Qualified Safety Parameter Display System (QSPDS)

Question 1

What are the power supplies for QSPDS A/B trains?

Answer 1

PNA-D25/PNB-D26
The Isolation Cabinets receive power from PNC-D27 and PND-D28.

Question 2

What is the primary function of QSPDS?

Answer 2

The Qualified Safety Parameter Display System functions primarily to provide indications to detect the approach to, the existence of, and the recovery from inadequate core cooling (ICC).

Question 3

Where does QSPDS output?

Answer 3

Outputs sent to ERFDADS and MCR indicators / recorders.

Question 4

What does the QSPDS RCS saturation margin display?

Answer 4

Displays the more limiting of RCS or Upper Reactor Vessel Head saturation margin.

Question 5

Describe the Reactor Vessel Level Monitoring system:

Answer 5

Measures the “collapsed” liquid level above the Fuel Alignment Plate (FAP). Heated Junction Thermocouple (2 channels). Uses a combination of heated and unheated TCs.
* Four per channel located in the vessel head.
* Four per channel located in the plenum.

Actual level is somewhere below the detector which was uncovered and above the next lower detector.

Question 6

When is the RVLMS Plenum reading invalid?

Answer 6

Whenever any RCP is running, the Plenum RVL indication is INVALID because a running RCP will circulate the water inventory through the plenum area such that the sensor may have a two-phase fluid flowing past it even under reduced inventory conditions. This fluid flowing past the sensor
could give a false level indication.

Question 7

Describe how QSPDS determines saturation margin:

Answer 7

RCS Saturation Margin - Hottest Thot or Tcold RTDs
Upper Head Saturation Margin - Hottest of the upper three unheated HJTCs from RVLMS (Upper Head Saturation Margin)
Representative CET Saturation Margin - Representative CET statistically derived from all valid CET inputs

Question 8

How is out-of-range data displayed in QSPDS?

Answer 8

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