Systems Exam 3 - Excore Instrumentation, Ps & Cs

Question 1

SR SHTDN FLUX HI alarm

Answer 1

→annunciates if flux increases to 300 cps or 5x background
→can be blocked
→this alarm also activates containment evacuation alarm

Question 2

SR FLUX DBLG Alarm

Answer 2

→annunciates if SR flux doubles in 9 minutes

Question 3

Source Range Detector

Answer 3

→BF3 Proportional Detector
→Rx Trip at 10^5 cps (can block above P-6)
→Pulse Height Discriminator: Eliminates pulses due to gamma ionization

Note: high voltage switching operations (or lightning) can spike SR detectors, causing trips.

Question 4

Intermediate Range Detector

Answer 4

→Compensated Ion Chamber (gamma interactions in both chambers are cancelled out by adjusting voltage of gamma only detector (inner can)
→Rx Trip when detector current output = 25% Rx Power
→Overcompensated (high compensation voltage) causes detector output to decrease (read lower than actual)
→Undercompensated (low compensation voltage) causes detector output to increase (read higher than actual)

Note: if one channel is undercompensated, you may not get the unblock of SR trips; can manually unblock SR trips at CB in this case

Question 5

Power Range Detector

Answer 5

→Uncompensated Ion Chamber
→amount of gammas compared to amount of neutrons is insignificant
→amount of background gammas is directly proportional to power level

Nuclear Engineering has estimated that the effect on PR NIS is approximately 0.8 % per degree at 100% power. The effect is decreased proportionally with power. For example at 50% power, the effect is halved or 0.4% per degree.

Question 6

Tech Spec 3.3.1 & 3.9.3 Source Range:

Answer 6

→Source Range Instrumentation is required in Mode 2 (below P6) through Mode 6
→in Mode 6, only visual count rate indication is required in the Control Room
→in Mode 3-5 the T.S. only applies if the Rod Control System is capable of withdrawal and one or more rods not fully inserted.

Question 7

Tech Spec 3.3.1 Intermediate Range:

Answer 7

The Intermediate Range Instrumentation is required in Mode 1 (below P-10) and Mode 2 (above P-6)

1 IR Channel inoperable, Mode 1 (<P-10) & 2 (>P-6):
→reduce THERMAL POWER to <P-6 in 24 hours, or
→increase power to >P-10 in 24 hours
→Mode 2 (<P-6) - Restore to operable prior to increasing power above the P-6 setpoint

Both IR channels inoperable Mode 1 (<P-10) & 2 (>P-6):
→suspend operations involving positive reactivity additions immediately, and
→reduce power to <P-6 in 2 hours

Question 8

Tech Spec 3.3.1 Power Range:

Answer 8

2 PR Channels Inoperable, enter LCO 3.0.3

Question 9

RX > 50% PWR UP PR DET FLUX DEV HI alarm:

Answer 9

any one detector deviating by > 5% of the average of all upper detectors

Question 10

RX > 50% PWR LWR PR DET FLUX DEV HI alarm:

Answer 10

any one detector deviating by > 5% of the average of all lower detectors

Question 11

Power Range Deviation alarm:

Answer 11

deviating by >5% of the average of all detectors

Question 12

From 100% power, approximately how long after a trip do we take to come down to where Source Range instruments are energized?

Answer 12

→approx. 15-18 minutes
→10^-10 cps
→Startup Rate = -1/3 dpm
→approx. 6 decades

Question 13

Where are the overlaps between SR, IR, and PR instruments?

Answer 13

→0% power on PR ≈ 10^-5 amps on IR
→3 to 5 x 10^4 cps on SR ≈ 10^-10 amps on IR

Question 14

P-6

→What is it?
→Setpoint
→Coincidence

Answer 14

→source range reactor trip block permissive
→Setpoint: >10^-10 amps
→Coincidence: 1/2 IR

Question 15

P-6

What does it do?

Answer 15

→Allows manual block of SR Hi Flux trip (2/2 block switches)
→Block switches also de-energize SR Hi Volts
→When <5x10-11 amps on 2/2 channels then: SR Hi volts re-energized, SR trip and Flux Doubling protection re-instated (aforementioned occurs automatically)

Question 16

P-7

→What is it?
→Setpoint
→Coincidence

Answer 16

→at power permissive
→Setpoint: none
→Coincidence: P-10 or P-13 met
(2/4 Excore NI >10% or 1/2 Turb Impulse Press >10%)

Question 17

P-7

What does it do?

Answer 17

Following Rx trips re-instated with P-7 met:
→PZR Lo Pressure
→PZR Hi Level
→RCP Undervoltage
→RCP Underfrequency
→Low Flow in 2 RCS Loops
Above trips are blocked when P-7 no longer met.

Question 18

P-8

→What is it?
→Setpoint
→Coincidence

Answer 18

→3 loop flow permissive
→Setpoint: >48%
→Coincidence: 2/4 PR channels

“8 and 3 look almost alike”

Question 19

P-8

What does it do?

Answer 19

→Allows for Rx trip when low flow condition is sensed on 2/3 channels on 1 RCS loop.
→Automatically blocked with 3/4 NIS channels < 48%.

Question 20

P-9

→What is it?
→Setpoint
→Coincidence

Answer 20

→turbine trip permissive
→Setpoint: >50%
→Coincidence: 2/4 PR channels

Question 21

P-9

What does it do?

Answer 21

→When met, generates Rx Trip if Turbine Trip occurs
→Automatically blocked when <50% on 3/4 PR channels.

Question 22

P-10

→What is it?
→Setpoint
→Coincidence

Answer 22

→nuclear at power permissive
→Setpoint: >10%
→Coincidence: 2/4 PR channels

Question 23

P-10

What does it do?

Answer 23

When met it performs the following:
→Feeds P-7
→Automatically blocks SR Trip and de-energizes SR Hi Volts
→Allows blocking of IR Trip and C-1
→Allows blocking of PR Trip (Low setpoint)
→SR Hi Flux at Shutdown annunciator and CNTMT Evacuation alarm defeated

When 3/4 PR channels <10% the following are automatically re-instated:
→IR Trip
→C-1
→PR Trip (Low setpoint)
→Removes permissive to P-7

Question 24

C-1

→What is it?
→Setpoint
→Coincidence

Answer 24

→IR Rod Stop (prevent reaching IR & PR Hi flux trips)
→Setpoint: IR amps ≈ 20% PR
→Coincidence: 1/2 IR channels

Question 25

C-1 What does it do?

Answer 25

→Stops outward rod motion in auto AND manual. →Can be manually blocked when P-10 is met (2/2 switches) →Automatically unblocked when P-10 no longer met.

Question 26

C-2 →What is it? →Setpoint →Coincidence

Answer 26

→PR Rod Stop (prevent reaching PR hi flux trip) →Setpoint: 103% →Coincidence: 1/4 PR channels

Question 27

C-2 What does it do?

Answer 27

→Stops outward rod motion in auto AND manual. →Can be bypassed at the NIS cabinets.

Question 28

C-3 →What is it? →Setpoint →Coincidence

Answer 28

→OTN16 Rod Stop & Turbine Runback →Setpoint: 3% < OTN16 Rx Trip setpoint (115 ± penalties) →Coincidence: 2/4 N-16 channels

Question 29

C-3 What does it do?

Answer 29

→Stops outward rod motion in auto AND manual. →Generates Turbine runback (runback works as follows, on for 1.5 sec @ 200%/min then off for 28.5 sec, cycle continues until C-3 clears).

Question 30

C-4 →What is it? →Setpoint →Coincidence

Answer 30

→OPN16 Rod Stop & Turbine Runback →Setpoint: 3% < OPN16 Rx Trip setpoint (>109%) →Coincidence: 2/4 N-16 channels

Question 31

C-4 What does it do?

Answer 31

→Stops outward rod motion in auto AND manual. →Generates Turbine runback (runback works as follows, on for 1.5 sec @ 200%/min then off for 28.5 sec, cycle continues until C-4 clears).

Question 32

C-11 →What is it? →Setpoint →Coincidence

Answer 32

→Control Bank D Rod Withdrawal Limit →Setpoint: 223 steps →Coincidence: N/A

Question 33

C-11 What does it do?

Answer 33

→Stops outward rod motion in auto only.

Question 34

Tech Spec 3.2.4 Quadrant Power Tilt Ratio (QPTR)

Answer 34

→action required once ≥1.02 →applicable in Mode 1, >50% →For each 1% QPTR above 1.00, reduce power 3% →verify QPTR every 12 hrs →perform evaluation to allow continued operation →if completion time not met, reduce power to <50% Note: this one is tricky. Action isn't required until 1.02, but you must take the action based on the amount above 1.00

Question 35

Tech Spec 3.2.3 Axial Flux Difference

Answer 35

→applicable in Mode 1 >50% →Spec not met when **two or more** PR NIs indicate out of spec →30 minutes to be <50% - no time for correction Background Info: →AFD = ΔI →inside the doghouse = acceptable; outside the doghouse = unacceptable "Half power, half an hour"

Question 36

Source Range Hi Flux Rx Trip →What does it protect against? →Setpoint? →Coincidence?

Answer 36

Source Range Hi Flux Rx Trip →Startup Accident →≥10^5 cps →1/2 Source Range Detectors

Question 37

Source Range Hi Flux Rx Trip Notes/What does it do?

Answer 37

Source Range Hi Flux Rx Trip →Can be manually blocked (2/2 switches) when P-6 is met. →Auto blocked when P-10 is met →When P-6 no longer met, trip is automatically reinstated. →Can be manually unblocked when P-10 no longer met

Question 38

Intermediate Range Hi Flux Rx Trip →What does it protect against? →Setpoint? →Coincidence?

Answer 38

Intermediate Range Hi Flux Rx Trip →Startup Accident →IR current ≈ 25% PR →1/2 IR Detectors

Question 39

Intermediate Range Hi Flux Rx Trip Notes/What does it do?

Answer 39

Intermediate Range Hi Flux Rx Trip →Can be blocked manually when P-10 is met. →When P-10 no longer met, trip is automatically reinstated.

Question 40

Power Range Hi Flux "Low Setpoint" Rx Trip →What does it protect against? →Setpoint? →Coincidence?

Answer 40

Power Range Hi Flux "Low Setpoint" Rx Trip →overpower condition, uncontrolled RCCA bank withdrawal →≥25% →2/4 PR detectors (alarm on 1/4)

Question 41

Power Range Hi Flux "Low Setpoint" Rx Trip Notes/What does it do?

Answer 41

Power Range Hi Flux "Low Setpoint" Rx Trip →Can be blocked manually when P-10 is met. →When P-10 no longer met, trip is automatically reinstated.

Question 42

Power Range Hi Flux "Hi Setpoint" Rx Trip →What does it protect against? →Setpoint? →Coincidence?

Answer 42

Power Range Hi Flux "Hi Setpoint" Rx Trip →DNB →109% →2/4 PR Detectors (alarm on 1/4)

Question 43

Power Range Hi Flux "Hi Setpoint" Rx Trip Notes/What does it do?

Answer 43

Power Range Hi Flux "Hi Setpoint" Rx Trip →Cannot be blocked.

Question 44

Power Range Hi Positive Trip Rate Rx Trip →What does it protect against? →Setpoint? →Coincidence?

Answer 44

Power Range Hi Positive Trip Rate Rx Trip →rod ejection →+5% w/time constant of 2 seconds →2/4 Channels (alarm on 1/4) "Five-two, peeeeewww!!!"

Question 45

Power Range Hi Positive Trip Rate Rx Trip Notes/What does it do?

Answer 45

Power Range Hi Positive Trip Rate Rx Trip →Must be manually reset at NIS cabinets →Setpoint is variable based on rate of power increase (i.e. 2.5 % in 1 second will actuate trip, 5% increase in 2 seconds will actuate trip, 10% increase actuates immediately)

Question 46

Source Range and Level Trip Bypass Switch

Answer 46

Note: losing power has the same effect as pulling fuses.

Question 47

Intermediate Range and Level Trip Bypass Switch

Answer 47

Note: losing power has the same effect as pulling fuses.

Question 48

Gammametrics

Answer 48

→2 ranges: Low range (0.1 cps to 10^5 cps) and Wide range (10^-8 to 200% power) →fission chamber detector →designed to operate under accident conditions; PAM equipment →indicates on MCB and RSP