ML17244A227

Duke Energy Presentation - H.B. Robinson 2017-09-07 Pre-sub Transmission Upgrade Meeting

ML17244A227
Person / Time
Site:	Robinson
Issue date:	09/07/2017
From:	Dennis Galvin Plant Licensing Branch II
To:
Galvin D, NRR/DORL/LPLII-2, 415-6256
References
Download: ML17244A227 (18)

Text

H.B. Robinson Steam Electric Plant, Unit No. 2 LAR Proposing to Add an Offsite Circuit to TS 3.8.1 and the Use of Automatic Load Tap Changers September 7, 2017

Duke Energy Attendees Art Zaremba (Manager, Nuclear Fleet Licensing)

Jordan Vaughan (Senior Nuclear Engineer, Fleet Regulatory Affairs)

David Carroll (Manager Nuclear Engineering, Major Projects)

Neil Belanger (Senior Operations Specialist, Major Projects)

Tom Ferrell (Project Engineer, Major Projects) 2 2

Agenda Introductions / Opening Remarks Transmission Upgrade Project Overview Current Versus Future HBRSEP Electrical Distribution System License Amendment Request Overview Additional Technical Justification for Proposed Change 3

Transmission Upgrade Project Overview Project

Description:

The Transmission Upgrade Project increases plant electrical distribution system reliability and availability by increasing the number of available offsite power sources.

The increase in offsite sources is accomplished with the design and installation of a second startup transformer (SUT) to be connected to the 230kV switchyard and a new replacement 115kV SUT.

Background:

Both the new replacement 115kV SUT and the new 230kV SUT will be equipped with a Load Tap Changer (LTC) with automatic and manual control capabilities. The LTCs can automatically maintain the 4.16kV bus voltages at the required voltage regardless of variations in switchyard voltage. The ability to maintain the 4.16kV bus voltages at required voltage will minimize the occurrence and effect of any overvoltage or degraded grid voltage on plant electrical equipment and safety related buses E1 and E2 for anticipated variations in switchyard voltage.

4

Transmission Upgrade Project Overview Big Picture Changes to HBRSEP Provides a second offsite power source.

Provides direct feeds to Emergency Buses E1 and E2 from the new replacement 115kV SUT and the new 230kV SUT (Bus E1 is no longer reliant on a Fast Bus Transfer after unit trip).

Allows the Energy Control Center to lower minimum required HBRSEP switchyard voltage. The LTCs compensate for this allowance.

Provides switchyard breaker controls for each LTC and SUT in the Main Control Room.

Current Status of project 5

5

Current HBRSEP Electrical Distribution System 6

6

Post RO31 HBRSEP Electrical Distribution System 7

7

LAR Overview - Proposed Change #1 Revise HBRSEP Technical Specification 3.8.1, AC Sources - Operating to reflect the addition of a second qualified offsite circuit Necessitated by the addition of the new 230kV SUT Proposed change is consistent with NUREG-1431, Revision 4, Standard Technical Specifications Westinghouse Plants Limiting Condition for Operation (LCO) 3.8.1.a modified to state: Two qualified circuits Conditions, Required Actions (RA) and Completion Times are also modified to reflect two qualified offsite circuits.

Only one change to HBRSEP TS 3.8.1 that is not within the scope of NUREG-1431 Maximum Completion Time for existing RAs A.2 and B.4 is currently 8 days (8 days from discovery of failure to meet LCO)

The new maximum Completion Time is modified to 10 days (10 days from discovery of failure to meet LCO) to reflect that there is now a 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> Completion Time for one offsite circuit inoperable This change is consistent with other Westinghouse plant TSs and is considered editorial 8

Proposed Change #1 TS Markups 9

9

Proposed Change #1 TS Markups (continued) 10

Proposed Change #1 TS Markups (continued) 11

Proposed Change #1 TS Markups (continued) 12

Proposed Change #1 TS Markups (continued) 13

Proposed Change #1 TS Markups (continued) 14

Proposed Change #1 TS Markups (continued) 15

LAR Overview - Proposed Change #2 Revise the current licensing basis as reflected in the HBRSEP UFSAR to allow for the use of LTCs in the automatic mode of operation on both SUTs (i.e., the new replacement 115kV SUT and the new 230kV SUT)

Operation of LTCs in the automatic mode requires prior NRC staff approval in accordance with 10 CFR 50.59 (automatic LTC operation creates a possibility for the malfunction of a SSC important to safety with a different result than any previously evaluated in the UFSAR)

Technical justification for the requested change will include LTC operational evaluation (including the Primary and Backup Controller setpoints, the 115kV/230kV SUTs Control and Limit Bands and ratings for the new SUTs) and a component level Failure Modes and Effects Analysis (FMEA).

A review of all plant electrical bus alignments was conducted for both normal and accident grid transients (applied the worst case transient voltage acceptance criteria from existing ETAP calculations). In all cases, the new replacement 115kV startup transformer and the new 230kV startup transformer with LTCs were able to provide the transient response necessary to prevent operation of the safety related buses DGVR relay. 16

Additional LAR Technical Justification The following additional technical justification will be provided in the LAR consistent with previous discussions with the NRC staff:

Grid Voltage Profile Summary (i.e., Grid Stability Study)

Steady State and Transient Load Flow Summaries Short Circuit Analysis Summary Demonstration of breaker coordination of new switchgear including coordination with existing switchgear 17

18