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OPTIMISATION OF PLASMA TORCH ELECTRODE DESIGN FOR NUCLEAR DISMANTLING TASKS

Objective

The plasma arc cutting torch has major role to play in the dismantling of nuclear facilities due to its advantages compared with other cutting techniques. However, it does have one serious drawback which is the comparatively short life of the plasma torch electrode. The replacement of the used electrode could have major cost and safety implications when the torch is operating remotely in a radioactive environment. The main objective of this project is therefore to improve the life of the electrode by at least a factor of 2, so as to reduce the cost and occupational radiation exposure when using this technique.

Novel plasma torch electrode designs and materials will be assessed, plasma modelling for the optimization of electrode characteristics applied, the novel electrodes manufactured and their performance tested on typical nuclear dismantling tasks. Recommendations from the result of this project will be made, which will allow European plasma torch manufacturers to retain a lead in the world market.

Experience obtained using plasma arc cutting for decommissioning of the Windscale Advanced Gas-Cooled Reactor, and the work being performed at the "Institut fuer Werkstoffkunde der Universitaet Hannover" will be taken into account.
The plasma arc cutting torch has a major role to play in the dismantling of nuclear facilities due to its advantages compared with other cutting techniques. However, it does have one serious drawback which is comparatively short life of the plasma torch electrode. The replacement of the used electrode could have major cost and safety implications when the torch is operating remotely in a radioactive environment. The main objective of this project is therefore to improve the life of the electrode by at least a factor of 2, so as to reduce the cost and occupational radiation exposure when using this technique.

After literature survey and requirements were completed the identification of potential electrode materials is near completion, but final verification of material choices is to be confirmed. For plasma arc process modelling, a useful and practical approach to this task has been defined and agreed. For the existing methods and electrodes, a database of experience with Hafnium electrodes is being compiled.
WORK PROGRAMME

1. Literature survey to obtain current information on plasma arc torch design, with particular reference to electrode life enhancement.

2. Requirements study to identify the necessary or desirable properties and features of the electrode material and the scope of the theoretical work to be carried out.

3. Identification of potential electrode materials with specialists of the Harwell Laboratory to select the materials to be included into the test programme.

4. Plasma arc process modelling and design of electrode/nozzle.

5. Testing existing methods and electrodes in order to allow for comparison with the tests performed on the new electrodes (6.).

6. Manufacture and testing of selected new electrodes to determine their performance, and comparison with those on the existing electrodes (5.).

7. Review of test results on the existing and new electrodes, comparison with the theoretical work and modifications to the electrodes to further improve their performance.

8. Manufacture and testing of revised electrodes as defined in 7.

9. Final evaluation of new electrode designs with respect to the potential benefits to the dismantling of nuclear facilities, including specific data on costs, waste arisings, working time and related radiation exposure of workforce and working area.

Coordinator

United Kingdom Atomic Energy Authority (UKAEA)
Address
Culham Laboratory
OX14 3DB Abingdon
United Kingdom

Participants (2)

ARC Kinetics Ltd
United Kingdom
Address
38 The Fairway
NN11 4NW Daventry
GOODWIN AIR PLASMA LTD
United Kingdom
Address
Kernan Drive
LE11 5JF Loughborough