05000389/FIN-2014008-01
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Finding | |
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| Title | Loose Part Damage in the Hot Leg Channel Head of Steam Generator 2B |
| Description | The inspectors identified an unresolved item associated with damage to the hot leg channel head of SG-2B as a result of foreign material in the reactor coolant system. Description: On April 8th, 2014, the licensee received indications from two channels of the loose part monitoring system during plant restart operations (Mode 3). Further evaluation of the loose part monitor signals indicated that a potential loose part was contained inside the SG-2B hot leg channel head. The licensee then commenced a cooldown and depressurization of the Unit 2 reactor to inspect the SG-2B hot leg channel head for damage and retrieve any loose object. The inspection found a single metallic (stainless steel) loose part and various indications of impact damage on the internal surfaces of the channel head. The extent of the damage included indentation marks on the channel head stainless steel cladding, tubesheet cladding, divider plate surface and welds, tube end seal welds, and existing tube plugs. The licensee entered the issue in the corrective action program as Condition Report 01955927 and initiated a root cause evaluation. The licensee determined that the loose part was foreign material, but had not yet determined how it was introduced into the reactor coolant system. The licensee evaluated the operability of the affected components for the next operating cycle (Areva Report 51-9222481-000) and initiated corrective actions to further review potential long term effects. The operability evaluation addressed the impact damage to all the channel head surfaces with respect to the structural integrity of the materials and corrosion of carbon steel components due to potential cladding damage. The licensee also evaluated the damage to the tube seal welds and the existing tube plugs with respect to the ability of the tubes to meet the tube integrity criteria during the next operating cycle. The tube integrity evaluation included conservative postulated damage and pressure testing of a tubesheet mock-up containing tube plugs that were exposed to similar impact damage. Even though the pressure test demonstrated that the damaged tube plugs maintained their design function, the licensee conservatively decided to replace the most degraded tube plug in SG-2B. The inspectors did not identify issues of concern with the operability evaluation of SG-2B for the next operating cycle. This is an unresolved item pending review of the licenses causal analysis of foreign material identified in the reactor coolant system. This issue will be tracked as unresolved item URI 05000389/2014008-001, Loose Part Damage in the Hot Leg Channel Head of Steam Generator 2B. |
| Site: | Saint Lucie  |
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| Report | IR 05000389/2014008 Section 1R08 |
| Date counted | Jun 30, 2014 (2014Q2) |
| Type: | URI: |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.08 |
| Inspectors (proximate) | D Dumbacher J Reyes J Rivera Ortiz M Coursey T Hoeg T Morrisseya Butcavagej Rivera Ortiz O Lopez Santiago |
| INPO aspect | |
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Finding - Saint Lucie - IR 05000389/2014008 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Saint Lucie) @ 2014Q2
Self-Identified List (Saint Lucie)
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