Incore Instruments

Question 1

Two systems that make up in core instruments

Answer 1

Core exit thermocouples

Movable incore detection system

Question 2

What are funtions we use MIDS?

Answer 2

Verify heat flux hot channel factor & nuclear enthalpy rise hot channel factor within T.S.

Calibrate excore NI’s for AFD

Verify rod positions when DRPI inoperable

Verify QPTR in spec w/ various sys inop

Question 3

Describe CET

Answer 3

65 (33, train A/ 32, train B)
Max range- 2300 deg

Two types (protruding-flow mixer, butt type-no mixer)

Two dissimilar metals(alumel, chrome) with hot junction and known cold reference junction

Question 4

Describe the Mids ?

Answer 4

6 incore fission chambers
6 drive units 
6 five paths
6 safety limit switches
6 withdrawal limit switches
6 ten paths

58 isolation vlvs, compression Seals, possible locations

1 storage area

Question 5

What interlock associated with leak in mids ?

Answer 5

If leak shows level in ten path, get a leak alarm, solenoid valve drains to RCDT

Question 6

What must be verified before allowing personnel in CNMT?

Answer 6

Mids stored, key not checked out since last stored

Question 7

Describe AFD/ AI

Answer 7

Top - bottom (PR Ni’s)=> + AI more power in top of core, - AI more power in bottom of core

AI +2 => top = 51%, bot = 49% @ 100% total power

Question 8

What are indication of failed PR Ni, upper detector (failed high)?
Channel ……
AI….
Drawer…..

Answer 8

Channel fail - high
AI fail - high *
Total - high, upper - high *, lower - normal
Channel deviation alarm
QPTR alarm *
Detector deviation alarm *
PR Rod stop
Rod movement demand (until dev > 10%)
* half channel failure

Question 9

Indications of failed high PR Ni ( lower)?
Power…..
AI…..
Drawer…..

Answer 9

Power - high
AI - low*
Drawer  (top - norm, bot - high *, tot - high)
Channel deviation alarm
PR Rod stop
Rod Control insertion demand (until dev > 10%)
QPTR alarm*
Detector deviation alarm*

Question 10

Indication of PR Ni upper detector failing low?Channel……
AI……
Drawer……

Answer 10

Channel - low
AI - low*
Drawer (top- low*, bot - norm, total low)
QPTR alarm*
Detector deviation alarm*
Channel deviation alarm

Question 11

Indications of PR Ni detector ( lower) failing low?
Channel……
AI…….
Drawer……

Answer 11

Channel - low
AI - high*
Drawer - (top - norm, bot - low*, total - low)
Channel deviation alarm
Detector deviation alarm*
QPTR alarm*

Question 12

Functions & controls of miscellaneous Control and indication Drawer

Answer 12

• compare all PR chnls to each other and generate alarm if any differs > 2% from average (if Prx > 50%)
• controls to bypass
  
  • upper channel bypass qptr alarm
  • lower channel bypass qptr alarm
  • bypass up to 2 channels PR Rod stop (C-2)
  • bypass up to 2 channels power mismatch …..

Question 13

Purpose of Comparator and Rate drawer?

Answer 13

Compares all PR channels and if any > 4% above lowest channel = alarm
- switch to defeat one Channel if failure present
Calculates SUR
- switch to select which channel to use for SUR