ML20073M984

Technical Description:Reactor Coolant Inventory Tracking Sys (Rcits) Conceptual Design

ML20073M984
Person / Time
Site:	Crystal River
Issue date:	04/15/1983
From:	FLORIDA POWER CORP.
To:
Shared Package
ML20073M968	List: ML20073M965 ML20073M984 ML20073N004
References
RTR-NUREG-0737, RTR-NUREG-737, TASK-2.F.2, TASK-TM NUDOCS 8304220350
Download: ML20073M984 (7)

Text

ATTACHMENT I TECHNICAL DESCRIPTION REACTOR C00 TANT INVENTORY TRACKING SYSTEM (RCITS)

CONCEPTUAL DESIGN CRYSTAL RIVER - UNIT 3 FLORIDA POWER CORPORATION 8304220350 830415 PDR ADOCK 05000302 P PDR

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SUMMARY

The Reactor Coolant Inventory Tracking System design concept is intended . .

to provide a continuous unambiguous control room indication of reactor vessel head and hot leg coolant inventory trending with reactor coolant pumps (RCPs) either running or tripped. The concept was designed to '

meet the parameters specified in NUREG-0737, item II.F.2. ,

The design concept encompasses the use of dif ferential pressure (DP)'

measurements across vertical elevations of the hot leg and the reactor .

vessel to infer coolant level when the RCPs are tripped, plus the use of RCP motor current measurements and pump inlet temperatures to infer-coolant inventory trends when the RCPs are running. The concept also includes density compensation for DP measurements due to temperature ,

effects on reference leg and process liquid density.

DP measurements cover a wide range measurement from the top to the bottom of the hot leg,-plus a narrow range measurement from the top of  %,

the reactor vessel (RV) head to the bottom of the hot leg. A total of four DP transmitters will he used to provide redundancy. - Each pair of wide and narrow range transmitters will be independently powered by Class 1E instrumentation power. They will be mounted within the con-tainment area. Seal chambers will be located at the high point of each reference leg to keep the legs full of water. .

The design concept includes removal of a control. rod drive mechanism to provide a penetration in the RV head for location of the top RV pressure -

tap. The top hot leg pressure tap will be located of f the hot leg high point vent. Florida Power Corporation has already processed and plans to install the lower pressure tap on the decay heat suction line during the 1983 refueling outage, s Class lE Qualified electronic analog equipment racks will be used to power the D? transmitters and process their outputs, with the reference leg and process temperature outputs, to compute the equivalent water \-

level. The racks will provide outputs to indicatoes in the control room, and to the computer.

RCP inlet temperature and motor current data will be processed by the computer to provide outputs for control room indication of coolant inventory trending when the RCPs are running.

A conceptual drawing of the system is shown in Figure 1. Individual parts of the system are described in the following paragraphs.

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4 . 1.' - ' TOP HOT LEG PRESSURE TAP n-The top hot leg pressure tap vill be located of f the hot leg -

high point vent. ,

, . .2. ' TOP REACTOR VESSEL PRESSURE TAP The top' reactor vessel..2pressure tap will be made - to a pene-

1. tration intthe reactor vessel head _ presently occupied by a control 1 rod drive mechanism.

3 '.' SEAL CHAMBERS

' seal . chamber will be installed at the high point.of each -

reference leg to ensure that.the reference leg to each DP transmitter remains full of water. The seal chambers will-be water reservoirs only and will not contain a bellows or diaphragm. There will be three connections in the seal-i- chambers. One will be atethe top for connection to a vint-valve, one at the bottom for connection to the reference leg of the transmitter, and the third at the center line on

' one end for connection to the pressure tap.

4.. RMOVABLE. SECTION OF RV HEAD REFERENCE LEG A removable section of stainless' steel tubing will be in-

- stalled between the reactor vessel top tap and the refueling.

cavity , wall for _ removal during refueling. Tubing configura-tion will be .such as to allow for thermal expansion and move-ment of the reactor ' vessel head. ,

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l 5. - ' SUPPORT FOR RMOVABLE SECTION OF RV HEAD REFERENCE LEG

[- A' ram v'able support for the removable section of tubing' be-tween the RV head .and the refueling cavity wall will be.. in-stalled on the cavity wall to provide seismic support ' for the tubing.

6.- _ BOTTOM HOT LEG PRESSURE TAP w

The bottom hot leg pressure tap will be located of f the decay heat suction line, and is scheduled for installation du-ing l '

the 1983 refueling outage by FPC.

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7. DIFFERENTIAL PRESSURE TRANSMITTERS Differential pressure transmitters, qualified as Class 1E in s accordance'with IEEE 323-1974, will be used.

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Four transmitters will be installed, two narrow range and two wide range. Each will have provisions for zero suppression and elevation. Each pair of narrow- and wide-range transmit-ters will be powered independently from a separate Class 1E electrical power source. One pair will be completely redun-dant.

The DP transmitters will be mounted inside containment.

The narrow-range transmitters will be calibrated for approx-imately 12 f t of water which, when compensated for system temperature variations, will be equivalent to the level of the coolant in the reactor vessel, above the bottom of the hot leg, when the RCPs are tripped.

The vide-range transmitters will be calibrated for approxi-mately 50 f t of water which, When compensated for system temperature variations, will be equivalent to the level of coolant within the hot leg when the RCPs are tripped.

The DP measurement system will not be functional when the RCPs are running or during venting operations. It will, however, be designed to withstand the conditions that will exist at those times without damage, and be fully recoverable af ter-wards.

8. REFERENCE LEG TDiPERATURE MEASUREMENT The system design will include the use of strap-on RTDs on the vertical portions of the water-filled reference legs to provide the temperature input required to convert the DP measurement to the equivalent coolant level.

9. HOT LEG TEMPERATURE. MEASUREMENT RTDs already installed in the hot legs will provide the pro-cess water temperature input required by the DP measurement system.

10. ANALOG EQUIPMENT RACKS Class 1E Qualified electronic analog equipment racks will be used to power the dif ferential pressure transmitters and pro-cess the outputs to compute coolant level. The racks will contain interconnected plug-in modules which perform the func-tions of current to voltage conversion, summation, function generation, division, and isolation.

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Two independently powered racks will be used. Each rack will process one narrow-range and one wide-range channel. Outputs of the racks will be sent to analog indicators located in the control room and to the computer.

Input and output terminals on the modules will be availble for monitoring from the front of the racks. In addition, each of the input modules will have provision for insertion of a test jack, which will disconnect the normal transmitter input and connect a test input. This will be used for calibration and troubleshooting.

- 11. COOLANT INVENTORY TRENDING WITH RCPs RUNNING The system concept provides a design to track reactor coolant inventory with the RCPs running. - It uses measurements of RCP motor current to infer the density of the pumped fluid. It also uses pump inlet temperature in an algorithm with the pump current measurements to derive an estimate of the pumped fluid void fraction.

Existing (non-Class 1E) current transformers and RTDs (one each per pump) are used to provide pump current and pump inlet tem-perature signals for input to a computer. The computer will use those two inputs to:

a. Calculate the corresponding saturated liquid and vapor densities for each temperature input.

b. Combine the densities with the pump current inputs in accordance with the void fraction algorithm.

c. Provide outputs for control room indication of the void fraction for any single pump, or the average i

void fraction for all pumps running, over a range of 15 to 40 percent void fraction.

Please refer to AttachmentII, entitled " Feasibility Study of Inventory Trending Methods with RC Pumps Operating."

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. 12. CONTROL ROOM INDICATION Analog coolant level indicators will be mounted on a panel in the control room in close proximity with the void fraction indica tors .

i During normal operation with the RCPs running, or during the venting operation, the data provided by the void fraction in-dicators will permit the operator to track the reactor coolant inventoty% The coolant level indicators will read of f scale high. Ov1.ational procedures will provide instructions to the operator that level indications are invalid under these condi-tions.

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W If the reactor coolant pumps are turned off and the system is not being vented, the coolant level indicators will pro-vide a true iudication of reactor coolant inventory in both the reactor and the hot legs.

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