05000338/LER-1981-034-03, /03L-0:on 810627,quadrant Power Tilt Ratio Indicated Tilt in Excess of 1.02 During Power Escalation. Caused by Control Rods Being Inserted Lower in Core than Desired While Increasing Reactor Power to 100%

/03L-0:on 810627,quadrant Power Tilt Ratio Indicated Tilt in Excess of 1.02 During Power Escalation. Caused by Control Rods Being Inserted Lower in Core than Desired While Increasing Reactor Power to 100%

ML20009G039
Person / Time
Site:	North Anna
Issue date:	07/22/1981
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20009G035	List: 05000338/LER-1981-034, Forwards LER 81-034/03L-0 05000338/LER-1981-034-03, /03L-0:on 810627,quadrant Power Tilt Ratio Indicated Tilt in Excess of 1.02 During Power Escalation. Caused by Control Rods Being Inserted Lower in Core than Desired While Increasing Reactor Power to 100%
References
LER-81-034-03L-02, LER-81-34-3L-2, NUDOCS 8108030271
Download: ML20009G039 (2)

LER-1981-034, /03L-0:on 810627,quadrant Power Tilt Ratio Indicated Tilt in Excess of 1.02 During Power Escalation. Caused by Control Rods Being Inserted Lower in Core than Desired While Increasing Reactor Power to 100%

Event date:
Report date:
3381981034R03 - NRC Website

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U.S. NUCLEAR REGULATORY COMMISSION LICENSEE EVENT REPORT CONTROL BLOCK / / / / / / / (1)

(PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION)

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OU E DOCKET NUMBER EVENT DATE REPORT DATE EVENT DESCRIPTION AND PROBABLE CONSEQUENCES (10)

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/ On June 27, 1981, during a power escalation, the quadrant power tilt ratio was

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/ calculated and results indicated a tilt in excess of 1.02.

The maximum quadrant /

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/ tilt ratio was 1.029 as measured by the upper detectors. This event is contrary /

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/ to T.S. 3.2.4.

The core tilt was reduced to within its limit (less than 1.02)

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/ within the 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> tine limit of Action Statenent a.1.

Therefore, the health and /

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/ safety of the general public were not affected. This event is reportable pur-

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/ suant to T.S. 6.9.1.9.b.

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SYSTEM

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VALVE CODE CODE SUBCCbd COMPONENT CODE SUBCODE SUBCODE

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ACTION FUTURE EFFECT SHUTDOWN ATTACHMENT NPRD-4 PRIME COMP.

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/Z/ (21) /0/0/0/'/ (12) /Y/ (23) /N/ (24) /Z/ (25) /Z/9/9/9/ (26 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS (27)

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/ The upper quadrant power tilt was caused by control rods being inserted lower in /

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/ the core than desired while increasing reactor power to 100 percent.

Immediate /

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/ corrective action was a rod withdrawal by the operator which restored the tilt to/

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/ less than 1.02 within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />.

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FACILITY METHOD OF STATUS

% POWER OTHER STATUS DISCOVERY DISCOVERY DESCRIPTION (32)

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Periodic Testing

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8 08030271 810722 W. R. CARTWRIGHT PHONE (703) 894-5151 pl)R ADOCK 050003g8 w

a

.o Virginia Electric and Power Company North Anna Power Station, Unit #1

Attachment:

Page 1 of I Docket No. 50-338 Report No. LER 81-034/03L- 0

Description of Event

On June 27, 1981, during power escalation, the core quadrant power tilt ratio was calculated using the excore detectors per PT-23 and results indicated a core tilt in excess of 1.02.

The maximum quadrant tilt ratio was 1.029 as measured by the upper detectors.

This event is contrary to T.S. 3.2.4 and reportable pursuant to T.S. 6.9.1.9.b.

Probable Consequences of Occurrence i

The limit of 1.02 provides DNB and linear heat generation ate protection for X-Y plane power tilts. A period of two hocrs of operation between 1.02 and 1.09 is allowed by Technicial Specifi-cations to allow for problem analysis and correction.

Beyond the two hour limit, a power reduction from 100% is necessary to rein-state the margin of uncertainty for FQ.

There was no effect on the safe operation of the plant as the tilt was reduced to within the limits before the time allowed by the Action Statement expired. Thus, at no time was the health and safety of the general public affected.

Cause of Event

(

ihe upper quadrant pos it was caused by having the control rof.s inserted lower in the core than desired while increasing reactor poser to 100%.

Immediate Corrective Action

After the presence of the tilt was determined, the control room operator witLdrew control rods which reduced the tilt to 1.009 within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />.

Scheduled Corrective Action No scheduled corrective action is required.

Actions Taken to Prevent Recurrence No further actions are required.

Generic Implications There are no generic implications associated with this event.

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