05000250/LER-2008-001, Human Error Causes Grid Disturbance Resulting in Dual Unit Trip
| ML081300742 | |
| Person / Time | |
|---|---|
| Site: | Turkey Point  |
| Issue date: | 04/25/2008 |
| From: | Jefferson W Florida Power & Light Group |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| L-2008-084 LER-08-001-00 | |
| Download: ML081300742 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(iv)(A), System Actuation 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)(viii)(B) 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 |
| 2502008001R00 - NRC Website | |
text
FPL APR 2 5 2008 10 CFR § 50.73 L-2008-084 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D. C. 20555-00001 Re:
Turkey Point Units 3 and 4 Docket Nos. 50-250 and 50-251 Reportable Event: 2008-001-00 Date of Event: February 26, 2008 Human Error Causes Grid Disturbance Resulting in a Dual Unit Trip The attached Licensee Event Report 05000250/2008-001-00 is being submitted pursuant to the requirements of 10 CFR 50.73(a)(2)(iv)(A) to provide notification of the subject event.
If there are any questions, please call Ms. Olga Hanek at 305-246-6607.
Very truly yours, Vice PresidenV Turkey Point Nuclear Plant Attachment cc:
Regional Administrator, USNRC, Region II Senior Resident Inspector, USNRC, Turkey Point Nuclear Plant an FPL Group company
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NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 08/31/2011 (9-2007)
Estimated burden per response to comply with this mandatory collection request: 50 hours5.787037e-4 days <br />0.0139 hours <br />8.267196e-5 weeks <br />1.9025e-5 months <br />. Reported lessons learned are incorporated into the licensing process and fed back to industry. Send comments regarding burden estimate to the Records and FOIA/Privacy Service Branch (T-5 LICENSEE EVENT REPORT (LER)
F52), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by internet e-mail to infocollects@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 may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 3. PAGE Turkey Point Unit 3 05000250 1 of 4
- 4. TITLE Human Error Causes Grid Disturbance Resulting in a Dual Unit Trip
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED MONTH DAY YEAR ISEQUENTIAL I REV M
H D
Y FACILITY NAME DOCKET NUMBER MONTHBER NO.DAYNYEA Turkey Point Unit 4 05000251 FACILITY NAME DOCKET NUMBER 2
26 2008 2008 -
001 - 00 4
25 2008
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR§: (Check all that apply)
El 20.2201(b)
El 20.2203(a)(3)(i)
El 50.73(a)(2)(i)(C)
[I 50.73(a)(2)(vii) 1 El 20.2201(d)
[I 20.2203(a)(3)(ii)
El 50.73(a)(2)(ii)(A)
E-50.73(a)(2)(viii)(A)
[I 20.2203(a)(1)
El 20.2203(a)(4)
El 50.73(a)(2)(ii)(B)
El 50.73(a)(2)(viii)(B)
El 20.2203(a)(2)(i)
El 50.36(c)(1)(i)(A)
El 50.73(a)(2)(iii)
[] 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL E] 20.2203(a)(2)(ii)
El 50.36(c)(1)(ii)(A) 0 50.73(a)(2)(iv)(A)
[E 50.73(a)(2)(x)
El 20.2203(a)(2)(iii)
[E 50.36(c)(2)
El 50.73(a)(2)(v)(A)
El 73.71(a)(4)
El 20.2203(a)(2)(iv)
El 50.46(a)(3)(ii)
El 50.73(a)(2)(v)(B)
El 73.71(a)(5) 100 El 20.2203(a)(2)(v)
El 50.73(a)(2)(i)(A)
El 50.73(a)(2)(v)(C)
El OTHER El 20.2203(a)(2)(vi)
El 50.73(a)(2)(i)(B)
El 50.73(a)(2)(v)(D)
Specify in Abstract below or in
CAUSE OF THE EVENT
The grid voltage disturbance occurred due to human error when a Protection and Control (P&C) field engineer disabled both levels of local protection at an electrical substation which then failed to actuate when a fault occurred during equipment troubleshooting. The inadvertent AFW actuation occurred due to inadequate procedural guidance.
ANALYSIS OF THE EVENT
Grid Disturbance On February 26, 2008, a Protection and Control (P&C) field engineer was diagnosing a switch that had malfunctioned at FPL's Flagami substation in west Miami. At approximately 1309 during the diagnostic process, a fault occurred. The engineer had disabled both levels of local protection, contrary to FPL's standard procedures and established practices. When the switch was operated, an arc developed which, aided by windy weather, evolved into a three phase fault. Because both levels of local protection were disabled, the fault was cleared remotely resulting in delayed clearing (1.7 seconds).
Inadvertent AFW Actuation Human performance and procedure reviews were conducted. None of the procedures prompted looking at the semaphore flag for the shutdown 4B SGFP. The operator was using all required human performance tools and obtained a peer check. A brief was conducted with the field operators but not the other control room operators.
The causal factor for this event was primarily written communication. The procedures do not contain any steps, precautions, limitations, or notes that would direct or suggest matching the semaphore. The only line of defense in this case was operator knowledge and awareness. However, a brief including other experienced staff may have recognized the hazard. Therefore, inadequate communication is a secondary causal factor.
Reportability
10 CFR 50.73(a)(2)(iv)(A) requires a written report of valid actuations of the reactor protection system and a pressurized water reactor's auxiliary or emergency feedwater system. Since reactor trips, and expected and inadvertent actuations of the AFW system occurred during the response to the reactor trips, these events are being reported herein.
ANALYSIS OF SAFETY SIGNIFICANCE The plant response to the grid voltage disturbance was as designed with only one minor complication, the loss of the 4C 4 KV bus. Offsite power remained available to the safety buses and the reactor coolant pumps did not trip. At the time of the inadvertent AFW actuation on Unit 4, the standby feed pumps had been put in service. AFW was not required to mitigate any plant condition at that time. Therefore, the safety significance of the plant trips and AFW actuation are minimal.
CORRECTIVE ACTIONS
Grid Disturbance Corrective actions include: A procedure requiring approved plans for disabling any relay protection, independent verification, more stringent requirements in switching procedures, and training for P&C field engineers and dispatchers on the new procedures.
Inadvertent AFW Actuation Applicable procedures will be revised to ensure the control switches for various components powered by the 4C 4 KV bus are placed in the appropriate position after a loss of power and to verify the control board switches are green flagged.
ADDITIONAL INFORMATION
EIIS Codes are shown in the format [EIIS SYSTEM: IEEE system identifier, component function identifier, second component function identifier (if appropriate)].
FAILED COMPONENTS IDENTIFIED:
None
PREVIOUS SIMILAR EVENTS
None