METHODE DE RECHARGE EN COMBUSTIBLE D'UN REACTEUR NUCLEAIRE

1337090 Fuelling reactors WESTING- HOUSE ELECTRIC CORP 9 June 1971 [8 July 1970] 19705/71 Heading G6C In a method of refuelling a nuclear reactor having a lower package including, within a pressure vessel, a core having fuel assemblies to be replaced and lower internals, and an upper package including the head of the pressure vessel, the upper internals, control rod drive mechanisms and housings, and electric cables, bolts locking the head to the pressure vessel are released, the upper package with all equipment attached is moved in a single lifting operation to a prepared location away from the lower package affording access to the core, and the fuel assemblies are replaced. The upper package also includes a missile shield and it is to a lug on this shield that a lifting device is connected for removal of the upper package. The removal of the control rods from the core with the upper package is compensated for by an increase in the concentration of neutron absorber, e.g. boron 10, in the reactor coolant. Typically, the refuelling can take place in a few days, at intervals of three to six months. During refuelling, a portion of the fuel assemblies is replaced. Because of the facility for rapid refuelling and the consequent lower time cycle, the fuel can be of lower enrichments and the concentration of neutron absorber in the reactor coolant reduced. All replacement fuel assemblies can be moved in a cart into the reactor containment in a single operation and replaced from the cart, or the assemblies can be moved individually into the containment. The invention is described with particular reference to a pressurized water reactor.