Harmonic perturbation theory for analysis of BWR regional instabilities

Journal Article · Sat Dec 31 04:00:00 EST 1994 · Transactions of the American Nuclear Society

OSTI ID:89265

Downar, T J; Phegley, D A

Boiling water reactor (BWR) regional instabilities have been the subject of considerable research for the last several years. March-Leuba and Blakeman provided one of the more succinct and concise explanations of the physical processes involved by describing the regional oscillation as a competition between the stabilizing subcritical neutronics and the destabilizing gain of the thermal-hydraulic void feedback. The amount of stability margin that exists is therefore related to the subcriticality of the first harmonic (i.e, the separation of the fundamental and first harmonic eigenvalues). The calculation of subcriticality for practical reactor problems is a significant computational expense because it requires consecutive applications of the power iteration method. An efficient and reliable method to estimate the subcriticality for arbitrary variations in core configuration would be an important contribution to BWR design and analysis. The method reported is based on second-order perturbation theory, and preliminary results indicate that the impact of variations in core composition and configuration can be reliably estimated without repetitive eigenvalue calculations. An original contribution of this work is an innovative method to predict the rotation of the first harmonic flux after a perturbation. This provides a second-order estimate of the harmonic eigenvalue, which, combined with a first-order estimate of the fundamental eigenvalue, yields an accurate perturbation estimate of the subcritical reactivity.

• OSTI ID: 89265
• Report Number(s): CONF-941102--
• Journal Information: Transactions of the American Nuclear Society, Journal Name: Transactions of the American Nuclear Society Vol. 71; ISSN 0003-018X; ISSN TANSAO
• Country of Publication: United States
• Language: English

Related Subjects

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
BWR TYPE REACTORS
EIGENVALUES
HYDRAULICS
PERTURBATION THEORY
REACTOR CORES
REACTOR STABILITY