ML20084S798

AO 50-254/75-10:on 750503,two Control Rods Withdrawn for Maint Separated by Only One Inserted Control Rod.Caused by Inadequate Procedure & Operator Error.Control Rod Drive Replacement Procedures Revised

ML20084S798
Person / Time
Site:	Quad Cities
Issue date:	05/13/1975
From:	Kalivianakis N COMMONWEALTH EDISON CO.
To:	Office of Nuclear Reactor Regulation
Shared Package
ML20084S800	List: ML20084S798 ML20084S802
References
AO-50-254-75-10, NJK-75-272, NUDOCS 8306170324
Download: ML20084S798 (3)

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NJK-75-272 ((j May 13, 1975 Di rector of Of fice of fluclear Reactor Regulation U. S. Iluclear Regulatory Commission Washington, D. C. 20555

Reference:

quad-Ci ties Nuclear Power Station Docket No. 50-254, DPR-29 Appendix A, Sections 3 3.0, 6.6.B.l.a Enclosed please find Abnormal Occurrence Report No. A0 50-254/75-10 for Quad-Ci ties Nuclear Power Station. This occurrence was previously reported to Region ilI, Di rectorate of Regulatory Operations by telephone on May 4, -

1975 and to you cod Region lil, Di rectorate of Regulatory Operations by telecopy on l'.ay 5,1975 This report is submitted to you in accordance with the requirements of Technical Specification 6.6.B.l.a.

Very truly yours, COMMONWEALTH EDISON COMPANY QUAD-CITIES NUCLEAR POUER STATION

d. 4 N N. J. Kallvianakis Station Superintendent NJK/JAS/lk cc: Region Ill, Directorate of Regulatory Operations J.S. Abel i

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s, N-i REPORT NUMBER: A0 50-254/75-i0 REPORT DATE: May 13,1975 OCCURRENCE DATE: May 3, 1975 FACILITY: Quad-Cities Nuclear Power Station Cordova, Illinois 61242 I DENTI FICATION OF OCCURRENCE :

Two control rods withdrawn for maintenance separated by only one inserted control rod.

t CONDITIONS PRIOR TO OCCURRENCE:

Unit I was shutdown with the mode switch in REFUEL.

DESCRIPT!CN OF OCCURRENCE:

lhree control rod drives (J-13, N-9, and J-15) were scheduled f or replacement during the Unit 1 outage. A test fixture was installed in the RPIS to sim-ulate a full in position signal for J-13 in order to allow the concurrent _

wi thdrawal of a second rod. On May 3,1975 at 0400 a.m. CRD J-13 was returr.ed to service but lef t at position 48. At 0831 a.m. CRD J-15 was withdrawn and taken out of service. At 1825, while returning J-15 to service, it was recognized that J-13 and J-15 were within a nine rod array and that Tech-nical Specification 3 3.D had therefore been violated. The initial action was to reinsert CRD J-13 A review of the nuclear instrumentation recorder charts (SRMs and IRMs) verified that no nuclear response had occurred.

DESIGNATION OF APPARENT CAUSE OF OCCURRENCE:

The apparent cause of this occurrence is attributed to inadequate procedure.

Although both maintenance and operating procedures for replacement of control rod drives contained no reference to the nine rod array criteria of speci-fication 3.3.D, a contributing cause of operator error must also be assigned.

ANA'.YSIS OF OCCURRENCE:

Since no observable response was indicated on any nuclear instrumentation, there were no significant consequences from the standpoint of public health '

and safety.

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\_ j A0-50-254/75-10 May 13,1975 i

3 Control rod J-15 is a peripheral rod on the west face of the core which is separated by one control cell from rod J-13 During BOC 2 startup test-ing a shutdown margin of 2.8% AK was demonstrated. At that time the full j withdrawal of two face adjacent rods and the partial withdrawal of a third adj acent rod to position 08 was required to achieve criticality in the calculated worst case. The core is calculated to become more shutdown with exposure so that the present margin is over 3% AK with the strongest "

rod out. '

Since the core was subcritical wi th two face-adjacent rods withdrawn at BOC, the May 3 configuration of two non-adjacent rods separated by a fully inserted rod would be subcritical with a wide margin. In addition the pe ri phe ra l location of J-15 further minimizes the worths involved in this 1 occurrence. Tnere were thus no adverse effects on public health & safety related to this occurrence.

CORRECTI VE ACTION:

Control Rod Drive Replacement procedures QOP 300-14 (Operating) and 45-3.13 u (Maintenance) will be revised to include references to the Specification 3.3.D limitation which allows only one rod in any nine rod array to have an inoperable accumulator and to the Specification 3.3.B.2 limitation which allows two drives to be removed only if the shutdown margin specification 3.3.A.1 is met. These requirements will also be reviewed with operating and maintenance personnel to minimize the possibility of a recurrence of -.

this incident.

i FAILURE DATA:

Since this is the first occurrence of its kind at quad-Ci ties Station, no safety implications related to cumulative experience exist.

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