Initial Core of Nuclear Reactor and Method of Loading Fuel Assemblies of Nuclear Reactor

摘要

In an initial core of a nuclear reactor, a plurality of water regions having a square cross section for occupying a cross sectional area capable of disposing four fuel assemblies are formed. No fuel assemblies are loaded in these water regions. In the initial core, each fuel assembly is supported by fuel supports. A pressure loss of a first orifice installed in a cooling water supply passage formed in first fuel supports disposed in a central portion of the initial core is larger than that of a second orifice installed in a cooling water supply passage formed in second fuel supports disposed in a peripheral portion surrounding the central portion. Each water region is formed right above a part of the first fuel supports disposed in the central portion. The control rod operation in the nuclear reactor can be simplified by action of cooling water in the water regions.