RD&D-Programme 2004 - SKB

The technology and procedures for casting, rough machining, inspection and delivery of inserts
will be further developed in cooperation with the foundries.
Methodology and equipment for nondestructive testing by means of ultrasound as an inspection
method will be developed. Besides detection of discontinuities in the casting such as porosities
and slag, the possibilities of using ultrasound to inspect the nodularity of the graphite in the
nodular iron will be studied, see also section 5.5.
5.4.2 Canister tubes, lids and bottoms
SKB started development of the fabrication technology for the canisters in 1994–1995. So far
four different methods have been used to fabricate copper tubes: roll forming, extrusion, pierce
and draw processing and forging. The method that has proved to give the most reliable results in
production of copper tubes is extrusion. Lids and bottoms are machined to specified dimensions
from blanks that have been preformed by hot forging. The technology for fabricating lids and
bottoms is applied in serial production.
Conclusions in RD&D 2001 and its review
The work is focused on showing that full-scale copper tubes can be fabricated by means of
these methods and satisfying applicable requirements. Important aspects are optimizing material
yield, process parameters and inspection methods.
Important aspects of the continued work of fabricating lids and bottoms are optimizing grain
size in the forged blanks and optimizing material yield and inspection methods. In order to
optimize material yield and grain size, different types of forging dies and different process
parameters will be tried. Computer simulation and laboratory-scale trials of the fabrication
methods in question, as well as material testing, will provide knowledge that can contribute
to the desired optimization of material specifications and fabrication technology.
Figure 5-11. Extruded and machined copper tube.
58 RD&D-Programme 2004