ML18017A142
| ML18017A142 | |
| 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 | |
| ML18017A143 | List: |
| References | |
| PLA-472, NUDOCS 8004290394 | |
| Download: ML18017A142 (8) | |
Text
REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)
ACCESSION NBR:8004290394 DOC,DATE! 80/04/18 NOTARIZED:
NO DOCKET FACIL:50 387 Susquehanna Steam Electric Station~
Unit 1~ Pennsylva 05000387 50 388 Susquehanna Steam Electric Station~
Unit 2i Pennsylva 05000388 AUTH ~ NAME "
AUTHOR AFfILIATION CURTIS'
~ N, Pennsylvania Power 8 Light Co.
REC IP ~ NAME RECIPIENT AFFILIATION GRIKR B ~ H ~
Region lg Philadelphiag Office of the Director
SUBJECT:
Forwards final deficiency rept re Guitar Hammer E 30 pushbutton sticking problem L dislodgement of Switch CH E 30AB from contact block Rationale encl re conditions of Amphenol female connectors not reportable under 10CFR50.55.
DISTRIBUTION CODE:
B019B COPIES RECEIVED:LTR ~ ENCL ~
SIZE!
TITLE: Construction Deficiency Repor t (10CFR50>55E)
NOTES: '5K~T T K.
'3h ~~+
Ch1 T & ~ ~~ J~
RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL ACTION!
14 PM~~~ ~
1 1
15 BC i 1
1 20 LA~~~~g 1
1 21 AD ~~~~~
1 INTERNAL:
0 1
1 0?
NRC PDR 1
1 05 2
2 07 EDO 8
STAFF 1
1 08 MPA 1
1 09 DEPY DIR DPM 1
1 10 GAB 1
1 11 STANDRDS DEV 1
1 13FIELD COOR/IE 1
1 16 AD FOR ENGR 1
1 17 AD PLANT SYS 1
1 17 AD REAC SFTY 1
1 22 DIR DPM 1
1 23 OELD 1
1 AD/RCI/IE 1
1 AD/SITE TECH 1
1 AEOD 1
1 DIRECTOR DSE 1
1 GEOSCIKNCES BR 1
1 HANAUERgS ~
1 1
ILC SYS BR 1
1 MATL ENG BR 1
1 MECH ENG BR 1
1 POKER SYS BR 1
1 STRUCT ENG BR 1
1 EXTERNAL: 03 LPDR 24 ACRS 1
1 16 16 04 NSIC 1
1 4.tw
~ ETR<
8Rse a
~ <ceca C p'a ~z TOTAL NUMBER OF COPIES REQUIRED: LTTR, ~ ENCL,, AB
r 5 fi v
Cl II
8004299 3 (Q 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 STEM 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/ll/79 PLA-409 dated 10/11/79 PLA-438 dated 01/ll/80 Dear Mr. Griers 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 PPGL 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.
$oi1 r/(
PENNSYLVANIA POWER IL LIGHT COMPANY
Mr. Boyce H. Grier April 18, 1980 Very truly yours, N.
W. Curtis Vice President-Engineering 6 Construction Attachment 1 Report on Cutler Hammer E-30 Pushbuttons Attachment 2 - Analysis of Amphenol Connector Condition FLW:mcb cc:
Mr. Victor Stello (15)
Director-Office of Xnspection s Enforcement U. S. Nuclear Regulatory Commission Washington, D.C.
20555 Mr. G. McDonald, Directo~r 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. 0.
Box 52 Shickshinny, Pennsylvania 18655
Sub ect Cutler Hammer E-30 Pushbuttons Descri tion ao 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.
these switches bear GE P/N 851E341P2GXGXXX and are purchased from Cutler-Hanmer under P/N CH E-30AC.
Ihese nonconfor-mances are documented on NCR 4313.
b.
A second condition, as described on Neet 20 of NCR 3403, involves switch (HV-1112D) CH E-30AB, which became dislodged due to failure of the mechanical locking device between the pushbutton operating module and contact block.
While this particular switch and the second switch of the same type which have failed were lnstalled in non-safety related equipnent, the concern is for similar switches used in safety related equipnent.
Cause a.
Ihe 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.
Du'ing the manufacturing process the lower edge of,the plastic pushbutton cap will have a sharp edge formed.
Ibis can becane wedged against the latch preventing the button frcm resetting when it is released.
b.
'Ihe dislodgement of the pushbutton operating module fran the contact block is apparently caused by the mechanical locking ring not being tightly locked.
Anal sis of Safet lications a.
CH E-30 pushbuttons are used in Class lE safety related circuits.
'Ihe 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 attetnpted.
Prospect Engineering has determined that the reported CH E-30 pushbutton sticking is a reportable deficiency under 10CR550.55 (e).
Attachment 1
Page 1 of 3
b.
The dislodgement of the CH E-30 locking device period.tted the contact blocks to disengage frcm the pushbutton operator sufficiently to prevent the con-tacts frcm changing state upon depression of the pushbutton.
Ghe identi-fied deficiency, had it gone uncorrected, could have prevented a safety system frcm performing its intended function.
Prospect Ehgineerizg has determined that the reported CH E-30 dislodged mechanical locking device is a reportable deficiency under lOCPB50.55(e).
Corrective Actions ao GE requested that Cutler-Hammer investigate the pushbutton sticking problem for the PGCC/ACR at the site.
After the investigation Cutler-Hamner reported.
that the problem was on pushbutton switches manufactured before November 1978.
En a report attached to a letter dated Pebruary 29, 1980 (DCN 116060), Cutler-Hamner stated that the sticking problem was first noted in June 1976.
'Ihey did not consider it to be a critical problem because if the button stuck on the first attempt to depress, it could always be depressed with further attempts.
Manufacturing changes were made in September 1977 and November 1978.
Cutler-Hanmer feels that, with these changes, it is reasonable to assme that devices made after November 1978 willnot exhibit this problem.
The date stamp is 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<hnzner 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 tlmes.
They 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.
Por the PGCC/ACR benchboards General ELectric has agreed to replace all Cutler-Hammer E-30AC operator pushbutton modules manufactured prior to November 1978.
The contact modules wLL1 not be replaced.
NCR 4313 shall be revised to re-flect the corrective action taken.
b.
'Ihe 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.
Ghe dislodgenent of the contact modules frcm the operating modules was in-vestigated and no manufacturing defect was apparent.
Since these same devices successfully passed an integrated system factory test at the manufacturers facQ.ity, it is assumed the locking devices worked loose during transit.
We locking devices for CH E-30 switches will be retightened to assure proper installation for both Units 1 and 2.
QC inspection wLLL verify that the locldng devices are tight.
Page 2 of-3
c.
ProJect Engineering is investigating the usage of Cutler-Hsoxner type E-30 pushbuttons in essential applications in 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 a.
9he 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.
ProJect Engineering instructions and field verification should insure no further dislodgement of the contact modules frcm the operating module.
c.
Bather investigations to date have fxLLed to locate any Cutler-Hammer type E-30 pushbutton switches being used in the remainder of the plant.
Page 3 of 3
Amphenol female connectors The anomalies mznnarized below have been noted during routine Quality Control surveillance and/or inspections of PGOC/ACR Panels.
phenol female connector pins are not seating properly in the dielectric.
The relative position of the pins often vary after mating and uranating of the connectors.
It has been observed that sane pins partially retract as the re-sult of turning the connector.
This is ~ially the case after pins have been rennved and reinserted into the connector dielectric.
WM.le perforrnirg pull tests on the individual conductors to check the holding force of the pin crimps to the wires, the connector fenale pins ~e extracted frcm the dielectric, in many instances, before the r~ed pull test force was achieved.
One of the methcds for performing the pull testing of conductor pin crimps was to use a hen+stat pull testing device.
The device was utilized. for pull testing to avoid complete rival of all pins frcm connectors.
The hamstat pull test method tended to amplify or further aggravate the Amphenol connector problem.
CAUSE General Electric conducted a causality study on the condition identified with these Amphenol connectors.
The results were attached to their letter GB-79-283 dated December 10, 1979 and forwarded to the NRC in our PLA-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 r~rk at the plant site.
ANALYSIS OF SAFETY'PLICRTIQNS The identification of pins which had backed out fran the dielectric raised a coreern relative to the connectors ability to maintain continuity.
- Heaver, regardless of how well the pin seats in the dielectric, as long as the male and female pins are mated together> the circuit continuity can be 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 deficiency under 10CFR50.55(e)
Attachnent 2