ENS 42475
ENS Event | |
|---|---|
12:04 Apr 5, 2006 | |
| Title | Both Trains of High Pressure Injection (Hpi) Declared Inoperable Due to Potential Air Binding of Pumps |
| Event Description | TMI declared both High Pressure Injection Trains not operable due to air void in the suction line from the Sodium Hydroxide tank. The postulated issued is that in the event of a small break LOCA where the plant would need to go on HPI piggy back Ops (the Low Pressure Injection supplying suction to the High Pressure Injection pumps) the air could cause the HPI pumps to become air bound.
The Plant entered a shutdown Tech Spec 3.0.1 at 0804 [EDT] and exited the timeclock at 0850 [EDT] when the Sodium Hydroxide tank was isolated, thus isolating the air void from the ECCS (Emergency Core Cooling System) pumps. The licensee is continuing their investigation into root cause and operability. The licensee will inform the NRC Resident Inspector.
The purpose of this call is to retract the notification (Event Number 42475) made by TMI Unit 1, Docket No. 50-289 / License No. DPR-50. On April 5, 2006, at 1408 hours0.0163 days <br />0.391 hours <br />0.00233 weeks <br />5.35744e-4 months <br />, the Shift Manager made a notification (Event Number 42475) to the NRC Operations Center in accordance with 10 CFR 50.72 (b)(3)(v)(D) (i.e. any event or condition that at the time of discovery could have prevented the fulfillment of the safety function of structures or systems that are needed to mitigate the consequences of an accident). The event was reported as 'Both trains of High Pressure Injection (HPI) Declared Inoperable due to potential air binding of Pumps.' On April 5, 2006, air voids were found in the NaOH tank piping, upstream of the HPI pumps, and the Shift Manager conservatively declared both trains of HPI inoperable due to the air voids. This placed TMI-1 in a 1-hour shutdown Limiting Condition for Operation (LCO). The isolation valves for the NaOH tank line piping were then Closed to eliminate the possibility that the voids could be transported to the HPI pumps. The HPI pumps were then declared operable and TMI-1 entered a 72-hour shutdown LCO. During the 72-hour LCO, the air bubble was vented from the system. An initial extent of condition evaluation was completed and an event response team was established. Numerical Applications, Inc. (NAI) was retained to perform GOTHIC Model run on the two phase flow conditions and determine the percent air density of the water at the suction to the Low Pressure Injection (LPI) pumps and the HPI pumps. The NAI analysis concluded that the densities of air found at the suction of the LPI and HPI pumps were below the safe operating level as stated by the pump manufacturers. Based on the results of the evaluation, TMI-1 has determined that the LPI and HPI pumps were operable. Past operability of these pumps with the maximum size air bubble found is affirmed. Therefore, this event does not meet the 10 CFR 50.72 or 10 CFR 50.73 reporting criteria and the notification for Event Number 42475 is retracted. The resident inspector has been notified. Notified R1DO (T. Jackson). |
| Where | |
|---|---|
Three Mile Island  Pennsylvania (NRC Region 1) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | |
| Time - Person (Reporting Time:+2.07 h0.0863 days <br />0.0123 weeks <br />0.00284 months <br />) | |
| Opened: | Kevin Coughlin 14:08 Apr 5, 2006 |
| NRC Officer: | Steve Sandin |
| Last Updated: | Jun 2, 2006 |
| 42475 - NRC Website | |
Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
Three Mile Island with 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | |
WEEKMONTHYEARENS 531062017-12-06T14:58:0006 December 2017 14:58:00
[Table view]10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident, 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Diesel Fuel Oil Tank Supply Non-Conforming with Licensing Basis for Tornado Generated Missiles ENS 520492016-06-28T14:55:00028 June 2016 14:55:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Both a & B Trains Hpi Inoperable Due to Void in Common Suction Line Resulting in Loss of Safety Function ENS 431392007-02-02T18:50:0002 February 2007 18:50:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident, 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Low Pressure Injection (Lpi) Net Positive Suction Head Flow Requirements Not Met for Certain Accident Sequences ENS 424752006-04-05T12:04:0005 April 2006 12:04:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Both Trains of High Pressure Injection (Hpi) Declared Inoperable Due to Potential Air Binding of Pumps ENS 414442005-02-16T01:55:00016 February 2005 01:55:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident, 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Possible Failure to Meet Design Basis Requirements of Positive Pressure in the Control Tower Envelope Following a Design Basis Accident. 2017-12-06T14:58:00 | |