Abstract: A system includes a containment vessel configured to prohibit a release of a coolant, and a reactor vessel mounted inside the containment vessel. An outer surface of the reactor vessel is exposed to below atmospheric pressure, wherein substantially all gases are evacuated from within the containment vessel.

Abstract: In a radio exchanging station comprising a selection processing execution processor and first through N-th call processing execution processors, an n-th call processing execution processor (1≦n≦N) periodically delivers, to the selection processing execution processor, an n-th use condition signal indicative of an n-th use condition of an n-th radio resource managed by the n-th call processing execution processor and an n-th load condition signal indicative of an n-th load condition of the n-th call processing execution processor. On the basis of first through N-th use conditions and first through N-th load conditions, the selection processing execution processor determines first through N-th call reception permissible numbers for distributing to the first through the N-th call processing execution processors, respectively.

Abstract: A quenching element of the size and shape of a graphite nuclear fuel ball is introduced to the stacked balls of a stacked ball nuclear reactor core to release a neutron absorbing substance upon being heated to a predetermined temperature, thereby controlling the reactivity of the reactor by causing this substance, which may be a gadolinium compound, to deposit upon the graphite surfaces of the fuel element balls.

Abstract: A fuel assembly for a pressurized water nuclear reactor incorporating fluid moderator spectral shift control means. During the first part of the fuel cycle when there is excess reactivity, neutron moderation may be decreased by replacing a portion of the water within the core with a less effective moderator such as heavy water. During the life of the fuel, the heavy water is gradually replaced with regular water. The fuel assembly incorporates the necessary means and apparatus to effectuate such control.

Abstract: A method of operating a gas-cooled nuclear reactor having graphite fuel elements in which, to reduce the reactor, a quenching element is introduced which takes a particle of a reaction-reducing substance in a sheath which will melt or release the substance in vapor form so that the substance can penetrate in gaseous form through the surrounding graphite body and deposit upon fuel elements.

Abstract: An improved reactor and fuel assembly design is disclosed wherein a liquid moderated thermal reactor is initially run with all or a portion of its fuel assemblies in an undermoderated boiling water mode to take advantage of increased conversion ratio at lower H/fuel ratios, and after a suitable period of operation, the neutron spectrum for all or a portion of the undermoderated boiling assemblies is shifted to lower energies to increase reactivity by converting a number of fuel assemblies to a nearer optimum moderated pressurized or non-boiling mode. The increased reactivity allows for continued operation of the modified assembly. The improved reactor and fuel assembly design results in improved fuel utilization and neutron economy and reduced control requirements for the reactor. The design may be augmented by reducing the number of fuel rods comprising the assembly after a suitable period of operation, as disclosed in the applicants copending application filed Nov. 1, 1977, Ser. No. 847,524.

Abstract: A fast nuclear reactor is described which comprises a conical reactor core surrounding an embedded array of heat pipes of, per se, novel structure, carrying either moderator or nuclear fuel material as part of their working fluid. This reactor system is self-regulating, because an excessive increase in reactivity drives the fuel or moderator working fluid out of the conical core region, thereby reducing reactivity. The heat pipes are protected against burnout by a novel heat pipe envelope shape and internal wicking structure designed to increase the working fluid circulation speed with increasing heat transfer loads.