ML20154F702

Special Rept:Positive Moderator Temp Coefficient Measured Above Tech Spec Limits.Rod Withdrawal & Boron Concentration Limits Established to Prevent Moderator Temp Coefficient from Becoming Positive

ML20154F702
Person / Time
Site:	Millstone
Issue date:	02/03/1986
From:	Romberg W NORTHEAST NUCLEAR ENERGY CO., NORTHEAST UTILITIES
To:	Murley T NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
MP-8685, NUDOCS 8603070509
Download: ML20154F702 (2)

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d February 3, 1986 MP-8685 Dr. Thomas Murley U. S. Nuclear Regulatory Commission Regional Administrator Region 1 631 Park Avenue King of Prussia, PA 19406

Reference:

Facility Operating License No. NPF 49, Docket No. 50-423

Dear Dr. Murley:

Positive Moderator Temperature Coef ficient This Special Report is being submitted within ten days pursuant to plant Technical Specification 3.1.1.3, Action a.3 and 6.9.2. Plant Technical Specification 3.1.1.3 required a Moderator Temperature Coefficient less positive than 0 Ok/k/0F for the All rods withdrawn beginning of cycle life (BOL), hot zero THERMAL POWER condition.

During the performance of startup physics testing a Positive Tempera ture Coefficient was measured for the Millstone Unit 3 Nuclear Power Plant. Measured values are as follows:

RCS ITC MTC Control Rod Position Boron Concentration

-1.03 + 0.92 All SHUTDOWN Banks Out 1570 All Control Banks Out

-2.5 .55 Control Bank D Fully Inserted 1502 ppm All other Control and Shutdown Banks Fully Withdrawn

-6.07 -4.12 Control Banks C and D Fully inserted 1383 ppm A!! other Control and Shutdown Banks Fully Withdrawn To prevent the Moderator Temperature Coefficient from becoming positive, Rod Withdrawal Limits and Boron Concentration Limits have been established.

These limits were established in accordance with the fuel vendors recommendations and include a 1 pcm/0F conservatism. It is estimated that the average core burnup at which time the Moderator Temperature Coefficient will be negative for the All rods out Xenon free condition is $570 MWD /MTU.

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r The licensee contact for this Special Report is David McDaniel and may be reached at (203) 444-4339.

Yours truly, NORTHEAST NUCLEAR ENERGY COMPANY

/ u (Jfy "n Wayne D. Rombe

• Station Superintendent Millstone Nuclear Power Station WDR/DM:sc I

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