I am worried about this operation for the following reasons: the CMS support system consists of 3 sets of titanium tie-rods in the horizontal, vertical and radial directions. This support system has been designed taking into account the weight of the cold mass (220 t for CMS), the magnetic forces due to the misalignment of the coil inside the iron yoke in the 3 directions (10 mm in any direction for CMS) and some potential earthquake effect (equivalent to 0.15 g in the 3 directions for CMS).
We did a lot of measurements to choose the type of titanium to be used (see for example Adv. in Cryo. Eng., vol 48A, pp 76-83, AIP, vol. 614, 2001). We have seen some kind of titanium alloy with a very bad behaviour at cryogenics temperature once a crack is generated in the rod: for Ti alloy Ti 6Al 4V ELI, the notch ratio is below 1 at cryogenics temperature, which means that a crack inside the support will propagate. Fracture toughness tests have confirmed the different behaviour of this material at cryogenics temperature with Ti 5Al 2.5 Sn ELI for example (the one used in CMS, but quite difficult to get nowadays). I don't know how the push-pull operation is comparable with earthquakes in Japan in term of vibrations and if our Japanese colleagues are taking some precaution for such phenomena. My opinion is that mechanical calculations and studies must be done on this point, including the repetitive effect. In any case, as we did for CMS, it would be a good thing to test all the tie-rods to be used in real conditions, i.e. under load (more than 100 % of the nominal value) and with one end at 300 K and the other around 4 K.