ML040980529

RIC 2004 Presentation - T11 - Wayne D. Lanning - Emergent Technical Topics

ML040980529
Person / Time
Site:	Oconee, Arkansas Nuclear
Issue date:	03/11/2004
From:	Lanning W Division of Reactor Safety I
To:
References
RIC 2004
Download: ML040980529 (7)

Text

Regulatory Information Conference 2004 Emergent Technical Issues - T11 Emergent Material Degradation Issues Wayne D. Lanning Director - Division of Reactor Safety NRC Region I March 11, 2004

Introduction P Fall 2003 - Reactor Coolant Pressure Boundary Leakage Issues P Potential Impact on Safety P Increasing Frequency of Events P Significant Impact on Licensee and NRC Resources Emergent Material Degradation Issues Pilgrim Nozzle Leak P Through wall leak found during a forced outage P Leak caused by circumferential flaw in weld not identified by previous inspections P Repaired via a weld overlay process (extended the outage and required NRC approval)

Emergent Material Degradation Issues Three Mile Island Pressurizer Heater Diaphram Leak P Leaks caused by through wall cracks in seal weld and base metal of diaphram P Evidence of leakage in this area during previous refueling outage P Boric acid caused minor damage to associated strongback P Repairs involved replacement of affected bundle

< Extended outage and required NRC follow-up)

Emergent Material Degradation Issues Millstone Pressurizer Heater Leaks P Walkdown Identified P Two identical leaks identified during the previous refueling outage P Leaking bundles removed for examination; confirmed axial nature of flaw P Corrected by installation of a mechanical clamping device

< Required NRC approval P Impacted licensee and NRC resources Emergent Material Degradation Issues P Other Fall 2003 examples:

< Pressurizer heater sleeve cracking

- Waterford

- ANO

< Plugged thermocouple well leak

- Oconee Summary P Continue to present challenges P Impact NRC and licensee resources P Highlights need for effective detection and prevention programs P Additional generic guidance under review