05000348/LER-2016-007

LER-2016-007, Plant Shutdown Required by Technical Specifications due to Inoperable Steam Flow Transmitters

Joseph M. Farley Nuclear Plant
Event date:	11-17-2016
Report date:	1-13-2017
Reporting criterion:	10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident
3482016007R00 - NRC Website

LER 16-007-01 for Joseph M. Farley, Unit 1, Regarding Plant Shutdown Required by Technical Specifications due to Inoperable Steam Flow Transmitters

ML17158B319
Person / Time
Site:	Farley
Issue date:	06/07/2017
From:	Wheat J T Southern Nuclear Operating Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NL-17-0543 LER 16-007-01
Download: ML17158B319 (6)

Reported lessons learned are incorporated into the licensing process and ted back to industry.

Send comments regarding burden estimate to the FOIA, Privacy and Information Collections Branch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by internet e-mail to Infocollects.Resource@nrc.gov, and to the Desk Officer, Office of Information and Regulatory Affairs, NEOB-10202, (3150-0104), Office of Management and Budget, Washington, DC 20503.1f 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.

Joseph M. Farley Nuclear Plant, Unit 1 05000- 348

A. PLANT AND SYSTEM IDENTIFICATION

Westinghouse - Pressurized Water Reactor

B. DESCRIPTION OF EVENT

On 11/17/2016 at 1859 with Unit 1 in Mode 1 at 99 percent power, the plant initiated a shutdown in accordance with Limiting Condition for Operation (LCO) 3.0.3 for having no operable steam flow channels [FT] for the C Steam Generator [SG]. The two steam flow channels on the 1C SG did not meet acceptance criteria for Technical Specification (TS) 3.3.2.

During full power engineering verification of beginning of cycle full power scaling values for steam flow normalization it was discovered that three steam flow transmitters were outside the acceptance criteria required by site procedures. The variance was in the non-conservative direction and would allow steam flow to exceed the TS 3.3.2 engineered safety features actuation system [JE] trip setpoint prior to a main steam isolation occurring. TS 3.3.2 requires two steam flow channels per steam line. Two inoperable steam flow transmitters on the 1C SG caused the plant to enter LCO 3.0.3. The shutdown was completed and the plant entered Mode 3 as required by LCO 3.0.3.

C. UNIT STATUS AT TIME OF EVENT

Mode 1, 99 percent power

D. CAUSE OF EVENT

The cause of this event has not yet been determined. A supplemental LER will be submitted upon the completion of causal analysis, and the cause will be provided at that time.

E. REPORTABILITY ANALYSIS AND SAFETY ASSESSMENT

This event is reportable as the completion of a plant shutdown required by Technical Specifications in accordance with 10 CFR 50.73(a)(2)(i)(A).

Steam flow channels perform a safety function by providing a high steam flow input to main steam line isolation logic circuitry. Each of the three steam generators is equipped with two redundant steam flow transmitters. A high steam flow signal from one of the two steam flow transmitters on two of the three steam generators coincident with a low-low reactor coolant system (RCS) average temperature signal from two of three RCS temperature channels generates a main steam line isolation signal that causes closure of all main steam line isolation valves. This signal is to mitigate the consequences of a main steam line break accident and the resulting rapid depressurization. Having both of the steam flow channels inoperable for the 1C SG caused a loss of safety function for this signal. Therefore this is also reportable as an event or condition that could have prevented fulfillment of a Safety Function needed to mitigate the consequences of an accident, in accordance with 10 CFR 50.73(a)(2)(v)(D).

Reported lessons learned are incorporated into the licensing process and fed back to industry Send comments regarding burden estimate to the FOIA, Privacy and Information Collections Branch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by Internet e-mail to Infocollects.Resource@nrc.gov, and to the Desk Officer, Office of Information and Regulatory Affairs, NEOB-10202, (3150-0104), Office of Management and Budget, Washington, DC 20503.1f 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.

Joseph M. Farley Nuclear Plant, Unit 1 05000- 348

NO

Two additional means of providing a main steam line isolation in the event of a steam line break were available. One is the low-steam-pressure main steam line isolation signal, and the other is the containment pressure signal. These functions remained fully capable of performing the main steam line isolation function during the periods that the steam flow channels were known to be out of tolerance.

Additional means of providing the necessary protection against a steam pipe rupture were maintained.

One of these was safety injection (SI) system actuation from low pressurizer pressure signals, high steam line differential pressure, low main steam line pressure, or high containment pressure signals. Another means available was the overpower reactor trips and the reactor trip occurring in conjunction with receipt of the SI signal. A third was the redundant isolation of the main feedwater lines to prevent sustained high feedwater flow which would cause additional cooldown.

The loss of the main steam line isolation from the high steam flow and low-low RCS average temperature signal was determined to be of low risk due to redundant trips for mitigation of a steam line break remaining operable.

F. CORRECTIVE ACTION

The steam flow transmitters were restored to operable status. New scaling data was calculated and the channels were rescaled. Further corrective actions will be determined upon completion of the causal analysis and will be scheduled to ensure timeliness of implementation before the next refueling outage.

G. ADDITIONAL INFORMATION

1) Previous Similar Events:

Joseph M. Farley Unit 2 LER 2013-001-00 was submitted on July 26, 2013 to report two instances of a condition prohibited by Technical Specifications due to the untimely renormalization of Steam Flow Transmitter FT-494 at the beginning of two operating cycles.

Joseph M. Farley Unit 1 LER 2013-003-00 was submitted on January 3, 2014 to report a condition prohibited by Technical Specifications due to the untimely renormalization of Steam Flow Transmitter FT-495 at the beginning of an operating cycle.

Joseph M. Farley Units 1 and 2 LER 2014-003-00 was submitted on June 2, 2014 for scaling errors that resulted in inoperable steam flow channels for durations longer than allowed by Technical Specifications.

2) Commitment Information: This report does not create any licensing commitments