ML19162A407

01_03_Exercise_A Task 2 Step 1

ML19162A407
Person / Time
Issue date:	06/13/2019
From:	Office of Nuclear Regulatory Research
To:
T. Rivera
Shared Package
ML19162A398	List: ML19162A399 ML19162A400 ML19162A401 ML19162A402 ML19162A403 ML19162A404 ML19162A405 ML19162A407 ML19162A408 ML19162A409 ML19162A410
References
Download: ML19162A407 (7)

Text

Step 1: Identify Internal Events PRA Sequences to be Included (and those to be excluded) in the Fire PRA Model INITIATING EVENTS IN THE PRA MODEL Initiator Average Description Accident Address in Fire Comments Frequency Sequence PRA Model?

(per yr) or Event (Y or N)

Tree Model

%T1 7.23E-01 Reactor Trip Transient Event Tree

%T2 9.33E-02 Loss of Condenser Transient Vacuum Event Tree

%T3 4.13E-01 Turbine trip Transient Event Tree

%T4 3.73E-02 Loss of Main Feedwater Transient Event Tree

%T5P 4.25E-02 Loss of Offsite Power Transient (Plant-Centered) Event Tree

%T5C 1.02E-02 Loss of Off-Site Power Transient (Grid-Related) Event Tree

%T5D 6.26E-03 Loss of Off-Site Power Transient (Weather-Induced) Event Tree

%T6 7.35E-03 Steamline/Feed line Main Break Upstream of Main Steamline Steam Isolation valves Break Event

INITIATING EVENTS IN THE PRA MODEL Initiator Average Description Accident Address in Fire Comments Frequency Sequence PRA Model?

(per yr) or Event (Y or N)

Tree Model or Downstream of Tree Feedwater Isolation Valves (Includes spurious-open atmospheric dump valves)

%T7 5.44E-03 Steamline Break Main Downstream of Main Steamline Steam isolation valves Break Event (Includes spurious-open condenser dump valves)

%T8 2.94E-04 Loss of 4160 V Bus 1 Transient Event Tree

%T9 2.94E-04 Loss of 4160 V Bus A Transient Event Tree

%T10 2.94E-04 Loss of 4160 V Bus B Transient Event Tree

%T11 2.94E-04 Loss of 4160 V Bus 2 Transient Event Tree

%T12 3.00E-03 Loss of 125 VDC Bus A Transient Event Tree

%T13 3.00E-03 Loss of 125 VDC Bus B Transient Event Tree

INITIATING EVENTS IN THE PRA MODEL Initiator Average Description Accident Address in Fire Comments Frequency Sequence PRA Model?

(per yr) or Event (Y or N)

Tree Model

%T15 Fault Tree Loss of CCW System Transient Model Event Tree

%T15-INIT

%T16 Fault Tree Loss of Service Water Transient Model System Event Tree

%T16-INIT

%T17 Fault Tree Loss of Instrument Air Transient Model Event Tree

%T17-INIT

%T21 3.41E-02 Closure of MSIV (1 SG Transient Loop) Event Tree

%T22 1.24E-02 Closure of both MSIVs Transient Event Tree

%T23 1.78E-01 Partial Load Rejection Transient Event Tree

%T24 5.79E-02 Spurious Steam Gen. Transient Isolation Signal Event Tree

%T25 7.23E-02 Reactor Trip With PORV Transient Opening/Demand Event Tree

%T26 Fault Tree Loss of Power from120 Transient Model VAC Buses A & B Event Tree

%T26-INIT

INITIATING EVENTS IN THE PRA MODEL Initiator Average Description Accident Address in Fire Comments Frequency Sequence PRA Model?

(per yr) or Event (Y or N)

Tree Model

%S 6.8E-03 Small LOCA (pipe Small LOCA breaks and RCP seal Event Tree LOCA)

%M 9.60E-06 Medium LOCA (pipe Medium breaks) LOCA Event Tree

%A 7.77E-05 Large LOCA (pipe Large LOCA breaks) Event Tree

%R 7.93E-03 Steam Generator Tube SGTR Event Rupture Tree

%I1 1.000E-07 Interfacing Systems ISLLPI LOCA at RCS/LPI Sequence Interface (1 MOV and 1 (single event check valve in series) model)

%I2 2.000E-07 Interfacing Systems ISLRHR LOCA at RCS/RHR Sequence Interface (2 MOVs in (single event series) model)

%I3 Fault Tree Interfacing Systems ISLCCW Model LOCA at RCS/CCW Sequence I3QINIT interface (Reactor Coolant Pump Cooler rupture)

%VR 2.70E-07 Reactor Vessel Rupture Single Event

INITIATING EVENTS IN THE PRA MODEL Initiator Average Description Accident Address in Fire Comments Frequency Sequence PRA Model?

(per yr) or Event (Y or N)

Tree Model in Master Fault Tree

ACCIDENT SEQUENCE OR EVENT TREE MODELS IN THE PRA Accident Sequence Description Additional Details Address in Comments or Event Tree Model Fire PRA Model?

(Y or N)

TRA Transient Includes transient-induced LOCAs such as stuck-open PORV and RCP seal LOCA SLOCA Small LOCA Pipe breaks & RCP seal LOCA MLOCA Medium LOCA Pipe breaks LLOCA Large LOCA Pipe breaks ATWS Anticipated Transients Reactor Protection System fails Without Scram safe on loss of power. Trip circuits are highly redundant and confirmed to be physically separated.

SGTR Steam Generator Tube Rupture MSLB Main Steamline Break Includes spurious opening of secondary relief valves.

ISLCCW Interfacing Systems Rupture of Reactor Coolant Pump LOCA at RCS/CCW Cooler interface ISLRHR Interfacing Systems Fire-induced opening of RHR LOCA at RCS/RHR suction valves Interface ISLLPI Interfacing Systems Fire-induced opening of LPI LOCA at RCS/LPI injection valve Interface New Spurious Safety Requires multiple spurious valve Injection with HPI openings and possibly 2nd pump start

ACCIDENT SEQUENCE OR EVENT TREE MODELS IN THE PRA Accident Sequence Description Additional Details Address in Comments or Event Tree Model Fire PRA Model?

(Y or N)

New Feedwater ramp-up or May require multiple spurious AFW spurious start events (need to check)

New RWST drain down Requires combination of either or event both MOV-5,6 with either or both MOV-3,4 spuriously opening.