Abstract

Belgoprocess started the industrial decommissioning of the main process building of the former Eurochemic reprocessing plant in 1990. The aims of the decommissioning project are to limit radiation risks to the population according to the universal criteria of the ALARA principle, to bring the building into the non-nuclear category, i.e. to decommission up to a level where no controls on contamination and radiation are required any longer and the ventilation may be shut down, and to decontaminate the building completely in view of a conventional demolition.

The decommissioning activities involve the removal and decontamination of equipment from each cell, the decontamination of the cell walls, ceilings and floors, and the dismantling of the ventilation system. These activities are followed by a complete monitoring of all surfaces in order to obtain the unconditional release of the remaining structures. Most of the work involves hands-on operations, but also tool automation and automatic positioning systems are successfully applied.

When decommissioning nuclear facilities, one of the most important hazard concerns the potential for internal contamination through inhalation of radioactive particles. Combinations of different kinds of protective clothing and equipment are used to protect the operators.

To carry out intervention activities in controlled areas, especially with alpha-contamination, a qualified and uniform system to provide breathing and cooling air to the operators in their protective clothing was developed, tested, and applied. As much as possible standardisation of the protective clothing systems was aimed at. Special attention was paid to minimise weight and dimensions of the components and to improve carrying comfort.

In order to follow-up the efficiency of the protective equipment, biological and physical monitoring is necessary. Using the developed equipment, physical condition tests and measurements of work load on the operators were executed under normal working conditions of plasma cutting and hydraulic hammering or scabbling. Compared to similar tests, carried out before using the systems that were utilised at that time, and although the physical condition of the operators showed to have decreased by 7%, the results of the measurements proved to be 20% more favourable, as compared to the proposed heat stress limits. Increases in heart rate and rectal temperature proved to be less explicit as with the former system, and operators’ recuperation during lunch time break proved to be 100%. As such, the positive influence of the developed combined breathing and cooling system was explicitly shown.

This paper describes the protective equipment that was developed and discusses the results of the operational tests.

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