ENS 51458

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v t e ENS Event
17:00 Oct 5, 2015
Title	Part 21 Report - Electromatic Relief Valve (Emrv) Cutout Switch
Event Description	Following the return of the actuator that failed bench testing to GEH, on 6/12/15 at 1804 [CDT], General Electric Hitachi (GEH) notified Dresden Station of a potential parts quality Potential Failure of the EMRV Cutout Switch. It has been determined the notification is applicable to DNPS [Dresden Nuclear Power Station], Units 2 and 3. The GEH investigation concluded that the EMRV actuator assemblies failed to change state because of the failure of the cutout switch to fully close and provide the appropriate current path. Multiple contributing factors were discovered which could have led to the presence of the gaps in the cutout switch. The most significant of these factors is a change in lever arm positioning causing increased forces in the tension spring which prevent proper closure of the cutout switch. Design changes to reduce wear caused by vibration on the actuators changed lever arm position and also allowed for additional dimensional tolerance which tended to increase force in the tension spring. Identification of Facility and Component: DNPS / EMRV Actuator, GEH Part Number 352B2632G001 Safety Significance (e.g., substantial hazard that is or could be created): Identified condition is a Potential Substantial Safety Hazard since it could cause affected EMRVs to fail to operate as designed, which could result in a loss of safety function. Potential to affect the Minimum Critical Power Ratio (MCPR), Reactor Coolant System (RCS), Automatic Depressurization System (ADS), and Low Set Relief Function Plants with similar GEH cutout switches: Quad Cities Nuclear Power Station. Part 21 Reference: EN#51386 The licensee notified the NRC Resident Inspector.

ENS 51458 +/-
Where
GE Hitachi Nuclear Energy Morris, Illinois (NRC Region 3)
Organization:	Dresden
Reporting

Other Unspec Reqmnt 10 CFR 21.21(d)(3)(i), Failure to Comply or Defect
Time - Person (Reporting Time:+29.1 h1.213 days <br />0.173 weeks <br />0.0399 months <br />)
Opened:	Aaron Thompson 22:06 Oct 6, 2015
NRC Officer:	Jeff Herrera
Last Updated:	Oct 6, 2015
51458 - NRC Website Loading map... {"minzoom":false,"maxzoom":false,"mappingservice":"leaflet","width":"350px","height":"250px","centre":false,"title":"","label":"","icon":"","lines":[],"polygons":[],"circles":[],"rectangles":[],"copycoords":false,"static":false,"zoom":6,"defzoom":14,"layers":["OpenStreetMap"],"image layers":[],"overlays":[],"resizable":false,"fullscreen":false,"scrollwheelzoom":true,"cluster":false,"clustermaxzoom":20,"clusterzoomonclick":true,"clustermaxradius":80,"clusterspiderfy":true,"geojson":"","clicktarget":"","imageLayers":[],"locations":[],"imageoverlays":null}
v • d • e

v t e Emergency Notification System
GE Hitachi Nuclear Energy with Other Unspec Reqmnt, 10 CFR 21.21(d)(3)(i), Failure to Comply or Defect
WEEKMONTHYEAR2015-10-05T17:00:00 [Table view]
[ENS list for GE Hitachi Nuclear Energy]

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