ML20080S874

Final Deficiency Rept,Item 89 Re Reactor Controls,Inc Control Rod Drive Installation Measurements.Initially Reported on 830311.Caused by Measurements Recorded Incorrectly or Measurements Exceeding Tolerance

ML20080S874
Person / Time
Site:	Fermi
Issue date:	02/10/1984
From:	Wells D DETROIT EDISON CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
89, QA-84-0080, QA-84-80, NUDOCS 8402290286
Download: ML20080S874 (2)

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February 10, 1984 OA-84-0080 Mr. James G. Keppler, Regional Administrator Region III U.S. Nuclear Regulatory Ccumission 799 Roosevelt Road Glen Ellyn, Illinois 60137

Subject:

Final Report of 10CFR50.55(e) Item on Control Rod Drive (CRD) Installation Measurcments (#89)

Dear Mr. Keppler:

This is Detroit Edison's final report involving the Control Rod Drive (CRD) installation measurements. This item was originally reported to Mr. H.M. Wescott of NRC Region III by Detroit Edison's Mr. D. Ferencz, Acting Supervisor - Construction Quality Assurance on March 11, 1983.

During the installation of the Control Rod Drives (CRD) by Reactor Controls, Inc., scxne of the measurements were recorded incorrectly, or were not taken. In addition, scme neasurements e:rceeded toler-ances as specified by drawing requirements. In one set of measure-nents, pertaining to the CRD attachment length, a dia: indicator was misread. Another error was made in measurement of the distance between the top of the uncoupling rods and the top of the spuds; the rods were in the up position instead of the required down posi-tion. No safety implications would have developed as a result of this problen.

The CRD uncoupling rod provides two functions: 1) lifts the CRD coupling plug slightly to provide a flow path for CRD cooling water; and 2) lifts the CRD coupling plug out of the spud to permit.

uncoupling of the drive frcm the blade frcrn under the vessel. Both of these functions can only be perforned when the CRD is fully with-drawn. CRD cooling water ficw is only approximately 0.3 gFm. If the uncoupling rod is too short to perform function 1), there are several leakage paths in the CRD which normally could provide this low flow rate. Even if there was zero leakage, the result would only be a high temperature drive when it was fully withdrawn. This is not a major problem since high CRD drive tmperatures are closely monitored and only increase the frequency of drive replacement. A cooling water flow path can easily be re-established by inserting the CRD one notch which would eliminate any proble:rs. If the uncoupling rod is too long, function 1) would not be affected; function 2) is only performed when the plant is shutdown and recoupling of the CRD drive to the blade is verified before a plant s$-MI 8402290286 840210 gDRADOCK05000g FEB 2 41984 TE29 10

s.,

Mr. James G. Keppler, Regional Administrator February 10, 1984 OA-84-0080 Page 2 startup. No safety implications exist whether the uncoupling rod is either too short to perform this function or too long so that coup 1-ing cannot be achieved. With a short rod, uncoupling can be per-formed frcan the top of the vessel, or if coupling cannot be per-

-formed, the drive would l>u replaced before the plant is started up.

Whether the uncoupling rod is either too short or too long, the resulting problems are ones of increased maintenance. Thus, failure to take the subject neacurenents has no safety implications.

All one hundred eighty-five (185) control rod drives have been remeasured and the uncoupling rod dimension was taken with the uncoupling rod in the required down position. In repeating the CRD attachment length measurement, the setup was altered to allow a

~ direct reading rather than interpreting a variance frcan a master reference. The activity was performed by Reactor Controls, Inc.,

under close scrutiny of Edison Field Engineering and Project Quality Assurance personnel. A total of three control rod drives exhibited uncoupling rod measurements exceeding the required tolerances or uncoupling rod distortion. (In our last report, EF2-62620, dated April 11, 1983, the number-of deficiencies was incorrectly reported.)

The deviations were &v'ented on Deviation Disposition Requests (DDRs), and dispositioned as " replace" or " rework" of the uncoupling rods. No CRD attachment length measurements were found to exceed the allowable. tolerances. As a result of this action, acceptable dimensions have been achieved for all' one hundred eighty-five (185) control rod drives.

If you.have questions concerning this matter, please contact Mr. G.M. Trahey, Assistant Director - Project Quality Assurance.

Very.truly yours,

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DAW /EHN/i t cc: Mr. Richard DeYoung, Director Office of Inspection and Enforcanent U.S. Nuclear Regulatory Ccmnission ,

Washington, D.C. 20555 Mr. Paul Byron, Senior Resident Inspector U.S. Nuclear Regulatory Ccmnission 6450 North Dixie Highway Newport, Michigan 48166