ML17044A089

EDG SR Presubmittal Meeting March 2, 2017

ML17044A089
Person / Time
Site:	Harris
Issue date:	03/02/2017
From:	Martha Barillas Plant Licensing Branch II
To:	Duke Energy Progress
Barillas M DORL/LPL2-2 301-415-2760
References
Download: ML17044A089 (25)

Text

Harris Nuclear Plant Pre-Submittal Meeting March 2, 2017 License Amendment Request for Emergency Diesel Generator Surveillance Changes NOTE: Technical Specification mark-up pages for this license amendment request are provided on pages 20-25 of this document for reference with the presentation material.

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Duke Energy Participants Sarah McDaniel, Regulatory Affairs Alan Morisi, Electrical Design Engineer Robert Muzzi, Electrical Design Engineering Tom Scattergood, Mechanical Design Engineering Adam Bingham, Safety Analysis Engineer Mark Grantham, Engineering Director Art Zaremba, Fleet Licensing Manager Jeff Robertson, Regulatory Affairs Manager Scott Thomas, Safety Analysis Manager 3

Agenda I. Steady-State Voltage and Frequency Limit Changes Description of Changes Reason for Changes Technical Evaluation - Overview II. Full Load Rejection Test Voltage Limit Change Description of Change Reason for Change Technical Evaluation - Overview III. Regulatory Guidance IV. Precedents V. Industry Efforts 4

Description of Changes: Steady-State Operation Parameters TS SR 4.8.1.1.2.a.4, SR 4.8.1.1.2.e, SR 4.8.1.1.2.f.2, SR 4.8.1.1.2.f.4.b, SR 4.8.1.1.2.f.6.b, &

SR 4.8.1.1.2.f.14:

Current voltage limit is plus or minus 10% of the nominal emergency diesel generator (EDG) voltage (6900 +/- 690 volts) and the current frequency limit is plus or minus 2% of the nominal frequency (60 +/- 1.2 hertz)

Proposed voltage limit is plus or minus 4% of the nominal EDG voltage (6900 +/- 276 volts) and the proposed frequency limit is plus or minus 0.8% of the nominal frequency (60 +/- 0.48 hertz)

The new proposed limits are for EDG steady-state operation in the isochronous mode or with the emergency power system isolated from the normal, offsite source.

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Reason for Changes: Steady-State Operation Parameters While evaluating operational experience, Harris identified that surveillance requirement limits for EDG steady-state voltage and frequency testing are non-conservative.

The lower end of the range (6210 VAC) is below the dropout setting of the Degraded Grid Voltage Relay (6420 VAC nominal).

The upper end of the range (7590 VAC) is above the maximum allowed operating voltage for the 6.6kV motors supplied by the 6.9kV emergency buses (7260 VAC).

Use of a higher than 60 Hz frequency was not previously considered in the EDG loading analysis, thus fuel consumption, motor-operated valve (MOV) stroke times, pump speed/output or impact on fan operations were not previously evaluated.

Administrative Controls: Surveillance procedures were revised to control voltage at a tighter band of 6500-7200 volts.

Surveillance results are being monitored to verify that voltage and frequency are maintained in the tighter bands proposed.

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Technical Evaluation Overview: Steady-State Operation Parameters Impact on electrical loading characteristics of the EDGs Impact of voltage & frequency variation on EDG driven equipment (pumps, motor-operated valve (MOV) stroke time, air handlers, EDG fuel consumption)

Impact on the operating range of the powered equipment Evaluation of Safe Shutdown Equipment & Impact to Accident Analyses Impact on MOV Operation Impact on Pump and Fan Operation

- Effects of bus frequency variations on motor speed change, pump and fan flow, and differential pressure 7

Description of Change: Full Load Rejection Test Voltage Limit TS SR 4.8.1.1.2.f.11:

Current voltage limit for the EDG full load rejection test is 110% of the EDG voltage at the start of the test Proposed limit is 8,280 volts, which is 120% of the EDG nominal voltage rating of 6900 volts 8

Reason for Change: Full Load Rejection Test Voltage Limit Change to full load rejection test limit is necessary to gain margin. Previous results have shown that inadequate margin exists.

The test requires that the EDG be paralleled to the grid just prior to load rejection. This reduces margin by approximately 2.5-3.0% due to the EDG being in the droop mode.

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Technical Evaluation Overview: Full Load Rejection Test Voltage Limit Load Rejection Test Voltage Limit of 8280 volts = 120% of nominal 6900 volts

- Standard industry value for peak voltage is 5000 volts (120% of nominal 4160 volts),

which is identified in the Improved Standard Technical Specifications (NUREG-1431)

- Impact of increased voltage limit on

• Emergency Diesel Generator, Cables, and Switchgear

• Voltage Regulator & Control Circuits

• Exciter Power Transformer

• 3-Phase Potential Transformer

• Voltage Regulator and Control Circuit

- Volt-Ampere Reactive Power (VAR) Loading 10

Emergency Diesel Generator - Photo 11

Emergency Diesel Generator - Drawing 12

Regulatory Guidance General Design Criterion 17, "Electric Power Systems General Design Criterion 18, "Inspection and testing of electric power systems Regulatory Guide 1.9, "Selection of Diesel Generator Set Capacity for Standby Power Supplies," Revision 2 Regulatory Guide 1.108, "Periodic Testing of Diesel Generator Units Used as Onsite Electric Power Systems at Nuclear Power Plants," Revision 1, as modified with the guidance of Information Notice 85-32, dated April 22, 1985 13

Precedents Steady-State Operation Parameter Changes April 27, 2016: Davis Besse Nuclear Power Station, Unit 1 increased the EDG minimum steady-state voltage and frequency acceptance criterion for TS surveillance testing December 10, 2009: Crystal River, Unit 3 restricted the voltage and frequency TS surveillance limits for both slow and fast EDG starts April 30, 2009: DC Cook Nuclear Plant, Units 1 and 2 increased the EDG minimum steady-state voltage, increased the minimum steady-state frequency, and lowered the maximum steady-state frequency acceptance criterion for TS surveillance testing Full Load Rejection Test Voltage Limit December 17, 2015: Braidwood Station Units 1 and 2, and Byron Station, Units 1 and 2, increased the voltage limit for the EDG load rejection surveillance requirement April 24, 2015: Seabrook Station, Unit No.1 increased the voltage limit for the EDG load rejection surveillance requirement December 2, 2013: Wolf Creek Generating Station increased the EDG full load rejection test voltage limit 14

Precedents: Steady-State Operation Parameters Davis Besse Davis Besse Nuclear Power Station, Unit 1, requested changes to minimum voltage acceptance criterion in May 2012 and received a non-acceptance per email dated June 21, 2012 (ADAMS Accession No. ML14324A82), based upon the need for the items listed below. Harris has made changes to the LAR to address each item.

1. Excerpts from calculation(s) that establish the limiting voltage at various safety busses for equipment operability. Minimum starting voltage for large motors and the voltage drop at the remote safety buses associated with starting large motors. Confirm minimum voltage observed during load sequencing or large motor starts will not adversely impact equipment that was running with EDG nominal voltage.

2. Verify that EDG loading is within the capabilities of the EDG at the onset of an event when the pumps may be operating at run out conditions and during steady-state conditions with the EDG operating at the upper end of the allowable voltage and frequency.

3. Verify that the degraded voltage relays do not have to be reset (if actuated) during a loss off offsite power event when the EDG is required to supply plant loads.

4. Explain how the minimum frequency of 58.8 Hz and steady-state frequency values 59.5H z and 60.5Hz are used to determine safeguards equipment operational requirements during design basis accident calculations.

5. Provide details on performance capabilities of accident mitigation equipment (pumps, motors, valves, etc.) when the EDG is operating at the lower end of the allowable voltage and frequency bands during design basis events.

6. Verify that motor operated valve performance is not adversely impacted (accident analyses) at the lower end of the TS allowable frequency coupled with the frequency/voltage variations allowed. The HNP LAR includes a summary of the evaluation of the proposed frequency range on MOVs. 15

Industry Efforts Status of WCAP-17308-NP, Revision 0, "Treatment of Diesel Generator (DG) Technical Specification Frequency and Voltage Tolerances Pressurized Water Reactor Owners Group (PWROG) submitted WCAP-17308-NP to the NRC in September 2012.

The NRC draft Safety Evaluation (DSE) for WCAP-17308-NP was issued for PWROG review in February 2016.

Dialog regarding PWROGs comments on the WCAP-17308-NP DSE and NRC response to these comments is on-going.

PWROG meeting provided licensees with the following update in December 2016:

The are two major issues remaining that need to be resolved for the PWROG to receive acceptance on WCAP-17308-NP, Revision 0, "Treatment of Diesel Generator (DG) Technical Specification Frequency and Voltage Tolerances" SR 3.8.1.2 (31-day Surveillance)

Consideration of manual connected loads WCAP-17308-NP will not be cited in the Harris LAR 16

Industry Efforts Westinghouse InfoGram 14-1 Material Properties for Loss-of Coolant Accident Mass and Energy Release Analysis The PWROG and Westinghouse are working to address the impact of InfoGram 14-1 for plants that are participating in the project. The details of the PWROG project were described during a meeting with NRC staff on June 1, 2016.

The project is expected to result in a supplement to topical report WCAP-10325-P-A, Westinghouse LOCA Mass and Energy Release Model for Containment Design, that demonstrates sufficient methodology conservatism to address the issue.

Harris is participating in the PWROG project and would implement the topical report supplement after NRC approval.

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Conclusion Change requested to TS SR 4.8.1.1.2.a.4, SR 4.8.1.1.2.e, SR 4.8.1.1.2.f.2, SR 4.8.1.1.2.f.4.b, SR 4.8.1.1.2.f.6.b, & SR 4.8.1.1.2.f.14 to restrict steady-state voltage and frequency test acceptance criterion Change requested to TS SR 4.8.1.1.2.f.11 to change the voltage limit for the EDG full load rejection test is 110% of the EDG voltage at the start of the test to 8,280 volts, which is 120% of the EDG nominal voltage rating of 6900 volts The proposed changes continue to provide adequate protection to public health and safety.

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