Callaway Energy Center Seismic Probabilistic Risk Assessment in ...

Attachment 2 to ULNRC-0655 1 Page 1 of 25

Callaway Energy Center Seismic Probabilistic Risk Assessment in Response to 50.54(F) Letter with Regard to NTTF 2.1 Seismic -- Supplemental Information

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Attachment 2 to ULNRC-0655 1 Page 2 of 25

Table of Contents

1 .0 Introduction

3

2.0 Model Refinements

3

2.1 Update to Seismic PRA Relay Database

3

2.2 Updated Component Mapping for Fragility Group SF-SBO12X

3

2.3 Update ofMutually Exclusive Logic

3

2.4 Updated Component Mapping for Fragility Group RelayO.l 8DG

4

2.5 Update of Operator Action OP-XHE-FO-TDPMNL

4

2.6 Fragility Parameter Updates

15

3.0 Model Sensitivities

16

3.1 fragility Groups Sf-AB-SURROG and SF-AXB-MV Sub-Grouping

16

4.0 Updated Model Results

23

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Attachment 2 to ULNRC-0655 1 Page 3 of 25

1.0 Introduction

The purpose of this document is to provide supplemental information to the Callaway Energy Center S-PRA 2.1 Submittal. Following Fact and Observation (F&O) closure for the S-PRA model, model refinements and sensitivities have been performed to refine the CEC S-PRA model, and improve risk metric results based on the insights. The following subsections provide: (1) a description of the changes to the model which was documented and submitted as part of the 2.1 Submittal and the updated risk-metric results, (2) a description ofthe sensitivities performed on the S-PRA model to identify areas of future refinement and potential improvements to risk-metric results, and (3) the top model contributors after performing the changes as described in (1) and as assessed in (2).

2.0 Model Refinements

Following the CEC F&O Closure the following model changes have been made: 1 Incorporated an updated version ofthe Seismic PRA Relay Database (Revision 3). 2. Updated component mapping of fragility group SF-SB1O2X based upon plant-specific insights. 3 . Updated mutually exclusive logic for relay groups 4. Updated component mapping for fragility group Relay_O. 1 8DG base upon plant-specific insights. 5. Incorporated updated timing input for operator action to manually operator the turbinedriven pump (OP-XHE-FO-TDPMNL). Performed detailed seismic HRA for bin $H2. 6. Incorporated fragility parameter updates for fragility groups SF-EEGO1X (CCW HXs), SFIE-S3 (VSLOCA), Sf-RLOXX (Main Control Panels RLO 1 -- RLOO6 and RLO 1 3 -- RL026), SF-ABTNX (N2 Tanks TKAO2 -- TKAO5), and SF-XPBO5 (AEPS Transformer).

2.1 Update to Seismic PRA Relay Database Following the F&O Closure, a cutset review meeting was held to identify potential areas of refinement for the S-PRA model. Based on this review, Callaway reached out to a supporting vendor to determine if any conservative component mapping was being applied for various fragility groups. Based on this review, it was determined that an older revision of the S-PRA relay database (Revision 2) was still being credited in the S-PRA model. Revision 3 of the S PRA relay database incorporates refinements to various relay mapping.

2.2 Updated Component Mapping for Fragility Group SF-$BO12X Based on review of the S-PRA model it was determined that fragility group SF-SB1O2X was mapped to failing reactor trip, but loss of the cabinet is expected to cause a reactor trip. The cabinet failure is therefore screened from failing the reactor trip function. Removal of this mapping removes fragility group SF-SB1O2X from the model.

2.3 Update of Mutually Exclusive Logic Following the model update to reflect the latest 5-PRA relay database, mutually exclusive logic was reviewed to ensure that all fragility groups were appropriately populating through the model, and were not being excluded based on mutually exclusive logic. Four (4) fragility groups were determined to be impacted by the mutually exclusive logic:

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Attachment 2 to ULNRC-0655 1 Page 4 of 25

.

Fragility group Relay_O.72 --

and BB-MOV-CC-V8000A internal events model.

This relay which are

group fails identified

basic events as mutually

BB-MOV-OO-V8000A exclusive events in the

.

Fragility group Relay_O.81 and BB-MOV-CC-V8000B internal events model.

This relay group fails basic events BB-MOV-OO-V8000B which are identified as mutually exclusive events in the

.

fragility group impact multiple

SF-BBRSV -- This fragility identified mutually exclusive

group fails multiple basic combinations in the internal

events events

which model:

0 BB-PRV-CC-V455A and BB-MOV-OC-V455A

0 BB-PRV-CC-V456A and BB-PRV-OC-V456A

0 BB-MOV-OO-V8000B and BB-MOV-CC-V8000B

0 BB-MOV-OO-V8000A and BB-MOV-CC-V8000A

.

Fragility group SF-FR-HEAF-A27

TRAINA and SA-SIS-TM-TRATNB in the internal events model.

This fragility group fails basic events SA-SIS-TM which are identified as mutually exclusive events

Texoclcuosrirveectctohme bisinsuaetisonwsitchanthoenmlyupturoalplyageaxtecdluassivme ulotugaicll,yloegxiccluwsaivseaidndtehdetionteenrsnuarleetvheanttsmmutoudaelll.y

2.4 Updated Component Mapping for Fragility Group Relay_O.18DG A fooBwrppaEaaeegssPrneiaSldditotoeyrtotroesnognprbginoeneoiunsnpitletogohdRhaertdeemsteshldeafamrtytootOamhRnne.eu1trlarhae8eleyvlDly_aiGbe.yOwuI.asafl.nnto8hddBfDestNaGhtsEaBeerDOwdtcG1atohosms1en1ifpEnataohicDnlniodseGtronrjNseut,sscBstttatOhlmiryfe2tia,y1cpftaah1petienielwoidsnaneucg,rtrtoeetNohrtfBheferamaOrgetc1osiotlvehm1itete1tydpinE.oaggnDnrodetGhunNeptoBrmuReOtelapa2lpuay1ptysi1_bn.nOrgoeW.w1abkh8eeaeDtrlwnlsGoeatw,ehrniseet

2.5 Update of Operator Action OP-XHE-FO-TDPMNL

Timing updates were provided for operator action The timing updates and updated HRA analysis for

to manually operator the OP-XHE-FO-TDPMNL

turbine-driven pump. were put through the

EPRI HRA screening criteria. Detailed HRA was performed to refine bin extended Tdelay of 7 hours, the SF12 detailed analysis was determined to ($H3). The resultant HFE updates were determined from this process.

2 (SH2). Based on the be applicable to bin 3

lIFE OP-XHE-FO-

TDPMM.

OP-XHE-FO-

TDPMNL

OP-XHE-fOTDPMNL

OP-XHE-FOTDPMNL

jIi:

1

2

3

4

Specific Action SH1-OP-XHE-FO-

TDPMNL

SH2-OP-XHE-FO-

TDPMNL

5H3-OP-XHE-FOTDPMNL

SH4-OP-XHE-FOTDPMNL

REP 8.0211-03

1.25E-02

1.25E-02

1.OOE+OO

Description

FAILURE TO OPERATE TDAFP lAW EC SUPPL. G'LINE, ATTACH. R (SEISMIC)

FAILURE TO OPERATE TDAFP JAW EC SUPPL.

G'LINE, ATTACH. R (SEISMIC)

FAILURE TO OPERATE TDAFP lAW EC SUPPL. G'LINE, ATTACH. R (SEISMIC)

FAILURE TO OPERATE TDAFP lAW EC SUPPL.

G'LLNE, ATTACH. R (SEISMIC)

Page 4 of 25

Attachment 2 to ULNRC-0655 1 Page 5 of 25

SH2-OP-XffE-fO-TDPMNL, FAILURE TO OPERATE TDAFP IA WECSUPPL G'LINE, ATTACH. R (SEISMIC)

Plant Analyst

-_:

Data File OP-XHE-FO-TDPMNLhra Name Rachel Christian, Westinghouse

File Size 1 175552

HEP Summary

Method HEP Distribution Tvne

I

I

I

Pt

P2

PCO

CBDTM

HCRJORE

Maximum

3-.02E-03 Beta

0.OOE+00

3.02E-03

---

---1

--

-

I Variance

file Date 6:6/2019

Pc THERP 9.SOE-03 I .4lE-04

Record Date 6/6/2019 Date 6/6/2019 6/6/2019

TnttI IWP

I.25E-02

R:Aw

I

fV

PkL icrniflt'nt

NA

Action is being performed to mitigate a seismic-induced initiating event

1 . Initial Conditions: Steady state fufl power operation.

2. Initiating Event: Complete loss ofboth AC and DC power

3. Accident Sequence (Preceding functional failures and Successes):

Reactortrip - successful S3O AC and DC failure

4. Preceding Operator Errors and Successes: None - Nothing is available due to complete loss ofAC and DC Operators alert emergency response center about condition.

5. Success Criteria: R.3 CLOSE AFP Turb Mech Trip/Throt Hv Using The Manual Handwheel:

R4. CHECK At Least One OfThe Following - OPEN ABHV0005, TDAFP Strn Sply from MS Loop 2

RI Slowly Crack OPEN, AlP Turb Mech Trip/Throt Hv, To Start Spinning AFW Pump Turbine: R7. Slowly RAISE TDAFP To 3850 RPM R8. STABILIZE TDAFP Speed - AT 3850 RPM R9. CHECK Auxiliary Feedwater Flowmte Indication AVAILABLE - It is not available since there is a complete loss ofboth AC and DC power R9 RNO - INSTALL Local Flowrate Monitoring using Attachment UU, Local Monitoring Auxiliary feedwater Flow Rates

6. Consequence ofFailure: SG dryout

.

Cognitive Procedure

.

Cognitive Step Number Cognitive Instruction

Procedures -

IC SUPP GUIDE (EMERGENCY COORDINATOR SUPPLEMENTAL GUIDELINE) Revision:21

6

Step 6 RNO

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Attachment 2 to ULNRC-0655 1 Page 6 of 25

Execution Procedure Execution Instruction Job Performance Measure

Attachment R, Starting TDAFP On Loss ofAC and DC Power Execution: Not Selected

JPM: Not Selected

-

Notes

wsSeeaiislskmmdioiccwa:lnlTysh, ienarsdeaumcaededd.prerNossoceetdedutihnreatsthaaedrCedioutigsoenndiatiltvowemoUritnkirlgoeacatodeviaennriedtidadtaiisnstsgreasecsvtmieonentnsst, prooefsgpeacdrbdbleyfastsihlueorfeewaorhtfheAqthutetaerknteht,ieofynorodceucxeuamtroapswleaonrdkailmnotaeadrg.nealasesveesnstmoernat re

Classroom Training Simulator Training

Trainini

.

--

0.5 per year jO.5 per year

Crew Member Shift Manager Shift Supervisor STA

Reactoqperators Plantoperators Mechanics Electricians

tC Technicians Health Physics Technicians Chernistiy Technicians

Included No No No Yes Yes Yes Yes Yes Yes Yes

Total Av&'ible 1

2 2 2 2 2 2

Required for Execution 0 0 0 1 2 2 2 0 0 0

Notes

aiMnsdsaeunscpseomdweeenvrterwnetqa.lukNidroeotdwe intshsae,tqaumreivaanadlpedonrwet sewsrehndeeteihndeerthdtehfeCoraocagtdnioditniitviioesnUiamlnpwreleocmrokvNeleonorateetdeddsaainnsdsreedssispsmtorenancsett.iotonsanpoisnetedrnbayl

initiating event the earthquake,

or a seismicallyfor example damage

Analyst Notes SPRA Detailed HRA

A.4.

The TDAFP is running and is not stopped due to loss of DC power.

The TDAFP has been supplying the SG for 8 to 12 hours after the reactor trip and loss ofall AC power.

The heat load reactor trip is

on the SG considered

is considerably less than at reactor trip. The to be extremely conservative for this HFE.

use

of

50

minutes

stated

in

the

Supplementary

Guide

within

It is assumed that the assumed the batteries

operator wilt be aware deplete in 8 hours and

of the depletion of the the operators will take

batteries action to

at least an hour prepare for this

before it happens. Therefore it is at least an hour before it happens.

Onerator Interview Insiehts

tSTILhnthoeeaircpsedad6tgiisiuotpiniarodocnoevolfiitmnodeeeqpcsulioesismpteeemvpnleletoeernsatritselndroogepfbqabtautiostoiaretnechdsdhAoominsfCercdnealitesrnaetRdorclrttDyiihnoeCmgn.osaipnrfkejreorecamdttiooitrnnhs.etwhTEeihlmlTeaSePlrCsgRo.eAnnceayesdsCutomooprodtbiiotnanaintiosrS.tOhatletvheel

operators will choose to align the TDAFW. indication following attachment U since

FrFTeeEhseeeEdtDCtPhoWuenmAtTrpoTD.lEARTRFohPaoenmifdnoSlupdtsaaoerfuafFltlwSePGloauasg.nleddfmoimrorpEelCelmAik-ee0nl.yt0slodtasiryseocintfsDEoCCpAepr-oa0tw.o0resr(pTtoahrueesnCet oApnrtottracocelhdRmuroeeon)mtTAhS,etAaCfLfoTwntEoruoRllNdRAmoTooEmre

Staff would more likely try likely start the Non-Safety LOW PRESSURE

to Aux

Equipment department

used is clearly has conducted

marked and locations provided. training on this several times

(top

drawer

of TSC

Cabinet).

Easy

to

find

and

use.

Operations

Training

No insights specific to seismic. This action has not been reviewed by an operator for seismic considerations.

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Attachment 2 to ULNRC-0655 1 Page 7 of 25

Timing Analysis -- Tsw HOW

Tdefay

THorn

Tcog

OU1it

Texe

I

I

1-0

T

-

--

TCEC Time available for cognition and recovery Time available for recovery SPAR-H Available time (cognitive) SPAR-H Available time (execution) ratio EPRI Minimum level of dependence for recovery

-

Tsw= 8hoursforbatterydepletion

---

Notes

I

L?S

-

ama State

-

-- $Hours 7 Hours Minutes 37.5 Minutes 22.5 Minutes 22.5 Minutes 22.5 Minutes 1.60 Minutes MD

Tdelay = 7 hours before the operators start to take action to compensate for the battery depletion. Seismic approach to increase Tdelay by 2 minutes account for additional distractions and confusion following the earthquake is not directly applicable for this action based on long Tdelay.

Tcog = 0 hours due to the long time before the battery depletion. The operators will be aware that the batteries are depleting and

will not need following the

any other indications. Seismic approach earthquake is not directly applicable for

to increase this action

Tcog based

by on

25% long

to account for additional distractions Tdelay. Note also that adjustment of

and confusion Cognitive

Unrecovered pcb further degrades the action reliability due to additional distractions and workload.

Texe 30 minutes to perform all ofthe local

..! confusionfollowing the earthquake)

actions

+

7.5

minutes

for

seismic

(25%

increase

to

account

for

additional

distractions

Pc Failure Mechanism Pca: Availability of Information Pcb: Failure ofAftention Pcc: Misread/miscommunicate data Pcd: Information misleading ?ce: Skip a step in procedure Pcf: Misinterpret Instructions Peg: Misinterpret decisionlogic Pch: Deliberate vIolation Initial Pc(without recovery credited)

Cocnitive Analysis

Branch a h a a g a 1 a

Notes Accessibility dunnga seismic event should be confirmed via an operator pathway walkdown.

HEP O.OOE+OO O.OOE+OO O.OOE+OO O.OOE+OO 6.OOE-03 O.OOE+OO O.OOE+OO O.OOE+OO 6.OOE-03

Page 7 of 25

Attachment 2 to ULNRC-0655 1 Page 8 of 25

Pea: Availability of information

Notes/Assumptions: Assumed atui,ns due to relay chattei

that

there

is

reasoizabte

anatogue

instrumentation

alternative

to

the

alarm

in

the

event

ofsptirious

lntei,zat events response applicable to S-PRA.

md. Avail in CR

CR Ind Accurate WarnIAtt in Proc.

Training on End.

Value

::::

-EE:.. -

No

:

.-

--

.

.. .

-:

:

.

(g) I e+OOO

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