05000260/LER-1984-001, :on 840108,during RCIC Flow Testing,Rcic Failed to Reach Rated Flow in Required 30 S.Caused by Probable Setpoint Drift.Electronic Governor Control Sys Recalibr

:on 840108,during RCIC Flow Testing,Rcic Failed to Reach Rated Flow in Required 30 S.Caused by Probable Setpoint Drift.Electronic Governor Control Sys Recalibr

ML20079R421
Person / Time
Site:	Browns Ferry
Issue date:	01/27/1984
From:	Jones G, Jacqwan Walker TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF ADMINISTRATION (ADM)
References
LER-84-001, LER-84-1, NUDOCS 8402020222
Download: ML20079R421 (3)

LER-1984-001, on 840108,during RCIC Flow Testing,Rcic Failed to Reach Rated Flow in Required 30 S.Caused by Probable Setpoint Drift.Electronic Governor Control Sys Recalibr

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(v), Loss of Safety Function
2601984001R00 - NRC Website

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During performance of flow testing of the Reactor Core Isolation Cooling (RCIC)

System, the operator observed that the RCIC failed to reach rated flow in the required 30 seconda.

Investigation revealed that the offset voltage signal supplied by the Electronic Governor Series M (EG-M) control box to the Electronic l

Governor Series R (EG-R) actuator was not within specified calibration limits l

during automatic initiation of RCIC. During calibration the electronic governor control system (consisting of the ramp generator, signal converter, and EG-M), was found to be outside calibration limits. During the last calibration of the electronic governor controls (approximately one year ago), the offset voltage was set at the extreme upper limit of calibration and the voltage drifted up.

The most probable cause for the failure of RCIC to attain rated flow within the specified 30-second time period is setpoint drift. The RCIC electronic governor control system (consisting of the ramp generator, signal converter, and EG-M control box), was recalibrated and RCIC returned to service.

This event is considered to be a random failure and no further recurrence control is planned.

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w we r-- assamm Unit 1 was at 63 percent power; Unit 3 was in cold shutdown for a refueling outage with all fuel removed from the vessel and in the spent fuel storage pool; Unit 2 was operating normally at 72 percent power. The Reactor Core Isolation Cooling (RCIC) system (BN) is unitized at Browns Ferry and only unit 2 was affected by the event.

At 1213 on January 8, during performance of the regular quarterly RCIC system flow test, the RCIC failed to reach rated flow in the required 30 seconds.

(Time to rated flow was 40 seconds.) Investigation revealed that the offset voltage signal supplied by the EG-M control box (SCO) to the EG-R actuator (TD) was not within specified calibration limits during automatic initiation of RCIC.

During the last calibration of the electronic governor controls, the offset voltage was set at the extreme upper limit of calibration and the voltage drifted up.

The most probable cause for the failure of RCIC to attain rated flow within the specified 30-second time period is setpoint drift. The EG-R actuator and EG-M control box Model Number B8270-957, are manufactured by the Woodward Governor Company.

The electronic governor control system was recalibrated per EMI-37 and RCIC system flow test was performed satisfactorily within 9 hours1.041667e-4 days <br />0.0025 hours <br />1.488095e-5 weeks <br />3.4245e-6 months <br /> of RCIC becoming inoperable.

Setpoint drift has not caused a similar event for more than twelve months. This is considered a random event and no further recurrence control is planned.

There were no safety consequences as a result of this event. The High Pressure Coolant Injection (HPCI) System (BJ) was available and operable as a redundant system to RCIC. RCIC would have provided rated flow and pressure, but in a longer period than required by the FSAR.

Based on its design functien of providing core cooling under an isolation condition, this had no effect on any design basis accident and the availability of HPCI provided additional assurance of safe operation.

Resoonsible Plant Section - NA Previous Similar Event BFRO-50-259/81080 gag.o.-u..

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TENNESSEE VALLEY AUTHORITY 8

CHATTANOOG A, TENNESSEE 37401 1

i Browns Ferry Nuclear Plant P. O. Box 2000 t*

Decatur, Alabama 35602 January 27, 1984 U. S. Nuclear Regulatory Commission Document Control Desk WashJngton, D. C.

20555

Dear Sir:

TENNESSEE VALLEY AUTHORITY - BROWNS FERRY NUCLEAR PLANT UNIT 2 - DOCKET NO. 50-260 - FACILITY OPERATING LICENSE DPR REPORTABLE OCCURRENCE REPORT BFRO-50-260/84001 The enclosed report provides details concerning RCIC failed to develop rated flow within specified time.

This report is submitted in accordance with 10 CFR 50.73 (a)(2)(v).

Very truly yours, TENNESSEE VALLEY AUTHORITY f

Ji&*

,4. T. Jones G

Power Plant Superintendent Browns Ferry Nuclear Plant Enclosure oc (Enclosure):

Regional Administrator U. S. Nuclear Regulatory Commission Office of Inspection and Enforcement Region II 101 Marietta Street, Suite 2900 Atlanta, GA 30303 NRC Inspector, Browns Ferry Nuclear Plant I

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An Equal Oracrtunity Emp! oyer