Perturbation theory based on a nodal model

Journal Article · Wed Jan 01 04:00:00 EST 1986 · Nucl. Sci. Eng.; (United States)

OSTI ID:6027164

Taiwo, T A; Henry, A F

The standard point kinetics equations and formally exact expressions for reactivity, prompt neutron lifetime, and effective delayed neutron fractions are derived from the matrix form of the nodal code QUANDRY. Perturbation theory expressions for reactivity based both on the standard quadratic-transverse-leakage form of QUANDRY and on the coarse-mesh finite difference (CMFD) form, made accurate by the use of discontinuity factors, are derived. With three-dimensional CMFD QUANDRY transient calculations taken as numerical standards, the accuracy of several standard point kinetics methods as well as the improved quasi-static method is tested. Results suggest that point kinetics methods are poor for rod ejection calculations, even if a precalculated table of rod worth versus position is used to infer the reactivity contribution of the moving rods. For transients not involving rod motion, the point kinetics equations are more accurate. Use of core-averaged (rather than node-dependent) temperature coefficients, however, can produce significant errors. The quasi-static scheme appears to yield acceptably accurate results but, for the tests run, consistently required more computing time than needed for the full three-dimensional solutions.

• Research Organization: Massachusetts Institute of Technology, Cambridge, MA 02139
• OSTI ID: 6027164
• Journal Information: Nucl. Sci. Eng.; (United States), Journal Name: Nucl. Sci. Eng.; (United States) Vol. 92:1; ISSN NSENA
• Country of Publication: United States
• Language: English

Related Subjects

22 GENERAL STUDIES OF NUCLEAR REACTORS
220100 -- Nuclear Reactor Technology-- Theory & Calculation
220900* -- Nuclear Reactor Technology-- Reactor Safety
ACCIDENTS
ACCURACY
BARYONS
COMPUTER CALCULATIONS
DELAYED NEUTRON FRACTION
ELEMENTARY PARTICLES
EQUATIONS
ERRORS
FERMIONS
FINITE DIFFERENCE METHOD
FISSION NEUTRONS
HADRONS
ITERATIVE METHODS
KINETIC EQUATIONS
NEUTRONS
NUCLEONS
NUMERICAL SOLUTION
PERTURBATION THEORY
PROMPT NEUTRONS
REACTIVITY
REACTOR ACCIDENTS
ROD EJECTION ACCIDENTS
TEMPERATURE DEPENDENCE
TIME DEPENDENCE