Determination of Multiplication Factors Using Experimental Lattice Parameters of Cluster-Type Fuel Lattices
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概要
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A new four-factor formula is proposed for deriving a " finite multiplication factor " <I>k</I>*-he ratio between neutron production and absorption rates in a finite medium-from experimentally determined lattice parameters in a slightly-enriched Pu-U lattice.<BR>The "two-group multiplication factor" <I>k</I>*<SUB>∞2</SUB>-related to τ+<I>L</I><SUP>2</SUP> and equal to (1 +τB<SUP>2</SUP><SUB>C</SUB>) (1+<I>L</I><SUP>2</SUP>B<SUP>2</SUP><SUB>C</SUB>) at criticality-is derived from <I>k</I>*.<BR>The experimental lattice parameters are corrected to account for neutron leakage, from which the " infinite multiplication factor " <I>k</I><SUB>∞</SUB> is derived.<BR>There are found differences between <I>k</I>*, <I>k</I>*<SUB>∞2</SUB> and <I>k</I><SUB>∞</SUB> amounting to about 1-2% in the Advanced Thermal Reactor (ATR)-type heavy-water lattice, despite the fact that all these three quantities are often indiscriminately called " infinite multiplication factor."<BR>The proposed four-factor formula for deriving <I>k</I>* was applied to the Deuterium Criti-cal Assembly (DCA) of 1.2%-enriched UO<SUB>2</SUB> lattices of 28-pin clusters in square arrays spaced at 22.5 cm. The values of <I>k</I>* calculated with a lattice design code METHUSELAH II were in fairly good agreement with those determined by experiment. The calculation tended to somewhat overestimate <I>k</I>*, particularly in lattices of highly voided coolant. A similar tendency was observed in the case of 1.5%-enriched UO<SUB>2</SUB> lattices of 22.5 cm pitch in the ATR Sumitomo-Two-Region Critical Facility.
- 一般社団法人 日本原子力学会の論文