ML19162A407
| ML19162A407 | |
| Person / Time | |
|---|---|
| Issue date: | 06/13/2019 |
| From: | Office of Nuclear Regulatory Research |
| To: | |
| T. Rivera | |
| Shared Package | |
| ML19162A398 | List: |
| 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 Frequency (per yr)
Description Accident Sequence or Event Tree Model Address in Fire PRA Model?
(Y or N)
Comments
%T1 7.23E-01 Reactor Trip Transient Event Tree
%T2 9.33E-02 Loss of Condenser Vacuum Transient 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 (Plant-Centered)
Transient Event Tree
%T5C 1.02E-02 Loss of Off-Site Power (Grid-Related)
Transient Event Tree
%T5D 6.26E-03 Loss of Off-Site Power (Weather-Induced)
Transient Event Tree
%T6 7.35E-03 Steamline/Feed line Break Upstream of Main Steam Isolation valves Main Steamline Break Event
INITIATING EVENTS IN THE PRA MODEL Initiator Average Frequency (per yr)
Description Accident Sequence or Event Tree Model Address in Fire PRA Model?
(Y or N)
Comments or Downstream of Feedwater Isolation Valves (Includes spurious-open atmospheric dump valves)
Tree
%T7 5.44E-03 Steamline Break Downstream of Main Steam isolation valves (Includes spurious-open condenser dump valves)
Main Steamline Break Event
%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 Frequency (per yr)
Description Accident Sequence or Event Tree Model Address in Fire PRA Model?
(Y or N)
Comments
%T15 Fault Tree Model
%T15-INIT Loss of CCW System Transient Event Tree
%T16 Fault Tree Model
%T16-INIT Loss of Service Water System Transient Event Tree
%T17 Fault Tree Model
%T17-INIT Loss of Instrument Air Transient Event Tree
%T21 3.41E-02 Closure of MSIV (1 SG Loop)
Transient 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.
Isolation Signal Transient Event Tree
%T25 7.23E-02 Reactor Trip With PORV Opening/Demand Transient Event Tree
%T26 Fault Tree Model
%T26-INIT Loss of Power from120 VAC Buses A & B Transient Event Tree
INITIATING EVENTS IN THE PRA MODEL Initiator Average Frequency (per yr)
Description Accident Sequence or Event Tree Model Address in Fire PRA Model?
(Y or N)
Comments
%S 6.8E-03 Small LOCA (pipe breaks and RCP seal LOCA)
Small LOCA Event Tree
%M 9.60E-06 Medium LOCA (pipe breaks)
Medium LOCA Event Tree
%A 7.77E-05 Large LOCA (pipe breaks)
Large LOCA Event Tree
%R 7.93E-03 Steam Generator Tube Rupture SGTR Event Tree
%I1 1.000E-07 Interfacing Systems LOCA at RCS/LPI Interface (1 MOV and 1 check valve in series)
ISLLPI Sequence (single event model)
%I2 2.000E-07 Interfacing Systems LOCA at RCS/RHR Interface (2 MOVs in series)
ISLRHR Sequence (single event model)
%I3 Fault Tree Model I3QINIT Interfacing Systems LOCA at RCS/CCW interface (Reactor Coolant Pump Cooler rupture)
ISLCCW Sequence
%VR 2.70E-07 Reactor Vessel Rupture Single Event
INITIATING EVENTS IN THE PRA MODEL Initiator Average Frequency (per yr)
Description Accident Sequence or Event Tree Model Address in Fire PRA Model?
(Y or N)
Comments in Master Fault Tree
ACCIDENT SEQUENCE OR EVENT TREE MODELS IN THE PRA Accident Sequence or Event Tree Model Description Additional Details Address in Fire PRA Model?
(Y or N)
Comments 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 Without Scram Reactor Protection System fails 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 LOCA at RCS/CCW interface Rupture of Reactor Coolant Pump Cooler ISLRHR Interfacing Systems LOCA at RCS/RHR Interface Fire-induced opening of RHR suction valves ISLLPI Interfacing Systems LOCA at RCS/LPI Interface Fire-induced opening of LPI injection valve New Spurious Safety Injection with HPI Requires multiple spurious valve openings and possibly 2nd pump start
ACCIDENT SEQUENCE OR EVENT TREE MODELS IN THE PRA Accident Sequence or Event Tree Model Description Additional Details Address in Fire PRA Model?
(Y or N)
Comments New Feedwater ramp-up or AFW spurious start May require multiple spurious events (need to check)
New RWST drain down event Requires combination of either or both MOV-5,6 with either or both MOV-3,4 spuriously opening.