Rod Control

Question 1

Design basis of Rod Control

Answer 1

• 10% step, 5%/min and maintain Tave w/in 5 deg of Tref (not challenge protection system)
• 95% LR, w/ SDCS (power in house loads w/o trip)

Question 2

Safety functions of Rod Control

Answer 2

• operate w/ speed low enough ensure reactivity addition rate limited upon failure
• maintain RCS integrity (CRDMs part of RCS Press boundary)

Question 3

Withdrawal sequence of CRDM

Answer 3

0- sc-energized,   mc/lc-de energized 
1- mc-energizes
2- sc-de energizes
3- lc-energizes (Rod moves 5/8")
4- sc-energizes
5- mc-de energizes
6- lc-de energizes
0- sc-energized, mc/lc-de energized

Question 4

primary purpose of RCU(Rod Control unit)

Logic cabinets

Power cabinets

Answer 4

Determine the speed and direction signals of automatic Rod movement

Sends appropriate current order to power cab

Takes current order to cause rods to move

Question 5

What are two sections that RCU breaks its logic into?

Answer 5

Demand- Tave vs. Tref

Anticipatory- Prx vs. Pturb (rate)

Question 6

What are the inputs to RCU?

Answer 6

Auctioneered high Ni’s (N41-N44)=> Prx

MSS Impulse pressure (PT-505A, 506A, 8)=>Pturb & Tref

Auctioneered high Tave

Question 7

Total error summer/ speed & direction programmer layout

Answer 7

• starts movement @ +/- 1.5 deg
• stops movement @ +/- 1 deg

1-3 deg error -> 8 steps/min
3-5 deg error -> 8-72 steps/min
>5 deg error -> 72 steps/ min

Question 8

Power supplies to Rod Control

Answer 8

13 D ( mg11)

13 E (mg12)

PJ-13 (lighting panel)

Question 9

What is done with Rod Control and rods themselves to minimize wear of control rods when operating ARO

Answer 9

Full out position is varied from 225 to 231 steps over life of control rods

During refueling rods are rotated 90 or 270 deg periodically

Question 10

Purpose of P to A converter?

Answer 10

Count CB D up and down steps to feed into C-11 Rod stop at > 220 steps

Question 11

Describe inputs and set points of RIL monitor

Answer 11

Inputs- auctioneered hi delta T( ind of power)
- bank demand

Compares what power is and what the RIL is for that power to bank demand

RIL- Lo ( RIL + 10 steps)

RIL- Lo-Lo (RIL)

Question 12

What can give you non-urgent failure alarm?

Is Rod movement still possible?

Answer 12

Loss of either power supply to Rod Control

Yes

Question 13

What can give you urgent failure in power cabinet?

Is Rod movement still possible?

Answer 13

Regulation failure- demand current not equal act current
Phase failure- one phase to coils failed
Logic error- 0 demand to s.c. and m.c.
Multiplex error- no demand and act current

Only individual bank control is available on non-affected cabinets

Question 14

What can give you urgent failure in logic cabinet?

Is Rod movement still possible?

Answer 14

Pulses/oscillator failure-
Slave cycles failure-

All modes of Rod movement prevented
(Except SCD, b/c separate pulses)