Systems Exam 3 - Rod Control Indication (DRPI) & RIL Monitor

Question 1

DRPI Accuracy

Answer 1

Accuracy ±4 steps if both trains available (+3 between coils plus 1 step for mechanical error)
→A Train only available (Failure of Train B) accuracy is -10, +4
→B Train only available (Failure of Train A) accuracy is +10, -4

Question 2

If indicated rod position is a multiple of 12, and a train failure occurs…

Answer 2

→rod position will still indicate the same position ( i.e. 12, 24, 36, etc. will also indicate 12, 24, 36, etc.)
→rods indicating between multiples of 12 will indicate +6 with A ONLY, and -6 with B ONLY (i.e. 42 will be 48 with A ONLY and 36 with B ONLY)

Question 3

RIL Basis

Answer 3

→Sufficient negative reactivity must be available to achieve the required shutdown margin at all times.
→Provide acceptable consequences following a postulated rod ejection accident.
→Maintain acceptable radial flux distributions during normal operations

Question 5

How often is an LED provided re: rod travel?

Answer 5

LED provided for every 6 steps of rod travel up to 228 steps

Question 6

Rod Deviation Alarms:

Answer 6

1. When any two rods within the same control bank are misaligned by greater than or equal to 12 steps.
2. When any shutdown rod is below 210 steps.

Question 7

RIL Inputs

Answer 7

-Inputs from N16 (Auctioneered HI), P/A Converter and Average TAVE (Set to 0)
-Provides alarm and annunciation when the control banks reach:
1. Automatic withdrawal limit (C-11: Control Bank D ≥223 steps)
2. Low insertion limits (10 steps above Low-Low limit)
3. Low-Low insertion limit (D146 @ 100%, C49 @0%)
4. SD Rods shall be maintained within 218 to 231 steps per COLR

Question 8

What are the MODES of applicability for TS 3.1.4 Rod Group Alignments and TS 3.1.7 Rod Position Indication?

Answer 8

Modes 1 & 2 - place rods in manual IMMEDIATELY and monitor and record Tave once per hour

Question 9

DRPI Urgent Failure

Answer 9

-Failure of both A data and B data
-Difference between A data and B data of more than one coil (6 steps)
-Central control card calculates the rod position to be greater than 228 steps (the highest DRPI indicator).

Results in:
1. GW light for affected rod(s) to light
2. Affected rod(s) will indicate rod bottom light

Question 10

If DRPI is lost in modes 3,4, or 5, what is the RO required to do?

Answer 10

Per TRM 13.1.39, Place the Rod Control System in a condition incapable of rod withdrawal IMMEDIATELY (OPEN RTB’s)

Question 11

In a normal full power lineup with all systems functioning as designed, DRPI indicates CB D at 216 steps. Where is the actual position of CB D?

Answer 11

This means that the actual position of CB D is between: 212 & 220