ML20084C994

AO 250-74-4:on 740218,recent Monthly in-core Detector Flux Map Found to Not Meet Requirements of Change 11 to Tech Spec for Power Level Greater than 75%.Caused by Failure to Comply W/Recent Changes in Tech Specs

ML20084C994
Person / Time
Site:	Turkey Point
Issue date:	02/27/1974
From:	Schmidt A FLORIDA POWER & LIGHT CO.
To:	Oleary J US ATOMIC ENERGY COMMISSION (AEC)
References
AO-250-74-4, NUDOCS 8304080440
Download: ML20084C994 (3)

Text

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February 27, 1974 f Mr. John F. O'I.cary, Director f, 'x Directorate of Licensing gyg s. .T 13 "

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U. S. Atomic Energy Conmission b Washington, D. C. 20545  ; O hVg \k@.,' '.-->7;{

Dear Mr. O' Leary

• , gg!gl cg' Os F ABNOIDIAl. OCCURRENCE NO. 250-74-4 FEBRUARY 25, 1974 l a 6s OCCURRENCE DATE: FEBRUARY 18, 1974 TURKEY FOINT UNIT NO. 3 Fall.URE TO FERFORM REQUIRED FUI.l. INCORE DETECTOR Fl.UN NAP A. Conditions Prior to Occurrence Unit No. 3 was operating at a load of 740 MWe (approxi-mately 950 of rated reactor power) . Reactor power had been maintained at this power level for about six hours following a controlled load increase fron 400 MWe (approximately 60% of rated reactor power) .

B. Description of Occurrence About 2:15 PM on February 18, 1974, it was determined that the recent monthly incore detector flux map did not meet the requireuent s o f Change No. 11 to the Tech-nical Specifications for operation of the reactor at power levels greater than 75% of rated reactor power. Ac-cordingly, immediate operator action was taken to re-duce load on Unit No. 3 to approximately 73% of rated reactor power in preparation for performing a full core flux map.

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Mr. John F. O' Leary, Director page 2 February 27, 1974 C. Designat ion of Apparent Cause Recently implemented changes to Turkey Point Unit Nos. 3 fa 4 Technical Specifications imposed additional surveillance requirements for operation of the reactor above 75% of rated reactor power. All of these require-ments were met except the February incore flex map did not meet the criteria specified for a full core flux map.

Therefore, operation of Unit No. 3 reactor above 75%

of rated reactor power did not comply with the recently implemented Technical Specifications.

D. Analysis of Occurrence A full core flux map was performed on Unit No. 3 reactor as soon as practical after reducing load below 75% of rated reactor power. Evaluation of the results of the full core flux map concluded that power distribution was well within acceptable limits. The specified hot channel factors, peak linear power density, radial power shapes, and axial power distribution were well within acceptable limits.

Comparison of the full core flux map with previous partial core flux maps , concluded that these surveil-lance tests were in agreement.

If an abnormal power distribution had occurred during this incident, the power range nuclear instrumentation system or the rod position indication system would have detected the condition. The operator would have been alerted to the condition by visual indication in the control room, actuation of alarms , or automatic operation of the reactor protection system. Manual operator action or automatic action by the reactor protection system would place the reactor in a safe condition and limit the effect of abnormal power distribution.

The incidents analyzed and presented in the Turkey Point Unit Nos. 3 f, 4 Final Sa fety Analysis Report assume conservative values for hot channel factors, limiting local rod power density, and power distribution. The full core flux map demonst rat ed that measured or cal-culated values for hot channel factors, local power

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Mr. John F. O' Leary, Director Page 3

_ _ February 27, 1971 density, radial power shapes, and axial power dis-tribution were more conservative than the values used in the safety analysis. Therefore, operation of Unit No. 3 reactor above 750 of rated reactor power at the time of this occurrence did not adversely affect the sa fe operat ion of the reactor or present any danger to the public health or safety.

E. Corrective Action Immediate operator action was to reduce load Thison Unit complles No. 3 below 750 of rated reactor power.

with the requirements of the recently imposed changes to Technical Specifications.

Performance of a full core flux map and evaluation of results demonstrated that reactor power distribution was well within acceptable limits.

to Precautions have been added to applicable procedures ensure that the requirements specified in the recently imposed Technical Specifications for reactor operation above 75% of rated reactor power are met.

F. Failure Data This is the first failure to nect a limiting condition for operation involving Power Distribution Limits.

Very truly yours,

(/2bbu+ b A. D. Schmidt Director of Power Resources VTC/kmw cc: Mr. Norman C. Moseley Mr. Jack R. Neuman 1

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