ML082810709

Issuance of Staff'S Summary of 2007 Steam Generator Tube Inspections Report

ML082810709
Person / Time
Site:	Palisades
Issue date:	10/16/2008
From:	Mahesh Chawla Plant Licensing Branch III
To:	Entergy Nuclear Operations
Chawla M, NRR/DORL, 415-8371
References
TAC MD8649
Download: ML082810709 (4)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 October 16, 2008 Vice President, Operations Entergy Nuclear Operations Palisades Nuclear Plant 27780 Blue Star Memorial Highway Covert, MI 49043-9530

SUBJECT:

PALISADES NUCLEAR PLANT - ISSUANCE OF STAFF'S

SUMMARY

OF 2007 STEAM GENERATOR TUBE INSPECTIONS REPORT (TAC NO. MD8649)

Dear Sir:

By letters dated April 7, 2008 and August 6,2008, Entergy Nuclear Operations, Inc., the licensee, submitted information summarizing the results of the 2007 steam generator (SG) tube inspections at Palisades Nuclear Plant. In addition to these reports, the U.S. Nuclear Regulatory Commission (NRC) staff summarized additional information concerning the 2007 SG tUbe inspections at Palisades in a letter dated January 4, 2008. The ~IRC staff comments and observations, based on the review of the reports are attached in the enclosure.

Based on a review of the information provided, the NRC staff concludes that the licensee provided the information required by their technical specifications. In addition, the staff concludes that there are no technical issues that warrant follow-up action at this time since the inspections appear to be consistent with the objective of detecting potential tube degradation and the inspection results appear to be consistent with industry operating experience at similarly designed and operated units.

Sincerely,

{)~~W1f1 fhL Mahesh L. Chawla, Project Manager Plant Licensing Branch 111-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-255

Enclosures:

As stated cc w/encls: Distribution via ListServ

SUMMARY

OF NUCLEAR REGULATORY COMMISSION STAFF REVIEW FOR 2007 STEAM GENERATOR TUBE INSPECTION REPORT PALISADES NUCLEAR PLANT TAC No. MD8649 DOCKET No. 50-255 By letters dated April 7, 2008, (Agencywide Documents Access and Management Systems (ADAMS) Accession No. ML080980422) and August 6,2008 (ADAMS Accession No. ML082200065), Entergy Nuclear Operations, Inc., the licensee, submitted information summarizing the results of the 2007 steam generator (SG) tube inspections at Palisades Nuclear Plant. In addition to these reports, the U.S. Nuclear Regulatory Commission (NRC) staff summarized additional information concerning the 2007 SG tube inspections at Palisades in a letter dated January 4, 2008 (ADAMS Accession No. ML073550079).

Palisades Nuclear Plant has two Combustion Engineering Model 2530 replacements SGs. Each SG has 8,219 mill-annealed, Alloy 600 tubes. The tubes have an outside diameter of 0.75 inches, and a wall thickness of 0.042 inches. Stainless steel eggcrate, lattice-type tube supports, diagonal straps, and vertical straps support the tubes at various locations. The tubes were expanded through the full depth of the tubesheet using an explosive process.

The licensee provided the scope, extent, methods, and results of their SG tube inspections in the documents referenced above. In addition, the licensee described corrective actions (Le.,

tube plugging) taken in response to the inspection findings.

As a result of the review of the reports, the NRC staff has the following comments/observations:

A visual inspection of the lower end of the batwings in the stay cavity area was performed. No broken batwings were identified.

One tube was identified that had an indication attributed to tube-to-tube wear. This tUbe was stabilized and plugged. The tube-to-tube wear was identified during an inspection with a rotating probe equipped with +Point' coil to confirm the morphology of a historical wear scar at a diagonal bar. The tube-to-tube wear indication, estimated to be approximately 3-inches long and a maximum depth of 16-percent, was not identified during the bobbin coil examination (neither on the differential or absolute channels).

The indication was located at the diagonal bar and extended below it by approximately 1 inch.

All historical wear indications are inspected with a rotating probe. Some tubes are believed to be in close proximity because of design tolerances on the bend angle for the 90-degree bend and the design tolerances on the length of the horizontal run of the tubing.

Enclosure

-2 A couple of tubes had possible loose part indications above the 8th cold leg tube support. One of the tubes was stabilized and plugged and a nearby tube (with no evidence of wear) was plugged. The licensee does not consider severance of this non-stabilized tube likely since the flow in this region is primarily upward (i.e., the cross-flow velocities are small). l\Iearbyactive tubes will continue to be monitored for evidence of degradation.

Based on a review of the information provided, the NRC staff concludes that the licensee provided the information required by their technical specifications. In addition, the staff concludes that there are no technical issues that warrant follow-up action at this time since the inspections appear to be consistent with the objective of detecting potential tube degradation and the inspection results appear to be consistent with industry operating experience at similarly designed and operated units.

October 16, 2008 Vice President, Operations Entergy Nuclear Operations Palisades Nuclear Plant 27780 Blue Star Memorial Highway Covert, MI 49043-9530

SUBJECT:

PALISADES NUCLEAR PLANT -ISSUANCE OF STAFF'S

SUMMARY

OF 2007 STEAM GENERATOR TUBE INSPECTIONS REPORT (TAC NO. MD8649)

Dear Sir:

By letters dated April 7, 2008 and August 6,2008, Entergy Nuclear Operations, Inc., the licensee, submitted information summarizing the results of the 2007 steam generator (SG) tube inspections at Palisades Nuclear Plant. In addition to these reports, the U.S. Nuclear Regulatory Commission (NRC) staff summarized additional information concerning the 2007 SG tube inspections at Palisades in a letter dated .January 4, 2008. The NRC staff comments and observations, based on the review of the reports are attached in the enclosure.

Based on a review of the information provided, the NRC staff concludes that the licensee provided the information required by their technical specifications. In addition, the staff concludes that there are no technical issues that warrant follow-up action at this time since the inspections appear to be consistent with the objective of detecting potential tube degradation and the inspection results appear to be consistent with industry operating experience at similarly designed and operated units.

Sincerely, lRAI Mahesh L. Chawla, Project Manager Plant Licensing Branch 111-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-255

Enclosures:

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