Abstract
Posiva executed the EB-DEMO project during 2007-2008, whose target was to show, what the actual level of competence was in sealing technology and quality control of copper canisters in the company at the time.
The demonstration of the preparedness of sealing the canisters was planned and decided to execute by welding a series of 12 copper lids to copper cylinders. The lids were full-size and manufactured according to actual design drawings. The copper shell was modelled with a 450 mm long part of a full-size copper cylinder. Longer or heavier part of cylinder can be used but 450 mm long canister is long enough to have similar temperature field near weld area as in the case of full scale canister.
The welding process parameters were defined beforehand according to the experience gained from earlier welding experiments and the parameters were not changed or trimmed during the demonstration test series, in spite of the fact that the demonstration was executed as three separate stages.
In the lid welds of the first test series, all the welds included plenty of indications that exceeded the acceptance level. The second test series included a few indications exceeding the acceptance level and the third series was throughout acceptable. It is evident that the minor process disturbances caused by the equipment did not cause the indications leading to rejection. Instead, the surface quality and cleanness of the components to be EB-welded seem to correlate strongly with the amount of welding faults. The number of faults became the less the better the surface cleanness was.
The outcome was that the current expertise in EB-welding and quality control of the weld using the available equipment led to acceptable sealing welds and the quality could be reliably verified by the NDT-methods.
The demonstration of the preparedness of sealing the canisters was planned and decided to execute by welding a series of 12 copper lids to copper cylinders. The lids were full-size and manufactured according to actual design drawings. The copper shell was modelled with a 450 mm long part of a full-size copper cylinder. Longer or heavier part of cylinder can be used but 450 mm long canister is long enough to have similar temperature field near weld area as in the case of full scale canister.
The welding process parameters were defined beforehand according to the experience gained from earlier welding experiments and the parameters were not changed or trimmed during the demonstration test series, in spite of the fact that the demonstration was executed as three separate stages.
In the lid welds of the first test series, all the welds included plenty of indications that exceeded the acceptance level. The second test series included a few indications exceeding the acceptance level and the third series was throughout acceptable. It is evident that the minor process disturbances caused by the equipment did not cause the indications leading to rejection. Instead, the surface quality and cleanness of the components to be EB-welded seem to correlate strongly with the amount of welding faults. The number of faults became the less the better the surface cleanness was.
The outcome was that the current expertise in EB-welding and quality control of the weld using the available equipment led to acceptable sealing welds and the quality could be reliably verified by the NDT-methods.
| Original language | English |
|---|---|
| Place of Publication | Eurajoki |
| Publisher | Posiva |
| Number of pages | 106 |
| Publication status | Published - Dec 2009 |
| MoE publication type | D4 Published development or research report or study |
Publication series
| Series | Posiva Working Report |
|---|---|
| Number | 2009-126 |