05000400/LER-2002-001

LER-2002-001,

Docket Number
Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(iv), System Actuation
4002002001R00 - NRC Website

SUMMARY:

On January 2, 2002 at 0305, the Harris Nuclear Plant (HNP) was manually tripped, during a plant startup following RFO-10, due to a failure of a Main Feedwater Regulating Valve Bypass Valve (EIIS: SJ-LCV). The plant trip was initiated at approximately 7% reactor power when Steam Generator (SG) divergent level swings were observed on all three SGs. SG level was being controlled in automatic by the Main Feedwater Regulating Valve Bypass Valves (MFRVBV) and the valves were traveling full open to full shut in response to the level swings. Following a full shut swing, "C" MFRVBV (1FW-198) failed to respond to an automatic open demand signal from the associated controller located on the Main Control Board. The Balance of Plant (BOP)operator attempted to open 1FW-198 by taking the controller to manual with a 100% demand, however, indication of actual valve position showed the valve to be shut. With "C" SG level at 30% narrow range level indication, the Unit Senior Control Operator (USCO) directed a manual reactor trip. The manual reactor trip was successful.

Event Summary:

During the plant start-up following RFO-10, power ascension to 7% power was needed to satisfy the initial conditions of plant procedure EPT-848T, Temporary Procedure for Steam Generator Water Level Control Test. The purpose of this test was to evaluate the automatic response of the MFRVBV to a 5% level deviation following a steam generator replacement which included a new main feedwater pump impeller resulting in a larger differential pressure across the MFRVBV. The plant was placed in the test condition at approximately 7% reactor power. At that point, oscillations occurred in the steam generator level control circuitry. Following full shut demand swings of the MFRVBV, the BOP operator observed that "C" MFRVBV (1FW-198) had a 20% open demand but indicated shut (singular green light) on the associated status light box valve position indication and that "C" SG had a lowering level trend by MCB level indication. The MFRVBV for "A" and "B" SGs were responding as expected to Manual/Automatic (M/A) station demand signal. With "C" MFRVBV controller at 100% open and the valve indicating full shut, the BOP reactor operator placed the "C" MFRVBV controller in manual. The USCO entered plant procedure AOP-010, Feedwater Malfunctions. The operator cycled the controller from 100% to 0% and back to 100% but the valve did not respond as evidenced by full shut indication on the main control board and lowering level in "C" SG. The MCR staff used the guidance of plant procedure GP-005, Power Operation (mode 2 to mode 1), to place "C" Feedwater Regulating Valve in service to recover "C" SG level.

In accordance with the operations pre-job brief, when "C" SG level decreased to 30%, the USCO ordered a manual reactor trip. The manual trip was successful. Reactor trip due to low SG level occurs automatically at 25% level.

HNP investigated the cause of the malfunction of 1FW-198. The most probable cause of the malfunction of 1FW-198 was determined to be an intermittent airflow obstruction in the current-to-pneumatic converter(I/P). Operating experience review showed numerous events where the I/P experienced intermittent failures. The "C" MFRVBV is the only one of the three MFRVBV to still use a Masoneilan model # 8005A I/P, which has no internal air filter, increasing the potential for contaminants to disrupt operation. HNP concluded that replacing the Masoneilan model # 8005A I/P with a Masoneilan Model 7000 I/P would reduce the probability of this failure from reoccurring.

FACILITY NAME (1) DOCKET LER NUMBER (6) PAGE (3) Harris Nuclear Plant, Unit 1 05000 YEAR SEQUENTIAL NUMBER REVISION 1111R/11:MO 3 � OF � 3

II. CAUSE OF EVENT

I/P converter for "C" FRV Bypass Valve to an internal blockage of air.

identifies the MFRVBV safety function is to Isolation Signal and is required to be a condition whereby a MFRVBV failed of the valve. The reactor trip was occurred as a result of the reactor System automatically actuated following the The Auxiliary Feedwater System remained heat sink makeup capability. Therefore, This condition is being reported in System Actuation.

Model 7000 I/P.

start up following a refueling outage, MFRVBV from the main control board.

board. The I/P Converter for this air- in the metering tube. The most probable foreign material in the air system related to was cleaned and reinstalled and the valve are designed to prevent recurrence event.

Component Failure: Component degradation. The (1FW-198) experienced a failure attributed

III. SAFETY SIGNIFICANCE

HNP Final Safety Analysis Report section 7.7 shut in 10 seconds or less on a Main Feedwater operable in modes 1 through 4. This event describes shut and that is the safety-related position successful and no significant adverse conditions trip. Additionally, the Auxiliary Feedwater trip as expected for the plant conditions.

available during and after the event to provide this event is not considered safety significant.

accordance with 10 CFR 50.73(a)(2)(iv) � as a

IV. CORRECTIVE ACTIONS

Replaced the I/P on "C" MFRVBV with a Masoneilan

V. PREVIOUS SIMILAR EVENTS

On December 22, 1989, with HNP preparing to operators attempted to open the "B' steam generator The MFRVBV would not open from the main control operated valve was found to have an obstruction cause of this failure was determined to be outage related maintenance. The metering tube was tested satisfactorily.

The corrective actions identified in this report of problems of the type identified in this