RPV Instrumentation

Question 1

What automatic level actions come from narrow range level instruments?

Answer 1

High level trips and LL1

Question 2

What #’s are the Narrow Range Detectors and what range do they measure?

Answer 2

N004, N017, N042 They measure from 150”-210”

Question 3

What #’s are the Wide Range Detectors and what range do they measure?

Answer 3

N024, N025, N026, N031 They measure from 0”-210”

Question 4

What #s are the Shutdown Range Detectors and what range do they measure?

Answer 4

N027A and N027B They measure from 150”-550”

Question 5

What #’s are the Fuel Zone Detectors and what range do they measure?

Answer 5

N036 and N037(with a R615 Recorder) They measure from -150” to +150”

Question 6

What conditions are the Narrow Range Instruments calibrated in and are the reference legs compensated?

Answer 6

Calibration: NORMAL CONDITIONS • 1030 psig reactor pressure • Drywell temperature 158°F • Reactor building temperature 70°F All instruments are Uncompensated Reference legs inside the drywell.

Question 7

What conditions are the Wide Range Instruments calibrated in and are the reference legs compensated?

Answer 7

Calibration: HOT, but NORMAL • 1000 psig reactor pressure • Reference leg drywell temperature 200°F • Variable leg drywell temperature 135°F • Reactor Building temperature 90°F Compensated reference legs, except for instruments used on RTGB (N026)

Question 8

What conditions are the Shutdown Range Instruments calibrated in and what happens to the instruments during refueling?

Answer 8

Calibration: NORMAL SHUTDOWN CONDITIONS • Reactor pressure 0 psig • Drywell temperature 70°F • Rx Bldg temperature 70°F • For alternate, Drywell/RPV temp 85°F Alternate transmitters (7468) provided for instrument input for refueling operations per GP-06 (head removal). These are pressure instruments, not D/P. Reference leg piping is removed during vessel head disassembly

Question 9

What conditions are the Fuel Zone Instruments calibrated in and are the reference legs compensated?

Answer 9

Calibration: CASUALTY CONDITIONS. • Reactor pressure 0 psig • Drywell temperature 350°F • Reactor Building temperature 140°F • NO JET PUMP FLOW Density compensated reference legs • Indication uses output from master units on ECCS analog trip cabinets • These indications are not accurate if RR pumps are running

Question 10

What wide range instruments are least affected by LOCA and why?

Answer 10

N026A&B - most of the reference leg is in the reactor building

Question 11

What wide range instruments are most affected by HELB in the reactor building?

Answer 11

N026A&B most of the reference leg is in the reactor building

Question 12

What are the Power supplies for the Narrow Range Instruments and Recorders?

Answer 12

Power: Instrument loops from DFWCS UPS Panel V9(10)A Div. II DC Panel 3(4)B Recorder power UPS Panel V7(8)A Fail As Is (FAI)

Question 13

What are the Power supplies for the Wide Range Instruments and Recorders?

Answer 13

Power: 26A/B instrument loops from 120 VAC Emergency power 26A Panel 31(32)A (E5/E7) 26B Panel 1(2)B (E6/E8) Recorder power UPS Panel V7(8)A Fail As Is (FAI) Remote Shutdown panel uses N026B transmitter and transfers instrument loop power to Div II DC MCC 1(2)XDB

Question 14

What RPV level indications are available in the control room with a loss of all AC power?

Answer 14

N004A/B/C (narrow) N036 (fuel)

Question 15

What is the Function of the N004’s?

Answer 15

• P603 Indication • Hi / Low level alarm • Input to DFCS for RPV level control • Level signal for recirculation limiter #2 • Main turbine & RFP high level trip

Question 16

What are uncompensated instruments used for? What are some advantages and disadvantages of uncompensated instruments?

Answer 16

They are used for all RTGB level indications Advantages: Ref legs are at drywell temperature (135dF) therefore: Less likely to flash on a rapid depressurization; they will flash if your in the Unsafe region of RPV saturation limit after reference legs heat up Disadvantages: More susceptible to drywell temp changes Non condensable gases come out of reference leg causing notching; use the backfill system to prevent. If notching occurs use the lowest indication.

Question 17

What are the most accurate temperature detectors?

Answer 17

RTDs - you must have power, linear output signal over a wide range.

Question 18

What to we use to measure RPV temperatures and why?

Answer 18

Thermocouples - they have no external power supply.

Question 19

How is Recirc loop flow measured

Answer 19

By flow venturis Four transmitters per loop feed flow units A Transmitters feed Recorders B Transmitters feed Indications APRMs use output

Question 20

What are the Power supply for the Shutdown Range instruments?

Answer 20

N027 A 120VAC Panel 1AB(2AB) ( Div 1 norm) N027 B 120VAC Panel 1B(2B) (Div 2) 7468 A 120VAC Panel 1AB(2AB) ( Div 1 norm) 7468 B 120VAC Panel 1B(2B) ( Div 2) 3331 120VAC Panel 1(2)B-DG (Div 2)

Question 21

Which shutdown range transmitter uses the black scale? Which one uses the red scale? How do you determine which one is used?

Answer 21

The N027 uses the Black scale The 7468 uses the Red scale There are keylock switches in the Rx Bldg to determine which transmitter is used.

Question 22

What are the Power Supplies for Fuel Zone indications?

Answer 22

N036 ECCS XU-63 (3/4A) B/U 11/12A DC N037 ECCS XU-64 (3/4B) R615 recorder 120VAC Panel 1B(2B) Div 2 AC.

Question 23

What interlock do the Fuel Zone Range indicators provide.

Answer 23

2/3rd core height interlock for RHR (spray) logic Only RTGB indications from ECCS panels

Question 24

The reactor vessel level indications on the P603 and P601 actually measure level where?

Answer 24

water level in the downcomer region except for N036 and N037 fuel zone instruments which measure water level within the shroud

Question 25

Which reference legs have backfill and why?

Answer 25

uncompensated reference legs to prevent non condensibles from coming out of reference leg and causing notching