05000244/LER-2006-004

LER-2006-004,

R.E. Ginna Nuclear Power Plant
Event date:	04-09-2005
Report date:	11-03-2006
2442006004R00 - NRC Website

I. PRE-EVENT PLANT CONDITIONS:

During the 2005 refueling outage, while in Mode 5, instrument calibrations were being performed on standby auxiliary feedwater (SAFW) flow transmitters FT-4084 and FT-4085. The calibrations included closing the instrument isolation valves. During the calibration when the transmitter venting steps were reached, a pressurized water source was not available. The work packages were then brought to the Outage Control Center (OCC) and it was decided to status the work packages to post maintenance testing awaiting a pressurized water supply. It was not known by the OCC that the transmitters were still isolated.

II. DESCRIPTION OF EVENT:

A.� EVENT:

On April 9, 2005, at approximately 0400 EDST, the plant transitioned to Mode 3, and continued the plant startup. Per the Ginna Technical Specifications (LCO 3.7.5), two trains of SAFW are required to be operable in Modes 1, 2, and 3.

On April 18, 2005, while at 100% power, technicians attempted to complete the work orders for the calibration of FT-4084 and FT-4085 and discovered that the transmitter high side and low side manifold valves were closed and the equalizing valve was open, isolating the transmitter. The venting of the transmitters was promptly completed and they were restored to their normal operational alignment.

On September 6, 2006, an unanalyzed condition was identified during the review of the previous issue discovered on April 18, 2005. The current review was being performed in response to NRC inspection questions regarding the previous issue.

The two SAFW trains are in addition to the typical safety-related AFW motor driven pump trains and turbine driven pump train, for a total of five safety-related AFW pump trains at the site. The two SAFW trains are designed to address a high energy line break (HELB) event or fire scenario which could disable the other three AFW pump trains.

Both of the flow transmitters, FT-4084 and FT-4085, perform several functions including control room indication of SAFW discharge flow and valve control functions for the pump discharge valve and pump recirculation valve.

With the flow transmitters isolated in both trains of the SAFW system, an unanalyzed condition existed due to the following: Assuming that there was need to manually start the SAFW pumps as the result of a postulated HELB, the inoperable flow transmitters would result in the recirculation valve and the pump discharge valve being both full open. Under a steam generator low pressure condition, (as a result of the HELB) with flow through both the open discharge valve and the open recirculation valve, the pump would be in a high flow rate condition. The operators would have no indication of flow through the discharge valves and would be operating the system based on steam generator water level. During the time assumed for the intact steam generator level recovery, the breaker for the pump motor could be expected to exceed its time delayed current protection setpoint and trip the motor, preventing delivery of feed water to the steam generator.

Both trains of the SAFW system are allowed by Technical Specifications to be concurrently inoperable for a period of up to 7 days. The actual inoperability occurred over 9 days while the flow transmitters were isolated.

Ginna did not report the event at the time the isolated transmitters were discovered because the transmitters' control function was not recognized to interact in an unanalyzed manner with the resulting unavailable control room indication and the low pressure steam generator condition associated with the HELB event.

THE EVENT:

None

C. DATES AND APPROXIMATE TIMES OF MAJOR OCCURENCES:

• April 9, 2005, 0400 EDST: Plant Mode change with both trains of SAFW flow transmitters isolated.

• April 18, 2005, 1540 EDST: SAFW flow transmitters discovered isolated.

• September 6, 2006, 2000 EDST: Determination made that the isolated SAFW flow transmitters resulted in an inoperability of both SAFW trains.

D. OTHER SYSTEMS OR SECONDARY FUNCTIONS AFFECTED:

None, since there were no failures of any structures, systems, or components.

E. METHOD OF DISCOVERY:

A detailed review of the SAFW system response was being performed in response to NRC inspection questions regarding the previous issue.

F. � SAFETY SYSTEM RESPONSES:

Because there was no equipment failure, no safety systems were energized. This LER was initiated because of the potential for failure, rather than an actual failure.

III. CAUSE OF EVENT:

The cause of this event was a lack of management reinforcement of standards and expectations associated with procedure adherence. The use of a tracking mechanism outside of the outage schedule for post-maintenance testing (PMT) had been used in past outages. Over the years, additional work was transferred to this system when plant conditions did not support completion of the maintenance activity. Closing work out to PMT prior to completing the work is not consistent with procedural guidance. This process was used as a work around to the existing processes to track work outside of the outage project. Since the practice had been successful in the past, management allowed the practice to continue.

Additionally, procedure T-44.3 "SAFW System Filling and Venting" was required to be performed. The initial conditions were signed off, however the procedure was never completed. The procedure was reported as completed to the OCC.

The delay in reporting this event was the result of plant personnel inappropriately using two separate Technical Specification Bases section descriptions to draw a conclusion with regards to system operability when the issue was first discovered. This conclusion was not documented in a formal Operability Determination at the time. Recently, further questions were raised with regards to operability and a formal Operability Determination was performed. This recent evaluation resulted in a determination that the original conclusion was erroneous.

IV. ASSESSMENT OF THE SAFETY CONSEQUENCES OF THE EVENT:

This event is reportable in accordance with 10 CFR 50.73, Licensee Event Report System, item (a)(2)(i)(B), which requires a report of, "Any operation or condition which was prohibited by the plant's Technical Specifications." , (a)(2)(ii)(B) "Any event or condition that resulted in: The nuclear power plant being in an unanalyzed condition that significantly degraded plant safety.", and (a)(2)(v)(B) "Any event or condition that alone could have prevented the fulfillment of the safety function of structures or systems that are needed to: Remove residual heat.

Flow transmitters FT-4084 and FT 4085 serve three main functions. The first is to throttle the SAFW pump discharge motor operated valves to less than 230 gpm when flow exceeds 240 gpm (note:

these values have been changed since the time of the event, but are the values which were in effect at the time). The second function is to open the pump recirculation valve back to the SAFW pump condensate test tank when flow is less than 80 gpm. The third is to provide discharge flow indication on the main control board (MCB). Isolation of these flow transmitters would cause them to indicate zero flow. As such, when the SAFW pumps were started, the discharge MOVs would go full open, and remain there, the recirculation valve would go full open and remain there, and MCB indication would show zero flow, regardless of actual flow. The potential effects of this condition were examined.

Analyses indicates that following a faulted steam generator (SG) event, the low pressure in the intact SG would result in a high SAFW pump flow rate with the discharge and recirculation valves full open.

This flow rate would cause the breaker time delayed current protection to trip the pump within a short period of time. The pump trip could occur prior to reaching a level in the intact SG which would procedurally allow the operators to manually throttle pump flow. As such, it is conservatively assumed that both SAFW pumps would fail during steam line breaks upstream of the main steam isolation valves (MSIVs), steam line breaks downstream of the MSIVs if either MSIV fails to close, and feedwater line breaks downstream of the feedwater check valves.

This postulated scenario was evaluated through the Ginna PRA model and the event results in an increase in core damage frequency (CDF) of 1.047E-05/yr and an increase in large early release frequency (LERF) of 1.220E-06/yr. Based on control room log entries, the plant entered Mode 3 at approximately 04:00 on 4/9/05. The flow transmitters were restored at approximately 16:00 on 4/18/05, such that this condition existed for approximately 228 hours0.00264 days <br />0.0633 hours <br />3.769841e-4 weeks <br />8.6754e-5 months <br />. Thus, the overall increase in plant risk due to this mispositioning is 2.73E-07 for CDF and 3.18E-08 for LERF.

V. � CORRECTIVE ACTIONS:

A. ACTION TAKEN TO RETURN AFFECTED SYSTEMS TO PRE-EVENT NORMAL STATUS:

The SAFW flow transmitters were promptly restored to their normal operational alignment.

B. ACTION TAKEN OR PLANNED TO PREVENT RECURRENCE:

Training was provided for all first line supervisors and managers on coaching and intervention.

One of the focal points of the training was reinforcement of standards and management expectations associated with procedure adherence.

• The site has implemented a comprehensive human performance program.

• A root cause investigation is in process to evaluate outage related Technical Specification compliance.

• The procedural checklists associated with plant Mode changes have been strengthened.

• The Technical Specification Bases have been revised to include the flow transmitters for operability of the system.

The site Operability Determination process is being strengthened.

VI. � ADDITIONAL INFORMATION:

A. FAILED COMPONENTS:

No structures, systems, or components failed as result of this event.

B. PREVIOUS LERs ON SIMILAR EVENTS:

A similar LER event historical search was conducted with the following results:

auxiliary feedwater pump. This event was the result of system lineups being performed out of order.

fans inoperable. This event was the result of inadequate tracking of components out of service.

C. THE ENERGY INDUSTRY IDENTIFICATION SYSTEM (EIIS) COMPONENT FUNCTION

THIS LER:

COMPONENT � IEEE 803 � IEEE 805 FUNCTION NUMBER � SYSTEM IDENTIFICATION Pump � P � BA Flow Transmitter � FT � BA