Investigations of the SPIZWURZ bundle after the 250 day-long dry-storage simulation

Due to the worldwide lack of final repositories, investigations concerning the interim dry storage period are more and more sought after. In this context, the dry-storage phase may exceed several decades and thus further evidence for the integrity of spent nuclear fuel for much longer storage periods needs to be collected.
Modelling and experiments close to real conditions are sufficient to forecast the recent and future spent nuclear fuel behaviour and state, especially because it remains highly complicated to open real storage casks for such investigations. With the QUENCH/LICAS facility at the Karlsruhe Institute of Technology, a bundle with 21 fuel rod simulators with a length of 2.5 m was heated mutually and then cooled uniformly in order to simulate the slow cooling process that is characteristic for the dry storage phase. Three cladding tube materials with two different hydrogen contents (100 and 300 ppm) and two different inner pressures (106 and 146 bar) were used and subjected to a cooling transient of 250 days. Pre-calculations predict a different amount of precipitated radial hydrides and hydrides in circumferential direction for the different temperature zones in the bundle. ... mehrNew knowledge and refined parameters used for modelling and the validation of existing codes will be gained. This paper presents preliminary results of the post-test examinations of the SPIZWURZ bundle test in the framework of the SPIZWURZ project.