ML20133F969

Submits Request for Relief from ASME Code Requirements,Section IX IAW 10CFR50.55a(g)(6)(i) Allowing Braidwood to Continue Operation W/Drain Line Leak of Unit 1,Train a Essential Svc Water Strainer

ML20133F969
Person / Time
Site:	Braidwood
Issue date:	01/09/1997
From:	Stanley H COMMONWEALTH EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GL-90-05, GL-90-5, NUDOCS 9701150079
Download: ML20133F969 (4)

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Commonwealth 1:dison Gimpany Braidwood Generating Station Route el. Ikix 84 llracetille, IL MlO7 Axil 9 Tri sis-4ss 2soi l

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January 9,1997 U.S. Nuclear Regulatory Commission Washington D.C. 20555 Attention: Document Control Desk

Subject:

Braidwood Station Unit 1 Request for Relief from ASME Code Requirements ERC Docket No. 50-456

Reference:

(1) Timothy J. Tulon letter to USNRC transmitting ,

operability assessment ofleak on drain line of Unit 1 Train A Essential Service Water Stainer, dated December 31,1996 I

4 In December, Commonwealth Edison identified a small leak on the drain line for the strainer associated with the Unit 1, "A" Train Essential Service Water Pump at l Braidwood Station. The affected piping is ASME Class 3, moderate energy piping.

Pursuant to the provisions of GL 90-05, ASME Class 3 moderate energy piping experiencing operational leakage can be considered operable if acceptable structural integrity is demonstrated and staff review and approval is sought. This provision is intended to prevent the undesirable shutdown of an operating unit in those cases where (l

j a fracture mechanics evaluation clearly demonstrates suff exists.

The Reference (1) letter provided, for the staffs review and acceptance, the basis by which the affected system was determined to be capable of performing its intended function.

1 # 094 9701150379 970g09 DR ADOCK 05000456 PDR A l'nicom Compan>

U. S. Nuclear Regulatory Commission Page 2 - January 9,1997 j

In further conversations concerning this leak, the Staff indicated that it would be .

necessary to submit a formal relief request to allow continued operation with the '

current system conditions. Pursuant to 10CFR 50.55a(g)(6)(i), Braidwood Station is aquesting relief form the provisions of ASME Section XI. The details of this relief i art, presented in the attached request.

Please direct any questions to: T. Simpkin, Regulatory Assurance Supervisor, at (815) 458-2801, extension 2980.

Sincerely,  !

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H. Gene St Site Vice 5 e'sident b Braidwood Nuclear Station HGS /fb/-.= a Attachcnt cc: A.B. Beach, Regional Administrator - Region III  !

R.R. Assa, Project Manager - NRR C.J. Phillips, Senior Resident Inspector - Braidwood Office of Nuclear Facility Safety - IDNS 1

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RELIEF REOUEST COMPONEN r IDENTIFICATION Code Class: 3

Reference:

Generic Letter 91 18 Generic Letter 90-05 1983 ASME Section XI,1983 Addenda Letter to NRC dated 12/31/96, Service Water System Operational Leakage.

Description:

Through wall leakage identified on the Unit 1 Essential Scnice Water System (SX) back flush line.

Component Number (s):

A 6"x8" reducer located on line ISX93AA-8" downstream from the l A SX System Strainer.

CODE REOUIREMENT 10 CFR 50.55a(g) requires nuclear power facility piping and components to meet the applicable requirements of Section XI of the ASME Boiler and Pressure Vessel Code (the Code).10 CFR 50.55a(g)(6)(i) allows the Licensee to submit relief requests to the Commission for evaluation when the Code requirements are determined to be impractical.

IWB-3000 of the ASME Section XI Code provides the acceptance standards for flaw indications in i

Class 3 piping components. Specifically, IWB-3122.2 or IWB 3122.3 require flaws to be either '

repaired or replaced in accordance with IWD-4000 or IWD-7000. IWD-4000 and IWD-7000 provide the requirements for repair or replacement of the flawed areas. Reliefis requested from performing i an immediate Code repair or replacement of the flaw detected in the Essential Senice Water Back Flush line Code Class 3 piping in accordance with ASME Section XI, Article IWD-4000 or IWD-7000. I BASIS FOR RELIEF Braidwood currently has a through wall leak, approximately 1/8" in diameter and leaking approximately 2 gpm, located on the bottom side of a 6"x8" reducer on the ASME Class 3 line ISX93AA-8". This line is the backwash line downstream from the Unit I A essential senice water strainer. This section ofline is not isolable from the strainer. The configuration of this pipe run is described as follows. A short 3 inch line extends vertically from the bottom of the strainer to a flanged connection. Beyond this flanged connection is another short 3 inch pipe section welded to a 3"x6" reducer. This reducer is welded to a 6 inch 90 degree cibow which connects to the 6'k8" reducer, where the flaw is located. This reducer is welded to an 8 inch pipe which attaches to a valve by a flanged connection. The flow direction is from the 3 inch pipe coming oft the strainer to the 8 inch valve. The line is normally stagnant at system pressure except during strainer backwash, which is approximately 5 minutes per 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> shift Flaw evaluations on Code Class piping are normally performed per the ASME Section XI Code. This evahtation in accordance with IWB-3000 is applicable to linear, planar and laminar crack-like indications. Wall thinning evahiation is not addressed within the Code. Consequently, Generic Letter 91-18 (Irformation to Licensecs Regarding Two NRC Inspection Manual Sections on Resolution of Degraded and Nonconforming Conditions and Operability) allows the licensee to use

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i the acceptance criteria specified in Generic Letter 90-05 for wall thinning mechanisms within Code

• i Class 3 moderate energy piping. Pursuant to the provisions of Generic Letter 90-05, ASME Code j

Class 3 moderate energy piping experiencing operational leakage can be considered operable if i

acceptable structural integrity is demonstrated and approved by the Staff. This provision is intended '

j to prevent the undesirable shutdown of an operating unit in those cases where a fracture mechanics evaluation clearly demonstrates the existence of sufficient structural integrity.  !

1 A Code repair or replacement of the SX backflush line flaw was attempted during the week of January 6,1997.

Successful implementation of the Code repair or replacement depended on the i i i achieving sufficient isolation of this pipe section from the cooling lake. Complications in isolating i this portion of SX pipe from the cooling lake using the upstream butterfly valve were encountered. i

This butterfly valve failed to provide suitable isolation to perform a Code repair or replacement without shutting the Unit down and consequently, the Code repair or replacement is impractical at '

this time.

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i l Braidwood has performed an evaluation of the flawed area using the 'Through Wall Flaw" approach l

of Generic Letter 90-05 (Reference submittal to the NRC dated 12/31/96). This evaluation  ;

demonstrated that the flaw stability and structural integrity comply with the guidelines of Generic i

! Letter 90-05 and are considered acceptable. Therefore, per the above referenced 90-05 evaluation, '

. this portion ofline is functional until a properly planned Code repair or replacement can be executed

{ during the Spring Unit I refueling outage. t PROPOSED ALTERNATE PROVISIONS  !

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L i Augmented inspections of five additional locations, utilizing Ultrasonic and Radiography techniques, j were conducted in accordance with the requirements of Generic Letter 90-05. Three of these five locations are sister components in both Units I and 2. All areas inspected had no localized wall i

thinning flaws below the applicable Code-required minimum wall thickness, T., and are acceptable i j

per the Generic Letter 90-05 Augmented Inspection criteria. Therefore, no further augmented

' inspections are required by Gencric Letter 90-05. However, areas were identified in the augmented

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inspection population that were below nominal pipe wall thickness and Braidwood will perform future inspections on these areas.

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! Braidwood will also perform a temporary non-code repair of this area using gasket material mechanically attached to the pipe. This temporary non-code repair will remain in place until a code i repair or replacement during the AIR 06 refueling outage can be completed. This outage is tentatively i scheduled to start 3/29/97. The above mentioned Generic Letter 90-05 evaluation bounds the ad of the proposed temporary non-code repair.

3 APPLICABLE TIME PERIOD l

t Reliefis requested until the Code repair or replacement can be properly completed.

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