ENS 42405
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ENS Event | |
|---|---|
06:30 Mar 11, 2006 | |
| Title | |
| Event Description | This report is being made pursuant to 10CFR50.72(b)(3)(ii)(B), Degraded or Unanalyzed Condition. During Division 1 Core Standby Cooling System (CSCS) valve replacement work, it was discovered that temporary seismic supports required to maintain this piping within the Safe Shutdown Earthquake (SSE) design envelope were not installed. This condition was discovered during the restoration phase of the maintenance and the requirements for the temporary supports no longer exist. At the time of discovery, the required permanent seismic qualified support system had been re-established. The Division 1 CSCS System is common to both units and circulates lake water from the Ultimate Heat Sink (UHS) to the Division 1 Residual Heat Removal (RHR) heat exchangers, Division 1 Diesel Generator cooler, Division 1 Emergency Core Cooling System (ECCS) area room coolers, Division 1 RHR Pump seal coolers, and the Low Pressure Core Spray (LPCS) motor coolers. During the period with the required seismic supports not installed, both Unit 1 and Unit 2 were in an unanalyzed condition due to the inability of the Division 1 CSCS piping to meet its seismic qualification. A postulated structural failure of the Division 1 CSCS piping during an SSE could affect areas containing redundant equipment due to flooding.
The licensee is investigating the failure to install the supports. The supports were only needed during the maintenance. The licensee notified the NRC Resident Inspector.
On March 11, 2006, it was identified that temporary seismic supports required to maintain the Core Standby Cooling System piping within the Safe Shutdown Earthquake (SSE) envelope during valve replacement activities were not installed. This was reported under 10 CFR 50.72 (b)(3)(ii)(B) as a degraded or unanalyzed condition that significantly degrades plant safety. Subsequent evaluations have been performed to demonstrate that the piping remained within the SSE envelope with the missing supports. These evaluations have concluded that the remaining supports were sufficient to ensure that piping would remain intact during an SSE. As such, this event notification is being retracted. The licensee notified the NRC Resident Inspector. Notified R3DO (D. Passehl) |
| Where | |
|---|---|
Lasalle  Illinois (NRC Region 3) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | |
| Time - Person (Reporting Time:+0.1 h0.00417 days <br />5.952381e-4 weeks <br />1.3698e-4 months <br />) | |
| Opened: | Terry Nance 06:36 Mar 11, 2006 |
| NRC Officer: | Bill Gott |
| Last Updated: | Mar 15, 2006 |
| 42405 - NRC Website
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Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
WEEKMONTHYEARENS 532132018-02-15T17:00:00015 February 2018 17:00:00
[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 Notification of Unanalyzed Condition Affecting Accident Mitigation for Tornado Generated Missiles ENS 506752014-12-12T21:00:00012 December 2014 21:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition with Reactor Core Isolation Cooling ENS 424052006-03-11T06:30:00011 March 2006 06:30:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition ENS 423482006-02-20T06:23:00020 February 2006 06:23:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Site Area Emergency - Reactor Scram ENS 418442005-07-14T21:10:00014 July 2005 21:10:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Station Blackout Temperature Analysis Higher than Rcic Governor Documentation ENS 413662005-02-02T21:42:0002 February 2005 21:42:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Single Failure Vulnurability in Ac Auxiliary Power System 2018-02-15T17:00:00 | |
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