ENS 43354

From kanterella

Jump to navigation Jump to search

v t e ENS Event
01:27 Mar 13, 2007
Title	Invalid Tubine Driven Auxiliary Feedwater Pump Starts
Event Description	This report describes three invalid actuations of the Unit 2 Turbine Driven Auxiliary Feedwater (TDAFW) pump that occurred on March 12,2007. This report is being made in accordance with 10CFR50.73(a)(1), which states, in part, 'In the case of an invalid actuation reported under 10CFR50.73(a)(2)(iv), other than actuation of the reactor protection system (RPS) when the reactor is critical, the licensee may, at its option, provide a telephone notification to the NRC Operations Center within 60 days after discovery of the event instead of submitting a written LER.' On March 12, 2007 at 2027, while performing operator rounds, Operations personnel heard a venting noise coming from the vicinity of the Main Steam Line 2-04 to Auxiliary Feedwater Pump Turbine Steam Supply Valve. One of the Operators put his hand close to the exhaust pilot valve, restricting the venting air flow, which increased the sensing pressure on one of the valve's ports. The valve swapped, exhausting the diaphragm. This caused the TDAFW steam supply valve to fail open and the TDAFW pump started and reached full flow. Operations responded to the event by manually running back the Main Turbine load to 1100 Mew to ensure Reactor Power remained less than 100%. The TDAFW pump was secured and the steam supply valve hand switch was placed in AUTO. At 2056, an I&C technician was leak checking the valve actuator and tubing joints. The I&C technician got within close proximity of the Main Steam Line 2-04 to Auxiliary Feedwater Pump Turbine Steam Supply Valve and restricted the venting air flow, which increased the sensing pressure on one of the exhaust pilot valve's ports. The pilot valve swapped, exhausting the diaphragm. The TDAFW Steam Supply Valve failed open again and the TDAFW pump started a second time and reached full flow. At 2100, Shift Operations placed the steam supply valve in pullout and declared the TDAFW inoperable. To prevent further inadvertent starts, Operations decided to close the upstream isolation valve. While in the process of closing the isolation valve, the Operator heard air venting from the vicinity of the Main Steam Line 2-04 to Auxiliary Feedwater Pump Turbine Steam Supply Valve. The Operator put his hand under the exhaust pilot valve such that the air flow was restricted, which increased the sensing pressure on one of the valve's ports. The pilot valve swapped, exhausting the diaphragm. The TDAFW steam supply valve failed open again and the TDAFW pump started a third time. Since the upstream isolation valve was partially closed, the TDAFW pump only reached a partial flow of 235 gpm. Shift Operations initiated a clearance to prevent further inadvertent TDAFW pump starts and a work order was initiated to determine the failure mechanism. On March 13, 2007 at 2223, Shift Operations declared the TDAFW pump operable. The specific train and system that actuated was the third AFW train on Unit 2. During each of the three TDAFW pump starts, the system started and functioned correctly. During the first two pump starts, the train actuation was complete. As described above, on the third start the train actuation was partial due to less than full flow being developed. The second and third TDAFW pump starts took place during trouble shooting and clearance isolation activities, respectively, which occurred prior to the cause being identified. The three AFW invalid actuations occurred due to incorrect setup of the exhaust pilot valve for the Main Steam Line 2-04 to Auxiliary Feedwater Pump Turbine Steam Supply Valve. The NRC Resident Inspector will be notified of this report.

ENS 43354 +/-
Where
Comanche Peak Texas (NRC Region 4)
Reporting

10 CFR 50.73(a)(1), Submit an LER, Invalid Actuation
Time - Person (Reporting Time:+1405.92 h58.58 days <br />8.369 weeks <br />1.926 months <br />)
Opened:	Gary Merka 15:22 May 10, 2007
NRC Officer:	Jeff Rotton
Last Updated:	May 10, 2007
43354 - 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":[{"text":"\u003Cb\u003E\u003Cdiv class=\"mw-parser-output\"\u003E\u003Cp\u003E\u003Ca class=\"mw-selflink selflink\"\u003EENS 43354\u003C/a\u003E - \u003Ca href=\"/Comanche_Peak\" title=\"Comanche Peak\"\u003EComanche Peak\u003C/a\u003E\n\u003C/p\u003E\u003C/div\u003E\u003C/b\u003E\u003Cdiv class=\"mw-parser-output\"\u003E\u003Cp\u003EInvalid Tubine Driven Auxiliary Feedwater Pump Starts\n\u003C/p\u003E\u003C/div\u003E","title":"ENS 43354 - Comanche Peak\n","link":"","lat":32.29839166666667,"lon":-97.78532222222222,"icon":"/w/images/d/d7/Luminant_icon.png"}],"imageoverlays":null}
v • d • e

v t e Emergency Notification System
Comanche Peak with 10 CFR 50.73(a)(1), Submit an LER
WEEKMONTHYEAR2019-11-01T00:19:00 [Table view]
[ENS list for Comanche Peak]

Retrieved from "https://kanterella.com/w/index.php?title=ENS_43354&oldid=90934"