Rod Block Monitor

Question 1

What is the purpose of RBM?

Answer 1

• Enforces MCPR Limit – takes rod position from RMCS and NOT RPIS
  
  1. RPIS inputs into Rod drive control cabinet (RDCS), RWM, and full core display

Question 2

RBM Reference ARPMs.

Answer 2

A RBM: A>C>D

B RBM: B>D>C

Question 3

RBM Bases

Answer 3

Limits localized overheating to prevent MCPR violation.

Question 4

When is RBM Bypassed.

Answer 4

• Joystick.
• REF APRM <30%
• Edge Rod selected.

Question 5

RBM Trips

Answer 5

Trip - APRM STP Power - Upscale

Low - ≥ 28-63% - 123%
INTMD - ≥63% - 83% - 118%
High - ≥83% - 113%

Question 6

D. RBM INOP Rod Block

Answer 6

(MU - SOO –Too Few – NU – NU – Mo Rod/ No Rod)

1. Module Unplugged (MU)
2. Switch out of operate (SOO)
3. <50% LPRM’s Selected Provide Input (Too Few)
4. Nulling sequence failure (NU)
5. Null sequence in effect (NU)
6. More than 1 rod selected (MoRod)
7. No “Control Rod Selected” signal (NoRod)