ENS 53968
ENS Event | |
|---|---|
03:06 Apr 1, 2019 | |
| Title | Unanalyzed Condition Due to Eccs Leakage |
| Event Description | At 2006 [MST], on 3/31/2019, the Palo Verde Nuclear Generating Station Unit 1 Shift Manager was informed that leakage was measured from the Train A Emergency Core Cooling System (ECCS) piping at approximately 100 ml/minute through a High Pressure Safety Injection (HPSI) A drain valve. This value exceeds the assumed 3000 ml/hour ECCS leakage for a large break loss of coolant accident analysis. At 0230 [MST] on April 1, 2019, the valve was flushed and the leakage reduced to 10 ml/minute (600 ml/hour) and was no longer above the limit of the safety analysis. This condition is being reported as an unanalyzed condition per 10 CFR 50.72(b)3)(ii)(B) and a condition that could have prevented the fulfillment of a safety function to the control the release of radioactive material per 10 CFR
50.72(b)(3)(v)(C). This event did not result in an abnormal release of radioactive material. Notification received by Caty Nolan and emailed to HOO.HOC@NRC.GOV The NRC asked a followup question: Why was the criterion for Control of Radioactive Material selected? per the PVNGS Unit 1 Shift Manager, this criterion was selected due to the potential of exceeding offsite dose projections, post recirculation, following a Design Basis Accident. The resident inspector has been notified.
An engineering evaluation concluded that the as-found ECCS leakage would not have degraded the performance of the Pump Room Exhaust Air Cleanup system; therefore, it remained operable. The evaluation also concluded that the as-found leakage was within the analysis margins for HPSI pump hydraulic performance and containment flood level following a Large Break Loss of Coolant Accident; therefore, the ECCS also remained operable. Based on the above information, the condition identified on March 31, 2019, was an unanalyzed condition per 10 CFR 50.72(b)(3)(ii)(B), but did not prevent the fulfillment of the safety function of the structures or systems that are needed to control the release of radioactive material per 10 CFR 50.72(b)(3)(v)(C). The NRC resident inspectors have been informed. Notified R4DO (Proulx). |
| Where | |
|---|---|
Palo Verde  Arizona (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | |
| Time - Person (Reporting Time:+3.57 h0.149 days <br />0.0212 weeks <br />0.00489 months <br />) | |
| Opened: | George Lester 06:40 Apr 1, 2019 |
| NRC Officer: | Caty Nolan |
| Last Updated: | May 15, 2019 |
| 53968 - NRC Website | |
Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
Palo Verde with 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition, 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | |
WEEKMONTHYEARENS 539682019-04-01T03:06:0001 April 2019 03:06:00
[Table view]10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition, 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Unanalyzed Condition Due to Eccs Leakage ENS 520832016-07-12T20:00:00012 July 2016 20:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Degraded Fire Barrier ENS 494112013-10-04T16:46:0004 October 2013 16:46:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Postulated Fire Event Could Result in a Hot Short That Could Adversely Impact Safe Shutdown Equipment ENS 488142013-03-09T02:21:0009 March 2013 02:21:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Spent Fuel Pool Criticality Analysis of Record Not Revised Following Power Uprate ENS 474592011-11-19T15:28:00019 November 2011 15:28:00 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 the Low Pressure Safety Injection System Was Subjected to High Pressure Resulting in Both Trains Being Declared Inoperable ENS 448462009-02-11T20:18:00011 February 2009 20:18:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Possibly Inadequate Backup Nitrogen Supply for Atmospheric Dump Operation ENS 431402007-02-03T19:32:0003 February 2007 19:32:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Technical Specification 3.0.3 Entered During Routine Surveillance Testing of Control Element Assemblies (Cea'S) ENS 428472006-09-19T08:05:00019 September 2006 08:05:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition, 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown Pressurizer Heater Capacity Less than Tech Spec Limit ENS 427322006-07-27T02:00:00027 July 2006 02:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Limiting Condition for Operation 3.7.4 Deemed to Be Nonconservative ENS 420502005-10-11T23:02:00011 October 2005 23:02:00 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, 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition, 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown Tech Spec Required Shutdown of Both Unit 2 and 3 ENS 417892005-06-23T15:23:00023 June 2005 15:23:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unit 2 Aux Feedwater Train Separation Not Maintained During Operation 2019-04-01T03:06:00 | |