ML040980529
| 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
PFall 2003 - Reactor Coolant Pressure Boundary Leakage Issues PPotential Impact on Safety PIncreasing Frequency of Events PSignificant Impact on Licensee and NRC Resources Introduction 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 POther Fall 2003 examples:
Pressurizer heater sleeve cracking
- Waterford
- ANO
Plugged thermocouple well leak
- Oconee Emergent Material Degradation Issues PContinue to present challenges PImpact NRC and licensee resources PHighlights need for effective detection and prevention programs PAdditional generic guidance under review Summary