Specific aspects of nuclear safety analysis when handling experimental fuel rods and fuel assemblies

Specific aspects of nuclear safety analysis when handling experimental fuel rods and fuel assemblies

This paper describes methodical specifics of nuclear safety analysis for handling (storage, transportation, and positioning during examination) of experimental fuel rods and fuel assemblies (FAs) from various reactors.
Examples of analysis of ensuring nuclear safety requirements for individual products (FAs, fuel rod assemblies) and joint systems formed during research work using the results of calculations of the effective neutron multiplication factor in the MCU family of programs are presented.
It has been demonstrated that it is possible to reduce labor costs when performing computational nuclear safety analysis, without losing the level of conservatism in setting limits for nuclear safety parameters for the whole variety of fuel assemblies and fuel rods that are transported for post-irradiation examinations.
Conservative assumptions were used in the computational analysis, which obviously lead to overestimated values of the effective neutron multiplication factor for the systems under consideration. Specifically, the following assumptions were made:
▪ the computational models do not contain neutron-absorbing structural materials;
▪ all plutonium isotopes are the fissile isotope 239Pu;
▪ and the nuclear fuel, including irradiated fuel, is fresh (excluding burnup and the accumulation of neutron-absorbing fission products).
The approach used allows established limiting parameters to be applied to new FAs and fuel rods without the need for additional analysis.
► Keywords: nuclear safety, analysis, neutron multiplication factor, MCU-RFFI/A code, MCU-FR code, fuel assembly, fuel rod, system, conservative approach.
Article language: Russian. Pp. 5–15. [in Russian]. DOI: 10.26277/SECNRS.2026.120.2.001.