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CUTTING OF CO2 PRIMARY CIRCUIT PIPES OF G2/G3 REACTORS USING EXPLOSIVE CHARGES

Objective

The project is part of the dismantling of the primary cooling circuit (CO2) of the G2/G3 gas-graphite reactors, composed of valves, blowers and tubes (diameters 800, 1200 and 1600 mm with respective thicknesses of 10, 15 and 20 mm), using explosive charges. It includes technical studies, experimental investigations and tests at industrial scale, carried out under real radioactive conditions.

The innovation of this project is the use of shock waves, produced by the explosive charges, to remove the inside contaminated oxide layer of the tubes.

The use of explosive charges seems beneficial because allowing to cut remotely large activated or contaminated items under improved protection and safety conditions for workers and with a minimum of secondary waste arisings.

The data output will mainly be related to:

the necessary time to carry out dismantling operations using explosive charges and their respective costs;
the safety and radiation exposure of personnel involved in the operations;
the effectiveness of shock waves for decontamination purposes.
The project is part of the dismantling of the primary cooling circuit of the G2/G3 gas-graphite reactors, composed of valves, blowers and tubes (diameters 800, 1200 and 1600 mm with respective thicknesses of 10, 15 and 20 mm), using explosive charges.

The cutting device has been optimized in order to use:
less plastic (a plastic ring supports the hollow shaped charge);
less explosive (the quantity of explosive must be constant behind the dihedral);
a steel dihedral instead of a copper one (copper is a poison for re-melting of cut steel). The safety agreement files have been drawn up. Experimental shootings have been carried out on a full sized mock-up and on confining mocks-up. The calculations of the confining box to be set around the hollow charges are now on the agenda.
WORK PROGRAMME

1. Assessment of basic cutting parameters

1.1. Definition of cutting power of dihedral-shaped charges (EPC)
1.2. Establishment of the agreement files (All)
1.3. Preliminary test series on flat steel plates (EPC)
1.4. Calculation of the minimum quantity of explosive for each thickness (EPC)

2. Pre-test series with bounded steel samples (simulating tube sections) (EPC)

3. Definition of pyrotechnic devices (EPC, COMEX)

4. Detailed engineering study of validation tests

4.1. General assessment of the test conditions (COMEX, EPC).
4.2. Definition and design of auxiliary equipment required during cutting operations (COMEX, EPC)
4.3. Selection of representative items to be cut (All)

5. Validation tests on G2/G3 tubes

5.1. Definition of test procedure as needed for agreement by authority (CEA)
5.2. Preparation of the test area (All)
5.3. Validation tests: 27 cutting operations on 800, 1200 and 1600 diameter tubes) (All)

6. Final evaluation of all relevant data collected, eg, specific data on costs, radioactive job doses, working time and secondary waste arisings (All).

Funding Scheme

CSC - Cost-sharing contracts

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

Participants (2)

Comex technologie SA
France
Address
Boulevard Des Océans
13275 Marseille
SA d'Explosifs et de Produits Chimiques
France
Address
La Dynamite
13310 Saint-martin-de-crau