Costumer has ordered test of sensitivity to brittle fracture of Sormat Concrete Screw Anchors according ETAG 001-3 point 5.1.2.5.. The orderer has requested analysis of the fractured surfaces to be investigated fractographically and material metallographically, to determine any possible faults in the material which might have caused the fracture to occur during the corrosion tests. The shape of the fracture surfaces on failed anchors is typical for brittle fractures, induced by hydrogen embrittlement at tensile loadings.

Naloga obsega raziskave korozije bakra v talni vodi in bentonitu podzemnega odlagališča izrabljenega jedrskega goriva v bodočem odlagališču Äspö na Švedskem. V bakrenih zabojnikih s 5 cm debelo steno, ki bodo obdani z bentonitom, bo v rovih v granitnem masivu 500 m globoko pod zemljo, odloženo izrabljeno jedrsko gorivo. V nalogi sodelujemo z KTH - Royal Institute of Technology Stockholm in naročnikom SKB (Svensk Kämbränsllehantering AB - Swedish Nuclear Fuel and Waste Management Co).

Analysis of the fractured surfaces were investigated fractographically, to determine any possible faults in the material which might have caused the fracture to occur. Two thermal cracks occurred on one bolt. Thermal crack was the origin of the fatigue crack. Cracks progressed on the two sides from thermal crack. Very large amount of oxide inclusions (stringers) are present in steel. The failure occured after approximately 10 years of service.

Poročilo vsebuje rezultate laboratorijskih raziskav efektivnosti novih inhibitorjev, ki naj bi bili aplicirani na površino betona. Ugotovili smo, da je pasivacija jekla možna le, če je vsebnost inhibitorja višja od vsebnosti kloridov v betonu (ostali parametri so manj pomembni). V kolikor ta pogoj ni zagotovljen, so možne izrazite lokalne oblike korozije. Dokazali smo, da tudi že po doseženi pasivaciji ob znižanju koncentracije inhibitorja (simulacija izpiranja iz betona) lahko pride do ponovne iniciacije korozijski procesov. Pokazali smo, da delovanje organskih inhibitorjev lahko relevantno ocenimo le s kombinacijo različnih elektrokemijskih metod.

Test Parcel of copper and bentonite was exposed for six years in the Äspo HardRock Laboratory, which offers a realistic environment for the conditions that will prevail in a deep repository for high-level radioactive waste disposal in Sweden. In January 2007 electric resistance (ER) sensors of pure copper were also installed in test package from deep repository. The results from the ER measurements of corrosion rate of copper from start in January 2007 to April 2011 are presented in this report. In summary, the measurements have shown that the corrosion rate of pure copper exposed to an oxic bentonite/saline groundwater environment can be followed by ER and electrochemical techniques, and corrosion rate decreases slowly with time to very low values (