ML18139A269

LER 80-026/01T-0:on 800512,during Power Escalation,Indicated Axial Flux Difference Deviated from Target Band for More than 1-h in 24-h Period.Caused by Unscheduled Boron Addition.Power Reduced to Less than 50%

ML18139A269
Person / Time
Site:	Surry
Issue date:	05/22/1980
From:	Joshua Wilson VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML18139A268	List: ML18139A267 ML18139A269 ML18139A270
References
LER-80-026-01T, LER-80-26-1T, NUDOCS 8005290453
Download: ML18139A269 (3)

Text

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J ! Dur~ng Power Escalation the indicated Axial Flux difference deviated from its target j J I band for greater than one hour in a twenty four ( 24) hour period.* In accordance with J I TS 3.12.B.4.b, power was reduced to less.than 50%. The power reduction took more J I than thirty (30) minutes which is contrary to T.S. 3.12 .. B.4.b.2 and. is reportable as J per T.S. 6.6.2.a.2. The Axial Flux Difference was returned to the band and power was J reduced, therefore the health and safety of the general public were not affected.

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J  ! The deviation was caused bv an unscheduled boron addition which initiated a ranid power reduction causing AFD to go out of the band. Power was reduced to less *than

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ATTACHMENT 1 SURRY POWER STATION, UNIT NO. 1 DOCKET NO: 50-280 REPORT NO: 80-026/0lT-0 EVENT DATE: 05-12-80 TITLE OF REPORT: AXIAL FLUX DIFFERENCE DEVIATION

1. Description of Event During an unscheduled power reduction on May 12, 1980, the Axial Flux Difference (AFD) deviated from its target band of +/-5% for greater than one (1) hour in a twenty-four (24) hour period. This is contrary to T.S.

3.12.B.4.b.l. and is reportable as per T.S. 6.6.2.b.2. In accordance with T.S., power was reduced to less than 50% and the high neutron flux setpoin~

was set at 55%. The power reduction took longer than thirty (30) minutes which is contrary to T.S. 3.12.B.4.b.2. and is reportable as per T.S.

6.6.2.a.2.

The AFD was returned to the band and power was reduced, therefore the health and safety of the general public were not affected.

2. Probable Consequences and Status of Redundant Systems Surveillance of the Axial Flux Difference assures that the limits of heat flux hot channel factor are not exceeded during normal operation or in the event of Xenon redistribution following power changes. This provided protection against exceeding the DNBR and peak fuel clad temperatures.

Provisions are made for possible deviations caused by rapid power reductions by allowing up to one hour outside the target band in a twenty-four hour period. If the AFD cannot be returned to the target band in one hour the power must be reduced to less that 50% to provide additional protection for the hot channel factors. Power was reduced and the AFD returned to its target band thereby eliminating possible violations of hot channel factors.

3. Cause The event was caused by an unscheduled boron addition which initiated a rapid power reduction causing the AFD to go out of the band. The boron addition resulted from the addition of water to the primary that had been flushing a mixed bed deminerilizer. This makeup water had a boron concentration of 1076 ppm while the RCS was 315 ppm. The boration reduced power from 95% to 80%. While stabilizing plant parameters at 80% power, the AFD deviated from the target band for greater than one hour. A power reduction was begun and the AFD was returned to its target band in forty-two (42) minutes. The reduction in power took longer than thirty (30) minutes because of the unstable plant conditions and the desire to prevent challanging safeguards with another rapid power reduction.

4; . Immediate Corrective Action The source of borated water to the makeup system was isolated. A power reduction was begun and continued until the unit was less than 50%

power. The AFD was returned to the target band during the rampdown.

ATTACHMENT 1 page 2

5. Subsequent Corrective Action Operations personnel will be reinstructed/retrained on the proper operation of flushing and returning deminerilizers to service.

6. Actions Taken to Prevent Recurrence Completion of corrective actions will prevent recurrence.

7. Generic Implications None