Nuclear Energy and Technology

Study of hydrogen generation and radionuclide release during wet damaged oxide spent fuel storage
Study of hydrogen generation and radionuclide release during wet damaged oxide spent fuel storage

A. Gayazov, S. Komarov, A. Leshchenko, K. Revenko, V. Smirnov (Sosny R&D Company), E. Zvir , P. Ilyin, V. Teplov (JSC “SSC RIAR”)

Nuclear Energy and Technology 5 (1), 2019

The paper describes the outcomes of the experiments to study hydrogen and gaseous fission products accumulation during simulations of the wet damaged VVER-440 SNF storage in air-tight canisters with the water drained and no drying conducted. Physical and chemical processes occurring during the damaged oxide SNF storage in wet environment are discussed. The experiments were carried out in two stages: 1) preliminary soaking of fine fuel particles in water in an air-tight canister, 2) water draining and keeping the wet SNF in the air-tight canister.

The experiments were conducted one after another using the same SNF canister and differing only in the SNF soaking temperature, i.e. 25 and 80 °С.

The radionuclide release into the liquid phase during the SNF storage under water was studied. Uranium and cesium isotopic concentrations were found to reach steady values when the SNF is kept under water for more than a month. The kinetics of hydrogen and gaseous fission product accumulation in the gaseous phase during wet storage of the spent fuel in the air-tight canister with the water drained coincide for both experiments. The kinetics demonstrate an abrupt decrease of the hydrogen and gaseous fission product accumulation rate in 46 hours. The data obtained can be applied for development and verification of the damaged SNF behavior models during SNF storage in wet environment under radiolysis.

 

In-service Change in the Flexural Rigidity of the VVER-1000 Fuel Assemblies
In-service Change in the Flexural Rigidity of the VVER-1000 Fuel Assemblies

S.V. Pavlov

Nuclear Energy and Technology, № 4, 2016

This paper describes a method and a facility for the hot cell testing of the irradiated VVER-1000 FA flexural rigidity. The method is based on measurements of the FA bowing induced by cross-sectional loading. The load applied to the spacer grids is perpendicular to the grid face, and the FA bowing is measured optically using a TV camera. The facility can also be used to test the flexural rigidity of the FA skeleton after all of the fuel rods are removed. Several tens of VVER-1000 FAs with a burnup of ∼4 to ∼65 МW day/kg U were tested by Dimitrovgrad Research Institute of Atomic Reactors. The generalization and an analysis of the test results have made it possible to identify the major factors that contribute to the in-service change in the flexural rigidity of the VVER-1000 FAs and to determine the experimental dependence of its change on burnup.

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