LOT 201.16 Excore NIs

Question 1

• LOT 201.16 Excore NIs*
• • *

What are the primary and backup methods of determining Rx power?

Answer 1

• Primary:*
• *ICS (U1169)**
• Backup:*
• *Average 4 NIs on CP011**

Alternate:

• ∆T
• 1^st stage pressure
• Generator MWe
• Condensate/Feedwater parameters

Question 2

• LOT 201.16 Excore NIs*
• • *

What will cause the following alarms?

• PR Upper detector deviation
• PR Lower detector deviation
• PR Channel deviation

Answer 2

• PR Upper Detector Deviation:*
• *Highest PR Channel Upper Detector Current > 2% above Average detector current [60 sec TC]**

Upper detector current ≤ 50% of full power current

• PR Lower Detector Deviation:*
• *Highest PR Channel Lower Detector Current > 2% above Average detector current [60 sec TC]**

Lower detector current ≤ 50% of full power current

• PR Channel Deviation:*
• *Highest to lowest PR channels deviate > 4% [5 sec TC]**

Question 3

• LOT 201.16 Excore NIs*
• • *

Where are the NIs physically located on the core?

Answer 3

• *PR (NI-44) [45˚]**
• 2 Detectors (Top and Bottom)*
• *Extended Range [90˚]**
• Center of core*
• *PR (NI-41) [135˚]**
• 2 Detectors (Top and Bottom)*
• *SR (NI-31) / IR (NI-35) [180˚]**
• SR on bottom / IR at midplane*
• *PR (NI-43) [225˚]**
• 2 Detectors (Top and Bottom)*
• *Extended Range [270˚]**
• Center of core*
• *PR (NI-42) [315˚]**
• 2 Detectors (Top and Bottom)*
• *SR (NI-32) / IR (NI-36) [0˚]**
• SR on bottom / IR at midplane*

Start at 45˚ and say PEPSI x2.

Question 4

• LOT 201.16 Excore NIs*
• • *

How many detectors and channels are there for each NI?

Answer 4

• Source Range:*
• *2 Channels (NI-31/32)**
• 1 ^detector/_channel*
• Intermediate Range:*
• *2 Channels (NI-35/36)**
• 1 ^detector/_channel*
• Power Range:*
• *4 Channels (NI-41 - NI-44)**
• ^{2 detectors}/_channel*
• Extended Range NI (Gammametrics):*
• *2 Channels (NI-45/46)**
• ^{1 detector}/_channel And ^{2 Fission Chambers}/_Detector*

Also has channels for Visual/audio rate, Power comparator, SUR, and Flux Deviation. (1 Channel each)

• Note:*
• Source, Intermediate, and Power Range located on CP011.
• Extended Range and PR are on a recorders on CP018.

Question 5

• LOT 201.16 Excore NIs*
• • *

What kind of detectors are the excore NIs?

Answer 5

• Source Range:*
• *BF₃ proportional counter**
• Intermediate Range:*
• *Compensated Ion Chamber**
• Power Range:*
• *Uncompensated Ion Chamber**
• Extended Range:*
• *Fission Chamber**

Accurately measures neutron leakage up to 120%.

Question 6

• LOT 201.16 Excore NIs*
• • *

When removing the control power fuses and instrument power fuses, which should be removed first?

Answer 6

Instrument Power Fuses then Control Power Fuses

If control power removed first, then Rx trip or Rod control stop could occur.

Question 7

• LOT 201.16 Excore NIs*
• • *

What excore NIs are available on the Remote Shutdown Panel?

Answer 7

Low Range Extended Range (NI-45A/46A)

Each extended range detector has 2 fission chambers. (1 High range / 1 Low range)

Question 8

• LOT 201.16 Excore NIs*
• • *

What areas of the gas filled detector curve does each NI operate in?

Answer 8

• Source Range:*
• *Proportional Region**
• Intermediate Range:*
• *Recombination Region**
• Inner Can*
• *Ionization Region**
• Outer Can*
• Power Range:*
• *Ionization Region**

Question 9

• LOT 201.16 Excore NIs*
• • *

What are your immediate actions for a PR Flux - High Alert? (109%) [1/4]

Answer 9

Verify NIs ≤ 100%

If > 100%, Reduce power to ≤ 100% using Rods

Question 10

• LOT 201.16 Excore NIs*
• • *

Where are the SR preamps and the extended range preamps physically located?

Answer 10

• SR Preamps:*
• *EAB 10’ Pen Space**
• Extended Range Preamps:*
• *EAB 10’ and EAB 60’**

Question 11

• LOT 201.16 Excore NIs*
• • *

How are the source range and intermediate range detectors compensated for gammas?

Answer 11

• Source Range:*
• *Neutrons and gammas interact with BF₃ gas**

Neutron pulse is 10x greater than gamma pulse

• Intermediate Range:*
• *Outer Can lined with B-10, Inner can is not**

Outer can detects neutrons and gammas

Inner can detects gammas only

Power range doesn’t need to be compensated b/c detector has low sensitivity to gammas b/c low BF₃ gas volume.

Question 12

• LOT 201.16 Excore NIs*
• • *

What powers the excore NIs?

Answer 12

• Source Range:*
• *DP1201/DP1202**
• Intermediate Range:*
• *DP1201/DP1202**
• Power Range:*
• *DP1201 - DP1204**
• Extended Range:*
• *DP001/DP002**

• Loss of power, NIs fail High.
• If still in SR or IR, Rx will trip if DP-1201/1202 are lost.

Question 13

• LOT 201.16 Excore NIs*
• • *

When performing a NI calorimetric, what conditions must be held stable for 5 mins?

Answer 13

RTP

Feedwater Flow

Blowdown Flow

SGWL

T_ave

Question 14

• LOT 201.16 Excore NIs*
• • *

How would power behave if the Intermediate range was undercompensated or overcompensated?

Answer 14

• Undercompensated:*
• *Higher than actual reading**
• Overcompensated:*
• *Lower than actual reading**

• If detectors are undercompensated, source range may not energize.
• Slightly undercompensated is preferred.

• Note:*
• If compensated correctly, source range will energize ≈ 15 mins after Rx shutdown.*

Question 15

• LOT 201.16 Excore NIs*
• • *

What are the ranges of the source, intermediate, and power range detectors?

Answer 15

• Source Range:*
• *10⁰ - 10⁶ CPS**
• 2.5 decades of overlap*
• Intermediate Range:*
• *10^-11 - 10^-3 amps**
• Power Range:*
• *0% - 120%**