Summary of RX Trips

Question 1

List RX Trips

-with coincidences and setponts

Answer 1

1) Manual 1 of 2 MCB Switches
2) Any SI Signal 1 of 2 SSPS Trains
3) SR High Flux 1 of 2 @ 10^5 cps when below P-6
4) IR High Flux 1 of 2 @ 25% below P-10
5) PR Overpower-Low Setpoint 2 of 4 @ 25% power when below P-10
6) PR Overpower-High Setpoint 2 of 4 @ 109% power
7) PR flux High-rate 2 of 4 ramping @ 5% with in 2 sec
8) Pressurizer high Pressure 2 of 4 @ 2385#
9) Pressurizer High Level 2 of 3 @ 92% when above p-7
10) Pressurizer Low Pressure 2 of 4 @ 1945 when above P-7
11) Loss of RX Coolant Flow
a) <90% in 2 of 3 flow channels in 2 of 4 loops when P-7 is enabled or 1 of 4 when P-8 is enabled
b) RCP voltage 10.2k for .85 secs on 1 of 2 pumps on 2 of 2 buses when above P-7
c) RCP frequency of 55.5hz for 5.1 cycles (.085 secs) on 1 of 2 pumps on 2 of 2 buses when above P-7
12) OT-Delta T 2 of 4 @121% RTP +/- Delta T penalties
13) OP-Delta T 2 of 4 111.6% RTP - Delta T penalties
14) S/G low level 2 of 4 in any 1 S/G @20%
15) Turbine Trip greater than P-9
16) SSPS General Warning 2 of 2 trains

Question 2

Define SR High range Flux RX Trip

Answer 2

1 of 2 @ 10^5 cps when below P-6

• When the IR detectors reach the P-6 setpoint of 10^-10 amps, this trip can be manually blocked with SSPS
• This trip protects the reactor from excessive power excursions caused by unexpected reactivity additions and high SUR while the reactor is operating in the source range.

Question 3

Define IR high Flux RX Trip

Answer 3

1 of 2 @25% equivalent current when below P-10

• When the PR detectors reach the P-10 set point of 10% power, this trip can be manually blocked
• This trip protects the reactor from excessive power excursions caused by unexpected reactivity additions and high SUR while the reactor is operating in the intermediate range

Question 4

Define PR Overpower-Low setpoint RX Trip

Answer 4

2 of 4 @ 25% power when below P-10

• When the PR detectors reach the P-10 setpoint of 10% power
• This trip provides protection against start up accidents as do the SR and IR trips

Question 5

Define Overpower-High setpoint RX Trip

Answer 5

2 of 4 @ 109% power

- This trip protects against excessive heat flux, leading to DNB, from fast reactivity excursions while in the PR

Question 6

Define PR Flux High-rate RX Trip

Answer 6

2 of 4 ramping @ 5% within 2 sec

• This trip signal NI bistable seals in
• The positivity rate trip protects against rapid flux increases, which characterize a control rod ejection event. Specifically, this trip complements the power range overpower-high setpoint trip to ensure that the power overshoot is not excessive from a mid-power rod ejection accident.

Question 7

Define PZR High Pressure RX Trip

Answer 7

2 of 4 @ 2385#
- This trip, along with operation of the Pressurizer and S/G safety valves, protects the RCS and its various components from an overpressure condition, such as a load rejection without a direct reactor trip.

Question 8

Define PZR high Level RX Trip

Answer 8

2 of 3 @ 92% when above P-7

• This is provided to prevent water relief through the pressurizer safety valves and to ensure adequate steam space volume for PZR pressure control
• Below P-7 this trip is blocked

Question 9

Define PZR low pressure RX Trip

Answer 9

2 of 4 @ 1945# when above P-7 (Lead/Lag compensated)

• This trip protects against excessive void formation and DNB
• This trip also serves to limit the range of the OT-delta T trip by establishing a lower limit on RCS pressure

Question 10

Define Loss of Reactor Coolant Flow RX Trip

Answer 10

Reactor Coolant flow of <90% in 2 of 3 flow channels in 2 of 4 loops when P-7 is enabled, or 1 of 4 loops when P-8 is enabled.
- This trip prevents the core from reaching the DNBR limit. This trip is not always sufficient so the next to anticipatory trips exist.

Question 11

Define OT Delta-T RX Trip

Answer 11

2 of 4 @ 121% of RTP +/- Delta-t penalties
-This trip prevents DNB for all combinations of pressure, power coolant temperature and AFD- provided that the transient is slow (approx 4 secs)

Question 12

Define OP Delta-T RX Trip

Answer 12

2 of 4 @ 111.6% of RTP - Delta-T penalties

- This trip protects against high fuel rod power density.

Question 13

Define SG low level RX Trip

Answer 13

2 of 4 in any one S/G @ 20%

- protects from loss of heat sink on loss feedwater.

Question 14

Define Turbine Trip RX Trip

Answer 14

Trips when greater than P-9

• Trip anticipates plant transients to avoid the resulting thermal transients
• trips is sensed by: Low EHC pressure 2 of 3 @ 700#
• or Stop valves shut, 4 of 4 off full open seat.

Question 15

SSPS General Warning RX Trip

Answer 15

2 of 2 trains

- SSPS monitors all safety related plant parameters and trips the plant should an unsafe condition exist.

Question 16

Define RCP pump voltage low trip

Answer 16

RCP voltage of 10,200 volts for .85 seconds of 1 of 2 pumps on 2 of 2 busses when above P-7.
- from 27 device, anticipates complete loss of power/flow

Question 17

Define RCP low frequency trip

Answer 17

C: RCP frequency of 55.5 Hz for 5.1 cycles (.085 seconds) on 1 of 2 busses when above P-7.
- This trip prevents the low frequency from dragging down the pump speed, and affecting the flywheel coastdown assumption.