Fuel assembly

Abstract

Abstract PURPOSE:To lessen the difference of reactivity during output and cool temperature operation by providing a water rod and an internal gap and decentering one of these or the side of water gap without inserting a control rod from the center in a channel box. CONSTITUTION:A D lattice fuel assembly 11a is arranged in square lattice of nine columns and nine rows by fuel rods 13 in a channel box 12. In the outside of the channel box 12 a wide gap GW in which a control rod 14 is inserted and a narrow gap GN in which the control rod 14 is not inserted are formed. Further, a cruciform internal gap 15 is arranged between the fuel rods 13, a large-diameter water rod W is kept away from the two faces which face the gap GW from the inchannel center and eccentrically arranged in the direction of approaching two faces which face the gap GN. Therefore, when average enrichment of the fuel assembly is heightened, the addition of gadolinia rods is reduced to the minimum, the reactivity is enlarged during output operation without needing the increase of slit number, and the reactivity difference can be lessened during the output and cool temperature operation.

Inventors

• 👤 Ryohei Ando

Bibliographic Details