ENS 50752
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ENS Event | |
|---|---|
22:45 Jan 22, 2015 | |
| Title | Unanalyzed Heat Exchanger Lineup Could Exceed Design Basis Temperatures |
| Event Description | On 1/20/15, it was determined that a certain line up of component cooling heat exchangers and shutdown cooling heat exchangers could exceed the design basis temperatures for the component cooling water system following a design basis accident. Although not a safety concern at this time because of low ultimate heat sink temperatures (which cools component cooling water), in the past the ultimate heat sink temperatures have been high enough to create this condition. This particular heat exchanger line up was unanalyzed in that the ultimate heat sink temperature limits were not known until 1/22/15. This issue has been entered into the corrective action program.
A review of Control Room logs for 2014 showed that in 1 instance for Unit 1 and 1 instance for Unit 2, the Units were in an unanalyzed lineup with ultimate heat sink temperature greater than the maximum now calculated. During these instances, both Units had an unanalyzed condition that had potential to significantly degrade plant safety and is reportable in accordance with 10 CFR 50.72(b)(3)(ii)(B). The NRC Resident Inspector has been notified.
Further engineering analysis has refined the ultimate heat sink temperature that provides an acceptable safety system response with the component cooling water and shutdown cooling heat exchanger lineups in question. The revised information demonstrates that the system lineups that occurred in the last 12 months did not result in an unanalyzed condition that significantly degrades plant safety. This event notification is retracted. The NRC Resident Inspector will be notified. The R1DO (Burritt) was notified.
The retraction statement provided on 3/3/15 incorrectly addressed system lineups limited to the last 12 months. The original withdrawal was prematurely submitted and therefore the original notification (Event report 50752) is not retracted and remains valid. The NRC Resident Inspector has been notified. The R1DO (Cook) was notified. |
| Where | |
|---|---|
Calvert Cliffs  Maryland (NRC Region 1) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | |
| Time - Person (Reporting Time:+-3.9 h-0.163 days <br />-0.0232 weeks <br />-0.00534 months <br />) | |
| Opened: | Bob Martin 18:51 Jan 22, 2015 |
| NRC Officer: | Jeff Herrera |
| Last Updated: | Mar 13, 2015 |
| 50752 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
WEEKMONTHYEARENS 536632018-10-11T04:00:00011 October 2018 04:00:00
[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 Air Start Solenoid Closure Failure ENS 534012018-05-14T17:05:00014 May 2018 17:05:00 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 Saltwater System Non-Conforming with Licensing Basis for Tornado Generated Missiles ENS 509612015-04-07T16:45:0007 April 2015 16:45:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 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, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Dual Unit Automatic Reactor Trips Due to a Voltage Transient Resulting in Generator Trips ENS 507522015-01-22T22:45:00022 January 2015 22:45:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Heat Exchanger Lineup Could Exceed Design Basis Temperatures ENS 498892014-03-10T20:53:00010 March 2014 20:53:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Postulated Hot Short Fire Event That Could Adversely Impact Safe Shutdown Equipment ENS 494492013-10-18T12:30:00018 October 2013 12:30:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Postulated Hot Short Fire Event That Could Adversely Impact Safe Shutdown Equipment ENS 483672012-10-03T04:10:0003 October 2012 04:10:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition Due to High Energy Line Break Barrier Being Partially Open ENS 476192012-01-23T18:00:00023 January 2012 18:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Breach in High Energy Line Break Barrier ENS 475122011-12-08T22:55:0008 December 2011 22:55:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition Potentially Could Affect the Common Control Room ENS 474132011-11-03T22:00:0003 November 2011 22:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Diesel Generator Starting Air Not Compliant with Appendix R Requirements ENS 438302007-12-08T05:50:0008 December 2007 05:50:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Reactor Power Inadvertently Increased Above Accident Analysis Limit 2018-05-14T17:05:00 | |
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