RPS Trips

Question 1

RPS trips occur on what?

RPS alarms occur on what?

Answer 1

Trips

• 2 out of 4 logic

Alarms

• 1 out of 4 logic

Question 2

What is the Variable High Power Trip?

Answer 2

Protects against positive reactivity excursions during power operation and while shutdown.

From TMM Variable High Power Output

• Trip
  
  • Min - 30%
  • Variable - 15% above Power Level
  • Maximum - 106.5%
• Pretrip
  
  • Min - 28.5%
  • Variable - 13.5% above Power Level
  • High - 105%

Question 3

What is the high power rate trip?

Answer 3

High Power Rate Trip

Protects against an uncontrolled rod withdrawal or boron dilution incident while the reactor is critical but at low power levels

Only when power is greater than 10^-4 % and less than 15%

From WR NI’s

• NI-3 feeds A/C Trip Units
• NI-4 feeds B/D Trip Units

Trip

• 2.6 DPM

Pretrip

• 1.5 DPM

Question 4

What is the Low Reactor Coolant Flow Trip?

Answer 4

Low Reactor Coolant Flow Trip

Protects against fuel damage on loss of coolant flow. (DNB)

Trip

• 96%

Pretrip

• 97%

Question 5

What is the A/B Steam Generator Low Level Trip?

Answer 5

Steam Generator Low Level Trip

Protects against loss of heat removal capability from the primary coolant system.

Trip

• 28%

Pretrip

• 31%

Question 6

What is the A/B Steam Generator Low Pressure Trip?

Answer 6

Steam Generator Low Pressure Trip

Protects against excessively high steam flow caused by a steam line break.

Trip

• 512 psig

Pretrip

• 570 psig

Question 7

What is the Pressurizer High Pressure Trip?

Answer 7

Pressurizer High Pressure Trip

Prevents operation when the reactor is generating more power than the secondary system is accepting .

Trip

• 2235 psig

Pretrip

• 2185 psig

Question 8

What is the TM/LP Trip?

Answer 8

TM/LP Trip

Prevent the violation of minimum Departure from Nucleate Boiling Ratio.

Trip

• Variable – OR - 1760# which ever is higher

Pretrip

• Variable – OR- 1810# which ever is higher

Question 9

What is the Loss of Load Trip?

Answer 9

Loss of Load Trip

Limits the primary coolant system stored energy and pressure caused by the suspension of normal steam removal. (prevents lifting Pressurizer/main steam safety valves)

Set point

• Any 20E/T trip (Blocked below 15% power)
• Auto Stop Oil <45#
• High Vibrations 40mils
• MSIV out of position
• ATWAS

Question 10

What is the Containment High Pressure Trip?

Answer 10

Containment High Pressure Trip

Provides an earlier action than would be available with only the thermal margin low pressure trip or the steam generator pressure trip.

Was added to the RPS to provide diversity of reactor trip for the loss of coolant
accident.

Set point

• 3.7#

Pre-Trip at 3.4#

Pre-trip has no alarm, illuminates white light on auxiliary trip unit

Question 11

EK0917, “ROD WITHDRAWAL PROHIBIT”

Answer 11

EK0917, “ROD WITHDRAWAL PROHIBIT”

Trip Setpoints:
Variable High Power Pre-Trip (2 of 4):
Minimum: 28.5%
Variable: 13.5% above reset power level
Maximum: 105%
or
High Power Rate Pre-Trip (1 of 4) at 1.5DPM (effective 10^-4 to 15%
power)
or
Removal/Failure of RPS Bistable
High Power Rate Pre-Trip/Trip (1 of 4) at less than 15% power
or
EM OFF