PNO-V-89-021, on 890330,control Rod 5 Failed to Insert on Manual Scram Following Anomalous Reactivity Indications During Calibr.Caused by 2-inch Spacer Between Connecting Rod & Control Rod Not Included When Drive Assembly Changed

PNO-V-89-021:on 890330,control Rod 5 Failed to Insert on Manual Scram Following Anomalous Reactivity Indications During Calibr.Caused by 2-inch Spacer Between Connecting Rod & Control Rod Not Included When Drive Assembly Changed

ML20244C111
Person / Time
Site:	General Atomics
Issue date:	04/03/1989
From:	Garcia E, North H NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
To:
References
PNO-V-89-021, PNO-V-89-21, NUDOCS 8904200052
Download: ML20244C111 (1)

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' PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE - PN0-V-89-21 Date: 04/3/89

This preliminary notification constitutes EARLY notice of events of POSSIBLE safety or

_public' interest significance. -The information presented is as-initially received without verification'or evaluation and is basically all that is known by Region V staff on this'date.-

FACILITY: General Atomicsu Emergency Classification San Diego.: California Notification of Unusual Event:-

- Docket,No. 50-163' Alert Site Area Emergency General Emergency X Not Applicable

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SUBJECT:

CONTROL R00 FAILURE TO INSERT ON MANUAL SCRAMc On March 30, 1989, at 6:50 P.M. PST, the licensee initiated a manual scram of the TRIGA ,

1 Mark-F reactor.following anomalous-reactivity. indications during calibration'of control rod number 5'fo110 wing change ~out of the drive assembly. Control rod 5 failed to insert; The reactor operator gently twisted the connecting rod and the rod immediately inserted;

Subsequent investigation by the licensee' determined that when the drive assembly had-been changed, a two inch spacer between the' connecting rod and the control portion of the rod-was.not included.

The Genera 1' Atomics TRIGA Mark F reactor is different from other IRIGAs in that it has five standard control rods and no transient ' control ' rod. The control portion of the rods are 13 inches long.instead of the standard 15. A two inch aluminum spacer

';batween the connecting rod and control portion is used to accommodate for the travel

, difference. ' This: spacer was missing-from the drive assembly.

LThe licensee has verified that the other four control rod assemblies have the. required spacer.' Other corrective actions include modifying the procedure for changing the

. drive' assembly'to. include a step requiring verification that-the~ spacer is in. place and adding spacers to all spare connecting rods. The licensee, manufacturer of the

)TRIGAreactors,dcesnotbelievethatanyotherTRIGAhasthemodified13inchcontrol ,

' rods;with' spacers.

' This information is current .as of 8:30 A.M. PST, April 3,1989.

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' CONTACT: Harry North (463-3762) or Emilio Garcia (FTS 463-3750)

. l DISTRIBUTION BY 5520: FAX T0: . .

l Date: 4-03-89 Date 4-03-89 Time-10:i5 AM l Chairman'Zech EDO RI INP0 ,

l Comm.. Roberts AE0D RII NSAC

.V l Comm. Carr PA0 RIII LICENSEE

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Comm. Rogers SLITP RIV RESIDENT INSPECTOR ,4)M J

' Com. Curtiss NRR HQS. OPERATIONS OFFILEn

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-ACRS RES- D0T: (Trans. Only, Applicable State)

A 8904200052 890403

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