Week 4: Engineered Safety Features Flashcards
What is the primary purpose of the Engineered Safety Features?
Protect the fuel cladding
Ensure containment integrity
Limit fission product releases to the environment within the guideline values of 10CFR100
What systems comprise the Engineered Safety Features?
Containment systems
ECCS
Fission product removal and control
Emergency HVAC and Filtration
Control room habitability
Auxiliary feedwater
What subsystems make up the Containment systems?
Containment structure
Containment heat removal
Containment isolation
Containment combustible gas control
What is the design basis of the Containment Structure?
To withstand the P/T of the DBAs without exceeding the design leak rate
To limit the release of radioactive material due to a DBA such that resulting dose to the public does not exceed 10CFR100 limits
What subsystems make up the Containment Heat Removal system?
RHR
Containment Fan Cooling
Containment Spray
What is the function of the Containment Heat Removal system?
To reduce the containment temperature and pressure following a LOCA or MSLB by removing thermal energy from the containment atmosphere.
What is the function of the Containment Isolation system?
To allow the normal or emergency passage of fluids through the containment boundary while minimizing the release of fission products from containment following a LOCA or FHA.
What protection signals impact the Containment Isolation system?
Containment Isolation Signal Phase A (CISA)
Containment Isolation Signal Phase B (CISB)
Containment Purge Isolation System (CPIS)
Main Steam Line Isolation (MSLI)
What is the function of a CISA signal? What are its setpoints?
To actuate closure of all valves that are not required to be open for the operation of essential equipment. Originates on SIS or manual actuation.
What is the function of a CISB signal? What are its setpoints?
To isolate penetrations that were not isolated be the CISA signal and which are not required for operation of the ESF equipment, notably isolation CCW to RCPs. Originates on a Containment Hi-3 signal at 27 psig or on manual actuation.
What is the function of a CPIS signal? What are its setpoints?
To detect any abnormal amount of radioactivity in the containment atmosphere or in the containment purge and to initiate appropriate action to ensure that any release of radioactivity to the environment is controlled. Originates on Hi-Hi alarms on either the Containment Atmosphere or Purge process monitors, CSIA, or manual actuation.
What is the function of a MSLI signal? What are its setpoints?
To isolate the MSLs in the event of a MSLB/LOCA. Originates on a Low Steam Line Pressure (615 psig), High Steam Pressure Rate (-100 psi / 50s), Containment Pressure Hi-2 (17 psig), or manual actuation.
What is the function of the Containment Combustible Gas Control System? What subsystems comprise it?
To maintain hydrogen concentration below 4% by volume in Containment what not exceeding 10CFR100 release limits.
This system is made up of:
Hydrogen Recombiners
Hydrogen Mixing System
Hydrogen Monitoring System
Hydrogen Purge System
What are the potential sources of hydrogen in Containment?
Zirconium-Water reaction
Radiolytic decomposition of water
Metal corrosion in post-LOCA environment
What is the function of the Emergency Core Cooling System?
To cool the reactor core and provide shutdown capability following the initiation of a LOCA, RCCA ejection, SLB/FLB, SGTR.
