Abstract: A radiocactive waste containing medium is circulated within two or more systems (1,2,3) separated from each other flowtechnically; and the circulated radioactive waste is exposed to neutron radiations of different energy spectrum in each system by operating a reactor physically united entirety of irradiated sections of the said systems as a nuclear reactor or an accelerator driven subcritical system. Each system (1,2,3) has a heat exchanger (9,10) and, in given cases, a circulating pump (10,21) and an expansion tank (5,16,27). The disclosed apparatus has two or more reactor regions (1,2,3) separated from each other by partitions (37,38) and, preferably, arranged coaxially within a reactor space encircled by a common shell structure (39). A particle beam (45) produced by a particle accelerator is preferably directed into the innermost reactor region (3).

Abstract: The concentration of boron dissolved in water is determined by positioning a measuring vessel between a radio-active neutron source and a neutron detector. The neutron source is disposed in a moderator and the detector is disposed in a relfector; while the test specimen, e.g. boric acid, is disposed between two flat parallel plates perpendicular to the path between the source and the detector. The time necessary for the detector to receive a certain number of neutrons varies linearly as the concentration of boron; and so the boron concentration can be displayed as a function of elapsed time in excess of that time necessary for the predetermined number of neutrons to be received through pure water.