Rod Worth Minimizer - .5

Question 1

When and why is RWM used?

Answer 1

Used at low powers because a rod drop accident is worse at low powers due to a high rod worth and is more likely to cause fuel damage.

Question 2

What causes an insert block?

Answer 2

It can only be from the ROD WORTH MINIMIZER. All other rod block signals cause only a withdraw block.

Question 3

What does RWM use to determine power?

Answer 3

Uses steam flow for the FWLC system to determine power.

Question 4

What is the RWM Low Power Setpoint (LPSP) and what happens as a result of passing it?

Answer 4

<15-18%
a) Enforces insert/withdraw sequence
b) Below this, the RWM alarm and Rod blocks in service.

Question 5

When is the Low Power Alarm Point (LPAP) in effect?

Answer 5

Between LPSP and Above LPAP
a) Provides error indications only below this.

Question 6

What does the RWM do above LPAP?

Answer 6

> 19-22%
a) Provides control rod info only.

Question 7

Out of Sequence Alarm / Rod Block

Answer 7

1. Blocks all rod motion.
2. Any combination of errors that results in >1 notch away from RWM sequence.

Question 8

Under what conditions will you get a withdraw error when operating control rods?

Answer 8

One notch out of sequence out. Rod withdraw block.

Question 9

What conditions of rod operation cause and insert error and what is the result?

Answer 9

One notch out of sequence in. Rod insert block.

Question 10

what causes a select error from the rod worth minimizer?

Answer 10

Rod selected out of sequence. Insert and Withdraw block.

Question 11

Insert and withdraw blocks occur when:

Answer 11

1. RWM detects a “Critical Self-Test Fault”
2. RPIS output to the RWM computer fails
3. Mode Switch on front of RWM computer display in INOP. (Can be bypassed on 10C651)
4. Insert or Withdraw error on any rod blocks all other rods.
5. Select error.

Question 12

What occurs in the event of a failed reed switch?

Answer 12

The RWM allows one notch of motion in either direction. The RWM will also suggest a substituted position.

Question 13

How is ALL RODS IN confirmed?

Answer 13

All rods at 00 position.

Question 14

How is SHUTDOWN confirmed?

Answer 14

All rods at 02 or 00 position
a) 02 or less is MAXIMUM SUBCRITICAL BANKED WITHDRAWL LIMIT
b) 00 with 1 rod out OR all rods at 02 or less is DESIGN BASIS SHUTDOWN

Question 15

How is RODS NOT FULL IN confirmed?

Answer 15

Displays # of rods and rods not full in.

Question 16

What are the 3 modes of the RWM other than normal operation?

Answer 16

1. INOP Mode – Insert and withdrawl block generated
2. Bypass Mode – Insert and withdraw blocks not applied
3. Test Mode – Insert withdraw blocks applied depending on test mode

Question 17

Fixing Insert/Withdrawal Errors (SO.SF-3)

Answer 17

1. A single rod insert error that does not exceed two notches can be corrected.
2. A withdraw error can be corrected.