ML20012F503

LER 90-007-00:on 900306,RCS Charging Line Rendered Inoperable Due to Deficient Piping Support Weld.Caused by Inadequate Work Controls & post-installation Insp Processes. Field Walkdowns & Weld Insps initiated.W/900405 Ltr

ML20012F503
Person / Time
Site:	Arkansas Nuclear
Issue date:	04/05/1990
From:	Ewing E, Scheide R ARKANSAS POWER & LIGHT CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
2CAN049010, 2CAN49010, LER-90-007, LER-90-7, NUDOCS 9004160031
Download: ML20012F503 (4)

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April 5, 1990 2CAN049010 U. S. Nuclear Regulatory Commission Document Control Desk '

Mail Station P1-137 Washington, D. C. 20555

SUBJECT:

Arkansas Nuclear One - Unit 2 Docket No. 50-368 License No. U : G Licensee Event u port No. 50-368/90-007-00 c Gentlemen:

In accordance with 10CFR50.73(a)(ii)(B), attached is the subject report concerning a Reactor Coolant System chargi.ng line which was rendered' inoperable due'to a deficient piping support weld which resulted from inadequate work controls during initial plant construction.

Very truly yours,

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E. C. Ewing General Manager, Technical Support and Assessment ECE/RHS/sgw-attachment cc: Regional Administrator Region IV U. S. Nuclear Regulatory Commission 611 Ryan Plaza Drive, Suite 1000 Arlington, TX 76011 i

INPO Records Center  ;

Suite 1500  :

' 1100 Circle 75 Parkway i Atlanta, GA 30339-3064 /[

9004160031 900403 PDR ADOCK 05000368 t S '"

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NRC Form 366 L'.5. Nuclear Regulatory Commission (9 83) Approved MB No. 3150-0104

. Expires: 4/30/92 L1CEN$(( [V[NT REPOR1 (L E A)

FACILIT) NAME (1) Arkansas Nuclear One, Unit Two lDOCAET NUMBER (2) IPAGE (3) 10151010101 31 61 Bil10F1013 TITLE (4) Reactor Coolant System Charging Line Rendered Inoperable Due to a Deficient Piping Support Weld Which Resulted from Inadequate Work Controls Ouring Initial Plant Construction i W $1E (b) LER NUMBER (6) 15equentiell REPORT DATE (7) OTHER FACILITIES INVOLVED (6) l l IRevision l l .

I j Monthi Day l Year lYear Number Number Month Day l Year Facility Names Docket Number (51 i .l l l 0 5 0 0 0 01 31 01 61 91 01 91 Olal '

01 01 7 '--' 01 0 014 01 51 91 01 0 5 0 0 0 *

, OPERATING i lTHIS REPORT 15 5UBMITTLD PUR5UANT O THE REQUIREMENTS OF 10 CFR 6: I L MODE (9) 3 (Check one or more of the followina) (11) '

i POWERI _ 20.402(b) l _ I 20.405(c) 1 ,,,1 50.73(a)(2)(iv) l_l 73.71(b)

LEVEll 20.405(a)(1)(i) l ,I 50.36(c)(1) l 50.73(a)(2)(v) (_ l 73.71(c)

.(10) 101010 7 20.405(a)(1)(ii) l _ l 50.36(c)(2) ll[I50.73(a)(2)(vii) l

20. 405(a)(1)(ii i ) l l.,,l 50.73(a)(2)(viii)(A)l_,,l Other Abstract (Specify in belou and l,,,,1l 20.405(a)(1)(iv) 13l50.73(a)(2)(1) 1 50.73(a)(2)(11) I,,,,1 50.73(a)(2)(viii)(B)] in Text, NRC Form p-i_I 20.405(a)(1)(v) l I 50.73(a)(2)(iii) l l 50.73(a)(2)(x) l 366A)

LICENSEE CONTACT FOR THI5 LER (12)

Name l Telephone Number l Area l Richard H. Scheide, Nuclear Safety and Licensing Specialist l Code l l5101119l6141-13111010 COMPLETE ONE LINE FOR EACH COMPONENT F AILURE DESCRIBED IN THIS REPORT (L3) l l l lReportablel ,

l l Reportablel Cause System Component IManufacturert to NPRDS l Cause System Component Manufacturer to NPRDS j i l i e I I I I I I I I I I I I I I I I I l 1 l 1 I I I I I l l I 1 i 1 i l l I I I l l I SUPPLEMEN REPORT EXPECTED (14) EXPECTED Month Day Year l $UBMIS$10N l~l Yes (if yes.' complete Expected Submission Date) llil No i DATE (15) l I I I I I )"

ABSTRACT (Limit. to 1400 spaces, i.e. , appTolimately fif teen single-space typewritten lines) (16)

On March 6,1990, while performing an evaluation of a Isometric Update Program walkdown of the Chemical and Volume Control System. Engineering personnel identified a deficient piping support weld on the charging line to the 'B' RCS cold leg inside containment. An engineering evaluation was conducted

which determined that the line could not be proven operable without a rigorous analysis since approximately 33 feet of piping would be left unsupported if it were assumed that the subject support would fail during a seismic event. In lieu of a rigorous analysis, it was conservatively determined, using f engineering judgement, that the charging line was inoperable in its 'as found' condition. The pipe support weld was not performed in accordance with the design drawings during initial plant construction, '

lherefore, the cause of this condition was determined to be inadequate work controls and post installation inspection processes. The deficient support weld was reworked and brought into conformance with the design drawings. In addition, the design review and post modification inspection processes which are in place at the present time require field walkdowns and weld inspections by Quality Control personnel which should prevent the occurrence of similar events.

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, , . . Form 1062.01B i NRC' form 366A' U.S. Nuclear Regulatory Commission t , (9 83) Approved OMD No. 3150-0104 Expires: 4/30/92 LICENSEE EVENT REPORT (LER) TEXT CONTINUATION i , IACIL11Y NAME (1) lDOCAE1 NUMBER (2) l LIR NUMETR (6) l FAGE (3) l l l l5equent141l 1 Revision l L- Arkansas Nuclear One, Unit Two I l Year Number Number l 10151010101 31 61 81 91 0 --

01 01 7 --

01 Ol0lPl0Fl0l3 1[KI (If more space is required, ese additional NRC f orm 366A's) (17) '

l A. Plant Status ,

At the time of discovery of this condition, Arkansas Nuclear One, Unit 2 (AND 2) was in the Hot Standby condition (Mode 3) with Reactor Coolant System (RCS) (AB) temperature at approximately 545 degrees and pressure at 2250 psig.

B. Event Description ,

On March 6, 1990, while performing an evaluation of a walkdown of the Chemical and Volume Cuntrol System (CVCS) (CB) piping in accordance with the Isometric Update Program, Engineering personnel identified a deficient piping support weld on the charging line to the 'B' RCS cold leg inside containment. The design drawing called for a 1/4 inch full length fillet weld to connect the support to the structural steel. However, the support was found to be only tack welded to the structural steel.

An engineering evaluation was performed to determine the operability of the charging line in its'

'as found' condition. This evaluation determined that the line could not be proven operable without a rigorous analysis since approximately 33 fret of piping would be left unsupported if it were assumed that the subject support would fail during a seismic event. In lieu of a rigorous ,

analysis, it was conservatively determined, using engineering judgement, that the charging line was inoperable in its 'as found' condition. However, the charging line for the 'C' RCS cold leg was unaffected by this condition.

C. Root Cause Since there was no rework of this support identified since plant construction, it was determined that the piping support weld was not performed in accordance with the design drawings during initial plant construction nor was the deficient weld identified during post installation inspection.

Therefore, the cause of this condition was determined to be inadequate work controls and post installation inspection processes which were in place during plant construction.

D. Corrective Actions The deficient support weld was reworked and brought into conformance with design before the unit was returned to power operation.

The Isometric Update Program, which identified the deficient welti discussed in this report, was initiated in 1987 to identify and resolve discrepancies between design drawings and the as-built condition of the plant. Although identification of weld discrepancies is not the primary l objective of the Isometric Update walkdowns, the program workplan indicates that the walkdown team will identify gross weld deviations for further evaluation. '

'In addition, the design review and post modification inspection processes which are in place at the present time require field walkdowns and weld inspections by Quality Control personnel which l should prevent the occurrence of similar events in the future.

E. Safety Significance i If a seismic event had occurred with the charging line piping support in its 'as-found' condition, it is possible that the support and its associated charging line would have failed, resulting in a non-isolable RCS leak. However, the resultant leak (2 inch line) would constitute a small break Loss of Coolant Accident for which ANO-2 is analyzed, and would be well within the capabilities of the High Pressure injection System to prevent core damage.

F. Basis for Reportability Since the deficient piping support weld could have resulted in failure of the charging line and a non-isolable RCS leak, this condition is considered to be reportable pursuant to 10CFR50.73(a)(2)(11)(B) as a condition outside the design basis of the plant.

This condition was also reported in accordance with 10CFR50.72 at 1650 on March 9,1990.

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Expirest' 4/30/92 LICENSEE EVENT REPORT-(LER) TEX 1 CONI]NUATION f FACILITY NAM [ (1) I DDCKET NUMBIR (2) j *LtR NUMBIR (6) PAGE(37' -

15equential l Revision f

~ Arkansas Nuclear One. Unit Two Year Num>er Number l

• 0151010101 31 ft 81 9I O -

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01 Ol01310FICl3

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Gi Additionel InformationL Similar previous events involving pipin0 support discrepancies which occurred during initial

. plant construction were reported in LERs 50 313/87 001 00, 60 313/B8 020 00, 50-313/89-013 00 and

'50 313/89-046-00.  :

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'- Energy. Industry lnformation System (Ells) codes are identified in the text as [XX).

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