COMPARISON OF PARTIAL ROUGHENING OF THE SURFACE OF FUEL ELEMENTS WITH OTHER WAYS OF IMPROVING PERFORMANCE OF GAS COOLED NUCLEAR REACTORS

Technical Report · Wed Oct 30 04:00:00 EST 1963

OSTI ID:4148005

Melese, G B

By properly roughening the surface of fuel elements in a gas-cooled nuclear reactor, the temperature drop between the surface and the coolant may be halved. The corresponding friction pressure drop is approximately doubled if only the downaow part of the fuel element is roughened. The total pressure drop in the reactor is usually only increased by 10 to 20%. Using this improvement in surface heat transfer coefficient, maximum internal and surface fuel temperatures could be decreased, coolant temperatures could be raised, and over-all pressure drop could be decreased by decreasing the mass flow or increasing the flow area. Also the power density could be increased, or the total number of fuel elements could be decreased. Similar improvements in reactor performance could be obtained with smooth rods but in a less efficient way. For instance, the number of fuel elements of given lengih and total volume could be decreased by a factor of 4 by doubling the rod diameter with either roughened or smooth elements. Total reactor power, maximum surface temperature, and coolant temperatures are assumed to be fixed. The pressure drop remains constant with partially roughened fuel elements, while the friction pressure drop in the core is multiplied by 4 for smooth elements, since the flow area per channel is only doubled in order to maintain the proper temperatures, while it was quadrupled for roughened elements. The decrease in number of rods is obviously smaller when the intennal fuel temperature is limiting, but the core friction pressure drop is smaller with partially roughened rods than with smooth rods. A large number of cases were studied and it was concluded that properly partially roughened fuel elements are always preferable to smooth elements from the viewpoint of overall performance. (auth)

• Research Organization: General Atomic Div., General Dynamics Corp., San Diego, Calif.
• NSA Number: NSA-18-006470
• OSTI ID: 4148005
• Report Number(s): GA-4624
• Country of Publication: United States
• Language: English

Related Subjects

BURNOUT
CONFIGURATION
COOLANT LOOPS
FRICTION
FUEL ELEMENTS
FUELS
GAS COOLANT
GAS FLOW
HEAT TRANSFER
HIGH TEMPERATURE
NEUTRON FLUX
POWER PLANTS
PRESSURE
REACTOR CORE
REACTOR TECHNOLOGY
RODS
SURFACES
TEMPERATURE
THERMAL CONDUCTIVITY
THICKNESS
VARIATIONS
VOLUME