Abstract: According to the present invention, a means of estimating the place of origin of a test subject by quickly and conveniently determining the genome type of JC virus infecting a test subject is provided. The present invention relates to a set of oligonucleotide probes for determining the genome type of JC virus infecting a test subject, such set containing: oligonucleotide probes (a-1) and (a-2); oligonucleotide probes (b-1) and (b-2); oligonucleotide probes (c-1) and (c-2); oligonucleotide probes (d-1), (d-2), (d-3), and (d-4); oligonucleotide probes (e-1), (e-2), and (e-3); oligonucleotide probes (f-1), (f-1), and (f-3); oligonucleotide probes (g-1), (g-2), and (g-3); oligonucleotide probes (h-1), (h-2), (h-3), and (h-4); oligonucleotide probes (i-1) and (i-2); oligonucleotide probes (j-1), (j-2), and (j-3); oligonucleotide probes (k-1), (k-2), and (k-3); and oligonucleotide probes (l-1) and (l-2).

Abstract: A core of a light-water reactor comprises a plurality of fuel assemblies each including a number of fuel rods. The fuel rod is provided with at least one area interposed between fuel areas in a clad of the fuel rod. The interposed area contains extremely reduced or substantially no fissile nuclide. At least two areas or layers with high enrichment of the fissile nuclide are formed in the axial direction of the reactor by the location of the interposed areas throughout the whole fuel assemblies arranged in the light-water reactor core.

Abstract: A fuel assembly for a nuclear reactor includes a number of fuel rods filled with a fuel material. A plurality of fuel rods have a partial effective fuel area filled with a fuel material and has a portion in which enrichment of a fissile nuclide is significantly reduced or the fissile nuclide does not exist at all on an axial level including a reactor shut-down zone at which subcriticality becomes small during a reactor operation period. The other fuel rods are filled with the fuel material throughout the entire axial length thereof. The first mentioned fuel rod may be provided with a partially interposed zone or may be constructed by a fuel rod having a length shorter than that of the other fuel rod. The tube means may be arranged in the fuel assembly so as to pass the moderator therethrough.

Abstract: A fuel assembly for a nuclear reactor comprises a fuel bundle in which a number of fuel rods are regularly arranged and a channel box surrounding the outer periphery of the fuel bundle. The interior of the channel box is designed so that the inner cross sectional area of the channel box increases from the upstream side of the coolant flow towards the downstream side thereof, for example, by stepwisely shaving the inner surface of the channel box. The corner portions of the channel box may be chamfered to improve the stress due to the inner pressure.

Abstract: Disclosed is a fuel assembly comprises a plurality of cylindrical fuel rods with a plurality of fuel pellets sealed therein, a plurality of small units each having a predetermined number of the fuel rods bundled spaced with a fixed intercentral distance and being arranged in such a manner that the intercentral distance between the component fuel rods falling on the mutually juxtaposed sides of the adjacent small units is larger than the intercentral distance between the adjacent fuel rods in the small units, and at least one water rod near the center of a cluster of the plurality of the small units.