Thermal-hydraulic analysis techniques for axisymmetric pebble bed nuclear reactor cores. [PEBBLE code]

Thesis/Dissertation · Sun Jan 01 04:00:00 EST 1978

OSTI ID:5417080

Stroh, K R

The pebble bed reactor's cylindrical core volume contains a random bed of small, spherical fuel-moderator elements. These graphite spheres, containing a central region of dispersed coated-particle fissile and fertile material, are cooled by high pressure helium flowing through the connected interstitial voids. A mathematical model and numerical solution technique have been developed which allow calculation of macroscopic values of thermal-hydraulic variables in the axisymmetric pebble bed nuclear reactor core. The computer program PEBBLE is based on a mathematical model which treats the bed macroscopically as a generating, conducting porous medium. The steady-state model uses a nonlinear Forchheimer-type relation between the coolant pressure gradient and mass flux, with newly derived coefficients for the linear and quadratic resistance terms. The remaining equations in the model make use of mass continuity, and thermal energy balances for the solid and fluid phases. None of the usual simplifying assumptions, such as constant properties, constant velocity flow, or negligible conduction and/or radiation are used. PEBBLE solves a coupled set of nonlinear finite difference equations, derived by integrating the corresponding nonlinear elliptic partial differential equations over a finite area, based on assumptions about the distribution of the variables between the nodes of the grid. This approach ensures that conservation laws are obeyed over arbitrarily large or small portions of the field.

• Research Organization: Colorado State Univ., Fort Collins (USA)
• OSTI ID: 5417080
• Country of Publication: United States
• Language: English

Related Subjects

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
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Nonbreeding
Graphite Moderated
COMPUTER CODES
ENERGY TRANSFER
FLUID MECHANICS
GAS COOLED REACTORS
HEAT TRANSFER
HOMOGENEOUS REACTORS
HYDRAULICS
MATHEMATICAL MODELS
MECHANICS
P CODES
PEBBLE BED REACTORS
REACTOR COMPONENTS
REACTOR CORES
REACTORS
SOLID HOMOGENEOUS REACTORS
THERMAL ANALYSIS