METHOD OF STUDYING XENON SPATIAL INSTABILITY WITH AN ANALOG COMPUTER

Journal Article · Wed Nov 01 00:00:00 EST 1961 · Nuclear Sci. and Eng.

OSTI ID:4814839

Pearce, R M

The spatial flux oscillations that may occur in a power reactor as a result of xenon and local temperature effects are studied on a general-purpose electrical analog computer. The linearized forms of the two-group diffusion equations with xenon-dependent coefficients are solved in one dimension using finite space intervals. The xenondependent coefficients are obtained at each space point by solving the linearized forms of the iodine and xenon equations using continuous integration, one second of computer time representing one hour of reactor time. Thus at each space point four operational amplifiers are required---one each for iodine, xenon, fast flux, and slow flux. The present application has ten space points on a radius, or on the halfthickness of a slab, requiring 40 amplifiers and 80 potentiometers. Good agreement is obtained with modal theory for predictions of the threshold fluxes in simple cases. Unlike some applications of modal theory, it is not assumed in the case of a persisting or pure mode that each of the oscillating variables is the product of a real function of space and a function of time. In fact it is found that the space shape changes continually during a cycle of an infinite train of oscillations, this behavior repeating in every cycle. This is partly a result of the xenon's lifetime against burnup varying through the reactor. The change of shape is less marked for the flux and iodine than for the xenon, and is most marked in the case of high equilibrium flux. At a central flux of 2.l x l0/sup 14/ cm/sup -2/ sec / sup -1, the maxima in the xenon occur 2.5 hr later at the outside of a cylinder or of a slab than at the center. Some examples of two-group mode shapes are also given for reflected and flattened reactors. (auth)

• Research Organization: Atomic Energy of Canada Ltd., Chalk River, Ont.
• NSA Number: NSA-16-003906
• OSTI ID: 4814839
• Journal Information: Nuclear Sci. and Eng., Vol. Vol: 11; Other Information: Orig. Receipt Date: 31-DEC-62
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

REACTOR TECHNOLOGY
AMPLIFIERS
ANALOG SYSTEMS
BURNUP
COMPUTERS
CONFIGURATION
CONTROL ELEMENTS
CYLINDERS
DISTRIBUTION
ELECTRONIC EQUIPMENT
ERRORS
FAST NEUTRONS
GROUP THEORY
HALF-LIFE
IODINE
NEUTRON FLUX
PERFORMANCE
PLANNING
PLATES
POISONING
POWER PLANTS
PRODUCTION
PROGRAMMING
REACTIVITY
REACTOR CORE
REACTORS
REFLECTORS
STABILITY
TEMPERATURE
THERMAL NEUTRONS
THICKNESS
TRANSFER FUNCTIONS
TRANSIENTS
TRANSPORT THEORY
VARIATIONS
XENON
ZONES