ML18017A145

Forwards Final Deficiency Rept Re Cutler-Hammer E-30 Pushbutton Switches

ML18017A145
Person / Time
Site:	Susquehanna
Issue date:	04/18/1980
From:	Curtis N PENNSYLVANIA POWER & LIGHT CO.
To:	Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML17138B266	List: ML17138B265 ML18017A145
References
NUDOCS 8004300374
Download: ML18017A145 (10)

Text

~~li REGULATOR NFORMATION DISTRIBUTION TEM (RIDS)

ACCESSION NBR 8000300370 DOC ~ DATE 80/00/18 NOTARIZED NO DOCKET FACIL:50-387 Susquehanna Steam Electric Stationi Unit 1E Pennsylva 05000387 BYNAME 50 388 Susquehanna Steam Electric StationE Unit 2q Pennsylva 05000388 AUTH AUTHOR AFFILIATION CURTISi N ~ H ~ Pennsylvania Power 8 Light Co, REC IP ~ NAME RECIPIENT AFFILIATION GRIEREB ~ H ~ Region ii Phi l adelphi ai Office of the Director

SUBJECT:

Forwards final deficiency rept re Cutler"Hammer E 30 pushbutton switches.

DISTRIBUTION CODE: 10198 COPIES RECEIVED:LTR Q ENCL'IZE:~~~

TITLE: Construction Deficiency Report (10CFR50R55E)

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TWO NORTH NINTH STREET, ALLENTOWN, PA. 18101 PHONE: (215) 821.5151 NORMAN W, CURTIS Vice President Engineering 8 Construction 821-5381 April 18, 1980 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 IN CUTLER HAMMER E-30 SWITCHES ERs 100450/100508 FILE 840-4 PLA-472

References:

PLA-399 dated 09/11/79 PLA-409 dated 10/ll/79 PLA-438 dated 01/11/80

Dear Mr. Grier:

This letter serves to provide the Commission with a final report of a deficiency on Cutler Hammer E-30 switches originally reported and discussed in the above listed references. In addition, notice is given that another condition involving Amphenol connectors discussed in the referenced letters has been evaluated by Bechtel and PPSL Engineering and determined to be not reportable. This information is forwarded in fulfillment of our obligations under the provisions of 10CFR50.55(e).

Attachment 1 is our final report of the deficiency surrounding Cutler Hammer E-30 Pushbutton switches. The attachment describes the deficient condition along with its safety implications and the corrective action being taken to achieve resolution.

Attachment 2 is the rationale supporting our conclusion that the conditions involving Amphenol female connectors is not reportable under the provisions of 10CFR50.55(e).

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

P o/1 gG re PENNSYLVANIA POWER IL LIGHT COMPANY

Mr. Boyce H. Grier April 18, 1980 Very truly yours, N. W. Curtis Vice President-Engineering & Construction Report on Cutler Hammer E-30 Pushbuttons - Analysis of Amphenol Connector Condition FLW:mcb cc: Mr. Victor Stello (15)

Director-Office of inspection 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 ect Cutler Hammer E-30 Pushbuttons Descri tion ae Cutler-Hammer pushbutton switches installed in PGCC/ACR benchboards, are sticking; of 189 switches inspected, ten switches do not retract when manual depression is relieved. Khese switches bear GE P/N 851E341P2GXGXXX and are purchased from Cutler-Hanmer under P/N CH E-30AC. Mesc nonconfor-mances are documented on NCR 4313.

b. A second condition, as described on Sheet 20 of NCR 3403, involves switch (Hlt'-lll2D) CH E-30AB, which became dislodged due to failure of the mechanical locking device between the pushbutton operating module and contact block.

WhU.e th1s particular switch and the second switch of the same type which have failed were installed In non-safety related equipnent, the concern is for s1milar switches used in safety related equipnent.

Cause

a. We sticking of the pushbuttons occurs on 2-button modules. When one pushbutton is depressed, a latch device is. actuated that prevents depres-sing the other pushbutton. During the manufacturing process the lower edge of .the plastic pushbutton cap wed. have a sharp edge formed. 'Ihis can becane wedged against the latch preventing the button fran resetting when it is released.

b. 'Ihe dislodgement of the pushbutton operating module from the contact block is apparently caused by the mechanical locking ring not being tights locked.

Anal sis of Safet lications

a. CH E-30 pushbuttons are used 1n Class lE safety related circuits. She sticking of the pushbuttons could result in the inoperation, misoperation, or improper line-up of electro-mechanical or solid state logic when push-button operation is attempted.

that the reported CH E-30 pushbutton sti~Engineering Prospect has determined is reportable a deficiency under 1CCHPj0.55 (e).

Attachment 1 Page 1 of 3

b. 'Ihe dislodgement of the CH E-30 locking device permitted the contact blocks to disengage from the pushbutton operator sufficiently to prevent the con-tacts fran changing state upon depression of the pushbutton. 9he identi-fied deficiency, had lt gone uncorrected, could have prevented a safety system fran performing its intended function.

Prospect Ehgfneerlng has determined that the reported CH E-30 dislodged mechard.cal locking device is a reportable deficiency under 10CFR50.55(e).

Corrective Actions ao GE requested that Cutler-Hammer lnvestigate the pushbutton sticking problem for the PGCC/ACR at the site. After the investigation Cutler-Hanrner reported.,

that the problem was on pushbutton switches ~actured before November 1978.

In a report attached to a letter dated February 29, 1980 (IXN U.6060), Cutler-Hsnrner stated that the sticking problem was first noted ln June 1976. Ihey did not consider lt to be a critical problan because on the first attempt to depress, it lf the button stuck could always be depressed with further attempts. Manufacturing changes were made in September 1977 and November 1978. Cutler-Hanrner feels that, with these changes, lt ls reasonable to assume that devices made after November 1978 will not exhibit this problem.

Ihe date stamp ls located under the button on top of the button plate and will show the month and year the device was manufactured.

In the letter Cutler-Hamner states that a sticking pushbutton can be corrected by scraping or buffing a slight radius to the sharp lower edge of the button where it contacts the latching device, or by operating the pushbutton several times. 'Ihey state that the operation of the pushbuttons should lmprove with use due to anoothing of the sharp edge of the button against the interlock surface.

For the PGCC/ACR benchboards General Electric has agreed to replace all Cutler-Hammer E-30AC operator pushbutton rrudules manufactured prior to November 1978.

The contact modules wD1 not be replaced. NCR 4313 shall be revised to re-flect the corrective action taken.

b We construction of the Cutler-Hammer type E-30 pushbutton switches is such that the contact blocks are held to the operating module by a locking ring mounted on the operating module and actuated by a quarter-turn locking screw.

'Ihe dislodgement of the contact modules from the operating modules was in-vestQated and no manufacturing defect was apparent.

Since these same devices successfuU.y passed an integrated system factory test at the manufacturers facQ.ity, lt ls assumed the locking devices worked loose during transit. 'Ihe locklzg devices for CH E-30 switches will be retightened to assure proper installation for both Units 1 and 2. QC inspection w111 verify that the locking devices are tight.

Page 2 oK 3

c. Prospect Zhgineering is investlgating the usage of Cutler-Hammer type E-30 pushbuttons in essential applications 1n the remainder of the plant. At the conclusion of the investigation. any deficiencies will be documented on NCR's and the field advised of any future corrective actions to be taken+

Conclusions ao Rate replacement of pushbutton operation modules that are, or are suspected of not operating properly should resolve the problem of the E-30 AC pushbuttons on the PGCC/ACR benchboards. NCR 4313 will track the replacement of the pushbutton modules on the PGCC/ACR benchboards.

4) ~ Prospect Engineering instructions and field verification should insure no further dislodgement of the contact modules frcm the operating module.

c. Ruther investigations to date have faQ.ed to locate any Cutler-Hammer type E-30 pushbutton switches being used in the remxfxder of the plant.

Page 3 of 3

Amphenol female connectors DESCRIPTION The anomalies sunmarized below have been noted during routine Quality Control surveillance ard/or inspections of PGCC/ACR Panels.

Amphenol female connector pins are not seating properly in the dielectric..

The relative position of the pins often vary after mating and unmating of the connectors. It has been observed that scme pins partially retract as the re-sult of turning the connector. This is especially the case after pins have been ramved and reinserted into the connector dielectric.

VM.le performing pull tests on the individual conductors to check the holding force of the pin crimps to the wires, the connector fenale pins were extracted fran the dielectric, in many instances, before the repaired pull test force was achieved.

One of the methods for performing the pull testing of corductor pin crimps was to use a he@stat pull testing device. The device was utilized for pull testing to avoid complete removal of all pins fram connectors. The hemostat pull test methcd tended to amplify or further aggravate the Amphenol connector problem.

CAUSE General Electric conducted a cpxality study on the cordition identified with these Amphenol connectors. The results were attached to their letter GB-79-283 dated December 10, 1979 and forwarded to the HRC in our PL@-438. GE conclUded that the probable cause of pin seating nonconformances was not due to connector design but rather to damaged mating connectors, errors during assembly or rework at the plant site.

ANALYSIS OF SAFER'MPLICATIONS The identification of pins which had backed out fran the dielectric raised a concern relative to the connectors ability to maintain continuity. However, regardless of how well the pin seats in the dielectric, as long as the male ard female pins are mated together; the circuit continuity can b maintained through the pins. In no instance was it reported that the pins failed to mate together.

Project Engineering has determined that the identified Amphenol connector pins, that did not seat properly in the dielectric, do not constitute a reportable def iciency under 10CFR50. 55 (e) .

Attachnent 2

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