Methodological features of nuclear safety analysis during storage of non-irradiated nuclear fissile materials

Methodological features of nuclear safety analysis during storage of non-irradiated nuclear fissile materials.

Akimov A. V., Malkov A. P., Samokhvalov R. V., Fraaz E. S.

Research institutions whose activities are associated with a large number of research and experimental work should perform temporary storage of nuclear fuel and nuclear fissile materials of various types. In this case, an important task is to ensure nuclear safety. Nuclear fuel can be presented in the form of standard and experimental fuel assemblies and components. Experimental fuel assemblies can be of all kinds unlike standard ones. The difference can be in the number and design features of fuel elements as well as in the fuel composition and enrichment. The examples of modeling of the safe storage conditions for standard and experimental fuel assemblies are presented. The diversity of the nuclear fissile materials lies in the composition and characteristics of these materials as well as in the parameters of the package they are stored in (geometry, size, volume). The racks for storing nuclear fuel have rigidly fixed cells. The racks for storing packages with nuclear fissile materials may not have cells due to the variety of their sizes and shapes and packages are placed in accordance with the marks applied to the shelves of the rack. The paper describes main methodological features of nuclear safety analysis during storage of non-irradiated nuclear fuel and packages with nuclear fissile materials. The need to analyze the storage irrigation or filling with water is presented considering the possibility of generation of a steam-water mixture in it. The paper also indicates the need for accounting of building constructions near which the racks are located.
Some results of the effective neutron multiplication factor calculations performed with the use of the MCU-RFFI/A software certified by Rostechnadzor are presented as an illustration of the methodological approaches used for the nuclear safety analysis and justification.

► Keywords: nuclear safety, storage, non-irradiated nuclear fuel, packages with nuclear fissile materials, effective
neutron multiplication factor, MCU-RFFI/A software.

Article language: Russian. Pp. 5–16. [in Russian]. DOI: 10.26277/SECNRS.2024.111.1.001.