05000338/FIN-2011011-03
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Finding | |
|---|---|
| Title | Missing Orifice Plate on 1J EDG |
| Description | Following the seismic event on August 23, 2011, and subsequent failure of the 2H EDG, all four EDGS were subject to thorough inspection and corrective maintenance. On September 3, 2011 during a post-maintenance EDG run, a leak was observed on 1J EDG engine-driven jacket coolant water pump. When the pump was removed for rebuild, it was discovered the pump did not have an orifice plate installed on the discharge of the pump. The orifice plate was subsequently found still attached to the discharge flange of the previously removed pump. An extent of condition was performed and it was observed that the 2J EDG was also missing its orifice plate on the jacket cooling water pump. A missing orifice plate on the jacket cooling water pump discharge flange can cause increased flow and pressure in the jacket cooling system, which in turn can cause 1) operating pressures to reach limitations; (2) degraded cooling capabilities; and (3) potential pipe strain that could lead to leakage or pump and piping fatigue. An installed orifice plate creates a pressure drop and corresponding decrease in flow throughout the system. As flow decreases, the temperature delta must increase to maintain the same amount of heat removal. It was determined the 2J EDG was missing its orifice plate since the last time it was worked on in 2004. A review of past performance data for the 2J EDG (back to 2005) was conducted and it was observed that due to the increased parameters, the temperature delta is lower at full load than normally (4-5 deg. vs. 10-14 delta T normally). Additionally, the 2J engine has required more work input from the engine which lowered the available horsepower to turn the electrical generator; however, past surveillance testing has demonstrated the ability of the 2J EDG to reach rated load. Because the degraded 2J EDG engine driven coolant pump caused some parameter changes on the 2J EDG and could have caused some degradation to the diesel since 2004, additional review by the NRC will be needed to determine whether the missing orifice plate represents a performance deficiency. An unresolved item will be opened pending completion of this review. The issue will be identified as URI 05000338, 339/2011011-03: Missing Orifice Plate on 1J and 2J EDG |
| Site: | North Anna  |
|---|---|
| Report | IR 05000338/2011011 Section 4OA5 |
| Date counted | Dec 31, 2011 (2011Q4) |
| Type: | URI: |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 93800 |
| Inspectors (proximate) | G Kolcum L Suggs M Chakravorty M Franke R Jackson S Park S Walker V Mccree Y Lie Leag Kolcum G Mccoy L Lake M Yoo R Clagg |
| INPO aspect | |
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Finding - North Anna - IR 05000338/2011011 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (North Anna) @ 2011Q4
Self-Identified List (North Anna)
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