ENS 48619
ENS Event | |
|---|---|
15:00 Dec 21, 2012 | |
| Title | Both Unit Two Auxiliary Feedwater Pumps Declared Inoperable |
| Event Description | 21 Motor Driven and 22 Turbine Driven Auxiliary Feedwater Pumps (AFWP) were declared inoperable at 0900 CST on 12/21/2012 due to the Condensate Storage Tank (CST) temperature exceeding 92 degrees F.
In accordance with procedure C28.6, 'Condensate Storage Tank Freeze Protection System', the maximum CST temperature shall not exceed 92 degrees F. This is to ensure the maximum AFWP discharge temperature is less than 100 degrees F when an AFWP is at design flow per USAR Table 11.9-2, 'Summary of Assumptions,' used in the AFW system design verification analyses. LCO 3.7.5 Condition D was entered for two AFW trains inoperable in Modes 1, 2 or 3. The AFWP's could start and run if required at the time of entry. Immediate action was taken to reduce the CST temperature. At 1315 CST temperature were lowered below 92 degrees F and LCO 3.7.5 condition D was exited. This condition is reportable per 10 CFR 50.72(b) (3) (v) (D) as an event or condition that could have prevented the fulfillment of a safety function. The licensee has notified the NRC Resident Inspector.
This notification is being made to retract Event Notification#48619, which reported 21 Motor Driven and 22 Turbine Driven Auxiliary Feedwater Pumps (AFWP) were declared inoperable due to the Condensate Storage Tank (CST) temperature exceeding 92 degrees F. Based on engineering analysis the 92 degree F was a margin value with no formal basis or evaluation. This value was added to the C28.6 procedure in the early 1990's as a precaution to provide Operations with additional operating information. After the 22 CST tank was found above the 92 degrees F temperature on 12/21/12, a formal engineering evaluation (EC 21354) was performed to determine CST heat values and provide an accurate number for temperature margin. The purpose of the CST tank temperature being at a specific value is to ensure that the AFWP discharge temperature stays at or under 100 degrees F to ensure the AF system can provide adequate decay heat removal if called upon during an accident. Engineering evaluation EC 21354 determined that the average CST tank temperatures could reach 96.5 degrees F before the AFWP discharge temperature could have reached 100 degrees F. Therefore, there was no loss of safety function or past operability concerns. The NRC Resident Inspector has been informed. Notified R3DO (Bloomer). |
| Where | |
|---|---|
Prairie Island  Minnesota (NRC Region 3) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | |
| Time - Person (Reporting Time:+0.28 h0.0117 days <br />0.00167 weeks <br />3.83544e-4 months <br />) | |
| Opened: | Tom Holt 15:17 Dec 21, 2012 |
| NRC Officer: | Howie Crouch |
| Last Updated: | Jan 17, 2013 |
| 48619 - 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 48619\u003C/a\u003E - \u003Ca href=\"/Prairie_Island\" title=\"Prairie Island\"\u003EPrairie Island\u003C/a\u003E\n\u003C/p\u003E\u003C/div\u003E\u003C/b\u003E\u003Cdiv class=\"mw-parser-output\"\u003E\u003Cp\u003EBoth Unit Two Auxiliary Feedwater Pumps Declared Inoperable\n\u003C/p\u003E\u003C/div\u003E","title":"ENS 48619 - Prairie Island\n","link":"","lat":44.62379722222222,"lon":-92.64153611111111,"icon":"/w/images/6/6c/Xcel_Energy_icon.png"}],"imageoverlays":null} | |
Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |