W3P88-0051, Responds to NRC Bulletin 88-001 Re Defects in Westinghouse Circuit Breakers.Util Does Not Use Westinghouse Series Ds Circuit Breakers & Not Subj to Insps Requested in Bulletin
| ML20151B785 | |
| Person / Time | |
|---|---|
| Site: | Waterford  |
| Issue date: | 03/29/1988 |
| From: | Burski R LOUISIANA POWER & LIGHT CO. |
| To: | Martin R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| Shared Package | |
| ML20151B787 | List: |
| References | |
| IEB-88-001, IEB-88-1, TAC-65955, TAC-65956, W3P88-0051, W3P88-51, NUDOCS 8804110269 | |
| Download: ML20151B785 (2) | |
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Refer: TAC 65955/65956 LO UISI AN A / 317 BARONNE STREET P. O. BOX 60340 POWER & L1GHT NEW ORLEANS, LOUISIANA 70160 (504)595 3100
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March 29, 1988 W3P88-0051 A4.05 QA Mr. Robert D. Martin Regional Administrator, Region IV 9 ' ' Wk U.S. Nuclear Regulatory Commission
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a 611 Ryan Plaza Drive, Suite 1000
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Arlington, TX 76011 MAR 30l968 Iil Subj ec.t : Uaterford 3 SES j
Docket No. 50-382 License No. NPF-38 NRC Eulletin No. 88-01
Dear Mr. Martin:
This reply to the subject Bulletir. provides the information requested concerning defects in Westinghouse circuit breakers.
The LP&L review conducted in response to this Bulletin determined that Waterford 3 does not utilize Westinghouse series DS circ uit breakers and is therefore not subject to the inspections requested or the safety concerns of Eu11ecin 88-01.
Should you require additiot.al information, please feel free to contact me or G.E. Wuller, Operational Licensing Supervisor, at (504) 464-3499.
This tesponse is submitted as requested under affidavit under provisions -
Section 182a of the Atomic Energy Act of 1954, as amended.
Very truly yours, e '
R.F. Burski Nuclear Safety & Regulatory Affairs Acting Manager RFB:GEW:ssf l
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Attachment:
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(original) l J.A. Calvo, NRC-NRR D.L. Wigginton, NRC-NRR I
NRC Resident Inspectors Office g
E.L. Blake W.M. Stevenson
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- t UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION Irithe matter of
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Louisiana Power & Light Company
) Docket No. 50-382 Waterford 3 Steam Electric Station
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AFFIDAVIT R.F. Burski, being' duly sworn, hereby deposes and says that he is i
Nuclear Safety and Regulatory Affairs Acting Manager, Nuclear Operations of Louisiana Power & Light Company; that he is duly authorized to sign and file with the Nuclear Regulatory Commission the attached response to NRC Bulletin No. 88-01; that he is familiar with the content thereof; and that the matters set forth therein are true and correct to the best of his knowledge, information and belief.
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R.F. Bu'rski Nuclear Safety & Regulatory Affairs Acting Manager Nuclear Operations STATE OF LOUISIANA)
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PARISH OF ORLEANS )
Subscrfbed and sworn to before me, a Notary Public in and for the Parish and State above named this 2 9 :d' day of
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OMB No.: 315000P.
NRCB 88-01 UNITED STATES hUCLEAR REGULATORY COMMISSION AM#
OFFICE OF NUCLEAR REACTOR REGULATION WASHINGTON, D.C. 20555 fEB 101986; February 5,1988 g[
NRC BULLETIN NO. 88-01:
DEFECTS IN WESTINGHOUSE CIRCUIT BREAKERS Addressees:
For Action - All holdtrs of operating licenses or construction permits for nuclear power reactors.
Purpose:
The purpose of this bulletin is to provide information on Westinghouse series DS circuit breakers and safety concerns associated with their use and to r that addressees using these breakers in Class 1E service perfom and docume inspection of the welds on the pole shafts and inspection of the alignment in the breaker closing mechanism.
Description of Circumstances:
The following occurrences have raised concerns about the use of these circuit breakers:
McGuire 2:
in response to manual trip demands from the control room.On July 2 The RTB had bound mechanically in the closed position because the main roller had become wedged between a raised segment of the close can and the nearby side frame plate.
Excessive lateral movement of the main drive link and a broken center pole lever to pole shaft weld pemitted the binding to occur.
The failure was reproduced once by the licensee during bench tests of the RTB at McGuire and several times during detailed laboratory investigations of fusion, inadequate extent of welding)g fabrication (i.e.,perfomed Westinghouse.
Substandard welding durin porosity, lack caused the weld to break. Details of this failure mode are given in Infomation Notice No. 87-35, Supplement 1, dated December 16, 1987.
The licensee visually inspected the remaining pole shaft welds of the defective i
McGuire breaker and the other McGuire RT8s and found indications of lac fusion (i.e., lack of characteristic weld bead ripple, notches at the edges l.
of the weld beads, and small evidence of base metal melting).
Catawba 1 and 2:
The licensee inspected all DS-416 RTBs and found a pole shaft with a crack about 1/4 inch long at the finish end of the antibounce lever weld.
l The licensee also observed lack of fusion at the start ends of the center pole 1
8802020034
NRCB 88-01 February 5, 1988 Page 2 of 5 lever and antibounce lever welos.
of the Catawba pole shaft in the laboratory of an NRC contractor revealed additional cracks, one at each end of the center pole lever weld.
of weld arc) of the original 120 degrees of weld are remained. crack After the Similarly, 86 degrees of weld arc remained af ter the antibounce lever weld defects ware removed.
the alignment of the main roller on the close cam surface.The licensee's inspect Two RT8s were found with excessive lateral tolerance, allowing the roller to strike th obse ved to be intact.
The licensee also noted that some pole shaft welds of this type of circuit breaker used in its hydroelectric plants had failed several years ago but that they have perfomed satisfactorily since they were repaired by additional welding on the opposite sides of the levers.
Sequoyah 2:
In April 1987, two fillet welds broke on the pole shaft assembly of a 05-416 circuit breaker that energizes the emergency fire protection cumps.
The weld failures apparently freed the center moving contact assembly (i.e.,
the Y-phase contact assembly), allowing it to move independently of the pole electrical phasing problem and erratic operation of the fire pump i
failed welds joined adjacent levers (the center pole lever and the antibounce The two lever) to the pole shaft. The two levers are connected by a pin. On the basis of engineering analysis, the licensee concluded that the center pole lever weld failed first because of excessive porosity; the antibounce lever weld then failed because it was inadequately sized and could not accommodate the load nomally supported by the center pole lever weld that was thrust upon it through the connecting pin.
Calvert Cliffs 1:
lever to the pole shaft in a DS-206 circuit breaker used in Class 1E servic for the control room habitability system was detected during routine mainte-nance surveillance.
No adverse effect on breaker performance had been noted; the weld for the adjacent antibounce lever was observed to be intact and car-rying the load of the broken weld.
The licensee's measurements showed that the leg size on the pole shaft side was 0.3 inch and the leg size on the lever am side was 0.1 inch.
On the basis of analysis, the licensee concluded that the failure was due to extensive lack of fusion of the weld to the lever as a result of improper weld technique.
The licensee examined an additional 10 welds on this pole shaft and another pole shaf t and found that the start ends of the welds in general were not fused properly to the levers and that the weld legs generally exhibited mismatches.
2 of the 10 welds.
Cracks were detected in the start ends of Westinghouse: Both connercial grade and Class 1E circuit breakers of the DS series use similar pole shafts or possess features associated with the observed binding and electrical phasing problems.
Specifically, Model Nos.05-206, DSL-206.05-416, DSL-416, and 05-420 are susceptible to these types of failures.
The welds of these pole shafts were randomly inspected during manufacture.
How-ever, no documentation confirms either that in-process inspections were performed
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NRCB 88-01 February 5,19R Page 3 of 5 performed during the dedication of the consnercial gra service.
Discussion:
As a result of the operating experiences and observations discussed above, is a question concerning the operability of RTBs and other Class 1E circuit breakers of the Westinghouse DS series.
Some DS series circuit breakers ma and Appendix B,10 CFR 50, and have inadequate wel I
shafts.
Excessive misalignment of the main rollers on the close cam also can occur.
GDC 1 and Appendix B require, in part, that components inportant of the safety functions to be performed.to safety be fabricated to cuality s Consequently, licensees should take all relevant welds ano roller clearances according to th fications and to take appropriate remedial actions to correct deficitncies. -
On December 1,1987, Westinghouse issued Technical Bulletin NSID-TB-87-11 (Attachment 1) as a result of its investigation of the McGuire 2 RTB failure.
It recomended inspection of the pole shaft welds and of the alignment in the breaker closing mechanism according to specific criteria and provided guidance for corrective actions if required, including a procedure for the removal and installation of pole shafts. The NRC has reviewed the Westinghouse technical bulletin and finds that it adeguately addresses the NRC concerns subject to certain changes discussed below.
Specifically, the NRC has concluded that RTBs should be inspected expeditiously, that in view of the Sequoyah 2 weld failures welds should be inspected for porosity, and that a bypass breaker not meeting l
the weld criteria in the Westinghouse technical bulletin should be removed from service.
Actions Requested:
The phrases "short term inspection" and "long-term inspection" used in this NRC Bulletin are consistent with the phrases as used in the Westinghouse technical bulletin.
Specifically, short-tem inspectioris refer to inspections of the three main pole levers (the left pole 1 tver, the center pole lever, and the right pole lever).
These short-term inwetions should be perfomed on break-ers at the next available opportunity (e.g., a maintenance outage) or during the next surveillance tast for the breaker, whichever is earlier.
Long term inspections refer to inspections of the four remaining welds on the pole shaft and to the direct check of the alignment of the breaker closing mechanism.
These long-term inspections should be performed on the breaker prior to restart following the next refueling outage. However, for plants that have not yet received an operating license, the implementation periods for the short-term and long-term inspections are modified by this NRC bulletin to mean before fuel loading.
As used in this NRC bulletin, the phrase "replacement pole shaft" may include a repa' red pole shaft.
However, since welding of a pole shaft lever may cause
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NRCB 88-01 February 5,1968 Page 4 of 5 after consultation with Westinghouse. distortion and misalignment of Any repaired pole shaft weld should meet the criteria in Section 6.1.1 of the Westinghouse technical bulletin, as sup-plemented below.
Adc'ressees using Westinghouse 05-206, OSL-206, 0S-416 DSL-416, and DS-420 circuit breakers in Class IE applications, including RTBs, are requested to perform short-term and long-tem inspections in accordance with the Idestinghous technical bulletin, except that the following changes should be made to the following sections:
6.0 Add the following:
However, inspection of the 3 main pole shaft welds for all RTBs (both main and bypass) should be completed within 30 days of receipt of this NRC bulletin.
6.1.1, 6.1.2, and 7.1 Add the following:
e) porosity - surface pin holes with cumulative diameters less than 1/16 inch in each inch of weld 6.2.4 Delete this section and the reference to it in Section 6.2.3.
With regard to Section 6.2.4, any RT8 with a pole shaft that does not meet the etiteria in Section 6.1,2 should be deemed inoperable and should not be used in the operating er bypass breaker position in the reactor trip switchgear.
pole shafts should be removed from service and a replacement pole shaft in-Such stalled in the breaker before returning it to service. The replacement pole shaft should meet the criteria in Section 6.1.1.
Reporting Requirements:
If addressees cannot meet this suggested schedule for short-terv and long-tem 4
inspections, they should justify to the NRC their proposed alternative schedules.
Records of inspections and corrective actions in response to this NRC bulletin shall be documented and maintained in accordance with plant procedures for Class 1E equipment.
Any addressee who does not have circuit breakers subject to this bulletin shall provide a letter to the NRC stating this fact within 60 days of receipt of this btlletin.
Addressees who do have circuit breakers subject to this bulletin shall provide letters of confimation to the NRC of the completion of the inspections. These letters shall include the number of breakers of each type inspected, the number of breakers of each type requiring corrective actions oue to pole shaft welds not meeting the acceptance criteria and the number of breakers of each type requiring corrective actions due to mechanism alignments not meeting the acceptance criteria.
These letters of confirmation shall be submitted to the NRC within (1) 30 days of completion 4
of the short-term in:pections and (2) 30 days of completion of the long-term inspections.
l NRCE 88-01 February 5,1988 Page 5 of 5 Since inspection of the three main pole shaft welds for all RTBs should be completed within 30 days of receipt of this bulletin, a letter of confirmation of completion of these inspections including the above information is requested within 60 days of receipt of this bulletin.
The letter-of confimation shall be submitted to the appropriate Regional Administrator under oath or affirmation under the provisions of Section 182a Atomic Energy Act of 1954, as amended.
In addition, the original copy of the cover letter and a copy of any attachment shall be transmitted to the U. S.
Nuclear Regulatory Comission, Document Control Desk, Washington D.C. 2055 for reproduction and distribution.
For purposes of NRC accounting, all corre-should bear the identifying number TACSspondence associated with this 65955/65956.
This request for information was approved by the Office of Management and Budg under blanket clearance number 31500011. Coments on burden and duplication should be directed to the Office of Management and Budget, Reports Management, Room 3208, New Executive Office Building, Washington D.C. 20503.
Although no specific request or requirement is intended, the following infoma-tion would be helpful to the NRC in evaluating the cost of complying with this bulletin:
(1) staff time to perform requested inspections, corrective actions, and associated operability testing (2) staff time to prepare requested documentation (3) additional cost incurred as a result of the ins ection findings (e.g.,
costs of corrective actions, costs of down time If you have any questions about this matter, please cu'c3 ca of the technical contacts listed below or the Regional Administrator of t.% sppropriate regional office.
Charles E. Rossi, Director Division of Operational Events Assessment Office of Nuclear Reactor Regulation Technical Contacts: Darl S. Hood, NRR K. R. Naidu, NRR (301)492-1442 (301) 492-0980 C. Vernon Hodge, NRR C. D. Sellers, NRR (301) 492-1169 (301)492-0930 Attachments:
1.
Westinghouse Technical Bulletin NSID-TB-87-11.
December 1, 1987 2.
List of Recently Issued NRC Bulletins
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