05000250/LER-2013-007, Regarding Manual Reactor Trip Due to Generator Load Drop

Regarding Manual Reactor Trip Due to Generator Load Drop

ML13199A227
Person / Time
Site:	Turkey Point
Issue date:	07/08/2013
From:	Kiley M Florida Power & Light Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
L-2013-211 LER 13-007-00
Download: ML13199A227 (5)

LER-2013-007, Regarding Manual Reactor Trip Due to Generator Load Drop

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
2502013007R00 - NRC Website

text

0 FPL.

JUL 0 82013 L-2013-211 10 CFR § 50.73 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D. C. 20555-0001 Re:

Turkey Point Unit 3 Docket No. 50-250 Reportable Event: 2013-007-00 Manual Reactor Trip due to Generator Load Drop The attached Licensee Event Report 05000250/2013-007-00 is submitted in accordance with 10 CFR 50.73(a)(2)(iv)(A) due to manual actuation of the reactor protection system.

If there are any questions, please call Mr. Robert J. Tomonto at 305-246-7327.

Very truly yours,

.ichael Kiley Vice President Turkey Point Nuclear Plant Attachment cc:

Regional Administrator, USNRC, Region II Senior Resident Inspector, USNRC, Turkey Point Nuclear Plant Florida Power & Light Company 9760 SW 344th St., Florida City, FL 33035

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 10/31/2013 (10-2010)

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

I3. PAGE Turkey Point Unit 3 05000250I 1 of 4

4. TITLE Manual Reactor Trip due to Generator Load Drop

5. EVENT DATE

6. LER NUMBER

7. REPORT DATE

8. OTHER FACILITIES INVOLVED SEUNILRVFACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR SEQUENTIALMBE REVNO. MONTH DAY YEAR FACILITY NAME DOCKET NUMBER 5

10 2013 2013 - 007 -00 7

8 2013

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

El 20.2201(b)

[I 20.2203(a)(3)(i)

[. E 50.73(a)(2)(i)(C)

[I 50.73(a)(2)(vii)

Mode 1 El 20.2201(d)

E] 20.2203(a)(3)(ii)

El 50.73(a)(2)(ii)(A)

[I 50.73(a)(2)(viii)(A)

[] 20.2203(a)(1)

El 20.2203(a)(4)

El 50.73(a)(2)(ii)(B)

[I 50.73(a)(2)(viii)(B)

El 20.2203(a)(2)(i)

El 50.36(c)(1)(i)(A) 0l 50.73(a)(2)(iii) 0l 50.73(a)(2)(ix)(A)

10. POWER LEVEL El 20.2203(a)(2)(ii)

El 50.36(c)(l)(ii)(A)

ED 50.73(a)(2)(iv)(A) 0l 50.73(a)(2)(x) 0l 20.2203(a)(2)(iii)

El 50.36(c)(2)

El 50.73(a)(2)(v)(A)

El 73.71(a)(4)

[E 20.2203(a)(2)(iv)

El 50.46(a)(3)(ii)0 El 50.73(a)(2)(v)(B)

El 73.71(a)(5) approx. 25%

El 20.2203(a)(2)(v)

El 50.73(a)(2)(i)(A)

El 50.73(a)(2)(v)(C)

El OTHER Dl 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

BACKGROUND INFORMATION

ANALYSIS OF EVENT Turkey Point Unit 4 implemented an extended power uprate. The turbine digital control system upgrade was one of the extensive changes to the secondary plant to support the extended power uprate (EPU). This system interfaced with the electro-hydraulic control (EHC) system.

During post modification testing (PMT) it was discovered that the LDA function quickly closed the control and intercept valves, but also dropped EHC header pressure which slowly closed other turbine steam valves that eventually would lead to a turbine trip. In response to this condition, engineering generated a change request notice (CRN) to correct this issue by revising the LDA pressure disarm logic to only monitor low pressure turbine inlet pressure.

To reset the LDA pressure armed value a dead band was established. The LDA system arming value was set to a pressure value of 100 psig, which was the predicted value of the low pressure turbine inlet pressure at 50% power. The dead band for LDA pressure had been incorrectly set to 50 psi. Subsequent adjustment during power ascension testing reduced the arming pressure value to 87.25 psig and this resulted in lowering the LDA disarmed value to 37.25 psig. Based on the available indication and the current procedural guidance, the Operations crew performed as expected.

This event could have been prevented, if the LDA armed status lights had been maintained, the control room operators could have correctly verified the status of the LDA system and stopped the downpower and corrected the condition. Additionally, if the dead band had been appropriate, an overlap arming of the two LDA parameters would not have occurred.

ANALYSIS OF SAFETY SIGNIFICANCE During a planned shutdown, the operating crew manually tripped the reactor. All systems operated as expected during the reactor shutdown, with the exception of N-3-32 source range detector which experienced a loss of detector voltage. There was no impact on the health and safety of the public. As a result, the safety significance of this event is very low.

CORRECTIVE ACTIONS

Corrective actions are documented in AR 1873643 and include the following:

1. Reducing the dead band of the LDA pressure arming setpoint.

2. Adding indicator lights to the Turbine Control System display to identify armed status.

SION

FAILED COMPONENTS IDENTIFIED: None

PREVIOUS SIMILAR EVENTS

None