A MODERATOR-CONTROLLED PRESSURIZED-WATER REACTOR

Technical Report · Tue Nov 25 00:00:00 EST 1958

OSTI ID:4277204

Levdahl, W J

Control of pressurized-water reactors is usually obtained by mechanical insertion of absorbing rods into the core. Ample control may also be provided by varying the leakage of neutrons from the reactor, One promising method of controlling the leakage is to provide void channels in the core and reflector which, when emptied or filled with water, produce changes in the neutron age and geometric buckling. In one high-powerdensity 80- to 100-Mw reactor based on this concept, the core is conceived as a 67-in.-long, 27 1/2-in.-diam cylinder consisting of annular rows of fuel elements, cooling water channels, and control water channels. The gross water density in each annular region can be individually controlled by completely filling or emptying the control channels within it. The reflector consists of water channels which can be filled or empticd, and the reflector is surrounded by a poison region. A fill tube is connected to each of the 100 or so control channels in the core and reflector; the fill tubes are bundled together and led to one of several hydrauiic control units which are seal-welded to the pressure-vessel heal. To empty the channel, the control channels are connected by the control units to high-pressure primary- coolant water for filling, or to a cold low-pressure water storage tank. The channel can empty rapidly (scram) by flashing flow when hot; if the reactor is cold, a high-pressure inertgas system can be used to force water from the tubes. The number of separate control channels may be selected so as to permit the change of reactivity in steps of any desired magnitude. All reflector and core control channels would be empty at cold shutdown and full at peak-xenon override. For normal power operation, at steady-state xenon, only the reflector channels and a few of the outer rows of the core channels would be full. This nonuniform distribution of moderator results in a rise of the power in the outer core regions and flattening of the radial peak-to-average power to a ratio as low as 1.1 to 1. The axial flux has a cosine distribution with local peaks near the reflector; this results in an axial peak-to-average power of approximates 1.42. This relatively uniform power distribution permits high specific power without excessive local heat flux. The relatively uniform n long core life since approximates 17 kg of the initiai 30-kg loading of U/sup 235/ can be consumed before the ability to override maximum xenon at full power is lost. (auth)

• Research Organization: Knolls Atomic Power Lab., Schenectady, N.Y.
• DOE Contract Number: W-31-109-ENG-52
• NSA Number: NSA-13-011494
• OSTI ID: 4277204
• Report Number(s): KAPL-1994
• Resource Relation: Other Information: Orig. Receipt Date: 31-DEC-59
• Country of Publication: United States
• Language: English

Related Subjects

REACTORS
BUCKLING
BURNUP
CONFIGURATION
CONTROL
CONTROL ELEMENTS
CONTROL SYSTEMS
COOLANT LOOPS
CYLINDERS
DISTRIBUTION
FERMI AGE
FLUID FLOW
FUEL ELEMENTS
FUELS
HEATING
HYDRAULICS
IN PILE LOOPS
INERT GASES
LEAKS
LEVELS
NEUTRON FLUX
NEUTRONS
OPERATION
POISONING
POWER
PRESSURE
PRESSURE VESSELS
REACTIVITY
REACTOR CORE
REACTOR SAFETY
REFLECTORS
SEALS
SHUTDOWN
STORAGE
URANIUM 235
VESSELS
VOLUME
WATER
WATER MODERATOR
WELDS
XENON
ZONES