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ABRASIVE WATER JET CUTTING TECHNIQUE FROM THE STAGE OF LABORATORY INTO REAL APPLICATION

Objective

In order to qualify the cutting by abrasive water jets for application in contaminated or activated environment, the cutting techniques developed for laboratory application (CEC contracts FI1D0069 and FI1D0067) are to be adapted for remote-controlled application. Secondly, concepts for the handling of the secondary waste are to be developed and proved.

First, the existing abrasive cutting head is to be adapted to remote-controlled work under a water shield up to 15 m, in an inaccessible environment. For this application, methods have to be implemented and proved to control the cutting operation, for instance the state of wear and the cutting results (eg, depth of the kerf, cutting through). Additionally, parts showing wear are to be remotely replaced so as to allow long-term reproducible operation.

The second step concerns investigations on the secondary waste. Besides a calculation of the composition and amount of secondary waste depending on cutting parameters, strategies will be developed and tested to catch the waste as close as possible at the place of production. Filtration techniques to separate abrasives and cut material from water and air will be adapted from other cutting techniques and will be tested.

All tests will be carried out under nonradioactive conditions, but at real scale in special water basins. The aim of this research work is to set up a tool which is suitable for work under realistic conditions. A control system and the remote replacement of worn parts are further important aims of this research work.
In order to qualify cutting by abrasive water jets for application in contaminated or activated environments the cutting techniques developed for laboratory application are to be adapted for remote controlled application. First, the existing abrasive cutting head is to be adapted to remote controlled work under a water shield up to 15 m, in an inaccessible environment. For this application, methods have to be implemented and proved to control the cutting operation, for instance the state of wear and the cutting results (eg depth of the kerf, cutting through). All tests are carried out under nonradioactive conditions, but at real scale in special water basins.

For the remote controlled application of abrasive water jets it is necessary to develop sensor systems to supervise both the state of the cutting tool and the cutting result. Measuring the sucked-in flow rates gives information about the state of the focusing tube (correlation of flow rate and diameter). Also the pressure loss in a specific length of the transport hose can be measured and correlated with the air flow rate. So the pressure loss can indicate the focus diameter, too. The supervision of the cutting result was attempted using sound pressure measurement and frequency analysis. There are sometimes characteristic frequencies for cutting through which cannot be seen in case of kerfing but the results of sound frequency analysis and the comparison of the sound intensity are not reliable for controlling the cutting result. Tests with a deflector plate and an accelerometer were carried out to find out the state of kerfing by the detection of reflected abrasives. The development of the new material for focusing nozzles gives an increase of the standing time by a factor of more than 40.
WORK PROGRAMME

1. Definition of cutting parameters for decommissioning purposes (UH-IW)

2. Development of controlling systems for processes parameters and the cutting result (UH-IW)

2.1. Preparation of a 2-dimensional feeding mechanism for underwater cutting tests.
2.2. Development of an on-line controlling system to detect the state of wear inside the cutting head.
2.3. Development and adaptation of controlling methods to verify the cutting result during or just after cutting.
2.4. Design of a cutting head which includes controlling systems, cutting tests to qualify the sensor systems.

3. Development of methods to remotely replace worn parts of the cutting head under water (UH-IW)

4. Characterization and handling of secondary waste

4.1. Preparation of test facilities for measuring aerosols and suspended particles when cutting in air and under water (UH-IW).
4.2. Measurement and characterization of the secondary emissions when cutting or kerfing in air or under water (CEA).
4.3. Development of methods to lower the spreading out of emissions in air or under water (UH-IW).
4.4. Cutting tests to determine the efficiency of measures to lower the emissions and to determine the filtration systems (UH-IW, CEA).

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

UNIVERSITAET HANNOVER
Address
Appelstrasse 11A
30167 Hannover
Germany

Participants (1)

Commissariat à l'Energie Atomique (CEA)
France
Address
Centre D'études De Saclay
91191 Gif-sur-yvette