ML20039G291
| ML20039G291 | |
| Person / Time | |
|---|---|
| Site: | Susquehanna  |
| Issue date: | 12/30/1981 |
| From: | Curtis N PENNSYLVANIA POWER & LIGHT CO. |
| To: | Haynes R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, PLA-985, NUDOCS 8201150505 | |
| Download: ML20039G291 (6) | |
Text
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M3 Pennsylvania Power & Light Company Two North Ninth Street
- Allentown, PA 18101 + 2151770 5151 Norman W. Curtis Vice President-Engineering & Construction-Nuclear c) 215/ 770-5381
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D December 30, 1981 ggg Mr. R. C. Haynes Director, Region I 9_
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U. S. Nuclear Regulatory Commission g gtgg,tgy gggggg 631 Park Avenue pcuan amERW I!!
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SUSQUEHANNA STEAM ELECTRIC STATION FINAL REPORT ON A DEFICIENCY INVOLVING LIMITORQUE LIMIT SWITCH ROTORS AND TORQUE SWITCHES ERs 100450/100508 FILE NOS. 821-10/840-4 PLA-985
Reference:
PLA-915 dated August 27, 1981
Dear Mr. Haynes:
This letter serves to prcvide the Commissicn with a final report on the deficiency involving Limitorque valve operator limit switch rotors and torque switches.
This deficiency was originally reported by telephone to Mr. L. Narrow of NRC Region I by Mr.
A.
Sabol of PP&L cn July 13, 1981. The referenced letter provided the Commission with an interim report on the subject deficiency.
The attachment to this letter contains a description of the problem, its cause, safety implications, and corrective action taken and planned. This information is provided pursuant to the provisions of 10 CFR 50.55(e).
Since the details of this report provide information relevant to the reporting requirements of 10 CFR 21, this correspondence is considered to also discharge any formal responsibility PP&L may have in compliance tnereto.
de trust the Commission will find this report to be satisfactory.
Very truly yours, f
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ydtwvN N. W. Curtis Vice President-Engineering & Construction-Nuclear JS:sab Attachment
$$821883fo!bbSh?g scQ
. SSES PLA-985 December 30, 1981 ERs 100450/100508 File 821-10/840-4 cc:
Mr. Richard C. DeYoung (15 copies)
Director-Office of Inspection & Enforcement U. S. Nuclear Regulatory Commission Washington, D.C.
20555 Mr. G. Mcdonald, Director (1)
Office of Management Information & Program Control U. S. Nuclear Regulatory Commission Washington, D.C. 20555 Mr. Gary Rhoads U. S. Nuclear Regulatory Commission P.O. Box 52 Shickshinny, PA 18655 l
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ATTACHMENT TO PLA-985 FINAL REPORT Subject Limitorque Limit Switch Rotors and Torque Switches Description of Problem A problem has been identified with the Melamine material limit switch rotors and torque switches on Limitorque valve operators. This material is used on valve motor operators both inside and outside of primary containment. The limit switches are valve position switches which are used for the control of the valve operator and for indication of valve position. The torque switches are used for a backup to the limit switch, or for control of the valve operator when valves are required to be opened or closed on predetemined Values of torque.
Cracks have been found which extend half way through the melamine limit switch
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rotors weakening them to the extent that they are easily broken. The torque switches have exhibited large cracks around the mounting screws and also have been observed to fail at the pin on the rotor shaft which engages the adjustment cams on the torque
' switches. The pins have been shearing off, thus disabling the torque switch.
Cause A cracked limit switch rotor was returned to the Limitorque Corporation for their evaluation.- The material supplier performed an analysis on the limit switch _ rotor which indicated that the composition of the melamine material was correct and the cracks were therefore not attributable to defective melamine.
Limitorque did state that the melamine material does have a tendency to crack during the post mold shrinkage period. _However, the cracks identified at Susquehanna are deeper than a normal shrinkage crack.
Limitorque could not determine a specific cause for the cracks in the melamine material.
Safety Impact 1
The limit switch and torque switch are used to control the safety related valve operations in various safety systems. The melamine material in these switches has exhibited cracking to an extent that can cause the failure of safety related valves to perform their safety functions and thereby adversely affect the safe operation of the plant. Consequently this condition is considered reportable under the provisions of 10 CFR 50.55(e).
Corrective Action PPr.L-Nuclear Plant Engineering has determined that the melamine is not a suitable material for use in this application with the current manufacturing process.
Page 1 of 2 i
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l ATTACHMENT TO PLA-985 The corrective action will be to replace all melamine material limit switch rotors and torque switches with components made of fibrite material which Limitorque Corp. has indicated is suitable for primary containment service.
Bis work is being tracked by Startup Technical Procedure TP 2.26 for Unit 1 and Common Systems, and Bechtel Field Procedure FP-E-ll for Unit 2 equipment.
Valve operators that have had their tcrque switches and limit switch rotors replaced will be included in the PP&L Program for assurin,g proper environmental qualification of Class IE equipment.
Page 2 of 2
Form 8.1.2 A
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NDI-QA-8.1.2 T's
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Pags 12 of 12 Oct. 10, 1980
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A. R. Sabol, Manager-NQA f
4 SU3 JECT:- Potential Reportable Defacts & Non Coupliance g'p4
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System / Component:
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References:
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G Drawing No.:
Various Spec. No.:
P.O. No.:
All PQ for Limitorque Procedure No.:
TP 2.26 Regulation:
10CFR50 Other:
3.
Descripticn of Deficiency or Defect; Durine implementation of TP 2.26 2
for Limitoroue Operator rework it was discovered chat the ninetic nin on the toroue switch for the SMB-000 and SMB-00 has been shenrine off
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which causes the toroue switch to be innoerative.
This has been corrected b by Limitorque bv making the new SMB-000 switch with a mern1 nin nnd,, cine a different design on the SMB-00.
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Signed:
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'Date Initial: O,
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-Funcrional Un19 Manager Dispo.,2. tion Serial No.:
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Date poTF: /9 pro ble74. W Method rwt*<fc/ h kAc b & "P*n ve rbstly{im ps ovi.ltd m B.I.2A & 9I43-i.de en B.
Evaluation Committee Convened
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Date 7-J-8/
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Reportable.o NRC 1.
(a) 10CFR21 (b) 10CFR50.55(e)
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.t. R. Sabol, Manager-SQA 34
. "3JZCT: ?::2ntial Reper:able Defe::s. Son Cor.;_iance RECEIVED S
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- ,yste:/C =ponent:
150/HV-E51-lF084 HV-E51-1F046
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2.
Apprepria:e
References:
N Q A SECTION Drawing Ko.:
P&ID M150 & M149 Spec. No.:
?.0. No.:
1F084 P015BC, 1F046 P015A Procedure No.:
TP 2.26 Regulation:
10 CFR 50 Other:
9 3.
Descrip; ion of Daficiency or Defe ::
In valve HV-E,51-lF084 cracks were noted in the grey material of the limit switch rotors. These cracks were found to extend half way through the rotor and weakened it to the extent that it was easily broken. The torque switch removed from valve HV-E51-lF046 exhibited similar large cracks around one of the mounting screws. All parts have subsequently been replaced. Reference QAAR C-81-59.
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Initial:
Functional U:}l: Ma:iager
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Disposition Serial No.:
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Previously Reported to NRC.
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Date
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Method B.
Evalu; icn Cc=.ittee Convened
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Date C.
Repor:able to NRC 1.
(a) 10CFR21 (b) 10CFR50.55(e)
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Verbal Cc=unica:icn Individual AA, S. 6, /
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