Monitors the water level in the RX vessel when the RCPs are not running. Determines the void content (water vs steam) in Reactor Coolant when one or more RCPs are running.

Used for the following:

• Assist in detecting the presence of a gas bubble or void
• Assist in detecting the approach to Inadequate Core Cooling 
• Indicates the formation of a void in RCS during forced flow conditions
• Indicates water level in RX and Refuel Cavity during refueling operations.

Uses 3 sets of DP cells to measure water level in vessel

1. Upper Range- measures DP between the top of the RX vessel and the RCS loop piping (21/24 Hot Legs) Displays are invalid when RCPs in service
2. Full Range- measures DP between the top of the RX vessel and the bottom of the vessel (incore instrumentation near seal table). Displays are invalid when RCPs in service
3. Dynamic Range: measures forced flow with RCPs running. Reactor Core and Internal Pressure drop for any combination of RCPs in service compared to the nirmal single phase pressure drop, provides indication of void content and density of circulating current.Displays are invalid when No RCPs in service

Hydraulic Sensors convey readings and prevent RCS from being transported outside containement via the sensing lines and DP cells, if a line were to break

Refueling operations- support the execution of mid loop by moving sensors from RX head to sense atmospheric pressure, track RCS level indication from 97.3 to 106ft.

RVLIS 

General Description:

• 2 Independent Trains (A/B)
• 4 RCS Penetrations- RX Head, 21/24 Hot Legs and Incore Instrument F-8
• Powered from: A Train B 115VAC VIB; B Train D 115VAC VIB
• Plasma Displays in MCR & Recorder for Train A, RP1

Wide Range T hot- RCS density Compensation

Train A- 22 loop

Train B- 24 loop

Wide Range RCS Pressure-RCS density Compensation

Train A- PT403

Train B-PT405

RCP Breaker Status-Pp running status(52 relay)

Power Supplies

Train A- B115VAC VIB

Train B-D115VAC VIB

Interconnecting Systems:

SPDS Computer- RVLIS sends vessel level inputs

PT403/405

The R's are always right pneumonic

PT403/405 are wide range pressure sensors, which read 0-2500# and feed multiple control systems

RHR- control pressure interlocks for valves and tell when to give open/close signal

RH1- PT403

RH2- PT405

RVLIS- needed for density calcs

Train A- PT403

Train B- PT405

Subcooling Margin Monitors- needed for pressure value to calc subcooling

SCMM A- PT405

SCMM B- PT403

POPS- measure pressure

POPs train A- PT405

POPs train B- PT403

Plant Conditions:

Heat Up- none of the RVLIS modes are providing readings

No RCPs I/S- 100% reading for Upper and Full Range, Dynamic Range is 34%

One RCP-No reading from Upper and Full, Dynamic 38%

Two RCP-No reading from Upper and Full, Dynamic 50%

Three RCP-No reading from Upper and Full, Dynamic 71%

Four RCP-No reading from Upper and Full, Dynamic 100%

Full Power-No reading from Upper and Full, Dynamic 102%

1. Upper Range- measures DP between the top of the RX vessel and the RCS loop piping (21/24 Hot Legs) Displays are invalid when RCPs in service
2. Full Range- measures DP between the top of the RX vessel and the bottom of the vessel (incore instrumentation near seal table). Displays are invalid when RCPs in service
3. Dynamic Range: measures forced flow with RCPs running. Reactor Core and Internal Pressure drop for any combination of RCPs in service compared to the nirmal single phase pressure drop, provides indication of void content and density of circulating current.Displays are invalid when No RCPs in service

Rx Head

21/24 RCS Hot Legs

Incore Instrument Tube F-8