RD&D-Programme 2004 - SKB

Figure 5-5. Positions for test bars in disc from a cast insert.
inserts from different foundries are included in the study. A relatively large number of test bars
are taken from different locations according to the pattern in Figures 5-4 and 5-5. All test bars,
as well as whole discs, are x-rayed to obtain values of the size and distribution of defects in the
casting. The strength properties are evaluated by conventional tensile testing, but also by compression
testing and fracture toughness testing. A fractographic analysis of the fracture surfaces
is then performed, and the microstructure is examined metallographically. The large quantity of
information will be used in a probabilistic analysis of the probability of failure, and a value will
be obtained of the critical defect size at the stresses to which the canisters will be exposed.
Strength calculations employing finite element methods are also being carried out within the
framework of the project. In addition, verifying compression tests are being done in a cold
isostatic press, see Figure 5-6. The test body, see Figure 5-7, consists of an insert about 70 cm
long but with full diameter. Both ends of the insert are covered by a screwed-on steel lid and
enclosed in a 5 cm thick copper tube with lid and bottom of copper. Aside from its length, the
test body is thus very similar to a real copper canister.
Figure 5-6. Schematic illustration of a Quintus cold isostatic press, which is used for verifying
compression tests of canister strength.
52 RD&D-Programme 2004