ML18067A439

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LER 97-005-00:on 961220,operation of Plant Outside Design Basis Occurred Due to an Unacceptable Repair on Main Steam Isolation Valves.Pipe Plugs Permanently Repaired
ML18067A439
Person / Time
Site: Palisades Entergy icon.png
Issue date: 03/21/1997
From: Kozup C
CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:
Shared Package
ML18066A923 List:
References
LER-97-005, LER-97-5, NUDOCS 9703270223
Download: ML18067A439 (5)
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NRCFORM386 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB NO. 3150-0104 (4195) EX))IRES 4l30l98 EBTIMATB> BURDEN PBI RE6PONSI! TO COMPLY WITH THS MN<<lf<TORY

~TIOH COlilCTIOH REQUEST: 50.0HRS. RS'ORTB>LE8SONSl.EMIEDARI!

INCORPORATB> NTO THE UCENSINO PROCEllll. AND FED MCI< TO' INDUSTRY.

LICENSEE EVENT REPORT (LER) FORWARD OOYeml REOMDING BURDEN ~TE TO THE ~TION AND RECORDS ~ BRANCH (T_. 1'331, U.S. NUClEAR REGULATORY

.. COIAllS-. WASHINGTON, DC -.ooot, AND TO THE-REDUCTION

  • (See reverse for required number of digits/charaders for each block) PRC>.JECT (31504104, OFACE Of' loMNMlEMEHT AND BUDGET, WASHNOTOH, DC 20503 .

. ~-*, *-E (1) CONSUMERS POWER COMPANY DOCKET NUMBER (2) Page (3)

PALISADES NUCLEAR PLANT 05000255 1of5 TITLE (4) LICENSEE EVENT REPORT 97-005 - OPERATION OF THE PLANT OUTSIDE THE DESIGN BASIS DUE TO AN UNACCEPTABLE REPAIR EVENT DATE (5} LER NUMBER (6) REPORT DATE (7) OTHER FACILITIES INVOLVED (8)

MONTH DAY YEAR YEAR I SEQUENTIAL NUMBER N

REVISIO

.NUMBER MONTH DAY YEAR FACILITY NAME FACILITY NAME DOCKET NU~

0500Q DOCKET NUMBER 12 20 97 97 .- 005 ~' 00 03 21 97 .. 05000 OPERATING THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CfR§:* (Check one or more) (11)

MODE(9) 20.2201(b) 20.2203(a)(2)(v) 50. 73(a)(2)(1)

N . . 50.73(a)(2)(1iJ)

POWER - 20.2203(8)(1) 20.2203(8)(3)(1) x 50. 73(a)(2)(11)

,.*:.. ~ ;

50. 73(a)(2)(ic)

LEVEL (10) 0 20.2203(a)(2)(1) 20.2203(a)(3)(ii) 50.73(a)(2)(iil) 73.71 20.2203(a)(2)(il) 20.2203(8)(4) 50. 73(a)(2)(iv) OTHER 20.2203(a)(2)(iii) 50.36(c)(1) 50. 73(a)(2)(v) Specify in Abstrad below

  • >:.:i;*t(f!'~'l 20.2203la)(2)(iv) 50.36lc)(2) 50.73(a)(2)(viJ1 or in NRC Form 366A LICENSEE CONTACT. FOR THIS LER (12)

NAME** .. ., .. ' TELEPHONE NUMBER (lndUde A_rea. C()de) , ~ .. .

Chartes S. Kozup, Licensing Engineer (616) 764-2000 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13l CAUSE SYSTEM COMPONENT MANUFACTURER REPORTABLE* CAUsE SYSTEM COMPONENT MANUFACTURER REPORTABLE TONPRDS TONPRDS

  • I'*
  • .E .se ISV. .. R585 Yes*. '

SUPPLEMENTAL REPORT EXPECTED.(14) MONTH DAY YEAR I YES If yes, COMPLETE EXPECTED COMPLETION DATE xI .NO EXPECTED SUBMISSION DATE (15)

ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines) (16)

On December 20; 1996, at approximately 1800 with the plant in hot shutdown and the. primarY coolant system (PCS) at 2066 PSIA and 532 degrees F, both Main Steam Isolation Valves (MSIV),

CV..,0501 and CV-0510, were found leaking steam_at the west stuffing box pipe pl.ugs .. At.1445 on_

January 6, 1997, with the plant at 20% power, temporary leak repairs were attempted, buteould not be performed. On CV-0501, the-drilling process penetrated the pressure boundary at an approximate depth of 1/8 inch. On CV-0.510, the pipe plug threaded area leakage was unstable.

Management decided to place the plant in cold shutdown for permanent repairs to the valves.

Subsequently, inspection of the valves determined that unacceptable repairs tiad been made to the IViSIV stuffing box pipe plugs which created the steam leaks. For CV-0501, the weld material over the hole in the pipe. plug most likely violated the minimum wall requirements;* however, this could not be validated. For CV-0.510, the low pressure cast iron plug did not meet the forged steel high pressure requirements .. These ASME Code-violations are considered to have resulted in operation of the plant outside of the design ba~is. It should be noted that the steam leaks were from the threaded portions of the pipe plugs and not due to the failure of the pipe plugs themselves .

. *-9703270223 970321 .

PDR ADOCK 05000255 s PDR

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.. NRC FORM 366a 4195 LICENSEE EVENT REPORT (LER)

  • U.S. NUCLEAR REGULAToRY COMMISSION TEXT CONTINUATION
  • 05000255 .. 20F5 PALISADES NUCLEAR PLANT 91 - 005 - 00 TEXT (If more space is required, use additional coPles of NRC Form 366A) (17)

EVENT PESCRIPTION During the 1996 refueling outage, corrective mainten~nee* ..\,as planned for CV-0501 [Sa, ISV] .to -:

permanently repair a steam leak that had developed on the west side stuffing box pipe* plug.

a During the previous cycle, steam.leak developed in the pipe plug threads, which wastemporarily repaired by drilling the pipe plug and seal injection. A new pipe plug was to be installed:. -As a:*:

preventative measure, the threaded area wa~ to be seal welded on thi$ pipe plug. Seal welds on the pipe plugs were to be completed on the other stuffing box for CV-0501 and on both stuffing

  • boxes *on CV-051 O [SB, ISV]. The work on the stuffing boxes was added to the existing work orders which were to disassemble, inspect, and repack these valves. These are Safety Related ASME Clas*s 2 valves requiring repair in accordance with ASME Section XI. The .Pipe plugs are part of the approved valve design, replacing packingleak--Off lines. They provide:.system jritegrity

. in the absence of packing leak-off lines and are part of the pressure.boundary:* They*are exposed>. *

  • to full *main stea_m pressure. .: * . -. * : . *** * *:.. * * . . "* * * . * *.

_Pre~job briefings were held for both valve repair a~ivities, but plant support personnel who were welding the pipe plugs were not included. The pipe plug work was discuss.ad .on the job* sites; but :: . .

. .multi-discipline' briefs were not held* for the pipe piug work activities. in addition, .work orders:* .. : .:~ : : ; ..

  • _. existed for the overall activities* on the valves. These work orders were nQft;J.s~d duri.ng:th~ pipe*:>: - *:
  • plug activities. Consequently, the job site lacked the needed information to. complete the work per* .

the instructions Which were part of the work order. The lack of a.single pointof accountability for .*

the overall MSIV work led to these ina_dequate pre-job briefings *arid the_ failure to.follow the

  • procedural guidance. ..

For CV-050f, the Wqrk order required the removai of the seal injection fittings, the removal *of the *

. : __ _drilled pipe plug, a new pipe plug installed, and the pipe. plug seal welded. The leak repair fitting.

Was removed; however, the drilled pipe plug was never removed. First, the drilled pipe plug was modified by grinding away the hex head area.to facilitate seal*welding of the'threaded area by improving worker accessability. A seal weld was then performed on the drilled pipe plug, which . .

  • had a hole through the center: Finally, the top face of the pipe plug was welded over to cover the * ..

drilled hole. The weld supervisor approved this approach, ev_en though the welding inspection

  • checklist (WIC) sketch depicted the pipe plug head in plaee with the weld.build'.'"up around the flats.

area. This failure to follow the work order instructions and the lack of a questioning attitude are considered _root causes to.this event For CV-0501, the leakage was not from theweld over the hole, but froni the threaded area of the pipe plug.-* .The weld material over the hole in the pipe plug most likely violated the minimum wall requirements of the ASME Code; however, this could not be validated.* *

  • I*

,. NRC FORM 366a U.S. NUCLEAR REGULATORY COMMISSION 4195 LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION YEAR REVISION NUMBER PALISADES NUCLEAR PLANT* 05000255 30F5 97 - 005 - 00 TEXT (If more space is required, use additional copies of NRC Form 366A) (17)

For CV-0510, the west stuffing box pipe plug was found degraded upon initial inspection by the welder. This particular pipe plug appeared to have a square head versus a hex head plug. In addition, the head was broken with no squared flats remaining. The weld supervisor was not made aware of this degraded condition until after the seal weld was completed. Similar to CV-0501 's west pipe plug, the pipe plug was modified by grinding away what was left of the square head to facilitate seal welding by improving worker aecessability. The WIC drawing depicted a hex plug head in pla~ with weld build-up around the flats area. During the welding, the welder not~ that weld adhesion was poor and it was difficult to* achieve fusion, as if the materials being welded were incompatible. Thjs condition concerned the welder, and he discussed it with the valve team project

  • manager, but it was not brought to the attention of the weld supervisor. This failure to 'follow the work order instructions and the lack of a questioning attitude are considered root causes to this event. The subsequent laboratory report indicated that the west pipe plug was cast iron versus :

forged steel. Pipe and weld specifications and the work order required a forged steel pipe plug.

For CV-0510, the low pressure cast iron plug did not meet the forged steel high pressure

  • requirements of the.ASME Code.

On December 20, 1996, the steam leaks were first observed. The Planning Department personnei

. were comfortable *that the leakage was not significant enougti to. war:rant imm~i~te attention and*

that duringthe previous cycle a similart.emporary leak injection was successful. Therefor~. a decision was made to w~it until .the* hol.iday season was concluded to enable *other' personnel to be available. to* properly plan* this work. At 1445 on January 6, 1997, with the plant at 20% power, the

  • temporary leak repairs were attempted but could not be performed. On CV-0501, the drilling process penetrated the pressure boundary at an approximate depth of 1/8 inch. On CV-0510, the pipe plug threaded area leakage*was unstable. Management decided to place the plant in c0ld
  • shutdown for*permanent repairs to the valves. On January 6, 1997, the plant was shut down to make the permanent repairs to CV-0501 and CV-0510. The leaking 3/4 inch pipe plugs were

- remove~ and new one inch ~pipe .plugs were installed .. The new pip*e plugs were installed. with . .

  • thread sealant, but were not seal welded due to the difficulty in accessing all areas to be welded.

The work was completed on January 11, 1997 and declared operable on January 13, 1997'.

On about February 24, 1997, the root cause evaluator of the steam leaks had concluded on the*

basis of laboratory analysis reports that the pipe pl~g in CV-0510 was cast iron. In addition, interviews conducted had confirmed that the pipe plugs had not been replaced during the outage.

This determination was slightly delayed because the evaluator was also working to resolve an*

unrelated issue with the main generator flexible connector overheating. In retrospect, sufficient

  • information was available.to conclude this issue was reportable on about February 19, 1997.

Therefore, this date could be viewed *as the discovery date for reporting purposes rather than March 6, 1997, when the actual reportability decision was made.

NRC FORM 366a U.S. NUCLEAR REGULATORY COMMISSION 4195 .

.,* ,,_..: *. *~*'

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION YEAR REVISION NUMBER 05000255 40F5

.PALISADES NUCLEAR PLANT 97 - 005 00 TEXT (If niore space Is required, use additional copies of NRC Form 366A) (17)

CAUSE OE THE EVENT For CV-051 O, the west pipe plug was cast iron versus forged steel as requ_ired by pipe and.weld

  • specifications. No records could be found that indicate that pipe plug repairs or modifications were ever made. Therefore, it appears the pipe plug has been in place since origlnal valve instailation during plar:it constn.J~ion. ..
  • The following .were* the *human performance errors with which lead to .the*inappropriate repairs to the stuffing box pipe plugs:: * *** ** *
1. Lack of single point accountability. for the overall MSIV work.
2. * . Fail~re 9fthe .work crews.to use . .

and.* adtiere to procedures.:

" . ~ .

3. * .Inadequate questioning attitude and lacl< of self~ecking.

. ANALYSIS Of ,EVENT CV-0501 and CV-051 Oare Safety Related ASME .Class 2 val_ves". which should be repaired in*

accordance with ASME- Section XI. The .pipe plugs are* part- of the approved. valve design

  • replacing packing leak-off lines. They provide system integrity in the absenee *of packing leak-off lines and are part of the pressure boundary_. They are expo.sad to full main steam pressure.

The MS IVs isolate the steam gel'.'!erators from the rest *af the Mciin Steam System.** The steam leakag-e discussed-abov*e would' r-e*present an additional. potential relea*s*e. path of contamir"fation-in ..

the event of a Steam Generator Tube Rupture Aceident (SGTR) or.a Main Steam Lille Break * .

Outside of Containment (MSLB). However, ttie leakage from these pipe plugs.would be_ very small compared to the large secondary coolant mass released directly to the atmosphere via the atmospheric dump valves during the cooldown portion of these events (and the initial blowdown from the MSLB). Sufficient margin exists in the SGTR and MSLB radiological dose calculations of record to account for this minor leakage and still meet dos*e limits*. Therefore, the safety significance of the failure of these pipe plugs is considered to be negligible. **

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  • NRC FORM 386a U.S. NUCLEAR REGULATORY COMMISSION 4195 LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION YEAR REVISION NUMBER 05000255. 50F5 PALISADES NUCLEAR PLANT 97 - 005 - 00 TEXT (If more space is required, use additional copies of NRC Form 366A) (17)

CORRECTIVE ACTIONS Both leaking pipe plugs were permanently repaired by installing 3000 psi, forg0d steel 1~inch pipe plugs, with high tem.perature sealant, through design change FES97-003. Seal welds were left in place on the east pipe plugs and were ~ot installed on the west pipe plugs. All work was approved and insp~cted by engineering.

The following action will be completed:

1.
  • Review and upgrade as necessary the procedural requirements for Weld Inspection Checklists, including the* use of sketches. * *
2. Review maintenance procedures and upgrade as necessary to assure requirements for work scope definition an_d controls a.re adequately:d~fined.
3. -Reinforce to the NOE organization that their responsibility requires verification that weld configuration* as well as weld quality meet Weld Inspection Checklist requirements .
4. . C6mmunicate.an*d reinforce expectations *to site maintenanceand eo~~truction ofg~nizations

.for the following:** * * * * **: * *

    • procedural adherence .
  • roles and responsibilities
  • work scope controls .
  • communications * .. * *
  • conservative decision making .
  • -- how and -* - .

when. to-* perform

- . -* ~,-.. .--a. multi-diseipline pr~-job briefing ADDITIONAL INFORMATION .

CV-0501 and CV-0510 are 30-inch; Atwood and Morrill Company valves, Model number 20815-H

  • with a design pressure- of 1000 psig and a design temperature of 550°F. *
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