초록 ▼

In an arrangement of an initial core, the core is loaded with 572 high enrichment fuel assemblies H with 4.2 wt % average enrichment and 300 low enrichment fuel assemblies L with 1.5 wt % average enrichment. The average enrichment of the core is about 3.3 wt %. In this core, only the low enrichment

In an arrangement of an initial core, the core is loaded with 572 high enrichment fuel assemblies H with 4.2 wt % average enrichment and 300 low enrichment fuel assemblies L with 1.5 wt % average enrichment. The average enrichment of the core is about 3.3 wt %. In this core, only the low enrichment fuel assemblies are loaded into the most outer position of the core and the high enrichment fuel assemblies are loaded into an area other than the most outer position. In this arrangement, the average enrichment of reload fuel assemblies is 3.7 wt %.

대표청구항 ▼

[ What is claimed is:] [1.] A fuel loading method for initially loading at least two types of fuel assemblies which contain nuclear fuel materials and have different average enrichments in the axial direction of the fuel assemblies into a core, comprising the steps of:loading initially first fuel as

[ What is claimed is:] [1.] A fuel loading method for initially loading at least two types of fuel assemblies which contain nuclear fuel materials and have different average enrichments in the axial direction of the fuel assemblies into a core, comprising the steps of:loading initially first fuel assemblies having a relatively low average enrichment in the axial direction of the first fuel assemblies into the most outer position of the core and initially loading second fuel assemblies having a relatively high average enrichment in a range of 4.0 wt % or more in the axial direction of the second fuel assemblies into an area other than the most outer position of the core; andafter at least a first operation cycle, exchanging at least a portion of the initially loaded second fuel assemblies for reload fuel assemblies having an average enrichment in the axial direction of the reload fuel assemblies which is higher than that of the first fuel assemblies and lower than 4.0 wt %.