Accident Mitigation Flashcards
What are the Accident Categories per the UFSAR?
- Condition 1 - Normal Ops transients
- Condition 2 - Moderate frequency
- Condition 3 - Infrequent faults
- Condition 4 - Limiting faults(Design Basis Accidents/DBAs)
How often are Condition 2 events likely to occur?
Condition 2 events are of moderate frequency, expected to occur during a calendar year
How often are Condition 3 events likely to occur?
Condition 3 events are infrequent, may occur during the lifetime of the plant
How often are Condition 4 events likely to occur?
Condition 4 events are limiting events, not expected to occur during the lifetime of the plant
What are the general aspects of accident mitigation and recovery?
- Actuation of engineered safety functions
2. Emergency procedures
What are the limiting faults assumed in the accident analysis?
- Large break loss of coolant
- Major steam line break
- Major feedwater line break
- NC pump shaft break or seizure
- Rod control assembly ejection
- Steam generator tube rupture
What are the indications of a Large Break Loss of Coolant?
NC system depressurizes
greater than or equal to 1 square foot breach
What are the large break LOCA protective functions?
- Reactor trip signals
2. Safety injection
What are the indications of a Major Steam Line Break?
- Steam flow rises
- NC temperature and pressure lower
- Positive reactivity
What are the protective functions associated with a Major Steam Line Break?
- Reactor trip signals
- Safety injection
- Redundant isolation of Feedwater
- Main steam isolation
What are the indications of a Major Feedwater Line Break?
- Insufficient water to the Steam Generators
2. NCS heatup or cooldown
What are the protective functions associated with a Major Feedwater Line Break?
- Reactor trip signals
- Safety injection
- Auxiliary Feedwater actuation
What are the indications associated with a Reactor Coolant Pump Shaft Break or Seizure?
- NC flow rapid reduction
- Reduced heat transfer
- Departure from nucleate boiling
- NC pressure rises
What are the protective functions associated with a Reactor Coolant Pump Shaft Break or Seizure?
- Reactor trip signals
2. Pressurizer safeties
What are the indications of a Rod Control Assembly Ejection accident?
- Positive reactivity insertion
2. Adverse core power distribution
What are the protective functions associated with a Rod Control Assembly Ejection accident?
- Conservative mechanical design
- Quality control
- Nuclear design
What are the indications of a Steam Generator Tube Rupture?
- NC pressure trends down
2. EMF alarms
What are the protective functions associated with Steam Generator Tube Rupture?
- Reactor trip signals
- Safety injection
- Time critical operator actions
- Limits on Iodine-131
What are the indications of a Design Basis Fuel Handling Accident?
Assumption is dropping a fuel assembly inside or outside of containment, resulting in the rupture of the cladding of all the fuel rods in the assembly
Higher radiation dose
What are the protective functions for a Design Basis Fuel Handling Accident?
- Administrative controls on fuel handling operations
2. Physical controls on fuel handling operations
What are the anticipated Containment radiation levels following a DBA LOCA?
- 335 Rem/hr from Xe-133
- 22.6 Rem/hr from Cs-137
* based on 10% fuel failure, and a 100% release of Xe and Cs*
Which radiation monitors are used to detect high levels or radiation in Containment?
EMF-53A and EMF-53B
Who will approve procedure deviations when operating in an accident condition?
- Two SROs
2. The second SRO is preferably the Shift Manager
