ML18030A167

Final Deficiency Rept Re Cracks in Limitorque Limit Switch Rotors Originally Reported 800923.Caused by Misalignment in Holes in Limit Switch Rotor & Pinion Shaft.Cracked Rotors Will Be Replaced

ML18030A167
Person / Time
Site:	Susquehanna
Issue date:	11/19/1980
From:	Curtis N PENNSYLVANIA POWER & LIGHT CO.
To:	Grief B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
10CFR-050.55E, 10CFR-50.55E, PLA-575, NUDOCS 8011250293
Download: ML18030A167 (6)

Text

REGUI ATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR: 801.1280298 ~Steam DDC.DATE: 80/11/19 NDTAIOED:

Electric. Stationi Unit ir Pennsylva'5 ND DDCKEiT 0 FAG IL: 50 387 Susquehanna 8 50"388 Susquehanna Steam Electric Station~ Unit 2i Pennsylva 050003 8 AUTH INANE AUTHOR AFF1IL1I ATION CURTIS',ri ~ Pennsylva'nia- Power 8 LIight Co; REC IP ~ NAME RECIPIENT AFFILIATION GRIEF,B,H, Region 1r=- Phil adelphiaE Office oIf the Director

SUBJECT:

Final deficiency rept re cracks in imi torque limit switch 1 rotors originally reported 800923 per team mtg last wk, Caused by misalignment in holes in limit switch rotor L pinion shaf t Cracked rotor s wi

~ 1 1 be r epl a'ced-..

DISTRIBUTION CODE': B019S COPIES RECEIVED:L1TR + ENCL< +

TITLE: Cons't ruc t,i on Def i c i ency Repof t (10CFR50. 55EO NOTES:Send I8E" 3 copies FSAR 8 all amends, 05000387 Send ILK" 3 copies FSAR 8 all amends. 05000388 REC'IP IEN T COPIES REC IPIENTI'D COPIES ID GODET/NAME> LiTTR ENCL CODE/NAME0 LTTR ENCLl ACTION: A/D L1ICENSNG- 1- 1 YOUNGBLOODrB 05 1 1

~ Ob 04'USHBROOKgM 1 1 STARKgR ~ 07 1 INTERNAL: AD/RC I/IEl 17 1 1 AEOD 18 1 1 ASLBP/J ~ HARD 1 1 D/DIR HUM FAC15 1 1 EDO 8 STAFF'9 1 1 EQUIP QUAl.l BR 1 1 1 HYD/GKO BR 22 1- 1 ILK< 09 LIC QUALI BR 12 1 1 MPA 20 1 NRC PDR 02 1 1 OELD 21 1 1 PROC/TST REV 13 1 1 QA BR 14 1 L 01 1 1 RUTHERFORDH ~ IE 1 1 OS DEV- 21 1 1 EXTERNAL): ACRS 16 16 16 LPDR 03 NSIC 08 1 1

<Oi/ 2 t'9go

't2.

TOTAL NUMBER OFT COP~IES REQUIRED; L'TTR ~ ENCL(

n 1

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TWO NORTH NINTH STREET, ALLENTOWN, PA. 1EI01 PHONEr (215) 821-5151 bi it-ir',i~

~g"'ORMAN tlV. CJRTIS SMttiDV $4,pt,~ p Vice Presibent-Engineering tt Construction-Nuclear 821-538 I g~

November 19, 1980 US ZVC

~t" Trtr'IJ J I IPP PEgygES kgiIttt(gf Mr. Boyce H. Grier Director, Region I U. S. Nuclear Regulatory Commission 631 Park Avenue King of Prussia, Pennsylvania 19406 SUSQUEHANNA STEAM ELECTRIC STATION FINAL REPORT OF A DEFICIENCy RELATING TO LIMITORQUE LIMIT SWITCH ROTORS ERs 100450/100508 FILES 840-4/900-10 PLA-575

Reference:

PLA-547 dated September 23, 1980

Dear Mr. Grier:

This letter serves to provide the Commission with a final report og a deficiency relating to defective Limitoraue limit stitch rotors. The condition was originally reported in the abave referenced letter. The information contained herein is submitted ir. conpliance to the provisions of 10CFR50.55(e) .

The attachment to this letter contains a cKescription of the defect, its probable cause, safety impact and significazce along with a corrective action plan. The condition is being controlled @neer Bechtel Nonconformance Report 56020 and action for Unit I is scheduled =or completion by April, 1981.

We trust the Commission will find the inforration forwarded by this letter to be satisfactory.

Very truly yours, N. W. Curtis Vice President-Engineering 6 Construction-Nuclear Attachment FLW:mcb goiV 5

i/

01 3R50Ã9 PENNSYLVANIA POWER 5 LIGHT COMPANY

Mr. Boyce H. Grier November 19, 1980 cc: Mr. Victor Stello (15)

Director-Office of Xnspection 6 Enforcement U. S. Nuclear Regulatory Commission Washington, D.C- 20555 Mr. G. McDonald; Director Office of Management Information 6 Program Control U. S. Nuclear Regulatory Commission Washington, D.C. 20555 Mr. Robert M. Gallo U. S. Nuclear Regulatory Commission P. O. Box 52 Shickshinny, Pennsylvania 18655

SUB JECT Limitorque Limit Switch Rotors DESCRIPTION OF PROBLEM The limit switches on the Limitorque Valve operators are valve position switches, which are used for the control of the valve operator and for indication of valve position. The limit switch assembly consists of two stationary fingers with a moving contact between the fingers. The moving contact is part of the limit switch rotor which is geared directly to the valve operator. The limit switch rotor is made of a phenolic material and is pinned to a metal pinion shaft. As the valve operates, the limit switch rotor turns, rotating the moving contact, thereby opening or closing the limit switch contact. During the preoperational checkout of the Limitorque Valve operators, cracks were found in the limit switch rotor where it is pinned to the pinion shaft. ~

CAUSE Initially, it was believed that the rotor cracks were caused by a misalignment in the holes in the limit switch rotor and the pinion shaft. When the pin was'nsef:ted through the holes during manufacturing, it was postulated that the cracking could have occurred.

Limitorque was requested to review the rotor cracking problem and determine if it occurred during manufacturing. Limitorque responded stating t~it was not possible for the cracking to have occurred via a misalignment in the holes. During manufacturing, the rotors were molded with a 3/32" diameter hole. The rotor was placed on an undrilled pinion shaft. A 1/8" diameter hole was drilled simultaneously through the rotor and pinion shaft, using the 3/32" holes as a guide. The pin was then inserted. Misalignment of the holes, which could cause the rotor cracking, has not been a problem under this manufacturing process.

The cracks were probably caused by constmction personnel bumping the limit switch rotor, when the valve compartment cover was removed. A field inspection of sixty (60) Unit 2 valve operators has been performed. The Unit 2'alves were inspected since there is less construction activities associated with these valves. Of the sixty valves inspected, only one (1) broken rotor was observed. However, there have been numerous broken rotors identified on Unit 1 valves. This tends to confirm that the cracked rotors were caused by construction personnel, 1 ANALYSIS OF SAFETY IMPLICATIONS The limit switches are used for the cont"ol of the valve operator and for indication as to valve position. A defe"tive limit switch rotor would result in the failure of a valve to operate and/or incorrect indication of the valve position. PPaL Engineering.has determined that the failure of a limit switch rotor is a reportable deficiency under the recgxirements of 10CFR 50.55(e) .

The affected Limitorque operators are used in many systems which are required for the safe shutdown of the 'plant.

Attachment to PLA-575 Page 1 of 2

CORRECTIVE ACTION An inspection of all l safety related valves on Unit and 2 will be performed.

The inspection of the Unit 2 valves will be done after all major construction activities associated with the valve operator is completed. Cracked rotors which are identified will be replaced, and tracked by Bechtel NCR 6020.

CONCLUSION Once the inspection of the Limitorcpxe operators is ccxnplete and all cracked rotors are replaced, failure of the limit switch rotor is not expected to occur nor will the Limotorque operator be prevented from performing its intended function.

Attachment,.to PLA-575 Page 2 of 2