ML14071A477

Report of Potential Defect Per 1OCFR Part 21 Primary Disconnect Assembly

ML14071A477
Person / Time
Site:	Beaver Valley, Browns Ferry, Saint Lucie, Seabrook, Turkey Point, River Bend, San Onofre, Fort Calhoun
Issue date:	02/26/2014
From:	Seiken A AZZ Incorporated
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
P21-01312014
Download: ML14071A477 (4)

Text

A AZZ N L Date: February 26, 2014 Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555 Part 21 Report No: P21-01312014

Subject:

Report of potential defect per 10CFR Part 21 primary disconnect assembly Pursuant to IOCFR 21.21 (d) (3) (ii), AZZ/NLI is providing written notification of the identification of a defect. This letter is to notify you of a potential manufacturing defect concerning primary disconnect assemblies used on Masterpact replacement cradles. These assemblies are used in the replacement of the circuit breakers in low voltage switchgear.

The following information is required per I0-CFR 21.21 (d) (4).

(i) Name and address of the individual or individuals informing the Commission.

Aron Seiken, Vice President Nuclear Logistics, Inc 7410 Pebble Drive Ft. Worth, TX 76118 (ii) Identification of the facility, activity, or the basic component supplied for such facility or such activity within the United States which fails to comply or contains a defect.

Facility:

Nuclear Logistics, Inc 7410 Pebble Drive Ft. Worth, TX 76118 The specific part which fails to comply or contains a defect:

Primary disconnect (p/n AHX30701) for Square D replacement low voltage switchgear breaker cradles (model LGSB4).

NUCLEAR LOGISTICS INC. www.azz.com 7410 Pebble Drive - Fort Worth, Texas 76118 - 800.448.4124 Phone

• 817.590.0484 Fax

(iii) Identification of the firm constructing or supplying the basic component which fails to comply or contains a defect.

The primary disconnect was manufactured by Square D Services (Schneider Electric) and supplied as a dedicated component by Nuclear Logistics, Inc.

(iv) Nature of defect or failure to comply and the safety hazard which is created or could be created by such defect or failure to comply.

S

• The cradle is an adaptor between the replacement circuit breaker and the existing switchgear cubicle.

Part of the interfaces is the primary disconnects (fingers). The cradle primary disconnects"connect to the bus stabs in the switchgear. The cradle primary disconnects are designed to account for vertical misalignment of the stabs in the switchgear. The primary disconnect fingers have vertical flexibility (float) that maintains tile finger pressure on the bus stabs when the bus stabs are not completely aligned in the vertical axis.

The fabrication drawing for the primary disconnect fingers had an incorrect tolerance. If the fingers are made with a dimension at tile low end of the specified tolerance, there will be interference with a mating part. This reduces or eliminates the vertical float for the fingers. If the cradle is installed in a switchgear cubicle with vertically misaligned bus stabs, the disconnect fingers may have inadequate contact pressure. This condition may result in a higher than normal contact resistance fi'om the cubicle stab to the cradle primary disconnect. The higher contact resistance at any one finger contact could cause an unacceptable temperature rise at that connection point. At very high temperatures, the springs that maintain the finger contact pressure could relax, which would further increase the connection resistance and cause additional overheating.

This would not be an issue if there was no vertical misalignment of the switchgear cubicle stabs. See the additional clarifications in section (vi) below.

(v) The date on which the information of such defect or failure to comply was obtained.

The information that there is a defect was obtained on January 28, 2014.

(vi) In the case of a basic component which contains a defect or fails to comply, the number and location of these components in use at, supplied for being supplied for, or may be supplied for, manufactured or being manufactured for one or more facilities or activities subject to the regulations in this part.

The issue is applicable to 1600amp cradles only. The same and similar disconnects are used in tile different cradle designs identified below. A list of the cradle types, primary disconnect part numbers and affected facilities (plants) in Table I as follows:

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Table 1 Plant Name Cradle/Breaker Primary Quantity Original breaker Type disconnect part type/Notes number OPPD- Ft. Calhoun LGSB4 with AHX30701 18 Original breakers: GE Masterpact NW AK-50.

breaker OPPD replaced all AHX30701 with narrower disconnect p/n R300112 TVA-Browns Ferry LGSB4 and LGSB21 AHX30701 28 Original breakers: GE with Masterpact NW AK-50.

breaker ° Entergy-River LGSB9 Masterpact R300112 5 Original breakers: AKR-Bend NW breaker 50.

Narrower disconnect.

FENOC-Beaver LGSB4 Masterpact AHX30701 20 Original breakers: GE Valley NW breaker AK-50 FPL-St. Lucie LISB2 Masterpact AJF30101 15 Original breakers: ABB NW breaker K- 1600 FPL-Turkey Point LISB2 Masterpact AJF30101 12 Original breakers: ABB NW breaker K- 1600 SCE-SONGS LISB2 Masterpact AJF30101 8 Original breakers: ABB NW breaker K-1600 Nextera Energy- LISB2 Masterpact AJF30101 4 Original breakers: ABB Seabrook NW breaker K- 1600 Additional details:

0 This issue does not affect all of the cradles identified above. Since the issue is a result of incorrect manufacturing tolerances, it will not be present on all cradles.

• The overheating issue could be a problem with replacement circuit breakers for GE AK-50 circuit breakers. Due to the construction of the switchgear cubicles, there can be vertical misalignment of the stabs in the switchgear. If the primary disconnect float is not adequate, the overheating issue identified above could occur.

" The overheating issue is expected to be much less prevalent or non-existent on the replacements for GE AKR and ABB K-line circuit breakers. The construction of the switchgear cubicles results in good vertical alignment of the stabs in the switchgear. so the amount of cradle finger vertical float is not as critical.

(vii) The corrective action which has been, is being, or will be taken; the name of the individual or organization responsible for the action; and the length of time that has been or will be taken to complete the action.

NLI has generated Technical Bulletin TB-14-001 to direct the plants for inspections to determine if the manufacturing defect is present in the specific applications. The Technical Bulletin will be issued to the potentially impacted plants by March 4, 2014.

NLI is in process of revising test plans to include verification of the proper operation of the primary disconnects during factory acceptance testing. The verification will be performed on 100% of supplied cradles.

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Square D Services is revising manufacturing drawings to eliminate any tolerance stack up issue that could limit the vertical movement of the finger contacts of the primary disconnect assemblies.

(viii) Any advice related to the defect or failure to comply about the facility, activity, or basic component that has been, is being, or will be given to purchasers or licensees.

NLI will submit NLI Technical Bulletin TB-14-001 to all facilities where the potentially impacted Masterpact breakers have been installed. The technical bulletin provides a summary of the issue and provides instructions for inspection and testing of the cradles.

Please contact me with any questions or comments.

Aron Seiken Vice President/General Manager Paec 4