DESIGN OF BIOLOGICAL SHIELD OF A TRANSPORT CONTAINER FOR IRRADIATED GRAPHITE MODERATOR OF NUCLEAR REACTOR OF RBMK-1000

Abstract

In given paper is discussed a theme of the providing of the biological shield of a container which is intended for exportation from NPP spots the bloks of the irradiated graphite moderator of nuclear reactors RBMK-1000 at a stage of such reactors decommission. With usage of the computer program systems Microshield (MS) and MCC 3D has been performed a design of container’s biological shield. This container can be used as for graphite blocks transportation, as for their storage. Year 2018 was a final one for the first unit of Leyningradskay NPP with reactor RBMK-1000, which has been under operation from 1973. The stop of this unit laid the beginning of step by step process of decommissions of such type power reactors at our country territory. For power reactors, in which as moderator of neutrons is used graphite, at ending of their service time is necessary to remove it from NPP stop and to keep(store) it safely-before reprocessing on final disposal. For the transportation and for the safe storage of graphite blocks (GB) of irradiated graphite moderator (IGM) it is necessary to develop special container, which will provide proper level of a management with IGM at the spot of decommissioning unit, at a way to spot of IGM reprocessing or/and its final disposal. The structure of container should to satisfy to requirements of radiation protection, providing the necessary level of a biological shield and also should to have proper strength characteristics and ability to bear supposing dynamic loads without loss of integrity and without loss of hermetically. The practical meaning of given work consists in the possibility of usage of its results by designing and manufacturing of containers for transportation and storage of IGM. The usage of such containers is actual by decommission process of nuclear power units with reactor RBMK-1000, because such usage will allow to accelerate significantly this process and fulfill the requirements of the ecological safety. The usage in given work of the modern program systems of modeling of biological shield allows to evaluate numerically shielding possibility of the structure materials, which could be used for the biological shield of containers and allows to choose optimal option of loading of graphite blocks in container. In the work is presented information about positive properties of the high-strength cast iron with spherical graphite inclusion as a perspective structural material for container’s body, which able to provide high level of the ecological safety during the exploitation of containers for irradiated graphite blocks.