COUPLED THERMOHYDRAULIC NEUTRONIC INSTABILITIES IN BOILING WATER NUCLEAR-REACTORS - A REVIEW OF THE STATE-OF-THE-ART

MARCHLEUBA J REY JM

J. Marchleuba et Jm. Rey, COUPLED THERMOHYDRAULIC NEUTRONIC INSTABILITIES IN BOILING WATER NUCLEAR-REACTORS - A REVIEW OF THE STATE-OF-THE-ART, Nuclear Engineering and Design, 145(1-2), 1993, pp. 97-111

60

INGLESE

Article

Nuclear Sciences & Tecnology

Nuclear Engineering and Design → ACNP

0029-5493

145

1-2

1993

97 - 111

ISI

0029-5493(1993)145:1-2<97:CTNIIB>2.0.ZU;2-G

This paper provides a review of the current state of the art on the to pic of coupled neutronic-thermohydraulic instabilities in boiling wate r nuclear reactors (BWRs). The topic of BWR instabilities is of great current relevance since it affects the operation of a large number of commercial nuclear reactors. The recent trends towards introduction of high efficiency fuels that permit reactor operation in an extended op eration domain with increased void and thereby increased void reactivi ty feedback and which often have thinner fuel rods and thereby decreas ed response times, has resulted in a decrease of the stability margin in the low-flow, high-power region of the operating map. This trend ha s resulted in a number of ''unexpected'' instability events. For insta nce, United States plants have experienced two instability events rece ntly, one of them resulted in an automatic reactor scram; in Spain, tw o BWR plants have experienced unstable limit cycle oscillations that r equired operator action to suppress. Similar events have been experien ced in other European countries. In recent years, the subject of BWR i nstabilities has been one of the more exciting topics of work in the a rea of transient thermohydraulics. As a result, significant advances i n understanding the physics behind these events have occurred, and a ' 'new and improved'' state of the art has emerged recently.