Neutronics Study of 1, 000-MWe Axially-Heterogeneous Large Liquid Metal Fast Breeder Reactor

• Published in: Journal of the Atomic Energy Society of Japan / Atomic Energy Society of Japan Vol. 28; no. 8; pp. 758 - 770
• Main Authors: KAMEI, Takanobu, YAMAOKA, Mitsuaki
• Format: Journal Article
• Language: Japanese
• Published: Atomic Energy Society of Japan 1986
• Subjects: axially-heterogeneous core; burnup; cost down; internal blanket; LMFBR type reactors; neutronic coupling; neutronic performance; power distribution; power flattening; reactivity; tank type reactors
• ISSN: 0004-7120; 2186-5256
• DOI: 10.3327/jaesj.28.758

Nuclear design has been performed of a 1, 000-MWe axially-heterogeneous fast breeder reactor and its neutronic performance has been compared with that of an equivalent homogeneous counter-part. In the design of the core, the radius, thickness and axial elevation of the internal blanket were optimized from the viewpoint of the breeding and burnup characteristics and flattening of the power distribution. The conventional axially-heterogeneous core has a disadvantage that the power distribution is axially distorted by the partial insertion of control rods because of the weak neutronic coupling between the lower and upper parts of the core fuel assembly which carries internal blanket pellets.The core designed in this study is featured by that the midplane of the internal blanket is shifted downward from the midplane of the core so that the power distribution can be flattened radially and axially even when the control rods are partially inserted. The core presented here has advantages over the homogeneous counterpart in bumup reactivity loss, maxi-mum fast neutron fluence, power peaking factor and the reactivity response to the movement of control rods in earthquakes. This core concept has a good potentiality in the cost down of the reactor and is a good candidate for the core which is adopted in a tank-type reactors.