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Start date | Reporting criterion | Title | Event description | System | LER | |
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ENS 46598 | 7 February 2011 06:00:00 | 10 CFR 21.21, Notification of failure to comply or existence of a defect and its evaluation | Potential Emergency Diesel Generator Bearing Failures | The following information was received via e-mail: Linear indications (hot tears) were observed on one main bearing by the FM (Fairbanks Morse) production inspector. The indications were only on one edge of the bearing. The indications went across the entire edge and extended about 1 inch deep into the bearing, being visible on the outside diameter and the inside diameter for about 1 inch. Subsequent 100% liquid penetrant inspection (PT) of all finished bearings in stock has found linear indications on 13 of 454 bearings (3% reject rate) made from permanent mold castings. No bearing failures in engines have been linked to linear indications. The root cause of the problem occurs during the casting of the aluminum material in the permanent mold. The linear indications occur only on one edge of the casting, which has been identified as the bottom of the casting. During the cooling and solidification of the molten material poured into the permanent mold tool, the material shrinks and must be continuously replenished with molten material from the top of the casting. If the top of the casting solidifies before the bottom, there is no additional molten material available from the top to feed the bottom as it cools and shrinks, resulting in tears (hot tears) to the material on the bottom of the casting. It is suspected these hot tears are occurring due to improper cooling of the mold tool core. Because there are no cooling passages within the solid mold tool core, the core becomes progressively hotter throughout the production run until the core reaches a temperature hot enough to cause the hot tears. Affected plants are: Limerick, Peach Bottom and Prairie Island. | Emergency Diesel Generator | |
ENS 44178 | 29 April 2008 05:00:00 | 10 CFR 21.21, Notification of failure to comply or existence of a defect and its evaluation | Part 21 Notification Regarding Identification of Defect Alco Snubber Valve Micro-Cracking | The reporting organization provided the following information via facsimile: Name and address the individual or individuals informing the Commission. Mr. Dominic Dedolph, Manager, Quality Assurance, Fairbanks Morse Engine, 701 White Avenue, Beloit, WI 53511. Identification of the facility, the activity, or the basic component supplied for such facility or such activity within the United States which fails to comply or contains a defect: Facility- Entergy (Indian Point). Basic component which fails to comply or contains a defect: ALCO Fuel Snubber Valve P/N 2402466-1. The snubber valves in the Emergency Diesel Generator are installed in the high pressure fuel line between the fuel injection pump and the injection nozzle and serve as a pulsation dampener. Nature of the defect or failure to comply and the safety hazard which is created or could be created by such defect or failure to comply. Nature of defect: Fairbanks Morse Engine (FME) evaluation has determined that a potential safety hazard exists for ALCO fuel injection snubber valves due to micro-cracking in the tip of the snubber valve created during the material surface hardening process when the tips of the snubber valve were quenched in water. Safety hazard which could be created by such defect: Micro-cracking in the tip of the snubber valve could potentially lead to material flaking . It has been postulated that the flakes (or particles) could be flushed downstream and become lodged in the nozzle, causing excessive fuel to enter the combustion space and wash the cylinder liner dry and lead to a piston seizure. The date on which the information of such defect or failure to comply was obtained. Deviation discovered on February 29, 2008. Evaluation completed on April 28, 2008. The corrective action which has been, is being, or will be taken; the name of the individual or organization responsible for the action; and the length of time that has been or will be taken to complete the action. Root cause analysis was performed and found that water quenching during the heat treatment process resulted in approximately 40% of the tips of the snubber valves to have micro-cracking present. When oil was substituted for the quenching medium, no snubber valves showed any signs of micro-cracking. The heat treatment process documentation has been updated to specify the quenching medium as oil. Oil has been used exclusively in the heat treatment process of all snubber valves produced by FME since March 1, 2008. Any advice related to the defect or failure to comply about the facility, activity, or basic component that has been, is being, or will be given to purchasers or licensees. FME is notifying Entergy (Indian Point) of the twelve (12) suspect pieces. | Emergency Diesel Generator |