Accident Mitigation

Question 1

What are the Accident Categories per the UFSAR?

Answer 1

1. Condition 1 - Normal Ops transients
2. Condition 2 - Moderate frequency
3. Condition 3 - Infrequent faults
4. Condition 4 - Limiting faults(Design Basis Accidents/DBAs)

Question 2

How often are Condition 2 events likely to occur?

Answer 2

Condition 2 events are of moderate frequency, expected to occur during a calendar year

Question 3

How often are Condition 3 events likely to occur?

Answer 3

Condition 3 events are infrequent, may occur during the lifetime of the plant

Question 4

How often are Condition 4 events likely to occur?

Answer 4

Condition 4 events are limiting events, not expected to occur during the lifetime of the plant

Question 5

What are the general aspects of accident mitigation and recovery?

Answer 5

1. Actuation of engineered safety functions

2. Emergency procedures

Question 6

What are the limiting faults assumed in the accident analysis?

Answer 6

1. Large break loss of coolant
2. Major steam line break
3. Major feedwater line break
4. NC pump shaft break or seizure
5. Rod control assembly ejection
6. Steam generator tube rupture

Question 7

What are the indications of a Large Break Loss of Coolant?

Answer 7

NC system depressurizes

greater than or equal to 1 square foot breach

Question 8

What are the large break LOCA protective functions?

Answer 8

1. Reactor trip signals

2. Safety injection

Question 9

What are the indications of a Major Steam Line Break?

Answer 9

1. Steam flow rises
2. NC temperature and pressure lower
3. Positive reactivity

Question 10

What are the protective functions associated with a Major Steam Line Break?

Answer 10

1. Reactor trip signals
2. Safety injection
3. Redundant isolation of Feedwater
4. Main steam isolation

Question 11

What are the indications of a Major Feedwater Line Break?

Answer 11

1. Insufficient water to the Steam Generators

2. NCS heatup or cooldown

Question 12

What are the protective functions associated with a Major Feedwater Line Break?

Answer 12

1. Reactor trip signals
2. Safety injection
3. Auxiliary Feedwater actuation

Question 13

What are the indications associated with a Reactor Coolant Pump Shaft Break or Seizure?

Answer 13

1. NC flow rapid reduction
2. Reduced heat transfer
3. Departure from nucleate boiling
4. NC pressure rises

Question 14

What are the protective functions associated with a Reactor Coolant Pump Shaft Break or Seizure?

Answer 14

1. Reactor trip signals

2. Pressurizer safeties

Question 15

What are the indications of a Rod Control Assembly Ejection accident?

Answer 15

1. Positive reactivity insertion

2. Adverse core power distribution

Question 16

What are the protective functions associated with a Rod Control Assembly Ejection accident?

Answer 16

1. Conservative mechanical design
2. Quality control
3. Nuclear design

Question 17

What are the indications of a Steam Generator Tube Rupture?

Answer 17

1. NC pressure trends down

2. EMF alarms

Question 18

What are the protective functions associated with Steam Generator Tube Rupture?

Answer 18

1. Reactor trip signals
2. Safety injection
3. Time critical operator actions
4. Limits on Iodine-131

Question 19

What are the indications of a Design Basis Fuel Handling Accident?

Answer 19

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

Question 20

What are the protective functions for a Design Basis Fuel Handling Accident?

Answer 20

1. Administrative controls on fuel handling operations

2. Physical controls on fuel handling operations

Question 21

What are the anticipated Containment radiation levels following a DBA LOCA?

Answer 21

1. 335 Rem/hr from Xe-133
2. 22.6 Rem/hr from Cs-137
   * based on 10% fuel failure, and a 100% release of Xe and Cs*

Question 22

Which radiation monitors are used to detect high levels or radiation in Containment?

Answer 22

EMF-53A and EMF-53B

Question 23

Who will approve procedure deviations when operating in an accident condition?

Answer 23

1. Two SROs

2. The second SRO is preferably the Shift Manager