AIRBORNE PARTICLE CHARACTERIZATION DURING MECHANICAL CUTTING OPERATIONS OF PROTOTYPIC FUEL DEBRIS SIMULANTS

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The general context of this article concerns the assessment of radioactive aerosols release risk during fuel debris (FD) retrieval operations at Fukushima Daiichi Nuclear Power Plant (1F). This assessment is crucial for ensuring the safety of workers and the wider public throughout the decommissioning efforts at the 1F facility.

The Dust Acquisition (DA) project, led by CRIEPI and carried out as a subsidized project of Decommissioning, Contaminated Water and Treated Water Management, funded by METI, in collaboration with ONET, CEA, and IRSN, aims to evaluate the airborne release fraction (ARF) coefficient, a key metric reflecting the amount of radioactive material suspended in the air, particularly during the mechanical cutting of prototypic FD-simulants containing depleted uranium oxide.

The experiments were undertaken by ONET/CEA/IRSN on a dedicated facility named FUJISAN2 located at CEA Cadarache. The generated particles underwent comprehensive sampling and characterization, including size distribution, morphology as well as mass and number concentration, using dedicated aerosol metrology devices.

This article will present the experimental facility, including its aerosol instrumentation, the cutting sequences, and the methodology implemented to characterize aerosol physical properties and determine ARF coefficients, using gathered aerosol data measured by the different instruments.

Comparative analyses are then presented in terms of particles mass concentration between the cutting trials on the different FD simulants, to understand the influence of the sample properties on particle generation.