ML20153H084

Special Rept:On 980925,inadequate Procedure Implementation Resulted in Possible steady-state Reactor Operation at 2.02 MW Thermal Power.Interim Reactor Manager Reviewed Calorimeter Data & Did Not See Any Obvious Errors

ML20153H084
Person / Time
Site:	University of Michigan
Issue date:	09/28/1998
From:	Simpson P MICHIGAN, UNIV. OF, ANN ARBOR, MI
To:	Michaels T NRC (Affiliation Not Assigned)
References
NUDOCS 9809300303
Download: ML20153H084 (2)

Text

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, SEP-28-98 05:15 PM PHOEHlX LAB 51595615"i"1 P.02

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1. MICHIGAN MFMORIAL PHOCNix TWOltC1 PHOCNik MEMORI AL LAt)OR ATORY rORD NtJCirAR RLAcTOR ANN ARROR. MICHICAN 3510 N iOO I

September 28,1998 l Theodore S. Michacts. Senior Project Manager U.S. Nuclear Regulatory Commission Non Power Reactors and Decommissioning Project Directorate Division of Reactor Program Management Office of Nuclear Reactor Management Washington, D.C. 20555-0001 Re: Reportable Occurrence No. 20. Inadequate Procedure Implementation Resulting in Possible Steady State Reactor Operation at 2.02 MV lermal Power.

Description of Event On Friday, September 25,1998 at 18:39 the Ford Nuc! car Reactor was started up in l preparation for 2 MW operation following a three week shutdown. At 19:29 reactor power l was increased from low power to a nominal 1 MW (50% on the 2 MW range of the Linear 4 Level channel) and the reactor placed in autoinatic control for a calosimetrie determination core thermal power, OP- 106.

The calorimeter was completed and analyzed to detennine the true 1 MW Linear Level ,

conttel setpoint at approximately 20:51. At 20:58 the setroint for automatic control was  ;

reduced from 50% to 49% to bring the true reactor power to 1 MW as determined by the calorimeter. The Assistant Manager for Operations was contacted and permission was granted to increase teactor power to 2 MW.

Power was increased and at 21:12 the reactor was put into automatic conuol at a Linear Level channel setpoint of 999. The calorimeter procedure indicated that the proper Linear Level automatic control setpoint should have been 987c.

At appioximately 23:30 the Interim Reactor Manager visited the Control Room to check on progress piior to leaving the facility. The Lead Reactor Operator b:ought to the Managei s attention that he beliesed the power level to be low. He felt this was the case because the primary coolant AT across the core was significantly less than what would be expected at 2 MW. The AT was 12.78"F at 23.00. The 2 MW core AT at the cuirent flow condition of 1000 gpm is expected to be approximately 13.SoF. In, addition a physical adjustment to the position of Safety Sptem Power Level channel ion chambers lad been required. The adjustment was needed to bring the Power Level channel's indicated power level up to the 2 MW operating band of 2 0 to 2.1 indicated power. A physical adjustment to the ion chamber positions had not been anticipated. 'lhere wcic no changes to the core configuration or maintenance performed on the Power Level channels that would have j affected their indicated powes to the extent of requiiing a physical adjustment to their i position subsequent to the last reactor operation at 2 MW on September 1.

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',:[/' ' D The interim Reactoi .%oiaget ieviewed the calorimeter data and did not see any obvious errors. He told the Lead Operator to maintain the current power level conecting for shim 9809300303 980928 PDR ADOCK 05000002 S PDR nwe en4, resmo raun4,m mi www om.ch edu/~mmpp/

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SEP-28-98 05:14 PM PHOEHIX_ LAB 3139361571 P 03

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, . I rod shadow and that the discrepancy would be investigated Monday,9/28. The Interim Reactor Manager was not informed at the time nor was he aware of the 1% "coirective" action already taken by the Lead Operator when power was increased from 1 to 2 MW at 2 t:12.

Saturday morning September 26, the Assistant Manager for Operations icviewed the calonimeter data with the intent of setting the target operating band for the core AT. It was at this point that he noticed the in correct Linear Level setpoint (99% instead of 98%) that had been initially established for 2 MW at 21:12 on September 25. At 10:47 the Assistant Manager of Operations lowered the Linear Level setpoint 1% to compensate for the prior error and contacted the Interim Reactor Manager to discuss the event and determine what additional actions should be taken.

The reactor may have been operated between 21:12 Friday, September 25 and 10.47 Saturday, September 26 at a steady-state power level of 2.02 MW thermal in violation of the licensed powei level of 2.0 MW thermal.

Safety Significance The safety significance operating at 2.02 MW thermalis minimal. The FNR SAR shows a steady-state power level of 4.68 MW at the minimum primary coolant flow of 900 gpm and 18 feet of pool head is required before boiling will occur in the hot channel.

Immediate Corrective Action Upon discovery Saturday of the error made in the Linear Level channel setpoint on Friday reactor power was reduced by 1% to compensate.

Sincerely,

/f FIiip A. Sim d7N%

Interim Reactor Manager I

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