ENS 40227
ENS Event | |
|---|---|
03:15 Oct 7, 2003 | |
| Title | Hpci System Inoperability Due to Failed Suppression Pool Level Switch at Dresden Unit 2 |
| Event Description | The Unit 2 HPCI system has been declared INOPERABLE due to the failure of a pressure suppression pool high-level switch during surveillance and being unable to maintain the HPCI pump suction lined up to the pressure suppression pool in standby lineup.
Per technical specification 3.3.5.1. required action D.2.2. with the high level switch INOPERABLE the HPCI system must have the pump suction aligned to the suppression pool with in 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or declare the HPCI system INOPERABLE when the required action completion time can not be met. The function of the suppression pool high-level switch causes the HPCI pump suction to automatically realign to the suppression pool when the suppression pool reaches the high level set point during an accident. When the pump suction swap to the suppression pool was performed the HPCI gland seal leak off pump began to run automatically. Further investigation determined that there was an unknown input into the HPCI gland seal leak off condenser (GSLO). Normally the GSLO does not have an input while in standby lineup and therefore does not normally operate while the pump suction is aligned to the Pressure Suppression Pool. The GSLO pump would have a discharge flow path with the HPCI system running and therefore would have the ability to maintain its design function. However in the standby line [-up] with the pump suction aligned to the suppression pool the GSLO pump did not have a discharge flow path. This inability to pump the GSLO condenser required the suction be realigned to the condensate storage tank and with the combination of a failed suppression pool high-level switch requires declaration of INOPERABITY of the HPCI system. This is a 14 day LCO. This is a single train system and reportable under SAF 1.8 Event or Condition That Could Have Prevented Fulfillment of a Safety Function. The INOPERABLE HPCI system function can be manually initiated from the main control room. Investigation and troubleshooting into the unknown HPCI GSLO input has been, initiated in parallel with the repairs to the failed suppression high level switch. The licensee intended on notifying the NRC Resident Inspector. |
| Where | |
|---|---|
Dresden  Illinois (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:+3.08 h0.128 days <br />0.0183 weeks <br />0.00422 months <br />) | |
| Opened: | Glen Morrow 06:20 Oct 7, 2003 |
| NRC Officer: | Rich Laura |
| Last Updated: | Oct 7, 2003 |
| 40227 - NRC Website
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Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (86 %) |
| After | Power Operation (86 %) |