Prairie Island Nuclear Generating Plant Meeting February 19, 2014

Diesel Generator Steady State Voltage and Frequency LimitsDiesel Generator Steady State Voltage and Frequency Limits

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Agenda

� Introductions Vincent

� Meeting purpose Davison

� Background Vincent

� Applicability of industry initiatives Mathew

� LAR scope Vincent

� Proposed TS and Bases changes Vincent

� Technical basis for changes Zamarripa

� Schedule Mathew

� Conclusion Davison

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Xcel participants

� Kevin Davison – Site Vice President

� Marty Murphy – Director Regulatory Affairs

� Joe Mathew – Design Engineering Manager

� Paul Zamarripa – Engineering Supervisor

� Dale Vincent – Regulatory Affairs Project Manager

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Meeting Purpose

� Establish dialog on this LAR

� Applicability of industry initiative (WCAP-17308)

� Proposed EDG SR changes

� Basis for changes

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Background

� EDG Frequency identified in CAP – 2006

�AL 98-10 compensatory measures

� EDG Voltage identified in IN – 2007-09

�AL 98-10 compensatory measures

� Meeting with NRC - June 2008

� PWROG adopt issue – 2009

� PWROG meeting with NRC – 2010

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Background(continued)

� EDG Exigent LAR - October 2010

� PWROG meeting with NRC – 2011

� NRC Frequency submittal finding – 2011

� EDG Voltage LAR – May 2012

� EDG Voltage limits revised – 2013

�AL 98-10 compensatory measures revised

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Applicability of Industry Initiatives

� WCAP-17308 methodology

�SRs verify EDG operate at nominal voltage and frequency

�Variation from nominal treated as uncertainty

�Minimal impact on supplied loads and EDGs

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Applicability of Industry Initiatives (continued)

� How does PINGP LAR align ?

�Assumes EDG operates at range extremes

�Significant impact on supplied loads

�Significant impact on EDGs

� PINGP LAR will not incorporate WCAP-17308

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LAR Scope

� EDG operating voltage

� EDG operating frequency

� Impact on supplied loads

� Impact on EDGs

� AL 98-10 submittal

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Proposed TS and Bases Changes

� SS Voltage lower and upper limits

� SS Frequency lower and upper limits

� TS Bases changes

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Proposed TS and Bases Changes (continued)

� Current TS

�SS Voltage lower voltage: 3740 VAC

�SS Voltage upper voltage: 4580 VAC

�SS Frequency lower limit: 58.8 Hz

�SS Frequency upper limit: 61.2 Hz

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Proposed TS and Bases Changes (continued)

� Proposed TS

�SS Voltage lower voltage: 4084 VAC

�SS Voltage upper voltage: 4400 VAC

�SS Frequency lower limit: 59.5 Hz

�SS Frequency upper limit: 60.5 Hz

Proposed TS and Bases Changes (continued)

� TS Revisions:

�SR 3.8.1.2 – monthly test

�SR 3.8.1.6 – 6-month fast start test

�SR 3.8.1.9 – 2-year 24-hour run test

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Proposed TS and Bases Changes (continued)

� TS Bases Revisions:

�Define “steady state”

�Clarify purpose of steady state voltage requirement

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Technical Bases for Changes

� Lower voltage limit

� 4084 VAC

� Within nominal rating of equipment

� Protective relaying calculations

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Technical Bases for Changes

� Lower voltage limit (continued)

� Degraded voltage setpoint basis

� Ready to load relay @ V-Hz permissive bkr closure

� PLC sequencing requires bus voltage > DV R/S [4027]

� Lower limit > DVR setting + error + R/S > 96.8% [4027]

� DV LL >94.5% used in DV calculation

� Exceeds the region of degraded voltage

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Technical Bases for Changes(continued)

� Upper voltage limit

� 4400 VAC

� Equipment ratings within nominal

� Protective relaying

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Technical Bases for Changes(continued)

� ESF pump motor performance with proposed V&F limits

� Motor terminal voltage affected

� With 4084 VAC pumps operate within specification

� Bus voltage remains above degraded voltage setpoint

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Technical Bases for Changes(continued)

� ESF pump motor performance with proposed V&F limits (continued)

� Frequency affects governed by affinity laws

� Pump speed (S) proportional to frequency (F)

� Discharge pressure proportional to pump speed squared (S2)

� Re-performed thermal hydraulic analyses

� +0.5 Hz – pumps not in run-out, flow rate not excessive

� -0.5 Hz – Necessary flow rates attained

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Technical Bases for Changes(continued)

� ESF Ventilation performance with proposed V&F limits

� Evaluations performed

� Auxiliary Building Special Ventilation (ABSVS)

� Shield Building Ventilation (SBVS)

� Containment ventilation

� EDG Rooms

� Control Room Ventilation

� Safeguards Screenhouse Ventilation

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Technical Bases for Changes(continued)

� MOV performance with proposed V&F limits

� MOV motor terminal voltage affected

� Apply degraded voltage

� Adequate torque

� MOVs will operate at lower voltage limit

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Technical Bases for Changes(continued)

� MOV performance with proposed V&F limits (continued)

� MOV frequency effects (continued)

� Analyses assumption +1.2 Hz

� Upper frequency

� Increase dP 4%

� Acceptable results

� Lower frequency

� Travel speed

� Actuation time

� Adequate margin

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Technical Bases for Changes(continued)

� Relay coordination and interface with TS 3.3.4 with proposed V&F limits

� Calculations performed across 75% - 110% of nominal 4kV motor rating

� Modeled in ETAP

� Coordination acceptable

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Technical Bases for Changes(continued)

� EDG loading with proposed V&F limits

� Unit 1 EDG Design Loading

� Licensed under AEC SG 9 paragraph C2 guidance

� 2000 Hr rating or 90% of 30 Min rating (3250 kW)

� Limit of 2750 kW

� Unit 2 EDG Design Loading

� Licensed under RG 1.9 Rev 2 paragraph C2 guidance

� Predicted load < short-time rating

� Limit of 5400 kW

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Technical Bases for Changes(continued)

� EDG loading with proposed V&F limits

� Evaluated loads for LOOP+SI

� Frequency 60.5 Hz

� Applied affinity laws to inductive loads

� All EDG adequately sized

� D2 (Unit 1 Train B) least margin

� 2335 kW load vs. 2750 kW rating

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Technical Bases for Changes(continued)

� EDG loading with proposed V&F limits

� Evaluated loads for SBO

� 10CFR 50.63 and RG 1.155

� Frequency 60.5 Hz

� Applied affinity laws

� All EDG adequately sized

� D1 (Unit 1 Train A) least margin

� 2560 kW load vs. 2750 kW rating

� Unit 2 EDGs much more margin

� Rated 5400 kW

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Technical Bases for Changes(continued)

� EDG loading with proposed V&F limits (continued)

� Minimum fuel oil capacity evaluated

� Calculations revised

� Values in TS Bases per LA

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Schedule

� LAR drafted

� Validation in progress

� Adjust for meeting input

� Plan to submit soon after addressing meeting input

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Conclusion

� Discussion

� Questions

� Closing statements