ML19320A045

RO 50-313/76-27:on 760914,power Level Cutoff Was Exceeded W/O Proper Xenon Reactivity Conditions.Caused by Sys Oscillation in Feedwater Control.Power Reduced & Future Will Be Decreased Before Switching Modes of Operation

ML19320A045
Person / Time
Site:	Arkansas Nuclear
Issue date:	09/28/1976
From:	Mardis D ARKANSAS POWER & LIGHT CO.
To:
Shared Package
ML19320A039	List: ML19320A038 ML19320A045
References
NUDOCS 8004140664
Download: ML19320A045 (4)

Text

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Iteportahic occurrenec Ucrort go. 50-313/76-27

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Report D.ite: 9/28 /76

. thcurrence Date

9/14/76 4

I:acility: Arkansas Nuclear One - Unit 1 Russellville, Arkansas 5.

Identification of Occurrence:

Exceeding power level cutoff (82.5%) without proper Xenon reactivity conditions per Technical Specification 3.5.2.5.4.

6 Conditions Prior to Occurrence:

Steady-State Power _ _X React 6r l' owe r _ 2055 MWth

'llut Standby Net Output 650 MWe Cold Shutdown Percent of 1 ull Power 80 Refueling Shutdown Load Changes During Routine Power Operation g

Routa,nc Startup Operation Routine Shutdown Operation Other (specify) i

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Description of Occurrence:

At 0637 hours0.00737 days <br />0.177 hours <br />0.00105 weeks <br />2.423785e-4 months <br /> on 9/14/76, the power level cutoff per Tech.. Spec. Fig. 3.5.2.lB was exceeded for three (3) minutes and Xenon reactivity was not within 10%

of the equilibrum valve. The power increase above the power level cutoff occurred when the reactor demand station of the ICS was placed in automatic following NI calibration.

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Attachuent "C"

!! arch 23, 1976 NSP-10 Itev. 4 Page 2 of 4 w-e,

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!!eportahic Occurrence 1:clinrt lui.

50-313/76-27 i

8.

1)esignation of Atiliarent Cause ol' ikcurrence:

Design l'rocedu re Manufacture Linusual Service Condition including Environmental

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Installation /

Construction Component I: allure Operator X

Other (specify)

X

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1 Due to system oscillation in feedwater control, reactor power level increased when switched from reactor demand in manual to the integrated mode of operation.

4 9.

Analysis of Occurrenec:

Due to the quick response of the operator in returning the power to below the power level cutoff, there was no hazard to the health and safety of the public.

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Reportable Occurrence I:cport sio. 50-313/76-27 10.

Corrective Action:

Power was reduced to < 82.5% power in approximately three (3) minutes.

In the future when at or near a cutoff limit, the power level will be decreased before switching modes of operation.

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Failure Data:

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Exceeding power level cutoff was also reported in Reportable Occurrence Report 50-313/76-17, but this was due to misinterpreting computer cal-

-l culation of Xenon worth.

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