QSPDS

Question 1

What is the primary purpose of QSPDS

Answer 1

Provide indications to detect:
Approach to, existence of, and recovery from

Inadequate Core Cooling ICC

(subcooling margin detector)

Question 2

What parameters are used by QSPDS

Answer 2

• CET’s
• RVLMS HJTC’s
• 3 Saturation margins: PZR press, 3 temp inputs
  
  • Hottest of RCS hot/cold leg RTD’s
  • Hottest of Top 3 HJTC’s
  • Rep CET derived from all CET’s

Question 3

What event caused the existence of QSPDS

Answer 3

Three mile island

Question 4

How are QSPDS and ERFDADS connected

Answer 4

They are linked via QSPDS/ERFDADS data link that shares virtually all data

Question 5

What are the power supplies to QSPDS

Answer 5

PNA-D25
PNB-D26

Isolation cabinets:
PNC-D27
PND-D28

Question 6

What indicator is used to determine QSPDS is still working/running

Answer 6

A flashing square in the upper left corner

Question 7

What parameters are monitored/displayed by QSPDS

Answer 7

• SG level
• SG press.
• SG DP
• AFW flow
• CNTMT press.
• CNTMT Sump level
• CTNMT H2 concentration
• CNTMT area radiation
• RCS radiation
• CST level
• Log Rx power
• RCS press (WR)
• Rx vessel level status
• Isolation vlv (CIAS) status (only parameter not directly
  sent to QSPDS from meter)

Question 8

Which QSPDS parameters are located on B02?

Answer 8

• Tsat margin (most limiting: RCS or upper head)
• Rep-CET
• CET sat margin
• Rx vessel water level - Head
• Rx vessel water level - Plenum

Values from Train A QSPDS

Question 9

What specific temperature is trying to be maintained while monitoring/maintaining Adequate Core Cooling

Answer 9

Fuel cladding temperature of 2200*F

Question 10

Which parameters are used to determine adequate core cooling

Answer 10

• Margin to saturation (subcooled margin)
• Rx vessel water level
• CET’s

Question 11

What are the only instruments that DIRECTLY measure coolant inventory loss

Answer 11

Heated Junction Thermocouples (HJTC’s)

Question 12

What level is measured by HLTC’s and why

Answer 12

• The collapsed liquid level above fuel plate

- its a direct measurement of level vs 2 phase calc.

Question 13

How does HJTC’s measure water levels, what values are normal vs abnormal

Answer 13

• 1 thermocouple is heated, difference in temp is used

Normal ▲T
- 90F
Void ▲T
- 200F OR unheated >700*F

Question 14

Describe the layout of HJTC’s

Answer 14

2 Channels with 8 sensors/channel

• 4 Sensors in Upper Head
• 4 Sensors in Plenum

Question 15

What limitation exists with the Plenum HJTC’s

Answer 15

The plenum HJTC’s are invalid if any RCP’s are running
-RCP’s my cause mixed phase flow even if reduced
inventory

Question 16

What is the range of CET’s

Answer 16

200-2300*F

Question 17

What is required to make Post Accident Monitoring (PAM) “Operable” in regards to QSPDS

Answer 17

Modes 1-3
PAM instrument for each Function shall be operable
- 4/8 HJTC’s/ channel 2 upper and 2 lower

Question 18

Where do HJTC’s enter the core

Answer 18

Through a spare CEDM nozzle in Rx vessel head