ML12121A509

Mitsubishi Nuclear Energy Systems, Part 21 Interim Report - Steam Generator Tube Wear

ML12121A509
Person / Time
Site:	San Onofre
Issue date:	04/19/2012
From:	Kadokami E Mitsubishi Nuclear Energy Systems
To:	Office of Nuclear Reactor Regulation
References
47833
Download: ML12121A509 (2)

Text

0411912012 U.S. NuclearRegulatory Commission OperationsCenter Event Report Pa-ze I Part 21 (PAR) Event# 47833 Rep Org: MITSUBISHI NUCLEAR ENERGY SYSTEMS Notification Date / Time: 04/13/2012 15:58 (EDT)

Supplier: MITSUBISHI HEAVY INDUSTRIES, LTD Event Date / Time: 04/13/2012 (EDT)

Last Modification: 04/19/2012 Region: 1 Docket #:

City: ARLINGTON Agreement State: Yes County: License #:

State: VA NRC Notified by: El KADOKAMI Notifications: BLAKE WELLING R1DO HQ Ops Officer: JOHN KNOKE KATHLEEN O'DONOHUE R2DO Emergency Class: NON EMERGENCY DAVID HILLS R3DO 10 CFR Section: VINCENT GADDY R4DO 21.21 (a)(2) INTERIM EVAL OF DEVIATION PART 21 GROUP EMAIL PART 21 INTERIM REPORT - STEAM GENERATOR TUBE WEAR This interim Part 21 is in regard to San Onofre Nuclear Generating Station, Unit 2, Steam Generator replacement.

"During the first refueling outage following steam generator replacement, eddy current testing identified ten total tubes with depths of 90 to 28 percent of the tube wall thickness. Some of the affected tubes were located adjacent to retainer bars. The retainer bars are part of the floating anti-vibration bar (AVB) structure that stabilizes the u-bend region of the tubes.

"Other tubes in the two steam generators had detectable wear associated with support points elsewhere in the AVB structure. Each steam generator has 9727 tubes with an 8 percent (778 tubes) design margin for tube plugging.

"Discovery Date: February 13, 2012 "Evaluation completion schedule date: May 31, 2012" "Those Mitsubishi Heavy Industries customers potentially affected by this issue have been notified and will receive a copy of this interim report."

Reference Document: UET-20120089 Interim Report No: U21-018-IR (0)

• *

• UPDATE FROM JOSEPH TAPIA TO KARL DIEDERICH ON 4/19/12 AT 1306 EDT * *

• 04/19/2012 U.S. Nuclear Regulatory Commission OperationsCenter Event Report Pake 2 Part 21 (PAR) Event# 47833 "On January 31, 2012, San Onofre Unit 3 shut down due to indications of a steam generator [SG] tube leak. Steam generator tube inspections confirmed one small leak on one tube in one of the two steam generators. Continuing inspections of 100% of the steam generator tubes in both Unit 3 steam generators discovered unexpected wear, including tube to tube as well as tube to tube support structural wear. Inspection, testing, and analysis of SG tube integrity in both Unit 3 SGs is ongoing. In-situ pressure testing identified eight Unit 3 SG tubes that did not meet the target performance criteria in Technical Specification for tube integrity. One of the failed tubes was the leaking tube that required the Unit 3 shutdown.

"Discovery date: February 21, 2012 "Evaluation completion schedule date: August 31, 2012" Notified R1 DO (Joustra), R2DO (Nease), R3DO (Peterson), R4DO (O'Keefe), and Part 21 Group via email.