ML20024E907

Final Deficiency Rept Re Miscellaneous Debris in Control Rod Drive Guide Tubes.Initially Reported on 830722.Debris Removed.Third Security Guard Posted at Reactor Vessel. Deficiency Not Reportable Per 10CFR50.55(e) or Part 21

ML20024E907
Person / Time
Site:	Susquehanna
Issue date:	08/19/1983
From:	Curtis N PENNSYLVANIA POWER & LIGHT CO.
To:	Murley T NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
10CFR-050.55E, 10CFR-50.55E, PLA-1803, NUDOCS 8309070193
Download: ML20024E907 (5)

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-PP&L Pennsylv:nin Pow r & Light Comp:ny Two North Ninth Street

• Allentown, PA 18101 e 215 / T105151 August 19, 1983 Dr. Thcmas Marley Regional Administrator, Region I U.S. Nuclear Regulatory Ccmmission 631 Park Avenue King of Prussia, PA 19406 SUSQUEHANNA STFAM ELETRIC STATICN REPORP OF A DEFICIENCY INVOLVING MISPFTJANEOUS DEBRIS IN CONTROL RG) DRIVE (CRD) GUIDE 'IUBES ER 100508 FILE 821-10 PIA-1803

Dear Dr. Murley:

This letter serves to provide the Ccmnission with a report on miscellaneous debris in several Unit #2 CRD guide tubes.

This deficiency was originally reported by telephone to Mr. E. C. McCabe of NBC Region I on July 22, 1983 by Mr. J. Saranga of PP&L.

The attachment to this letter contains the results of PP&L's investigation into the subject deficiency. Based upon the infonnation provided in the attachttent, PP&L considers this deficiency not to be a reportable condition under the provisions of 10CFR50.55(e) or 10CFR21.

We trust the Ccmnission will find this report satisfactory.

Very truly yours, N. W. Curtis Vice President-Engineering & Construction-Nuclear MHC:po Attachment 8309070193 830819

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August 19,'1983 2 PIA-1803 ER 100508 FILE 821-10 Copy to:

Mr. Richard C. DeYoung (15)

Director-Office of Inspection & Enforcenent '

U.S. Nuclear Regulatory Cantnission Washington, D.C. 20555-Mr. G. Mcdonald, Director Office of Managenent Information & Program Control U.S. Nuclear Regulatory Cminission Washington, D.C. 20555 Mr. Gary Rhoads U.S. Nuclear Regulatory Cminission P.O. Box 52 shickshinny, PA 18655 Records Center Institute of Nuclear Power Operations 1100 Circle 75 Parkway, Suite 1500 Atlanta, GE 30339

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, FDEL REPORP SUBJICT:

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l Miscellaneous debris in several-Unit 2 control rod ~ drive' (CRD) guideItubes. -

DESCRIPTIW:

During final installation of' reactor internals, foreign material was found to be present in a-CRD guide tube / blade assembly. As a result, an inspection of all 185 guide tubes was performed. It was discovered that 19 of the 185 guide-tubes had debris in then. All the debris was located in the guide tubes on

. top of the velocity limiter section of the CRD blade. The debris consisted of grinding wheels (only found in 3 tubes) and such degradable matariala as-cloth, paper, string, and wood splinters.

CAUSE:

In an atteipt to determine how the debris got into the guide tubes, investigations into the source of the grinding wheels and the time period of possible debris introduction to the guide tubes were conducted. The results of. the investigation-into the grinding wheels source revealed that wheels of the type found have not been purchased for use at SSES by any group performing work at.SSES. Therefore, it is concluded the source of the grinding wheels is

' indeterminable.

The investigation into de+amining the time period of possible introduction of the debris into the tubes resulted in the conclusion that the debris was most likely intrMvwl after the blades were installed into the guide tubes (as all the debris found in the tubes was found on tcp of the velocity limiter section of the control blades). Blade installation took 16 days (5/6/83 to 5/22/83).

This installation activity included checking the guide tubes for debris prior to installation of the blades. Upon installation of the blades and at the conclusion of each work shift, the staging racks which were located on elevation 818 of the reactor building were covered with Visqueen. The racks were covered with Visqueen and sat on Elevation 818 until guide tube installation activities cmmenced 7/16/83 (cmpleted on 7/18/83). During this installation activity, the debris was accidentally discovered. Therefore, the debris was probably intr M v wl to the guide tubes after blade installation and before guide tube installation.

SAFETY IMPLICATINS:

Iwo types of debris were found - degradable materials and grinding wheels.

Based upon the nature of the degradable materials (described previously in Description), it is determined that they are not capable of adversely affecting the safe operation of the CRD assemblies, or cause damage to the reactor core.

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1he grinding wheels, however, could potentially restrict the movment of the

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control rods, thereby possibly affecting the. safe operation of the CRD aa==hlies. Failure of the control rods to insert during a scram poses a -

concern fran the standpoint of assuring sufficient shutdown reactivity to maintain reactor subcriticality following scrm. Analyses, therefore, were performed to assess core shutdown margin ===Mng that all three control rods

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are stuck in their fully withdrawn position. The calculations indicate that no degradation of core shutdown margin would result and the Technical.

Specification requirments (Tech. Spec. 3/4.1.1) would easily be' met. This is expected since the three affected control rods are radially dispersed in the core, thus resulting in relatively low reactivity _ worths.

The possibility that the debris could cause a control rod to han= stuck during withdrawal was also considered. Assuming that a control rod han = s stuck and the control rod drive becmes decoupled, the control red could at a

-later optimtun nrnent drop'out of the core. The wisiiequences of this -

postulated event is a design basis for SSES Unit #2 and the analysis for it is presented in Susquehanna SES FEAR section 15.4.9, Control Rod Drop Accident Analysis.

The possibility of all .three CRD bladaa getting stuck and dropping out of the core simultaneously was not considered as numerous systm (Rod Sequence Control System and Rod Worth Minimizer) and operator failures are needed for this to occur.

If it is postulated that the grinding wheel debris exits the CRD tubes into the reactor vesml, their effects on the fuel would also be of concern.

However, assuning the debris could make its way to the lower plenum region, passage through the lower tie plate would be inprobable due to the size of the grinding wheels steel ccuponents. Therefore, any damage 'to the fuel rods would be unlikely. Furthermore, due to the small size of the~ metal debris,

any flow blockage which may occur would be minimal and have an insignificant effect on fuel rod performance.

-In light of the above, the miscellaneous debris found in the CED guide tubes, would not, if they had gone undetected, have affected the safe operation of SSES Unit #2.

CORRECPIVE ACTICNS:

As previously discussed a 100% inspection was performed (on 7/19/83) upon identification of the debris in the tubes. This inspection was performed with the aid of flashlights, binoculars and a camera with a zoom lens (no pictures were taken). The inspection results were documented on General Electric Special Process Control Sheet (SPCS) number 219S-1, Rev. O. All debris was removed by using an aluminum pole with approved nuclear grade tape. No damage was incurred by the presence of the foreign material.

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. k - h, Upon coupletion of the 100% inspection of 7/19/83,':a third security guan!'was posted at the reactor vessel. 'Ihis guard's duties were and are to monitor all N:-

activities performed in and'around the reactor vessel during periods when - ; ,

physical work is being acomplished in the vessel. ,

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