THE INTERNAL INSULATION OF REACTOR PRESSURE TUBES. 2. PERFORMANCE OF FULL- LENGTH STAGNANT WATER LAYERS
Heat transfer tests on full-length insulators inside reactor pressure tubes show that multiple stagnant water layers can restrict the tube wall temperature to a value close to the mean moderator temperature. Thus, the allowable stress for a Zircaloy pressure tube can be increased significantly or a magnesium alloy can be used as the pressure tube material. In either case a reduction in parasitic neutron capture is obtained. Alternatively, the higher stress can be used to give a higher operating pressure and temperature for the reactor coolant, and hence a higher thermal efficiency. The insulation is composed of layers of stagnaht water formed by a spiral of dimpled foil contained in the annulus between a full-length thin inner tube and the pressure tube. With a simulated fuel load on the ingulation in a horizontal pressure tube the thermal performance of the test insulator was satisfactory although some dimple distortion occurred. However, these tests were only of several hours duration. The metal-to-metal conduction through the dimples on the foil was found to be small and essentially independent of the number of dimples per unit area. At reactor pressure and temperature conditions, the pressure tube was shown to be free of hot spots. The heat loss from the coolant to the moderator exceeded the value calculated for pure conductive heat transfer through the water layers by twenty per cent. For example, an insulator made up of a 0.100-inch thickness of heavy water subdivided into seven layers by six turns of dimpled foil would transmit 15,600 Btu/(hr)(ft/sup/sup 2/) if the inner boundary of the insulation were at 500 deg F and the outer boundary at 200 deg F. (auth)
- Research Organization:
- Atomic Energy of Canada Ltd., Chalk River, Ont.
- NSA Number:
- NSA-13-015703
- OSTI ID:
- 4237326
- Report Number(s):
- CRCE-823; AECL-781
- Country of Publication:
- Canada
- Language:
- English
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Related Subjects
BURNOUT
CAPTURE
COOLANTS
CROSS SECTIONS
EFFICIENCY
FOILS
FUEL ELEMENTS
HEAT TRANSFER
HEAVY WATER
HIGH TEMPERATURE
LAYERS
MAGNESIUM ALLOYS
MECHANICAL STRUCTURES
MODERATORS
NEUTRONS
NUMERICALS
PERFORMANCE
PRESSURE
REACTOR FUELING
REACTORS
TESTING
THERMAL CONDUCTIVITY
THERMAL INSULATION
THERMAL STRESSES
THERMODYNAMICS
TUBES
WATER
ZIRCALOY