05000251/LER-2015-001, Regarding Automatic Auxiliary Feedwater System Actuation During a Planned Reactor Trip

Regarding Automatic Auxiliary Feedwater System Actuation During a Planned Reactor Trip

ML15050A241
Person / Time
Site:	Turkey Point
Issue date:	01/29/2015
From:	Kiley M Florida Power & Light Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
L-2015-028 LER 15-001-00
Download: ML15050A241 (5)

LER-2015-001, Regarding Automatic Auxiliary Feedwater System Actuation During a Planned Reactor Trip

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(iv)(A), System Actuation
2512015001R00 - NRC Website

text

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L-2015-028 10 CFR § 50.73 January 29, 2015 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D. C. 20555-0001 Re:

Turkey Point Unit 4 Docket No. 50-251 Reportable Event: 2015-001-00 Date of Event: November 30, 2014 Auxiliary Feedwater System Actuation The attached Licensee Event Report 05000251/2015-001-00 is submitted pursuant to 10 CFR 50.73 (a)(2)(iv)(A).

If there are any questions, please call Mr. Mitch Guth, Licensing Manager at (305)246-6698.

Sincerely, Michael 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 3440h St., Florida City, FL 33035

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 0113112017 (02-2014'

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

1. FACILITY NAME

2. DOCKET

6. LER NUMER

3. PAGE YEAR SEQUENTIAL REV Turkey Point Unit 4 05000251 YN NO.

3 of 4

2015 -

001 00

CAUSE OF THE EVENT

The causal analysis determined the following:

" The appropriate operating margin to prevent AFW actuation was not established prior to the reactor trip for the planned shutdown.

" The just-in-time training did not prepare crews to reduce the probability of having an unnecessary AFW actuation on a planned reactor trip.

ANALYSIS OF THE EVENT

On November 28, 2014, an unidentified steam leak was discovered on the south end of the Unit 4 HP turbine. Due to an excessive amount of steam, personnel could not gain access to identify the source of the steam leak. A load reduction was necessary to allow personnel to enter the area but visibility and accessibility was limited. On November 30, the Unit 4 was manually tripped from 23% power.

Following the trip, the 4C SG level decreased to 16% NR, the low-low level setpoint, and AFW actuated.

Providing feedwater through the main feedwater bypass valves to the generators would have been sufficient to maintain reactor coolant temperature stable after the trip, since Unit 4 was at the beginning of cycle (BOC) plant conditions with low decay heat load.

On a planned shutdown, reducing steam demand prior to tripping the reactor and the turbine reduces the SG level shrink, and therefore reduces the probability of an AFW actuation following the reactor trip. The operating procedure, 4-GOP-103, permitted Operators to trip the reactor manually when reactor power decreases to approximately 15 to 25% power. However, prior to that step, the procedure includes a note to caution the Operators that a" Manual trip below 20% power reduces the probability of unnecessary Auxiliary Feedwater Actuation and enables more effective control of steam generator levels."

For this event, the reactor was tripped from 23% power, in order to minimize the risk of having a secondary transient due to the unidentified HP turbine steam leak, which increased the probability of an AFW actuation. This operating margin reduction, along with the delay in the expeditious performance of the procedural steps in 4-EOP-ES-0. 1 (due to the unexpected dual indication observed at FCV-4-478 controls),

resulted in not establishing feedwater flow to the generators using the Feedwater Bypass Valves promptly, reaching the SG low-low level setpoint setting of 16% NR, and thus actuating AFW.(02-2014)

U.S. NUCLEAR REGULATORY COMMISSION Q'I, LICENSEE EVENT REPORT (LER)

CONTINUATION SHEET APPROVED BYOMB: NO.3150-0104 EXPIRES: 0113112017 Estimated

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

1. FACILITY NAME Turkey Point Unit 4

3. PAGE 4

of 4

ANALYSIS OF SAFETY SIGNIFICANCE AFW initiated on a low-low SG level signal and added cooler water to the generators. As expected, Operators closed the Main Steam Isolation Valves to control the cooldown. AFW was later secured.

During this event, Operator actions were successful in controlling the cooldown, stabilizing the plant and maintaining the reactor in a safe condition. As such, the safety significance of this event is very low.

CORRECTIVE ACTIONS

Corrective actions are in accordance with condition report AR 2009853 and include:

1. Change the applicable operating procedures to establish available margin to avoid unnecessary AFW actuation during a planned reactor trip.

2. Develop simulator scenarios that more closely model the plant response during a planned shutdown and train Operators to reduce the probability of an unnecessary AFW actuation during a planned reactor trip.

ADDITIONAL INFORMATION

ENIS Codes are shown in the format [IEEE system identifier, component function identifier, second component function identifier (if appropriate)].

FAILED COMPONENTS IDENTIFIED: None

PREVIOUS SIMILAR EVENTS

None