ORNL-1816 - the Molten Salt Energy Technologies Web Site

ANP QUARTERLY PROGRESS REPORT
Plastic bottom and end sections make leak-proof
containers of the two channels which are filled
with a dilute electrolyte (HCI in H,O). With the
two outer plates grounded and the center plate
maintained at a given a-c voltage, heat is generated
within the fluid volume in each channel.
Coolant passages are attached to the outside of
the outer plates which uniformly remove the heat
erated within the free-convecting fluid. Small
holes drilled vertically down each of the three
plates for the entire 36 in. permit insertion of wall
thermocouple probes for measuring the wall temperat
any level. The variables to be measured
are coolant flow rate and temperature rise, power
input to the apparatus, and the three wall temper-
R EFFECTIVENESS OF
EACTOR COOLANTS
R. M. Burnett
H. F. Poppendiek
Reactor Experimental Engineering Division
One of the considerations in the selection of a
coolant for a nuclear reactor or any heat exchange
system is the amount of flow work required for
removal of a unit of heat. This quantity, which
is referred to as the “cooling work modulus,”
varies with the geometry of the system, the fluid
velocity (and flow regime), and the properties of
the fluid.
A memorandum is being prepared that gives the
development of equations for calculation of the
cooling work modulus for turbulent flow. Curves
which simplify computation are provided, and the
results of a study of a specific reactor are pre-
sented for illustration. This study has been
performed for an idealized reactor coolant system
which is considered to be somewhat representative
of actual solid-fuel-element reactors. In this
analysis the cooling work modulus is related to
the reactor geometry, the heat removal rate, the
thermal properties of the coolant, and certain
nt temperature differences which are de-
y such factors as mean coolant temper-
olant melting and boiling temperatures,
corrosion and mass transfer, and thermal
the thermal properties of a coolant are found
fluence its effectiveness in transferring heat
the reactor. An ideal coolant is indicated
to be one that has high thermal conductivity, heat
capacity, and density and a low viscosity, but the
relative merits of actual fluids depend strongly
on the temperature differences which are taken
as limiting in the system.
ART CORE HYDRODYNAMICS
J. 0. Sradfute L. D. Palmer
F. E. Lynch G. M. Winn
Reactor Experimental Engineering Division
G. L. Muller
Pratt & Whitney Aircraft
The experimental flow system for studying the
hydrodynamic characteristics of proposed ART
cores was completed, and several photographs of
particles and grids were made which yielded much
information about the apparatus but no quantitative
data. Some qualitative evidence for the existence
of two, and possibly three, regions of flow sepa-
ration in the ART core currently being tested
was obtained by visual observation. Additional
qualitative observations are continuing which are
soon to be supplemented with quantitative data,
but these preliminary observations indicate that
the core with ideal entrance conditions must be
considered to be unacceptable and that it will
be necessary to use vanes at the entrance.
It was found that sufficient light is available
to produce photographs of particles flowing with
the water at a Reynolds number of 100,000, al-
though at such high velocities the flash duration
is a little long. It is believed that this can be
remedied with a different flash tube, which is
being procured. In addition, these first photo-
graphs revealed the need for an additional light
source arranged to illuminate the particles con-
tinuously so that their tracks would represent a
line on the photograph. This is necessary to
reduce the uncertainty associated with identifying
the two images of each particle. A 1000-w incan-
descent projection bulb proved to be inadequate,
and arrangements are being made to test two
different mercury-vapor light sources; they will
increase the light intensity by a factor of 10 to
20, which should resolve the illumination problem.
Several details such as the quality of the grid
photographs, the settling velocity of the particles,
and the reliability of the Hewlett & Packard Co.
electric counter have received attention. A new
grid was made with much finer, shallower lines
than the first. The photographs of the new grid
were far superior to those of the old one, since
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