ENS 53756
ENS Event | |
|---|---|
06:00 Nov 27, 2018 | |
| Title | En Revision Imported Date 12/4/2018 |
| Event Description | EN Revision Text: INOPERABILITY OF EQUIPMENT FOR CONTROL OF RADIOLOGICAL RELEASE
At 2130 CST on 11/27/2018, Division 1 Main Steam Positive Leakage Control System (MS-PLCS) was declared inoperable because of a leaking check valve that caused excessive cycling of the associated air compressor. Division 2 MS-PLCS had been declared inoperable on 11/27/2018 at 1400 CST when a pressure control valve in the system exceeded the maximum allowable stroke time. Because MS-PLCS supplements the isolation function of the main steam isolation valves (MSIVs) by processing fission products that could leak through the closed MSIVs, both divisions of MS-PLCS inoperable at the same time represents a condition that could prevent the fulfillment of a safety function of an SSC [Structures, Systems and Components] that is needed to control the release of radioactive material. The station diesel air compressor is available to supply backup air to the safety relief valves as required by the Technical Requirements Manual." [This is associated with operability of the safety relief valves, due to the inoperable MS-PLCS air compressor.] The unit is in a 7 day shutdown Limiting Condition for Operation (LCO), 1-TS1-18-Div 1 & 2 MSPLCS-685, for the two divisions of MS-PLCS being inoperable. The licensee notified the NRC Resident Inspector.
This event was initially reported under 10 CFR 50.72(b)(3)(v)(C) as a condition that could have prevented the Main Steam Positive Leakage Control System (MS-PLCS) from fulfilling its safety function to control the release of radioactive material. Division I was declared inoperable due to a failed component. Division II was declared inoperable due to a pressure control valve in the system exceeding the maximum allowable time to close by 0.50 seconds. An engineering evaluation has since been performed and concluded that the 2 second maximum allowable time to close was based on the pressure control valve being classified as a rapid closure valve and was established from the original baseline data of 0.50 seconds. This baseline data is an administrative target value per the In-Service Testing Program. There are no technical specification requirements associated with the 2 second closure time. The engineering evaluation also determined that the volume of air supplied through the pressure control valve during the extra 0.50 seconds of valve closure would have an inconsequential effect on the pressure within the volume of leakage barrier between the Main Steam Isolation Valves associated with the MS-PLCS pressure control valve or have any effect on containment over-pressurization. Based on the information provided by the engineering evaluation, the Division II MS-PLCS has been declared operable-degraded non-conforming since time of initial discovery. Consequently, this event is not reportable as a condition that could have prevented the Main Steam Positive Leakage Control System (MS-PLCS) from fulfilling its safety function. The [NRC] Resident Inspector has been notified via e-mail. Notified the R4DO (Gaddy). |
| Where | |
|---|---|
River Bend  Louisiana (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | |
| Time - Person (Reporting Time:+23.67 h0.986 days <br />0.141 weeks <br />0.0324 months <br />) | |
| Opened: | T. W. Gates 05:40 Nov 28, 2018 |
| NRC Officer: | Thomas Kendzia |
| Last Updated: | Dec 3, 2018 |
| 53756 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (99 %) |
| After | Power Operation (99 %) |
WEEKMONTHYEARENS 537562018-11-27T06:00:00027 November 2018 06:00:00
[Table view]10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material En Revision Imported Date 12/4/2018 ENS 519282016-05-13T17:00:00013 May 2016 17:00:00 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Existing Design Inadequacy Could Prevent Standby Gas Treatment System Operablity ENS 516372016-01-06T04:58:0006 January 2016 04:58:00 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Secondary Containment Declared Inoperable 2018-11-27T06:00:00 | |