Stages of physical investigations of the radiation shielding in the first nuclear submarine ‘Leninskii komsomol’

Abstract

In Refs. I-3 a great deal of attention is devoted to recollections of the development of reactors for ships, specifically, the first nuclear powered submarine "Leninskii komsomol" in the USSR and there is virtually no information about the development of the small and low-mass radiation (biological) shielding. In this connection, we decided to present in a more or less systematic form the investigations on the physics of shielding for submarines since the end of 1952 (when the design work started) and up to June 1958 (dock trials).The structural analysis of the arrangement of the reactor equipment and radiation shielding was performed at the Scientific-Research Institute of Chemical Machinery (later Scientific-Research and Design Institute of Electrotechnical Machinery) [3]. The mass and dimensional characteristics of the submarine determined, to a large extent, the size and mass of the radiation shielding.The shielding materials were determined on the basis of the laws and interaction of neutrons and 7 rays with matter, when the materials must contain the maximum possible amount of hydrogen atoms and elements with a high (average) atomic number. Such materials include water, lead, iron, and some other materials. Special shielding materials were produced, for example, carborite --a pressed mixture of graphite with boron carbide (approximately 10% boron by mass) for shielding in the directions toward the bow and stern. In addition, a combination (arrangement) of shielding materials such that the combination would be equally effective for both neutrons and 3' rays, including capture 3" rays, was required. As it turned out, a heterogeneous mixture of iron with water (approximately 50-60% by volunie) was approximately equivalent in this sense [4].In developing the shielding, the principle of screening of the more radioactive equipment by less radioactive equipment was also applied. A heat-resistant boron carbide fill was used in the gaps between this equipment.The total radiation shielding of the reactors in all directions was impossible for mass-dimension considerations, and for this reason the technical task of the scientific directorate of the Institute of Atomic Energy was directed, specifically, toward incomplete shielding, which could lead to the possibility of 3' rays from the reactor and capture radiation from the shielding materials, mainly in the form of radiation scattered in water, entering the service locations in the submarine, corridor passages, and so on, which could result in excessive irradiation of the sailors.The fact that there is virtually no information on the interaction of neutrons and 3" rays with matter in the case of passage through a large mass of the shielding (wide beam geometry or infinite geometry), when besides me unscattered radiation component, the multiply scattered component, which was many times stronger, had to be taken into account, had a large influence on the design of the shielding at that time (end of 1952 --start of 1953). It should also be noted that at that time exhaust...