ENS 44470
ENS Event | |
|---|---|
13:05 Sep 7, 2008 | |
| Title | Isolation Condenser Declared Inoperable Following Surveillance Testing |
| Event Description | Unit 2 Isolation Condenser did not meet acceptance criteria per DOS 1300-01 Isolation Condenser 5 year heat removal capability test. This is a single train system and cannot fulfill its safety function. The Isolation Condenser is a single train system. The function of the IC System is to respond to main steam SAFETY ANALYSES line isolation events by providing core cooling to the reactor. The IC System is an Engineered Safety Feature System, and credit is taken in the loss of feedwater transient analysis for IC System operation.
Unit 2 entered a 14-day TS LCO A/S 3.5.3 at 0249 CDT on 09/07/08 after declaring the IC System Inoperable. The Action Statement (A/S) requires restoration of the IC System to Operable status within 14 days or place the unit in hot shutdown within 12 hrs followed by entry into cold shutdown in the following 24 hrs. The licensee is performing maintenance to adjust the cooling flow valve stroke time in order to re-test and exit the LCO A/S. The licensee informed the NRC Resident Inspector.
The licensee is retracting this report based on the following: The purpose of this notification is to retract ENS notification 44470 made on September 7, 2008 for Dresden Nuclear Power Station. After further evaluation, Dresden has determined that the Isolation Condenser did successfully pass its 5-year heat removal test on September 7, 2008. The evaluation corrected the steam flow rate based on a more accurate instrument and calculated the heat removal rate by multiplying the mass flow rate through the Isolation Condenser times the difference in enthalpy between the steam going to the condenser and the condensate leaving the condenser. Therefore, the Isolation Condenser was capable of performing its safety function and the ENS report is being retracted. The licensee informed the NRC Resident Inspector. Notified R3DO (Kozak). |
| Where | |
|---|---|
Dresden  Illinois (NRC Region 3) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat | |
| Time - Person (Reporting Time:+1.67 h0.0696 days <br />0.00994 weeks <br />0.00229 months <br />) | |
| Opened: | Glen Morrow 14:45 Sep 7, 2008 |
| NRC Officer: | Steve Sandin |
| Last Updated: | Oct 31, 2008 |
| 44470 - NRC Website
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Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (67 %) |
| After | Power Operation (67 %) |
WEEKMONTHYEARENS 578412025-07-30T21:45:00030 July 2025 21:45:00
[Table view]10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat Potential Inoperability of Residual Heat Removal (RHR) System ENS 560232022-07-30T03:17:00030 July 2022 03:17:00 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat RHR Capability Lost Due to Suction Bay Level ENS 480802012-07-10T07:36:00010 July 2012 07:36:00 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat Invalid Group 5 Isolation Due to Failed Test Switch During Surveillance ENS 468572011-05-17T15:30:00017 May 2011 15:30:00 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat Temporary Blockage of Suction Source for Containment Cooling Service Water ENS 454722009-11-02T12:12:0002 November 2009 12:12:00 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat Loss of Shutdown Cooling ENS 446262008-11-03T12:52:0003 November 2008 12:52:00 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat Recirc Loop Temperature Element Failed ENS 444702008-09-07T13:05:0007 September 2008 13:05:00 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat Isolation Condenser Declared Inoperable Following Surveillance Testing ENS 441402008-04-15T12:00:00015 April 2008 12:00:00 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat, 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident High Pressure Coolant Injection Declared Inoperable ENS 413702005-02-04T01:15:0004 February 2005 01:15:00 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat, 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition 4160 Volt Relaying and Metering Single Failure Vulnerability ENS 407032004-04-24T15:50:00024 April 2004 15:50:00 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat Isolation Condenser Declared Inoperable 2025-07-30T21:45:00 | |