Analog Rod Position Indication System “IRPI”Indication System “IRPI”

Section 8.2

Objectives (IRPI)1. State the purpose of the rod position indication

system.

2. Briefly describe the operation of the following:

a Individual (analog) Rod Position Indicationa. Individual (analog) Rod Position Indication,

b. Group demand position indication, and

c. Bank demand position indication

3. List the conditions that will initiate a rod deviation alarm.

Purpose(s)• Provide indication of actual and demanded

control rod position.– Actual: IRPI

– Demanded: Step counters (Group)

P/A converters (Bank)

• Provide alarms for misaligned rods.

• Provide alarms for excessive rod insertion to ensure shutdown margin.

4

5Fig. 8.2-2: Rod Bottom / Rod Drop Alarm

8.2.3.8 Rod Deviation Monitor(Main Plant Computer Program) OBJ -3

• Rods within bank > ±12 steps from demand

• Any 2 rods within bank > 12 steps from each other

• S/D bank rod <220 steps

• Control banks not in proper sequence• Control banks not in proper sequence

Digital Rod Position Indication System “DRPI”System “DRPI”

Section 8.3

Objectives (DRPI)1. State the purpose of the rod position indication

system.

2. Briefly describe the operation of the following:

a Individual (digital) Rod Position Indicationa. Individual (digital) Rod Position Indication,

b. Group demand position indication, and

c. Bank demand position indication

3. List the conditions that will initiate a rod deviation alarm.

Purpose(s)• Provide indication of actual and demanded

control rod position.– Actual: DRPI

– Demanded: Step counters (Group)

P/A converters (Bank)

• Provide alarms for misaligned rods.

• Provide alarms for excessive rod insertion to ensure shutdown margin.

B19

A20

B20

A21

B21

DATA CABINET"B"

CONTROL BOARDDISPLAY UNIT

Figure RPI - 2.1DRPI AND GROUP DEMAND SYSTEMS

Ref to Figure 8.3-1

A1

B1

A2

B2

A3

B3

A4

B4

A5

B5

A6

DATA CABINET"A"

RPI - 165/96

Containment

ROD CONTROLSYSTEM

2 2 6 2 2 6 2 2 6 2 2 6

2 2 6 2 2 6 2 2 6 2 2 6

2 2 6 2 2 6 2 2 6 2 2 6

2 2 6 2 2 6

2 2 6

GROUP DEMANDSTEP COUNTERS

11

Fig. 8.3-1

BANK A

CENTRALCONTROLFAILURE

RODDEVIATION

URGENTALARM

1 R 2

1 2 3

1 2 3

GW

228

168

192

144

216

Figure RPI - 5.2DRPI DISPLAY

BANK BGW

228

168

192

144

216

BANK CGW

228

168

192

144

216

BANK AGW

228

210

BANK B BANK C BANK D BANK EGW

228

210

CONTROL SHUTDOWN

BANK DGW

228

168

192

144

216

100% - no failures

Figure 8.3-3

ALARMS

DATA AFAILURE

DATA BFAILURE

1 2 3

1 2 3

1 2 3

120

96

72

48

24

RB

RPI - 305/96

120

96

72

48

24

RB

120

96

72

48

24

RB

TR

18

RB

TR

18

RB

E11 L11 L5E5 H6 F8 H10 K8 F2 B10 K14 P6 B6 F14 P10 K2 H2 B8 H14 P8 F6 F10 K10 K6 D4 M12 D12 M4 H8 D2 B12 M14 P4 B4 D14 P12 M2 G3 C9 J13 N7 C7 G13 N9 J3 E3 C11 L13 N5 C5 E13 N11 L3 H4 D8 H12 M8

120

96

72

48

24

RB

Fig. 8.3-4

8.3.4 Rod Deviation Monitor(Main Plant Computer Program) OBJ -3

• Rods within bank > ±12 steps from demand

• Any 2 rods within bank > 12 steps from each other

• S/D bank rod <220 steps

• Rods operating out of sequence• Rods operating out of sequence

Rod Insertion Limits

Section 8.4

Objectives1. State the purposes of the control rod

insertion limits (RILs).

2. List the inputs into the rod insertion limit computers and comparatorscomputers and comparators.

3. Explain why the rod insertion limits increase with increasing reactor power.

Purposes• Maintain an adequate shutdown margin,

• Maintain nuclear peaking factors within limits, and

• Minimize the reactivity effects on the core due to an ejected rod.

COMPARATOR

TAUCTIONEERED HIGH

Figure 8.4-1 Rod Insertion Limit Circuit

COMPUTER

AUCTIONEERED HIGHT AVG

COMPUTER

CONTROL BANK"A" POSITION

COMPUTER COMPUTER

CONTROL BANK"B" POSITION

CONTROL BANK"D" POSITION

CONTROL BANK"C" POSITION

COMPARATOR COMPARATOR COMPARATOR

“A” “B” “C” “D”

19

LOWALARM

LOW-LOWALARM

RECORDER

LOWALARM

LOW-LOWALARM

LOWALARM

LOW-LOWALARM

LOWALARM

LOW-LOWALARM

PO

SIT

ION

(ST

EP

S)

Figure 8.4-2 Rod Insertion Limits vs. Thermal Power

BANK C

228

200

150

(0.0, 118)

(0.55,228)

(1.0, 189)

20

BANK D

FRACTION OF RATED THERMAL POWER

RO

DB

AN

KP

100

50

(0.05,0) .2 .4 .6 .8 1.0