ML20043G093

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LER 90-006-00:on 900511,average Power Level Exceeded Licensed Limit by Approx 1.64 MW When Cleanup Sys Placed in Svc W/O 7.84 MW Loss Added Into Heat Balance Calculation. Caused by Personnel Error.Procedures changed.W/900608 Ltr
ML20043G093
Person / Time
Site: Oyster Creek
Issue date: 06/08/1990
From: Cervenka P, Fitzpatrick E
GENERAL PUBLIC UTILITIES CORP.
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-90-006, LER-90-6, NUDOCS 9006190044
Download: ML20043G093 (5)
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GPU Nuclear Corporationi 8{ Post Office Box 388 ' Route 9 South Forked River, New Jersey 087310388 > 609 971 4000 -l Writer's Direct Dial Number:  ; June 8, 1990 f 4 U.S. Nuclear Regulatory Commission f ATTN Document. Control Desk  ; Washington, DC 20555 

                 - Dear Sir

Subject:

Oyster Creek Nuclear Generating Station

  • Docket No. 50-219 Licensee Event Report This letter. forwards one (1) copy of Licensee Event Report'(LER) No. 90-006.

Very truly yours, . C E. E. Fitz trick Vice President & Director 

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Enclosure , 

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U.S.. Nuclear Regulatory Commission 475 Allendale Road King of Prussia,.PA 19406 Mr. Alexander W. Dromerick U.S. Nuclear Regulatory Commission LWashington, DC 20555 NRC, Resident Inspector Oyster Creek Nuclear Generating Station Forked River, NJ 08731 9006190044 900608 < PDR ADOCK 05000219 S PDC g GPU Nuclear Corporation is a subsidary of General Public Utilities Corporation N 

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The cause of this occurrence is personnel error. This activity was not controlled by plant procedures and the individuals involved did not ensure adequate controls were estab1Lahed to control the evolution. Procedure changes will be made to ensure that the computer inputs to the heat balance are adequately controlled. ge.. see 

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0l016 - Op o12 0F 0 lh Tert e a== anse a summum one asumme mac asse asaw nn Date of Occurrence The condition was discovered on May 11, 1990 at approximately 2330 hours, i Identification of Occurrence on May 11, 1990, the plant was operated above the licensed steady state power level of 1930 megawatts thermal, as averaged over an eight hour shift. This condition is prohibited by the Technical Specifications and is reportable in accordance with 10CFR50.73.A.2.i.B. l. Conditions Prior to the Occurrence On May 9, 1990 the plant was operating at full power and preparations were underway to remove the Cleanup System from service for component testing. The Minimum Critical Power Ratio (MCPR) was at 92.8% of its limit. The Maximum Average Planar Linear Heat Generation Rate (MAPLHGR) was at 81.6% of its limit. Description of Occurrence On May 9, 1990, at approximately 2235 hours the Cleanup System was taken out of service. The Shift Technical Advisor on duty conferred with the Group Shift Supervisor (GSS) as to whether an adjustment should be made to the heat balance. to account for the removal of the Cleanup System (EIIS-CE). The Cleanup System operation requires an adjustment to the heat balance calculation of 7.84 

                    , megawatts thermal to account for system losses. When the Cleanup System is out of service 7.84 thermal megawatts can be subtracted from the heat balance calculation. .This allows reactor power to be increased by an equivalent amount without exceeding maximum power limitations. After discussion, the CSS                                                         1 concurred with the adjustment, and the Shift Technical Advisor (STA) removed j                      the Cleanup System input to the heat ba, lance on the plant computer (CFI-CPU).

I On May 11, 1990, at 1325 hours, reactor power was reduced in anticipation of placing the Cleanup System back into service. At 1400 hours the cleanup System was placed into service and at 1445 reactor power was returned to near full power. The reactor was operated at or near full power for the next nine and a half bours without the appropriate adjustment (7.84 megawatts) added to the heat balance calculation. {- 

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At 2330 hours, the Shift Technical Advisor on duty (different from the original) recognized that the cleanup System was not accounted for in the heat ~ balance calculation and immediately informed the GSS. The appropriate adjustment was made to the heat balance.and reactor power was reduced accordingly. The average power level for the nine and a half hours after the Cleanup System was returned to service was approximately 1923.8 megawatts, uncorrected. Corrected this equates to 1931.64 megawatts, which exceeds the license limit of 1930 megawatts. 

  ?                                         Accarent Cause of Occurrence The cause of this occurrence is attributed to personnel error while performing an activity not covered by plant procedures. The activity of adjusting the heat _ balance calculation is not covered by plant procedures. The Group Shift Supervisor and the Shift Technical Advisor discussed the evolution and agreed that it.was proper and appropriate to make the adjustment. These individuals
              ' failed to ensure-that adequate controls were put in place to re-adjust the heat balance calculation prior to placing the cleanup System back into service. The STA did make a log entry noting the heat balance adjustment, however this in itself did not provide a means to control the evolution. Existing controls such as-a temporary procedure change or equipment controls were available; however they were not utilized.

Analysis of Occurrence and Safety Assessment 

              'The' safety significance of the event is considered minimal as the power level averaged only 100.08% and because of the available margins to the thermal' operating limits. Even if the power le, vel averaged 1930 megawatts during the nine and a half hour period, the corrected power-level would only be 1937.84 megawatts or 100.4%. The actual average power level over the nine and a half hour period was approximately 1931.64 megawatts (corrected) or 100.08%.                               The
              ~ Loss of) Coolant Accident (LOCA) analysis is performed assuming 102% of rated power. -There was ample margin to the Maximum Average Planar Linear Heat Generation Rate (MAPLHGR) limit (18%). A review of analyzed transient responses,, indicates that operation of the reactor at a power level of 1931.64 megawatts would have had virtually no effect on transient response and therefore would not have caused a safety limit to be exceeded. There was added protection due to the 7% margin to the operating limit critical Power Ratio (CPR).

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Oyster Creek, Unit 1 tort o ses .. mic w asmawim o l5 l0 lo lo l 2l1l 9 9l0 -- 0l0l6 - 0l 0 0l4 0F 0 lh l porrective Action Procedure changes will be made to ensure that the computer inputs to the heat balance are adequately controlled. l This Licensee Event Report will'be issued as Required Reading for licensed personnel and Shift Technical Advisors. The purpose of the Required Reading is j to reinforce that approved methods of equipment control must be utilized when~ l performing activities that are not specifically addressed in plant procedures. [ i i; 

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