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DEVELOPMENT, MANUFACTURING, COMMISSIONING AND TESTING OF AN AUTOMATED DEVICE FOR THE PROJECTION OF CHEMICAL GELS AND ITS APPLICATION TO G2/G3 REACTOR PIPES

Objective

This project is aimed at industrial-scale testing of an automatic machine designed to spray gel or foam compounds inside pipes with a contamination level of up to 200 Bq/g due mainly to cobalt-60. The envisaged decontamination performance is about 8 metric tons a week to less than 1 Bq/g; the scrap metal will then be melted down on the site for unrestricted release.

The innovative nature of this project lies in the automation of all steps of the decontamination process.

This contract will demonstrate that 450 tons of steel can be released for unrestricted use after automatic decontamination and provide a cost-effective alternative to any manual decontamination process.

The contractual work involves the internal decontamination of 450 tons of ordinary carbon steel pipes with diameters ranging from 0.5 m to 1.6 m, using an automatic decontaminant gel spraying machine. The dose rate is about 0.3 mGy/h at the pipe surface contact.

These pipes belong to the graphite-gas reactors G2 and G3, which are presently under stage 2 decommissioning.

The contractor is coordinating all decommissioning operations concerning the G2 and G3 gas-cooled reactors at Marcoule. The present state of knowledge is based primarily on CEC research contract FI1D0003, covering small-scale manual gel spraying. The process will begin by spraying a highly alkaline gel or foam, followed by pressurized water rinsing. This will eliminate all greasy or oily deposits accumulated during 22 years of reactor operation.

In some cases, it may be necessary to follow this procedure by spraying with strongly acid gels or foams, followed by rinsing; this step may be repeated in exceptional circumstances.
A spray machine has been designed for surface treatment inside pipework. It comprises the following: a chassis; a beam supported by the chassis and with a front bearing mounted at the end; a mobile carriage running along the length of the beam between the front end and the other end; a cylindrical axle supported by front and rear bearings; means of rotating the axle and fixing it to the carriage; means for moving the carriage along the beam; a decontamination head mounted on the end of the axle; a containment bonnet mounted on the end of the beam so as to close off and seal the pipe to be decontaminated.

All the movements are implemented from a control panel connected to a Telemecanique TSX 47-20 process microcomputer. Some manual orders can be carried out through the computer by functional groups, and were tested: up and down movements of the chassis; forward and backward beam movements; 360 degree beam rotation to the left and to the right; basic foam projection; acid foam projection; water rinsing.
WORK PROGRAMME

1. Supply and adaptation of equipment

2. Implementation and commissioning testing of the device

3. Preparatory work and preliminary active decontamination tests

4. Industrial decontamination of 450 tons of contaminated pipes

5. Analysis of results

6. Generation of specific data

PROGRESS OF WORK AND RESULTS OBTAINED

No significant work was completed in this just starting contract.

Coordinator

Commissariat à l'Energie Atomique (CEA)
Address
Centre D'études Nucléaires De La Vallée Du Rhône Cité De Marcoule
30205 Bagnols-sur-cèze
France