that resulted in automatic actuation of the reactor protection system.

Sincerely, 7

Timothy P. Cleary Enclosure cc:

See page 2 printed on recycled paper

U.S. Nuclear Regulatory Commission Page 2 May 22, 2009 Enclosure cc (Enclosure):

INPO Records Center Institute of Nuclear Power Operations 700 Galleria Parkway, SE, Suite 100 Atlanta, Georgia 30339-5957 Mr. Siva P. Lingam, Project Manager U.S. Nuclear Regulatory Commission Mail Stop 08G-9a One White Flint North 11555 Rockville Pike Rockville, Maryland 20852-2739 NRC Resident Inspector Sequoyah Nuclear Plant 2600 Igou Ferry Road Soddy-Daisy, Tennessee 37379

NRC FORM 366 (9-2007)

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION (9-2007)

LICENSEE EVENT REPORT (LER)

(See reverse for required number of digits/characters for each block)

APPROVED BY OMB NO. 3150-0104 EXPIRES 08/31/2010

, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.

1. FACILITY NAME Sequoyah Nuclear Plant (SQN) Unit 1

2. DOCKET NUMBER 05000327

3. PAGE 1 OF 6

4. TITLE:

Units 1 and 2 Reactor Trip on Reactor Coolant Pump (RCP) Buses Undervoltage

5. EVENT DATE

6. LER NUMBER

7. REPORT DATE

8. OTHER FACILITIES INVOLVED MONTH DAY YEAR YEAR SEQUENTIAL NUMBER REV NO.

MONTH DAY YEAR FACILITY NAME SQN Unit 2 DOCKET NUMBER 05000328 03 26 2009 2009 - 003 - 00 05 22 2009 FACILITY NAME DOCKET NUMBER

9. OPERATING MODE

11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply) 1

10. POWER LEVEL 96 20.2201(b) 20.2201(d) 20.2203(a)(1) 20.2203(a)(2)(i) 20.2203(a)(2)(ii) 20.2203(a)(2)(iii) 20.2203(a)(2)(iv) 20.2203(a)(2)(v) 20.2203(a)(2)(vi) 20.2203(a)(3)(i) 20.2203(a)(3)(ii) 20.2203(a)(4) 50.36(c)(1)(i)(A) 50.36(c)(1)(ii)(A) 50.36(c)(2) 50.46(a)(3)(ii) 50.73(a)(2)(i)(A) 50.73(a)(2)(i)(B) 50.73(a)(2)(i)(C) 50.73(a)(2)(ii)(A) 50.73(a)(2)(ii)(B) 50.73(a)(2)(iii) 50.73(a)(2)(iv)(A) 50.73(a)(2)(v)(A) 50.73(a)(2)(v)(B) 50.73(a)(2)(v)(C) 50.73(a)(2)(v)(D) 50.73(a)(2)(vii) 50.73(a)(2)(viii)(A) 50.73(a)(2)(viii)(B) 50.73(a)(2)(ix)(A) 50.73(a)(2)(x) 73.71(a)(4) 73.71(a)(5)

OTHER Specify in Abstract below or in (If more space is required, use additional copies of (If more space is required, use additional copies of (If more space is required, use additional copies of (If more space is required, use additional copies of (If more space is required, use additional copies of NRC Form 366A) B.

Corrective Actions to Prevent Recurrence:

The other CSST and CTT buses were inspected to identify any degraded bus and to ensure bus enclosures were sealed properly. Degraded bus insulation on CSST C, CTT A, and CTT B was repaired. The preventative maintenance procedures for bus inspections will be enhanced to provide specific bus inspection instructions.

VII.

ADDITIONAL INFORMATION

A.

Failed Components:

The failed component of this event was a 6900-volt CSST D outdoor non-segregated three phase bus.

B. Previous LERs on Similar Events:

A review of previous reportable events for the past 10 years did not identify any

C. Additional Information

None.

D. Safety System Functional Failure:

This event did not result in a safety system functional failure in accordance with 10 CFR 50.73(a)(2)(v).

E.

Unplanned Scram with Complications:

This condition did not result in an unplanned scram with complications.

VIII.

COMMITMENTS

None.