HEAT TRANSFER AND STABILITY STUDIES IN BOILING WATER REACTORS. Quarterly Progress Report VIII, October 1, 1962 to January 1, 1963

Technical Report · Tue Jan 01 04:00:00 EST 1963

OSTI ID:4716865

The operation of the pressurized boiling loop was improved by installing an automatic pressure control. Installation of Inconel-sheathed thermocuples calibrated at 43 to 225 deg C is reported. Progress was made in developing the instrumentation for the measurements in non-steady states. The measurement of the anode current of a photomultiplier, in use in the radioactive method for void fraction measurement, was developed in a small air-water loop. Preparations are being made for use of this method in the pressurized loop. Calibrations were carried out with the capacitance method using the static void column. The measurement showed a good reproducibility. The onset of plug flow could be observed. The technique for measuring the transfer functions from power to the dependent variables as void fraction and flow rate was further established. Burnout and hydraulic stability experiments were carried out at saturation temperatures of 230, 200, 180, and 140 deg C with a 7-rod bundle test section using the hot patch technique. In these series the subcooling was varied. Burnout did not occur at 230 deg C at a channel power of 600 kw with 14 and 40 kw subcooling, when the uniform heat flux was 133 w/cm/sup 2/, the highest heat flux in the patch 292 w/cm/sup 2/ and exit quality about 20%, but it did at 550 kw, when the subcooling was increased to 94 kw. The oscillations in inlet velocity were recorded. The transition from noise to periodic flow oscillations occurred approximately in the following conditions: 230 deg C, 600 kw, 200 deg C, 500 kw, 180 deg C, 450 kw and 140 deg C, 325 kw. The effect of exit construction was to make the system less hydraulically stable. Trip occurred during a period of divergent periodic velocity oscillations. A steady state and hydraulic instability program with a single rod annulus geometry is under way. Experiments were carried out at 120, 160, 200, and 230 deg C saturation temperatures. Going from 150 kw to 160 kw at 160 deg C, the amplitude of the flow oscillations increased by a factor of 5. The period of these oscillations was about 0.9 seconds. Increasing the power from 160 kw to 200 kw, gave only a slight further increase in amplitude. Subcooling increased considerably the period of the oscillations. At 200 deg C these oscillations started at about 200 kw and at 230 deg C at 330 kw. Before the onset of the oscillations, small fluctuations in saturation temperature could be observed with a period of 20 seconds and an amplitude of a few degrees C. The program will be continued with void fraction and flow rate measurements and observing the signals from these quantities. A digital computer program was made for calculating the recirculation rate in test loops. In this program subcooled boiling is incorporated. The model was designed in such a way, that different heat flux distributions and geometries and correlations for the expansion loss, acceleration loss, slip factor, two-phase friction loss and entrance loss, can easily be substituted. The testing of the program was finished. A systematic analysis will now be carried out. The general flow equations were formulated for the insteady case, starting from fundamental fluid dynamics. Much emphasis was placed upon the correct representation of the increased heat transfer and frictional pressure drop under boiling conditions. Similarity parameters were derived which govern the solution of the exact equations. The steady state case was considered in more detaii. A correlation and criterion could be derived for the increased frictional pressure drop respectively the occurrence of burnout. A comparison of quantitative data derived from the theory with experimental results will be made. A description of the loop behavior is now under way, starting from the geometry and operating conditions of the present loop. This will be programed for an analog and a digital computer. (auth)

• Research Organization: Eindhoven, Netherlands. Technische Hogeschool
• NSA Number: NSA-17-024622
• OSTI ID: 4716865
• Report Number(s): EURAEC-540
• Country of Publication: United States
• Language: English

Related Subjects

AIR
ALUMINUM ALLOYS
ANALOG SYSTEMS
ANODES
BOILING
BURNOUT
CANNING
CHROMIUM ALLOYS
COMPUTERS
CONFIGURATION
CONTROL SYSTEMS
COOLANT LOOPS
COOLING
CURRENTS
DIGITAL SYSTEMS
ELECTRONIC EQUIPMENT
EQUATIONS
FLUID FLOW
FRICTION
FUEL ELEMENTS
HEAT TRANSFER
HYDRAULICS
IN PILE LOOPS
INCONEL ALLOYS
MEASURED VALUES
NICKEL ALLOYS
NIOBIUM ALLOYS
OPERATION
OSCILLATIONS
PHOTOMULTIPLIERS
POWER
PRESSURE
PROGRAMMING
RADIOACTIVITY
REACTOR TECHNOLOGY
REACTORS
RODS
SIGNALS
STABILITY
STANDARDS
TEMPERATURE
TESTING
THERMOCOUPLES
TITANIUM ALLOYS
TRANSFER FUNCTIONS
TRANSIENTS
VELOCITY
WATER
WATER COOLANT
WATER MODERATOR
ZONES