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11:25 || 14 11.6
MICROCOPY RESOLUTION TEST CHART
NATIONAL BUREAU OF STANDARDS -1963

DISTRIBUTION OF THIS DOCUMENT IS UNLIMITED
Paper sponsored by R. H. Chapman, member of ANS.
under contract with Union Carbide Corporation.
*Research sponsored by the U.S. Atomic Energy Commission
November 5-9, 1967
Chicago, Illinois
Winter Meeting
1967 American Nucles. Society
Prepared for Presentation at the
LEGAL NOTICE
This report as prepared as an account of Government sponsored work. Neither the United
States, aor the Commission, nor any person acting on behalf of the Commission:
A. Makes any warranty or reprecentation, expressed or implied, with respect to the accu-
racy, completeness, or usefulness of the information contained in this report, or that the use
of any information, apparatus, method, or process disclosed in this report may not infringe
privately owned righta; or
B. Adaucas any llabilities with respect to the use of, or for damages resulting from the
use of any information, apparatus, method, or proceso disclosed in this report.
As used in the above, "person acting on behalf of the Commission" includes way on-
ployee or contractor of the Commisslon, or employee of such contractor, to the extent that
such employee or contractor of the Commission, or employce of such coatractor prepares,
dissemiates, or provides access to, any information pursuant to his employmeat or contract
with the Commission, or his employment with such contractor,
Oak Ridge, Tennessee
Oak Ridge National Laboratury
G. J. Kidd, Jr.
C. A. Brandon
HELIUM-COOLED REACTOR FUEL ELEMİXTS*
IN-PILE HEAT TRANSFER STUDIES OF ROUGHENED
MASTER
2083.00 ; PN 165
RECEIVED BY DTIE AUG 29 1967 Carif-671102--2
ORNU A-320g
Son 180
L
IN-PILE HEAT-TRANSFER STUDIES OF ROUGHENED
tul
HELIUM-COOLED REACTOR FUEL ELEMENTS
C. A. Brandon
G. J. Kidd, Jr.
As a part of the Oak Ridge National Laboratory's Advanced Gas-Cooled
Reactor Program, heat-transfer data were obtained "in-pile" for four gas-
cuolcà reactor fuel elements in connection with an irradiation study of oxide
fuel elements.
The purpose of the present investigation was threefold:
(1) to study the effects of surface roughness on gas-cooled fuel elements,
(2) to evaluate various correlating techniques for high-temperature, high-
CO
heat-flux, heat transfer to helium, and (3) to demonstrate the feasibility
of obtaining reliable heat-transfer data in a reactor core.
. The experimental assemblies were tested in gas-cooled Loop No. I which
S were
соте
consisted of 102 pellets clad in type 304 stainless steel tubes. The enrich-
ment of the fizel pellets vas varied to compensate for the reactor axial neutron
flux gradient and thus achieve an approximately uniform heat flux distribution.
Each element was contained in a cylindrical shroud tube thus forming an annular
coolant passage. One smooth and three roughened surface elements were studied;
two v the roughened elements had spirally wrapped wires brazed to the surface
and the other had a square thread machined on it. Based on the work of previous
25
investigators, 3-7 the roughness was selected to have a nominal pitch-to-h-ight
ratio (p/e) of 7 and a dimensionless height (y* = e Tog/w) of between 35
and 50 where the normalization factor is a ratio of the friction velocity
(
7/8) in the absence of surface roughness to the kinematic viscosity (v).
Heliun, at 20 atin, was used as the coolant and the flow rato
was varied from 15 to 150 kg/nr. Data were obtained for heat fluxes
from 30 to 100 watts/cm and for wall-to-bulk temperature ratios up
to 1.44 over a Reynolds number range of 10% < No. <4 x.10%. The
məxinum wall temperature was 840°C and the maximu:n exit gas tempera-
ture was 600°C. The heat ?? variivid vas achieved by operating
e
the reactor an ihree power levels. At «ach level the flow rate and
inlet gas temperature were varied. In reducing the data adjustments
were made to account for gamma heating in the structural members of
the system, bypass Tlow, and thermocouple placement and calibration.
The results are shown in Fig. 1 in terms of the Colburn j factor
as a function of Reynolds number.
The data are correlated by the
Re
B
modified Colburn equation,
j = C 150:2 (1-/T.)-0.6 .
The value of C was determined to be 0.022 for the data obtained with
the smooth surface and 0.014 for data obtained with the roughened surfaces.
els
There appears to be no significant difference between the wire wrapped
and machined roughness a.lthough the scatter in the data makes an
absolute conclusion impossible.
This study demonstrates that a twofold increase in heat transfer
can be obimined by the use of the types of surface roughness tested.
The heat-transfer uata were correlated satisfactorily by the Colburn
equation, modified by the factor (T./T,)*0.0 to account for the effects
of fluid property variation, in the range of heat flux studied. Finally,
this experiment has demonstrated the feasibility of obtaining worthwhile
heat-transfer data "in-pile", although careful attention to design
and fabrication details is requircu.
REFERENCES
1.
M. F. Osborne, E. L. Long, and J. G. Morgan, Post Irradiation
Examination of ORR Loop 1 Advanced Fuc.l Elements, USAEC Report
ORNL IM-863, Oak Ridge National Laboratcry, July 3, 1954.
2.
D. E. Trauger, Some Major Fuel. Irrad:iation Test Facilities
of the Oak Ridge National Laboratory, USALSC Report ORNL-35714,
Oak Ridge National Laboratory, April 1964.
3.
Zyunkiti Nagaoka and Akitosi Watanabe, Maximun Rate of Heat
Transfer with Minimun Loss of Energy, Congress International,
duFroid, 7th Congress, Amsterdam, 1936.
4.
H. Brauer, Flow Resistance and Heat Transi'er in Annuli with
Rough Center Tubes, Atomkernenergie, 6: 152–161 (1961) (AEC-
Tr-6264, translated from the German for Oak Ridge National
Laboratory by the Technical Library Research Service].
V. Walker, The Improvement of Fuel Element leat Transfer by
Surface Roughening, Nucl. Eng., 144–1.48 (April 196.1).
6.
D). Wilkie, Forced Convection Heat Transfer from Surfaces Roughened
by Transverse Ribs, Proceedings of the Third International Ileat-
Transfer Conference, August 7-12, 1956, Vol. I, pp. 1-19, Chi(60,
1967.
7.
N. Sheriff and P. Gumley, Heat-Transfer and Friction Properties
of Surfaces with Discrete Roughness, Int. J. Heat Mass Transfer,
9: 1297–1320 (1966).
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RUN
NO.
ROD
DIAMETER
(cm)
CHANNEL
DIAMETER
(cm)
FUELED
LENGTH
(cm)
ROUGHNESS
TYPE
ORNL.-DWG 67-4796
ROUGHNESS
PITCH
HEIGHT
(mm/turn)
(mm)
o 85
1.90
1.90
2.44
2.44
45.7
45.7
0.14
1.05
A
A 10P
OP-!
1.90
190
2.44
2.46
324
WWIRE
SMOOTH
WIRE
WRAPPED
WIRE
WRAPPED
MACHINED
SQ THREAD
086
1.05
32.4
0.16
1.05
PM
2.18
2.67
30.5
0.18
1.05
0.01
0.009
.
0.008
0.007
0.006
OOO
otoma
j=0.541 Net
0.005
7
0.004
0.003
j=0.022 NEW
0.002
Iman
4
5
6
7
8
9
109

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17 Roma
END

DATE FILMED
10 / 13 / 67







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