05000247/FIN-2010002-02
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Finding | |
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| Title | Refueling Cavity Leakage into Containment |
| Description | The inspectors identified an unresolved item in that the Entergy technical staff has not evaluated the impact of reactor refueling cavity water leakage on the dissimilar metal welds between the stainless steel liner and the carbon steel studs that attach the liner to the concrete wall. During reactor refueling activities that occur for approximately two weeks every other year, when the refueling cavity is flooded, water (containing approximately 2700 ppm boric acid) has leaked at a rate of between 2 and10 gpm. The water dripped on equipment in the 46 foot level of containment. The effects of the leakage have not been evaluated with regard to liner attachment welds and carbon steel hardware. The reactor refueling cavity leakage has been documented in Entergy\'s corrective action program back to 1993. Entergy personnel had previously attempted to repair this leakage by applying various chemically bonded coatings to the stainless steel liner in various prospective leak locations. The coatings have not proven effective in stopping the leakage. As documented in CR-IP2-2008-01629 Entergy plans to research available technologies to identify a new permanent coating material and to apply this new material to specified areas of the leaking liner during the next three refueling outages. Completion of these activities is planned for 2014. Until a new permanent coating is identified and applied, a temporary coating material would be used as an interim measure to minimize leakage. If this remediation plan does not stop the leakage by 2014, Entergy will perform additional monitoring to assess the condition of potentially affected structures. During the refueling outage in April 2010 (2RF019) the inspectors determined that Entergy personnel had not identified a new permanent coating material and had applied a temporary coating to prospective leak locations. The inspectors determined the reactor refueling cavity liner is a safety-related structure. The UFSAR section 9.5.1.4, Protection Against Radioactivity Release from Spent Fuel and Waste Storage states: The reactor cavity, refueling canal and spent fuel storage pit are reinforced concrete structures with a seam-welded stainless steel plate liner. These structures are designed to withstand the anticipated earthquake loadings as seismic Class I structures so that the liner prevents leakage even in the event the reinforced concrete develops cracks. The reactor refueling cavity liner is classified as a QA category A structure in design drawing UE&C #9321-F-1283. The stainless steel liner is attached to the concrete cavity walls by a system of carbon steel Nelson Studs which are listed as being seismically qualified in drawing detail K. In CR-IP2-2000-09120 (documented in calendar year 2000), Entergy staff stated that the dissimilar metal weld between the stainless steel liner and the Nelson Studs may be subject to attack by galvanic corrosion or by intergranular stress corrosion cracking if sufficient concentrations of chloride ionic impurities are present due to leaking from the concrete cavity walls. This condition report was administratively closed without taking documented corrective action. Although there is no known degradation to this point, the inspectors concluded additional information is required by Entergy related to their assessment of this condition in accordance with Entergy procedures. The inspectors acknowledge that the leakage only occurs for approximately two weeks every other year, when the refueling cavity is flooded with water. For the remaining period of each operating cycle, this area is dry and area conditions should not be conducive to corrosion. (URI 05000247/2010002-02, Refueling Cavity Leakage into Containment) |
| Site: | Indian Point  |
|---|---|
| Report | IR 05000247/2010002 Section 4OA2 |
| Date counted | Mar 31, 2010 (2010Q1) |
| Type: | URI: |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71152 |
| Inspectors (proximate) | T Burns T Hedigan D Caron D Jones J Noggle M Gray M Halter P Cataldo P Prescott R Latta S Barrb Haagensene Gray E Keighley J Noggle J Schoppy M Gray O Ayegbiso S Barr |
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Finding - Indian Point - IR 05000247/2010002 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Indian Point) @ 2010Q1
Self-Identified List (Indian Point)
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