ENS 50375
ENS Event | |
|---|---|
17:18 Aug 15, 2014 | |
| Title | |
| Event Description | On 8/15/2014 at 1218 CDT, the 'B' Standby Gas Treatment (SBGT) System was undergoing its monthly surveillance testing. With the 'B' fan running, as part of the surveillance, the 'A' Standby Gas Treatment Mode Select Switch was taken to Manual. This renders the 'A' SBGT subsystem inoperable. Almost simultaneously the 'B' fan Flow Indicating Controller went blank and flashed an error message although indicated flow through the 'B' train remained at 4073 SCFM. Based on the indication seen on 'B' controller, regardless of flow, the 'B' SBGT subsystem was also declared inoperable. In accordance with the surveillance the 'A' SBGT mode switch was placed back in the AUTO position on 8/15/2014 at 1220 CDT, restoring that train to operability. The 'B' SBGT was still considered inoperable based on its flow indicating controller being blank and flashing an error message. For a period of two minutes both SBGT subsystems were considered inoperable which is a condition that could have prevented the fulfillment of the safety function of SBGT system to control the release of radioactive material. This is considered a 8-hour reportable event per 50.72(b)(3)(v)(C) 'Any event or condition that at the time discovery could have prevented the fulfillment of the safety function of structures or systems that are needed to control the release of radioactive material.'
During the 2 minutes that 'A' SBGT was in Manual, the 'B' SBGT train maintained 4073 scfm train flow which is at the required flow rate per STP 3.6.4.3-01B. In addition, the 'A' train could have been initiated manually at any time during that 2 minutes by the operator who was stationed at the panel performing the surveillance. The licensee notified the NRC Resident Inspector.
The purpose of this notification is to retract a previous report made on 08/15/2014 at 1802 (EDT) (EN 50375). Notification of the event to the NRC was initially made as a result of declaring both trains of the Standby Gas Treatment (SBGT) System inoperable. Specifically, during performance of planned surveillance testing required by Technical Specification (TS) Surveillance Requirement (SR) 3.6.4.3.2, with the 'B' train of SBGT running as part of the testing, the 'A' SBGT train's mode switch was taken to manual. This action renders the 'A' train inoperable. Simultaneously with this action, the 'B' SBGT Flow Indicator Controller went blank and flashed an error message. This resulted in the 'B' train being declared inoperable. Subsequent to the initial report, NextEra Energy Duane Arnold (NextEra) has determined that TS SR 3.6.4.3.2 contains a note that states, 'When a SBGT subsystem is placed in an inoperable status solely for the performance of VFTP testing required by this Surveillance on the other subsystem, entry into associated Conditions and Required Actions may be delayed for up to 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />.' The 'A' SBGT train mode switch was in manual for approximately 2 minutes; therefore, entry into the associated conditions and actions was not required. Therefore, this event is not considered a Safety System Functional Failure and is not reportable to the NRC as a Licensee Event Report (LER) per 10 CFR 50.73. The NRC Senior Resident Inspector has been notified. Notified R3DO (Dickson) |
| Where | |
|---|---|
Duane Arnold  Iowa (NRC Region 3) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | |
| Time - Person (Reporting Time:+0.73 h0.0304 days <br />0.00435 weeks <br />9.99954e-4 months <br />) | |
| Opened: | Mark Gilbert 18:02 Aug 15, 2014 |
| NRC Officer: | Daniel Mills |
| Last Updated: | Sep 16, 2014 |
| 50375 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (95 %) |
| After | Power Operation (95 %) |
Duane Arnold with 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | |
WEEKMONTHYEARENS 534962018-07-09T05:00:0009 July 2018 05:00:00
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