ML17074A352

3/29/2017, Entergy Presentation for River Bend Station Pre-submittal Meeting for Control Building Air Conditioning New Technical Specification License Amendment

ML17074A352
Person / Time
Site:	River Bend
Issue date:	03/29/2017
From:	Schenk T Entergy Operations
To:	Lisa Regner Plant Licensing Branch IV
Regner L
References
Download: ML17074A352 (20)

Text

1 RIVER BEND STATION PRE-SUBMITTAL MEETING License Amendment Request (LAR): Technical Specification 3.7.7, "Control Building Air Conditioning (AC) System" March 29, 2017

2 OPENING REMARKS Tim Schenk Regulatory Assurance Manager River Bend Station

3 INTRODUCTIONS Tim Schenk Regulatory Assurance Manager River Bend Station

4 Agenda Introduction Tim Schenk - Reg. Assurance Manager Proposed Change Tim Schenk - Reg. Assurance Manager Overview - HVK and HVC Tim Schenk - Reg. Assurance Manager System Risk Evaluation Paul Sicard - Sr. Staff PRA Engineer Closing Comments Tim Schenk - Reg. Assurance Manager

5 PROPOSED CHANGE Tim Schenk Regulatory Assurance Manager River Bend Station

6 Proposed Change RBS is requesting to add a new Technical Specification related to "Control Building Air Condition (AC) System".

This amendment will establish a Completion Time of 14 days to allow adequate time to complete maintenance activities on the Control Building AC System equipment and thus reduce the need for unnecessary plant shutdowns.

7 OVERVIEW -

HVK AND HVC SYSTEM Tim Schenk Regulatory Assurance Manager River Bend Station

8 HVK System Design

System Description

The Control Room Air Condition system consists of the heating, ventilating and air conditioning system (HVC) and chilled water system (HVK).

Control Building Chilled Water (HVK) q Four 100% capacity refrigeration compressors/chillers (2 per division), associated valves, chilled water pumps, service water pumps, instrumentation, and compression tanks.

• Division I - HVK-CHL1A & HVK-CHL1C

• Division II - HVK-CHL1B & HVK-CHL1D q The chilled water system functions during normal, shutdown, and accident conditions to supply chilled water to the cooling coils in HVC-ACU1A/B, HVC-ACU2A/B, and HVC-ACU3A/B.

q The Normal Service Water system provides cooling water to the chiller condenser. In a DBA or loss of Normal Service Water the Standby Service Water system functions as the Ultimate Heat Sink.

q The Standby Service Water system is also connected to the Chilled Water piping circuit and in the event both trains of HVK fail it can function as the cooling medium for HVC-ACU1A/B, HVC-ACU2A/B, and HVC-ACU3A/B.

q The HVK Chillers are safety related and are supplied with power from their respective safety related buss or Emergency Diesel Generator

9 HVK Diagram - Normal Flow Path for 1 of 2 Redundant Divisions From Make- Temperature ACU3A - Chiller Up Water From Service Control Valve Equipment Rm Water Expansion Tank ACU1A - Main ACU2A - Battery, Control Room Switchgear, Inverter, and General Area To Service Water Chiller 1A Pump 1A Chiller 1C Pump 1C

10 HVC System Design Control Building HVAC (HVC) q Two 100% capacity

• Division I - HVC-ACU1A, HVC-ACU2A, & HVC-ACU3A

• Division II - HVC-ACU1B, HVC-ACU2B, & HVC-ACU3B q The HVC ACUs function to provide cooling, heating, ventilation to the following areas in the Control Building:

n HVC-ACU1A/B

• Main Control Room n HVC-ACU2A/B

• Standby Switchgear Rooms Cable Chase Rooms

• General Areas Remote Shutdown Rooms

• Inverter Charger Rooms Battery Rooms n HVC-ACU3A/B

• Chiller Equipment Rooms q The HVC ACUs are safety related and are supplied with Power from their respective safety related buss or Emergency Diesel Generator

11 HVC Diagram - Normal Flow Path -

1 of 2 Redundant Divisions

12 HVC Diagram - Normal Flow Path -

1 of 2 Redundant Divisions

13 RISK EVALUATION Paul Sicard Senior Staff PRA Engineer River Bend Station

Rev 5 Second Dry Run - March 24, 2016 14 Risk Evaluation: Cont.Bldg.AC TS

• Evaluated risk (ICCDP and ICLERP) of proposed TS with respect to RG 1.177 criteria (ICCDP < 10-6, ICLERP < 10-7)

• Evaluated risk of 14 day outages of HVC and HVK trains

• Used RBS PRA Rev.5-RHU

--based on Rev.5 Model of Record

--includes improved more rigorous modelling of Control Building room heat-up (RHU) developed 2015-16 to investigate chiller risk impacts

• External event risk included

• Demonstrated risk of 14 day outages of HVC and HVK trains meet RG 1.177 criteria

Rev 5 Second Dry Run - March 24, 2016 15 Risk Evaluation: Cont.Bldg.AC TS

• RBS PRA Rev.5-RHU:

• accounts for detailed Control Building heatup calculations performed 2015

• uses refined realistic heat loads

• credited metal heat sinks in Switchgear Rooms

• credits battery room fans for Battery and DC Equipment Rooms

• detailed equipment survivability studies performed to demonstrate acceptable equipment performance

• only operator action required is to open room doors within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> of event

• PRA model also credited Service Water direct cooling of HVC-ACU2A(B)

• Resulted in low impact on CDF of HVC/HVK trains out of service

Rev 5 Second Dry Run - March 24, 2016 16 Risk Evaluation: Cont.Bldg.AC TS

• ICCDP results for 14 day LCO:

• External Events addressed with multiplier, as done for ILRT submittal and in various industry SAMA submittals

• Includes RG 1.177 Common Cause Failure treatment

• Meets RG1.177 criteria of <10-6 ICCDP.

• RBS LERF two orders of magnitude less than RBS CDF.

Rev 5 Second Dry Run - March 24, 2016 17 Risk Evaluation: Cont.Bldg.AC TS

• Risk of proposed Completion Times smaller than existing TS completion times.

--comparison based on External Events, average maintenance unavailability assumed, RG 1.177 CCF treatment for HVC/HVK:

HVC Div.1 3.52E-07 HVC Div.2 3.13E-07 HVK Div.1 1.95E-07 HVK Div.2 1.65E-07 Service Water A 2.71E-06 Service Water B 1.93E-06 HPCS 2.87E-07 EDG A 5.94E-07 EDG B 7.52E-07 EDG C 1.42E-06 RHR A 5.69E-06 RHR B 2.08E-06

Rev 5 Second Dry Run - March 24, 2016 18 Risk Evaluation: Cont.Bldg.AC TS

• RBS manages on-line risk per site and corporate procedures (ADM-0096, EN-WM-104)

--protected trains

--work only one Division at a time during work weeks

--schedule maintenance for <50% of TS LCO time

• Defense-in-depth and Safety Margin maintained

--no modifications to plant

--design criteria maintained

--no overreliance on programmatic controls; Loss of Control Building HVAC procedure calls for electrical equipment room doors to be open <4 hours as only required recovery action

19 Risk

Conclusions:

Cont.Bldg.AC TS

• Evaluated risk (ICCDP and ICLERP) of proposed TS consistent with RG 1.177 criteria

• Risk of 14 day outages of HVC and HVK trains demonstrated to meet RG 1.177 criteria (ICCDP < 10-6, ICLERP < 10-7)

• Used RBS PRA Rev.5-RHU

• External event risk included

• Similar risk as TS LCOs for other systems

20 CLOSING COMMENTS Tim Schenk Regulatory Assurance Manager River Bend Station