ML060330170

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Slides on Emergency Diesel Generator Completion Time Extension License Amendment Request
ML060330170
Person / Time
Site: Prairie Island  Xcel Energy icon.png
Issue date: 02/01/2006
From:
Nuclear Management Co
To:
Office of Nuclear Reactor Regulation
References
FOIA/PA-2010-0209
Download: ML060330170 (45)
v • d • e


Text

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Emergency Diesel Generator Completion Time Extension License Amendment Request February 1, 2006 1

NRC/NMC meeting Agenda Opening Remarks - Gabe Salamon Amendment Purpose - Dale Vincent Electrical Design - Mike Johnson Risk Assessment - Tom Asmus Amendment Overview - Dale Vincent Action Item Review - Dale Vincent NMC COotatlo MWNrExe 2

Opening Remarks GabELSalamon - NMC Manager of Licensing Chris Mundt - Engineering Design Manager Dale Vincent - Licensing Engineer Mbike Johnson - Electrical Engineer Tom Asmus - PRA Engineer Cmow '0 NMC MiarEx=Ab 3

Amendment Purpose Current TS 3.8.1 EDG Completion Time 7 days This LAR proposes to increase Completion Time to 14 days Allows ELDG preventive maintenance activities on-line

- Some PMs require more than 7 days

- Improve quality of PM cof1nt" NMC%

80MMAExor" 4

Current TS L.

AC Sources-Operating 3.8-1 3-8 ELECTRICAL POWER SYSTEMS 3.8-1 AC Sources-Operating LCO 3.8-1 The following AC electrical sources shall be OPERABLE:

a Two paths between the offsite transmission grid and the onsite 4 kV Safeguards Distribution System; and

b. Two diesel generators DOGs) capable of supplying the onsite 4 kV Safeguards Distribution System.

APPI:CABI=Y MODES 1, 2, 3, and 4.

________________________(NM) 5

TS Changes AC Sources-Operating 3.8.1 ACTIONS CONDMON REQUIRED ACION COMPLETION T4EE B. (continued) B. 31 Detemijue OPERABLE 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> DG is not inoperable due to common cause failure.

OR B-3-2 Perforn SR 3-8-1-2 for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> OPERABLE DG.

AND B.4 Restore DG to OPERABLE status.

AND , . .

L44-days from discovery of filure to meet LCO NMCA dawodS M~r E 6

TS Changes AC Sowts-erawig 3.8.1 ACTIONS AX Restorepathto 7 days urrdiwi siagns.

AND 4A214dys from discoveiy of fail to meet LCO LI

.,i o" e NMC_

. l v 7

Prairie Island Electrical Distribution System Comirtdt8d NMC MlorExkaE-8

Safeguards AC Distribution System

  • Two independent 4KV buses per Unit
  • Each Safeguards 4KV Bus has two paths from the offsite transmission system P Each Safeguards Bus has one Emergency

.-Diesel Generator OffEach Safeguards Bus has a dedicated

,Sequencer which senses UV/DV and transfers the bus to the alternate so r the EDG i _l_i QC L~~

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Prairie Island Substation

  • Four 345 KV transmission lines
  • One 161 KV transmission line

, Breaker <ind a half scheme It

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ri NMCb

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$' 11

--.__ -_-_- -- I oI

--1 FIGURE 8.2-2 REV.23 12

Offsite Source Voltage Each of the two paths are designed to provide required voltage to the safeguards loads following a trip of both Units Continuous monitoring is provided by real-time analysis software utilized by the Transmission System Operator (TSO)

  • TSO procedural guidance directs notification of the plant Control Room Supervisoo real-time analysis alarm _

NMC CommdflTdr io MMExcMS 13

i go ErM-

Emergency Diesel Generators a- Each Safeguards Bus is connected to an Emergency Diesel Generator dedicated to that bus Each EDG is capable of sequentially starting and supplying one set of redundant engineered satety features Each EDG is started by its respective Safeguards Bus sequencer on a UV/

signal or on an Si signal lCA 5NN rent P ~~15- _e

Station Blackout Design

  • Each Safeguards Bus has a bustie available to the same Train bus on the opposite Unit
  • Each EDG is capable of sequentially starting and supplying the hot shutdown loads for its Unit along w ith the essential loads of the fopposite Unit in the event of a SBO iVNMCo iWL 16

Design Strengths

  • Multiple transmission lines each capable of supplying full power requirements
  • Two 345 KV buses with breaker and a half scheme

' Bustie to the same Train bus on the opposite

'Unit for SBO conditions

  • Multiple possible electrical system al Jo. s to provide two paths to each safegu rs bu-s 17

Design Strengths LEGEND OMNG IOOAM 345 5H

- PATH 1-1

- PATH 1-2

- PATH 1-3

- PATH 1-4 I.

PATH FROM GRID - UNIT I NImazM-18

Design Strengths

  • Diverse EDG manufacturers and cooling system design Real-time analysis and monitoring of predicted substation bus voltage following trip of both UInits iet 19

PRA Risk Assessment NMC"%

cumtJoiuhns 20

PRA Risk Assessment

  • PRA Model updates
  • PRA Model Description
  • Completion Time Extension Analysis

-Risk Sianificant Confiauration Avoidance Configuration Risk Management Program (CRM P) iNi Cond SoNuDr it C]

S 21

PRA Model Description

  • IPE submitted to NRC on March 1, 1994 and accepted on May 16, 1997
  • IPE has been substantially updated since 1997 Exhibit E of stubmittal nrovides sumnmrv of aII revisions

'The rev 2.1 model was used for EDG analvsis NMCo'%

C~lW~OrVAxcgbiW J 22

PRA Model Description

  • WOG peer review performed in September 2000
  • 37 Findings and Observations (F&O) resulted

- 5 significance level A

. ;. 9 <n cnn Iia/gaI R

,innif

  • 33 of 37 F&Os were dispositioned before LAR submitted
  • Exhibit F of submittal details the F& -

IlC L,-

Iq 23 H

PRA Model Description Internal events model includes internal flooding Model includes support system initiating event fault trees (i.e. Loss of Cooling Water)

Model is large fault tree small event tree style NNIC Ccmmdfled S M"VEm~

11--owww"wk 24

PRA Model Description I

i IF E iA hi.

i LERF model includes individual containment penetration modeling The equipment hatch, the fuel transfer tube

,and the containment airlocks are also UI A\

NMC~

1M121xcaffM.

25

PRA Model Updates Updates included in PRA rev 2.1 model for EDG analysis:

- Updated LOOP initiating event frequency

- Updated important system fault trees Upgraded HRA for key actions and added misalignment and miscalibration events

- Updated failure data for EDG and AFW systems

- Updated CCF values for EDG and AFW

- Updated internal flooding analysis IC 26 a

PRA Model Updates iResults of recent PRA update:

- CDF decreased

- LOCA and transient CDF contributions increased

- LOOP CDF contribution decreased

- Internal flooding CDF contribution decreased

-SGTR CDF contribution was unchanged t mwbExcB~m JF CgwW

= .

27

PRA Model Updates CDF Comparison from Previous PRA Model dating Event Unit 1CDF Results (per yr) Unit 2CDF Results (per year)

_ _ _ Rev 2.0 Rev 2.1 Rev 2.0 Rev 2.1 LOCAs 5.OOE-06 7.88E-06 5.02E-06 7.88E-06 kFtansients 3.22E-06 3.07E-06 5.68E-06 4.44E-06 S. GTR 2.92E-06 2.1OE-06 3.00E-06 2.1OE-06 LOOP 5.70E-06 1.45E-06 6.46E-06 1.66E-06 nal Flood 5.09E-06 2.44E-07 5.09E-06 .

I 2-T44E-kZ k tic Total 2.19E-05 1.47E-05 2.52E-05 1.63M-<

cwaverso NMC If 4%

28

completion Time Extension Analysis "ACDF and ALERF Assumptions:

- 14 day overhaul performed every 18 months for each EDG

- Corrective maintenance increases by ratio of proposed to current Completion Time (14/7)

- Only a single EDG is in CM or PM at any one time

- Turbine-driven AFW pump is assumed to e in maintenance when an EDG on the sam unit is, NMC '

wesUViWt bMWacrExArly4 29

ACDF and ALERF Results Results for Increased CM and PM Risk Parameter Unit 1 Unit 2 RG 1.1 74 criteria Base Line CDF 1.47E-5 1.63E-5 NA e Line LERF 5.74E-7 5.74E-7 NA Delta CDF 2.91 E-7 3.68E-7 <1 E-6 Delta LERF <5.OE-10 <5.OE-10 <1E-7_

tIV~ NMC.wP' Cbvl*TWnad oMmiEW&WW 30

rCompletion Time Extension Analysis ICCDP and ICLERP Assumptions:

- CCF terms for EDG in the same CCF group are set to 0 when inoperable EDG is in PM

- Remaining EDG in CCF group has new CCF factors calculated usinq smaller group size NMC QW>ff~ lob ta E itO 31

ICCDP and ICLERP Results ICCDP and ICLERP for EDG When EDG is Inoperable for Preventative Maintenance Unit DG Inoperable Delta CDF ICCDP ICLERP 1 D1 3.69E-06 1.41 E-07 < 5E-10 D2 4.37E-06 1.67E-07 < 5E-10 D5 4.95E-06 1.90E-07 < 5E-10 D6 5.35E-06 2.05E-07 < 5E-10 2 D1 5.05E-06 1.94E-07 < 5E-1O D2 3.16E-06 1.21 E-07 < 5E-10 D5 7.35E-06 D6 6.28E-06 NMCq condrAWd IoMJfExoeW: tj.

32

Discussion of Results ICCDP and ICLERP results are less than RG 1.177 limits because:

- Each 4kV bus is supported by its own dedicated EDG LJUOLII %0clcapul'iLy LbtLVVKII I C1 I IC; Li Oi I IJPUOIL Ul III 4kV buses is easily accomplished from the control room

- EDGs are diverse so CCF potential is i ignif IC m

  • B 33 fess_.

p Fire and Other External Events The extended EDG Completion Time is an administrative change and does not have a significant impact on the likelihood of occurrence of fires or SBO I>Thi lhifity ton hibutei frnm the opposite i int same train 4 kv bus to a non-fire affected

,,bus mitigates the risk from fires NMCf%

W~00rE 34

Fire and Other External Events I

  • Seismic events were evaluated in the IPEEE using the seismic margins assessment
  • No significant seismic concerns were identified
  • X,-,Hinh winds, Pxftrnal floods Rnd other Pxtprnal 4events were evaluated in the IPEEE
  • The proposed changes to the EDG Completion Time have an insignifica teffe __

on the risk profile from external even s tars_ ' _ _ _ _ __ :NM L C J 35

J

tsk Significant Configuration Avoidance Avoidance of risk significant plant configurations is assured by:

- Potential combinations of equipment out of service will be managed by the configuration risk management program

- The condition of the offsite nower supnnlv nd switchyard will be evaluated prior to entering the extended EDG Completion Time for elective maintenance

- No elective maintenance will be scheduld h switchyard that would challenge offsite wer availability during the proposed extende Completion Time NM9 KNMC 36

tisk Significant Configuration Avoidance Avoidance of risk significant plant configurations 4k is assured by:

-The system dispatcher will be contacted once per day and informed of the EDG status along with the power needs of the facility

- The turbine-driven AFW pump on the associated unit will not be removed from service for planned maintenance activities during the extenderEDG>

Completion Time _

DYEWfS b NMC At E X

37

Risk Significant Configuration Avoidance r,,,

Avoidance of risk significant plant configurations is assured by:

- Assure operating crews are briefed on the EDG work plan and procedural actions regarding:

bvLOOP and SBO X4 kV safeguards bus bustie

/ Reactor Coolant System bleed and feed

_- MC 38

.4

Risk Significant Configuration Avoidance

[Avoidance of risk significant plant configurations is assured by:

- Weather conditions will be evaluated prior to lentering the extended Completion Time for elective maintenance. An extended EDG Completion Time will not be entered for elective maintenance purposes if official weather forecasts are predicting severe conditions.

NMCa 39

,onfiguration Risk Management Program

,+

by Configuration dependent assessment of risk iph is performed prior to scheduled work Severe weather effect on offsite power can also be assessed

' A quantitative risk assessment is performed Liby utilizing the current level 1 PRA model

' Operations management is trained t p risk assessments for emergent work _

NMC 40

LAR Overview Cover letter Exhibit A - Licensee Evaluation Exhibits B and C TS/Bases pages xi D stxnIDll MU -UOMI ntments Exhibits EE- Summary of PRA Revic3io Exhibit F - Peer Review Certificatioi PINGP PRA AjMCrxor'%

Nmn*d 41

LAR Overview Submitted 11/21/05 Request approval in 1 year

- Need for Unit 1 diesel overhaul in 2007 It Omwwto NMC

&rEx 42

Licensee Evaluation Offsite power and grid reliability - 3. I Diesel generator description - 3.2 It~Station blackout capability 3.3

  • &- RG 1.1 55 EDG reliability program - 3.4 IBenefits of the proposed TS changes -

I Deterministic basis for extension4.3 -

NMC %

Cmmibd IOMWr&Q&Whoz ii 43

Licensee Evaluation

  • Delta CDF/LERF
  • Incremental Conditional CDP/LERP
  • Fire
  • External Events Aed;-.e 44 A Avdr,ksgfcrtcr)~u I IVI I& - 2VUJIU I ION-OIJIIIIII.. l IL UUI IIIVUI CLIUI I -6 .+e
  • Commitments
  • Tier 3 - Configuration risk management pro ram -

I s P4.4.3 - 4 Industry Precedents - 4.5 ---

NMC Ccami to MEXd f

44

Closing Comments Robust Electrical Design Risk Assessment Results

  • Extend Completion Time from 7 days to 14 days
  • Maximize reliability of Diesel Generators Action Item Review NMC~ T QommW~tW1 OMCAkWOkc~1 45
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