ML19321B190

Forwards LER 80-015/03L-0

ML19321B190
Person / Time
Site:	Cooper
Issue date:	07/02/1980
From:	Lessor L NEBRASKA PUBLIC POWER DISTRICT
To:	Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML19321B191	List: ML19321B190 ML19321B193
References
CNSS800402, NUDOCS 8007280584
Download: ML19321B190 (2)

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, 9-Cooper NUCLEAR STATroN P.o. Box 98. SRoWNVILLE. NEBRASKA 68321 Nebraska Public Power Distn.c t TELE ~o~E mu 8n-nu CNSS800402 July 2, 1980 Mr. K. V. Seyfrit U.S. Nuclear Regulatory Commission Office of Inspection and Enforcement Region IV 611 Ryan Plaza Drive Suite 1000 Arlington, Texas 76011

Dear Sir:

This report is submitted in accordance with Section 6.7.2.B.3 of the Technical Specifications for Cooper Nuclear Station and discusses a reportable occurrence that was discovered on June 6, 1980. A licensee event report form is also enclosed.

Report No.: 50-298-80-15 Report Date: July 2, 1980 Occurrence Date: June 6, 1980 Facility: Cooper Nuclear Station Brownville, Nebraska 68321 Identification of Occurrence:

Observed inadequacy in implementation of administrative or pro-cedural controls.

Conditions Prior to Occurrence:

The reactor was in the "RUN" mode at approximately 39% rated thermal power.

Description of Occurrence:

Technical Specification 4.3.C.1 was not met, in that reactor power exceeded 40% prior to the time that all centrol rods were scram time tested after a refueling outage.

Designation of Apparent cause of Occurrence:

Personnel error, in that the control room operator failed to realize that an incorrect rod was scram tested and then returned to an incorrect position.

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Mr. K. V. Seyfrit July 2, 1980 Page 2.

Analysis of Occurrence:

Control rod 14-31 is a deep control rod in rod sequence A-1 and was at position 00 while the 50% rod density sequence A-1 rods were being scram timed per Technical Spscification Section 4.3.C l.

Control rod 14-31 was incorrectly scrammed instead of control rod 14-35. After control rod 14-31 was incorrectly scrammed, it was then incorrectly withdrawn to position 48 where it remair.ed for approximately one hour before being noticed and inserted to po-sition 00 where it should have been. Prior to the withdrawal of control rod 14-31, reactor thermal power was 39% of rated thermal power; af ter the withdrawal of control rod 14-31, reactor thermal power was approximately 41% of rated thermal power. At power levels above 30% of rated thermal power, the Rod Block Monitor (RBM) System prevents rod withdrawals in high power regions of the core so that a rod withdraw] error cannot cause a power transient severe enough to damage the fuel cladding. The RBM System did not block the incorrect withdrawal of control rod 14-31 as the with-drawal of control rod 14-31 did not increase the power density in that region of the core enough to exceed the RBM trip setpoints.

Based upon this, it was deduced at the time of the incident, that no thermal limits were exceeded. Later, a BWR computer core sim-ulator case was run for control rod 14-31 at position 48; this simulator run verified all thermal limits to be well within the Technical Specification Limiting Condition of Operation values.

Additionally, there was no increase in of f-gas activity which would have been indicative of a PCIOMR failure. Thus, this occurrence presented no adverse consequences from the standpoint of public health and safety.

Corrective Action:

The rod was immediately returned to its correct position and power returned to less than 40%. The incident was immediately evaluated by the Reactor Engineer and the Operations Supervisor as described above. Scram time testing was completed and the power ascension was continued.

The event was discussed with the personnel involved. The procedure governing this evaluation was modified and this event report will be routed to all licensed operators.

Sincerely, W

L. C. Lessor Station Superintendent Cooper Nuclear Station LCL:cg_

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