ML053290020

Enclosure 1, Meeting Summary High Energy Line Break

ML053290020
Person / Time
Site:	Oconee
Issue date:	11/14/2005
From:	Duke Energy Corp, Duke Power Co
To:	Office of Nuclear Reactor Regulation
Olshan L N, NRR/DLPM, 415-1419
Shared Package
ML053290022	List: ML053290020 ML053290025 ML053290041
References
Download: ML053290020 (14)

Text

Oconee Nuclear Station High Energy Line Break Outside Containment Summary of East Penetration Room Activities NRC Update November 14, 2005

Agenda Main Feedwater Piping Inspections Electrical Penetrations Inspections and Repairs Status of East Penetration Room (EPR)

Flood Prevention Modifications 2

MFDW Piping Inspections Unit 2 East Penetration Room FAC Insp. Girth Butt Area (typ.) Weld (typ.)

Elect.

Pen.

Area Attachment Weld (typ.)

3

MFDW Piping Inspections Q Depending on the unit, there are between 13 to 16 girth butt welds and between 3 to 5 attachment weld locations currently in the elective ISI category. The girth butt welds are inspected by UT.

Q Attachment weld locations include the attachment welds at the rupture restraints (8 attachment welds per rupture restraint).

These welds are visually inspected as well as receiving either a MT or PT.

Q Each unit has four locations inspected as part of the Flow Accelerated Corrosion (FAC) Program. The base metal at these locations is inspected by UT.

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MFDW Piping Inspections Previous Inspections:

Elective inspections of girth butt welds began in 2003.

To date 3 girth butt welds in Unit 1 and 5 girth butt welds in Unit 3 have been inspected.

During the current 2EOC21 outage, 11 girth butt welds will be inspected. In addition, a limited amount of base metal adjacent to these welds will be inspected. 3 attachment weld locations will also be inspected (including the 8 attachment welds at each rupture restraint).

All four FAC locations in Unit 1 were inspected in 2003. Two of the four FAC locations in Unit 2 were inspected in 2004. All four FAC locations in Unit 3 were inspected in 2003.

UT inspection data collected to date shows that no weld or piping component location has a thickness less than code minimum

(.986).

5

MFDW Piping Inspections Future Inspections:

All girth butt welds and attachment welds in all units will be inspected by the Spring of 2008. Afterwards, all welds will be inspected once during a given ISI interval.

Additional locations will be added to the FAC inspection program.

Piping base metal downstream of the isolation valves not enclosed by the guard pipe will receive, at a minimum, a UT inspection every ten years.

Attachment welds at the terminal end (inside the guard pipe) will be visually inspected every ten years.

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Electrical Penetrations Configuration of electrical penetration enclosures has not been maintained.

Initiated inspection and repair program to restore the enclosures to correct configuration.

Inspections performed on selected Unit 2 EPR electrical penetrations consisting of all HELB mitigation related (4) and 6 other penetrations with missing covers.

No degradation of terminal boards or connections was noted. Some minor rusting of enclosure interior bottom and minor debris was found.

Inspection and restoration of other units penetrations are planned for the upcoming Unit 3 (Spring 2006) and the Unit 1 (Fall 2006) outages.

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Electrical Penetrations /

cont.

8

Electrical Penetrations /

cont.

9

Electrical Penetrations /

cont.

10

Electrical Penetrations /

cont.

11

Electrical Penetrations /

cont.

QActivities are underway to create a Preventative Maintenance Program.

QProgram will ensure that the electrical penetrations cover boxes will be free from debris and corrosion.

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EPR Flood Prevention Modification Conceptual design of flood outlet device will be completed by 11/21/05. Detailed design will be completed by 1/15/06. First units installation package will be completed by 2/8/06. Remaining units packages will be completed by 3/1/06. Implementation will begin with the Spring 2006 Unit 3 outage.

Design of impoundment modifications will begin in the first quarter of 2006. Design completion is expected by the third quarter of 2006.

Flood outlet device and wall/door modifications will be designed to mitigate both the full guillotine break and the 1/2 D x 1/2 t crack scenario defined in the Giambusso letter.

Modifications will ensure that the resulting water level in the EPR will not cover critical instrumentation.

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Summary Q Inspection of MFDW piping welds and base metal is underway. These inspections will give greater confidence of the structural integrity of the MFDW piping. All welds are to be inspected by Spring 2008.

Q Inspection and Repair of Electrical Penetrations is underway.

Q A Preventative Maintenance Program for the Electrical Penetrations is under development.

Q Design work has begun on the EPR flood prevention modification.

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